From dc50eab76b709d68175a358d6e23a5a3890764d3 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 18 May 2024 19:39:57 +0200 Subject: Merging upstream version 6.7.7. Signed-off-by: Daniel Baumann --- Documentation/arch/arm64/cpu-feature-registers.rst | 2 + Documentation/arch/arm64/elf_hwcaps.rst | 15 +- Documentation/arch/arm64/silicon-errata.rst | 7 + Documentation/arch/ia64/aliasing.rst | 246 ----- Documentation/arch/ia64/efirtc.rst | 144 --- Documentation/arch/ia64/err_inject.rst | 1067 ------------------- Documentation/arch/ia64/features.rst | 3 - Documentation/arch/ia64/fsys.rst | 303 ------ Documentation/arch/ia64/ia64.rst | 49 - Documentation/arch/ia64/index.rst | 19 - Documentation/arch/ia64/irq-redir.rst | 80 -- Documentation/arch/ia64/mca.rst | 198 ---- Documentation/arch/ia64/serial.rst | 165 --- Documentation/arch/index.rst | 5 +- Documentation/arch/loongarch/introduction.rst | 4 +- Documentation/arch/powerpc/associativity.rst | 105 ++ Documentation/arch/powerpc/booting.rst | 110 ++ Documentation/arch/powerpc/bootwrapper.rst | 131 +++ Documentation/arch/powerpc/cpu_families.rst | 237 +++++ Documentation/arch/powerpc/cpu_features.rst | 60 ++ Documentation/arch/powerpc/cxl.rst | 469 ++++++++ Documentation/arch/powerpc/cxlflash.rst | 433 ++++++++ Documentation/arch/powerpc/dawr-power9.rst | 101 ++ Documentation/arch/powerpc/dexcr.rst | 58 + Documentation/arch/powerpc/dscr.rst | 87 ++ .../arch/powerpc/eeh-pci-error-recovery.rst | 336 ++++++ Documentation/arch/powerpc/elf_hwcaps.rst | 231 ++++ Documentation/arch/powerpc/elfnote.rst | 41 + Documentation/arch/powerpc/features.rst | 3 + .../arch/powerpc/firmware-assisted-dump.rst | 381 +++++++ Documentation/arch/powerpc/hvcs.rst | 581 ++++++++++ Documentation/arch/powerpc/imc.rst | 199 ++++ Documentation/arch/powerpc/index.rst | 49 + Documentation/arch/powerpc/isa-versions.rst | 101 ++ Documentation/arch/powerpc/kasan.txt | 58 + Documentation/arch/powerpc/kaslr-booke32.rst | 42 + Documentation/arch/powerpc/kvm-nested.rst | 634 +++++++++++ Documentation/arch/powerpc/mpc52xx.rst | 43 + Documentation/arch/powerpc/papr_hcalls.rst | 302 ++++++ .../arch/powerpc/pci_iov_resource_on_powernv.rst | 312 ++++++ Documentation/arch/powerpc/pmu-ebb.rst | 138 +++ Documentation/arch/powerpc/ptrace.rst | 157 +++ Documentation/arch/powerpc/qe_firmware.rst | 296 ++++++ Documentation/arch/powerpc/syscall64-abi.rst | 153 +++ .../arch/powerpc/transactional_memory.rst | 274 +++++ Documentation/arch/powerpc/ultravisor.rst | 1117 ++++++++++++++++++++ Documentation/arch/powerpc/vas-api.rst | 305 ++++++ Documentation/arch/powerpc/vcpudispatch_stats.rst | 75 ++ Documentation/arch/powerpc/vmemmap_dedup.rst | 101 ++ Documentation/arch/riscv/acpi.rst | 10 + Documentation/arch/riscv/boot-image-header.rst | 59 ++ Documentation/arch/riscv/boot.rst | 169 +++ Documentation/arch/riscv/features.rst | 3 + Documentation/arch/riscv/hwprobe.rst | 104 ++ Documentation/arch/riscv/index.rst | 24 + Documentation/arch/riscv/patch-acceptance.rst | 59 ++ Documentation/arch/riscv/uabi.rst | 68 ++ Documentation/arch/riscv/vector.rst | 140 +++ Documentation/arch/riscv/vm-layout.rst | 157 +++ Documentation/arch/sh/index.rst | 6 - Documentation/arch/x86/amd-memory-encryption.rst | 2 +- Documentation/arch/x86/amd_hsmp.rst | 18 + Documentation/arch/x86/boot.rst | 2 +- Documentation/arch/x86/iommu.rst | 2 +- Documentation/arch/x86/resctrl.rst | 38 +- Documentation/arch/x86/topology.rst | 12 +- 66 files changed, 8596 insertions(+), 2304 deletions(-) delete mode 100644 Documentation/arch/ia64/aliasing.rst delete mode 100644 Documentation/arch/ia64/efirtc.rst delete mode 100644 Documentation/arch/ia64/err_inject.rst delete mode 100644 Documentation/arch/ia64/features.rst delete mode 100644 Documentation/arch/ia64/fsys.rst delete mode 100644 Documentation/arch/ia64/ia64.rst delete mode 100644 Documentation/arch/ia64/index.rst delete mode 100644 Documentation/arch/ia64/irq-redir.rst delete mode 100644 Documentation/arch/ia64/mca.rst delete mode 100644 Documentation/arch/ia64/serial.rst create mode 100644 Documentation/arch/powerpc/associativity.rst create mode 100644 Documentation/arch/powerpc/booting.rst create mode 100644 Documentation/arch/powerpc/bootwrapper.rst create mode 100644 Documentation/arch/powerpc/cpu_families.rst create mode 100644 Documentation/arch/powerpc/cpu_features.rst create mode 100644 Documentation/arch/powerpc/cxl.rst create mode 100644 Documentation/arch/powerpc/cxlflash.rst create mode 100644 Documentation/arch/powerpc/dawr-power9.rst create mode 100644 Documentation/arch/powerpc/dexcr.rst create mode 100644 Documentation/arch/powerpc/dscr.rst create mode 100644 Documentation/arch/powerpc/eeh-pci-error-recovery.rst create mode 100644 Documentation/arch/powerpc/elf_hwcaps.rst create mode 100644 Documentation/arch/powerpc/elfnote.rst create mode 100644 Documentation/arch/powerpc/features.rst create mode 100644 Documentation/arch/powerpc/firmware-assisted-dump.rst create mode 100644 Documentation/arch/powerpc/hvcs.rst create mode 100644 Documentation/arch/powerpc/imc.rst create mode 100644 Documentation/arch/powerpc/index.rst create mode 100644 Documentation/arch/powerpc/isa-versions.rst create mode 100644 Documentation/arch/powerpc/kasan.txt create mode 100644 Documentation/arch/powerpc/kaslr-booke32.rst create mode 100644 Documentation/arch/powerpc/kvm-nested.rst create mode 100644 Documentation/arch/powerpc/mpc52xx.rst create mode 100644 Documentation/arch/powerpc/papr_hcalls.rst create mode 100644 Documentation/arch/powerpc/pci_iov_resource_on_powernv.rst create mode 100644 Documentation/arch/powerpc/pmu-ebb.rst create mode 100644 Documentation/arch/powerpc/ptrace.rst create mode 100644 Documentation/arch/powerpc/qe_firmware.rst create mode 100644 Documentation/arch/powerpc/syscall64-abi.rst create mode 100644 Documentation/arch/powerpc/transactional_memory.rst create mode 100644 Documentation/arch/powerpc/ultravisor.rst create mode 100644 Documentation/arch/powerpc/vas-api.rst create mode 100644 Documentation/arch/powerpc/vcpudispatch_stats.rst create mode 100644 Documentation/arch/powerpc/vmemmap_dedup.rst create mode 100644 Documentation/arch/riscv/acpi.rst create mode 100644 Documentation/arch/riscv/boot-image-header.rst create mode 100644 Documentation/arch/riscv/boot.rst create mode 100644 Documentation/arch/riscv/features.rst create mode 100644 Documentation/arch/riscv/hwprobe.rst create mode 100644 Documentation/arch/riscv/index.rst create mode 100644 Documentation/arch/riscv/patch-acceptance.rst create mode 100644 Documentation/arch/riscv/uabi.rst create mode 100644 Documentation/arch/riscv/vector.rst create mode 100644 Documentation/arch/riscv/vm-layout.rst (limited to 'Documentation/arch') diff --git a/Documentation/arch/arm64/cpu-feature-registers.rst b/Documentation/arch/arm64/cpu-feature-registers.rst index de6d8a4790..44f9bd7853 100644 --- a/Documentation/arch/arm64/cpu-feature-registers.rst +++ b/Documentation/arch/arm64/cpu-feature-registers.rst @@ -268,6 +268,8 @@ infrastructure: +------------------------------+---------+---------+ | SHA3 | [35-32] | y | +------------------------------+---------+---------+ + | B16B16 | [27-24] | y | + +------------------------------+---------+---------+ | BF16 | [23-20] | y | +------------------------------+---------+---------+ | BitPerm | [19-16] | y | diff --git a/Documentation/arch/arm64/elf_hwcaps.rst b/Documentation/arch/arm64/elf_hwcaps.rst index 76ff9d7398..ced7b335e2 100644 --- a/Documentation/arch/arm64/elf_hwcaps.rst +++ b/Documentation/arch/arm64/elf_hwcaps.rst @@ -174,7 +174,7 @@ HWCAP2_DCPODP Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0010. HWCAP2_SVE2 - Functionality implied by ID_AA64ZFR0_EL1.SVEVer == 0b0001. + Functionality implied by ID_AA64ZFR0_EL1.SVEver == 0b0001. HWCAP2_SVEAES Functionality implied by ID_AA64ZFR0_EL1.AES == 0b0001. @@ -222,7 +222,7 @@ HWCAP2_RNG Functionality implied by ID_AA64ISAR0_EL1.RNDR == 0b0001. HWCAP2_BTI - Functionality implied by ID_AA64PFR0_EL1.BT == 0b0001. + Functionality implied by ID_AA64PFR1_EL1.BT == 0b0001. HWCAP2_MTE Functionality implied by ID_AA64PFR1_EL1.MTE == 0b0010, as described @@ -232,7 +232,7 @@ HWCAP2_ECV Functionality implied by ID_AA64MMFR0_EL1.ECV == 0b0001. HWCAP2_AFP - Functionality implied by ID_AA64MFR1_EL1.AFP == 0b0001. + Functionality implied by ID_AA64MMFR1_EL1.AFP == 0b0001. HWCAP2_RPRES Functionality implied by ID_AA64ISAR2_EL1.RPRES == 0b0001. @@ -308,6 +308,15 @@ HWCAP2_MOPS HWCAP2_HBC Functionality implied by ID_AA64ISAR2_EL1.BC == 0b0001. +HWCAP2_SVE_B16B16 + Functionality implied by ID_AA64ZFR0_EL1.B16B16 == 0b0001. + +HWCAP2_LRCPC3 + Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0011. + +HWCAP2_LSE128 + Functionality implied by ID_AA64ISAR0_EL1.Atomic == 0b0011. + 4. Unused AT_HWCAP bits ----------------------- diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst index 7acd64c61f..29fd5213ee 100644 --- a/Documentation/arch/arm64/silicon-errata.rst +++ b/Documentation/arch/arm64/silicon-errata.rst @@ -235,3 +235,10 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ASR | ASR8601 | #8601001 | N/A | +----------------+-----------------+-----------------+-----------------------------+ ++----------------+-----------------+-----------------+-----------------------------+ +| Microsoft | Azure Cobalt 100| #2139208 | ARM64_ERRATUM_2139208 | ++----------------+-----------------+-----------------+-----------------------------+ +| Microsoft | Azure Cobalt 100| #2067961 | ARM64_ERRATUM_2067961 | ++----------------+-----------------+-----------------+-----------------------------+ +| Microsoft | Azure Cobalt 100| #2253138 | ARM64_ERRATUM_2253138 | ++----------------+-----------------+-----------------+-----------------------------+ diff --git a/Documentation/arch/ia64/aliasing.rst b/Documentation/arch/ia64/aliasing.rst deleted file mode 100644 index 36a1e1d484..0000000000 --- a/Documentation/arch/ia64/aliasing.rst +++ /dev/null @@ -1,246 +0,0 @@ -================================== -Memory Attribute Aliasing on IA-64 -================================== - -Bjorn Helgaas - -May 4, 2006 - - -Memory Attributes -================= - - Itanium supports several attributes for virtual memory references. - The attribute is part of the virtual translation, i.e., it is - contained in the TLB entry. The ones of most interest to the Linux - kernel are: - - == ====================== - WB Write-back (cacheable) - UC Uncacheable - WC Write-coalescing - == ====================== - - System memory typically uses the WB attribute. The UC attribute is - used for memory-mapped I/O devices. The WC attribute is uncacheable - like UC is, but writes may be delayed and combined to increase - performance for things like frame buffers. - - The Itanium architecture requires that we avoid accessing the same - page with both a cacheable mapping and an uncacheable mapping[1]. - - The design of the chipset determines which attributes are supported - on which regions of the address space. For example, some chipsets - support either WB or UC access to main memory, while others support - only WB access. - -Memory Map -========== - - Platform firmware describes the physical memory map and the - supported attributes for each region. At boot-time, the kernel uses - the EFI GetMemoryMap() interface. ACPI can also describe memory - devices and the attributes they support, but Linux/ia64 currently - doesn't use this information. - - The kernel uses the efi_memmap table returned from GetMemoryMap() to - learn the attributes supported by each region of physical address - space. Unfortunately, this table does not completely describe the - address space because some machines omit some or all of the MMIO - regions from the map. - - The kernel maintains another table, kern_memmap, which describes the - memory Linux is actually using and the attribute for each region. - This contains only system memory; it does not contain MMIO space. - - The kern_memmap table typically contains only a subset of the system - memory described by the efi_memmap. Linux/ia64 can't use all memory - in the system because of constraints imposed by the identity mapping - scheme. - - The efi_memmap table is preserved unmodified because the original - boot-time information is required for kexec. - -Kernel Identity Mappings -======================== - - Linux/ia64 identity mappings are done with large pages, currently - either 16MB or 64MB, referred to as "granules." Cacheable mappings - are speculative[2], so the processor can read any location in the - page at any time, independent of the programmer's intentions. This - means that to avoid attribute aliasing, Linux can create a cacheable - identity mapping only when the entire granule supports cacheable - access. - - Therefore, kern_memmap contains only full granule-sized regions that - can referenced safely by an identity mapping. - - Uncacheable mappings are not speculative, so the processor will - generate UC accesses only to locations explicitly referenced by - software. This allows UC identity mappings to cover granules that - are only partially populated, or populated with a combination of UC - and WB regions. - -User Mappings -============= - - User mappings are typically done with 16K or 64K pages. The smaller - page size allows more flexibility because only 16K or 64K has to be - homogeneous with respect to memory attributes. - -Potential Attribute Aliasing Cases -================================== - - There are several ways the kernel creates new mappings: - -mmap of /dev/mem ----------------- - - This uses remap_pfn_range(), which creates user mappings. These - mappings may be either WB or UC. If the region being mapped - happens to be in kern_memmap, meaning that it may also be mapped - by a kernel identity mapping, the user mapping must use the same - attribute as the kernel mapping. - - If the region is not in kern_memmap, the user mapping should use - an attribute reported as being supported in the EFI memory map. - - Since the EFI memory map does not describe MMIO on some - machines, this should use an uncacheable mapping as a fallback. - -mmap of /sys/class/pci_bus/.../legacy_mem ------------------------------------------ - - This is very similar to mmap of /dev/mem, except that legacy_mem - only allows mmap of the one megabyte "legacy MMIO" area for a - specific PCI bus. Typically this is the first megabyte of - physical address space, but it may be different on machines with - several VGA devices. - - "X" uses this to access VGA frame buffers. Using legacy_mem - rather than /dev/mem allows multiple instances of X to talk to - different VGA cards. - - The /dev/mem mmap constraints apply. - -mmap of /proc/bus/pci/.../??.? ------------------------------- - - This is an MMIO mmap of PCI functions, which additionally may or - may not be requested as using the WC attribute. - - If WC is requested, and the region in kern_memmap is either WC - or UC, and the EFI memory map designates the region as WC, then - the WC mapping is allowed. - - Otherwise, the user mapping must use the same attribute as the - kernel mapping. - -read/write of /dev/mem ----------------------- - - This uses copy_from_user(), which implicitly uses a kernel - identity mapping. This is obviously safe for things in - kern_memmap. - - There may be corner cases of things that are not in kern_memmap, - but could be accessed this way. For example, registers in MMIO - space are not in kern_memmap, but could be accessed with a UC - mapping. This would not cause attribute aliasing. But - registers typically can be accessed only with four-byte or - eight-byte accesses, and the copy_from_user() path doesn't allow - any control over the access size, so this would be dangerous. - -ioremap() ---------- - - This returns a mapping for use inside the kernel. - - If the region is in kern_memmap, we should use the attribute - specified there. - - If the EFI memory map reports that the entire granule supports - WB, we should use that (granules that are partially reserved - or occupied by firmware do not appear in kern_memmap). - - If the granule contains non-WB memory, but we can cover the - region safely with kernel page table mappings, we can use - ioremap_page_range() as most other architectures do. - - Failing all of the above, we have to fall back to a UC mapping. - -Past Problem Cases -================== - -mmap of various MMIO regions from /dev/mem by "X" on Intel platforms --------------------------------------------------------------------- - - The EFI memory map may not report these MMIO regions. - - These must be allowed so that X will work. This means that - when the EFI memory map is incomplete, every /dev/mem mmap must - succeed. It may create either WB or UC user mappings, depending - on whether the region is in kern_memmap or the EFI memory map. - -mmap of 0x0-0x9FFFF /dev/mem by "hwinfo" on HP sx1000 with VGA enabled ----------------------------------------------------------------------- - - The EFI memory map reports the following attributes: - - =============== ======= ================== - 0x00000-0x9FFFF WB only - 0xA0000-0xBFFFF UC only (VGA frame buffer) - 0xC0000-0xFFFFF WB only - =============== ======= ================== - - This mmap is done with user pages, not kernel identity mappings, - so it is safe to use WB mappings. - - The kernel VGA driver may ioremap the VGA frame buffer at 0xA0000, - which uses a granule-sized UC mapping. This granule will cover some - WB-only memory, but since UC is non-speculative, the processor will - never generate an uncacheable reference to the WB-only areas unless - the driver explicitly touches them. - -mmap of 0x0-0xFFFFF legacy_mem by "X" -------------------------------------- - - If the EFI memory map reports that the entire range supports the - same attributes, we can allow the mmap (and we will prefer WB if - supported, as is the case with HP sx[12]000 machines with VGA - disabled). - - If EFI reports the range as partly WB and partly UC (as on sx[12]000 - machines with VGA enabled), we must fail the mmap because there's no - safe attribute to use. - - If EFI reports some of the range but not all (as on Intel firmware - that doesn't report the VGA frame buffer at all), we should fail the - mmap and force the user to map just the specific region of interest. - -mmap of 0xA0000-0xBFFFF legacy_mem by "X" on HP sx1000 with VGA disabled ------------------------------------------------------------------------- - - The EFI memory map reports the following attributes:: - - 0x00000-0xFFFFF WB only (no VGA MMIO hole) - - This is a special case of the previous case, and the mmap should - fail for the same reason as above. - -read of /sys/devices/.../rom ----------------------------- - - For VGA devices, this may cause an ioremap() of 0xC0000. This - used to be done with a UC mapping, because the VGA frame buffer - at 0xA0000 prevents use of a WB granule. The UC mapping causes - an MCA on HP sx[12]000 chipsets. - - We should use WB page table mappings to avoid covering the VGA - frame buffer. - -Notes -===== - - [1] SDM rev 2.2, vol 2, sec 4.4.1. - [2] SDM rev 2.2, vol 2, sec 4.4.6. diff --git a/Documentation/arch/ia64/efirtc.rst b/Documentation/arch/ia64/efirtc.rst deleted file mode 100644 index fd83284083..0000000000 --- a/Documentation/arch/ia64/efirtc.rst +++ /dev/null @@ -1,144 +0,0 @@ -========================== -EFI Real Time Clock driver -========================== - -S. Eranian - -March 2000 - -1. Introduction -=============== - -This document describes the efirtc.c driver has provided for -the IA-64 platform. - -The purpose of this driver is to supply an API for kernel and user applications -to get access to the Time Service offered by EFI version 0.92. - -EFI provides 4 calls one can make once the OS is booted: GetTime(), -SetTime(), GetWakeupTime(), SetWakeupTime() which are all supported by this -driver. We describe those calls as well the design of the driver in the -following sections. - -2. Design Decisions -=================== - -The original ideas was to provide a very simple driver to get access to, -at first, the time of day service. This is required in order to access, in a -portable way, the CMOS clock. A program like /sbin/hwclock uses such a clock -to initialize the system view of the time during boot. - -Because we wanted to minimize the impact on existing user-level apps using -the CMOS clock, we decided to expose an API that was very similar to the one -used today with the legacy RTC driver (driver/char/rtc.c). However, because -EFI provides a simpler services, not all ioctl() are available. Also -new ioctl()s have been introduced for things that EFI provides but not the -legacy. - -EFI uses a slightly different way of representing the time, noticeably -the reference date is different. Year is the using the full 4-digit format. -The Epoch is January 1st 1998. For backward compatibility reasons we don't -expose this new way of representing time. Instead we use something very -similar to the struct tm, i.e. struct rtc_time, as used by hwclock. -One of the reasons for doing it this way is to allow for EFI to still evolve -without necessarily impacting any of the user applications. The decoupling -enables flexibility and permits writing wrapper code is ncase things change. - -The driver exposes two interfaces, one via the device file and a set of -ioctl()s. The other is read-only via the /proc filesystem. - -As of today we don't offer a /proc/sys interface. - -To allow for a uniform interface between the legacy RTC and EFI time service, -we have created the include/linux/rtc.h header file to contain only the -"public" API of the two drivers. The specifics of the legacy RTC are still -in include/linux/mc146818rtc.h. - - -3. Time of day service -====================== - -The part of the driver gives access to the time of day service of EFI. -Two ioctl()s, compatible with the legacy RTC calls: - - Read the CMOS clock:: - - ioctl(d, RTC_RD_TIME, &rtc); - - Write the CMOS clock:: - - ioctl(d, RTC_SET_TIME, &rtc); - -The rtc is a pointer to a data structure defined in rtc.h which is close -to a struct tm:: - - struct rtc_time { - int tm_sec; - int tm_min; - int tm_hour; - int tm_mday; - int tm_mon; - int tm_year; - int tm_wday; - int tm_yday; - int tm_isdst; - }; - -The driver takes care of converting back an forth between the EFI time and -this format. - -Those two ioctl()s can be exercised with the hwclock command: - -For reading:: - - # /sbin/hwclock --show - Mon Mar 6 15:32:32 2000 -0.910248 seconds - -For setting:: - - # /sbin/hwclock --systohc - -Root privileges are required to be able to set the time of day. - -4. Wakeup Alarm service -======================= - -EFI provides an API by which one can program when a machine should wakeup, -i.e. reboot. This is very different from the alarm provided by the legacy -RTC which is some kind of interval timer alarm. For this reason we don't use -the same ioctl()s to get access to the service. Instead we have -introduced 2 news ioctl()s to the interface of an RTC. - -We have added 2 new ioctl()s that are specific to the EFI driver: - - Read the current state of the alarm:: - - ioctl(d, RTC_WKALM_RD, &wkt) - - Set the alarm or change its status:: - - ioctl(d, RTC_WKALM_SET, &wkt) - -The wkt structure encapsulates a struct rtc_time + 2 extra fields to get -status information:: - - struct rtc_wkalrm { - - unsigned char enabled; /* =1 if alarm is enabled */ - unsigned char pending; /* =1 if alarm is pending */ - - struct rtc_time time; - } - -As of today, none of the existing user-level apps supports this feature. -However writing such a program should be hard by simply using those two -ioctl(). - -Root privileges are required to be able to set the alarm. - -5. References -============= - -Checkout the following Web site for more information on EFI: - -http://developer.intel.com/technology/efi/ diff --git a/Documentation/arch/ia64/err_inject.rst b/Documentation/arch/ia64/err_inject.rst deleted file mode 100644 index 900f71e93a..0000000000 --- a/Documentation/arch/ia64/err_inject.rst +++ /dev/null @@ -1,1067 +0,0 @@ -======================================== -IPF Machine Check (MC) error inject tool -======================================== - -IPF Machine Check (MC) error inject tool is used to inject MC -errors from Linux. The tool is a test bed for IPF MC work flow including -hardware correctable error handling, OS recoverable error handling, MC -event logging, etc. - -The tool includes two parts: a kernel driver and a user application -sample. The driver provides interface to PAL to inject error -and query error injection capabilities. The driver code is in -arch/ia64/kernel/err_inject.c. The application sample (shown below) -provides a combination of various errors and calls the driver's interface -(sysfs interface) to inject errors or query error injection capabilities. - -The tool can be used to test Intel IPF machine MC handling capabilities. -It's especially useful for people who can not access hardware MC injection -tool to inject error. It's also very useful to integrate with other -software test suits to do stressful testing on IPF. - -Below is a sample application as part of the whole tool. The sample -can be used as a working test tool. Or it can be expanded to include -more features. It also can be a integrated into a library or other user -application to have more thorough test. - -The sample application takes err.conf as error configuration input. GCC -compiles the code. After you install err_inject driver, you can run -this sample application to inject errors. - -Errata: Itanium 2 Processors Specification Update lists some errata against -the pal_mc_error_inject PAL procedure. The following err.conf has been tested -on latest Montecito PAL. - -err.conf:: - - #This is configuration file for err_inject_tool. - #The format of the each line is: - #cpu, loop, interval, err_type_info, err_struct_info, err_data_buffer - #where - # cpu: logical cpu number the error will be inject in. - # loop: times the error will be injected. - # interval: In second. every so often one error is injected. - # err_type_info, err_struct_info: PAL parameters. - # - #Note: All values are hex w/o or w/ 0x prefix. - - - #On cpu2, inject only total 0x10 errors, interval 5 seconds - #corrected, data cache, hier-2, physical addr(assigned by tool code). - #working on Montecito latest PAL. - 2, 10, 5, 4101, 95 - - #On cpu4, inject and consume total 0x10 errors, interval 5 seconds - #corrected, data cache, hier-2, physical addr(assigned by tool code). - #working on Montecito latest PAL. - 4, 10, 5, 4109, 95 - - #On cpu15, inject and consume total 0x10 errors, interval 5 seconds - #recoverable, DTR0, hier-2. - #working on Montecito latest PAL. - 0xf, 0x10, 5, 4249, 15 - -The sample application source code: - -err_injection_tool.c:: - - /* - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, but - * WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or - * NON INFRINGEMENT. See the GNU General Public License for more - * details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - * - * Copyright (C) 2006 Intel Co - * Fenghua Yu - * - */ - #include - #include - #include - #include - #include - #include - #include - #include - #include - #include - #include - #include - #include - #include - #include - #include - - #define MAX_FN_SIZE 256 - #define MAX_BUF_SIZE 256 - #define DATA_BUF_SIZE 256 - #define NR_CPUS 512 - #define MAX_TASK_NUM 2048 - #define MIN_INTERVAL 5 // seconds - #define ERR_DATA_BUFFER_SIZE 3 // Three 8-byte. - #define PARA_FIELD_NUM 5 - #define MASK_SIZE (NR_CPUS/64) - #define PATH_FORMAT "/sys/devices/system/cpu/cpu%d/err_inject/" - - int sched_setaffinity(pid_t pid, unsigned int len, unsigned long *mask); - - int verbose; - #define vbprintf if (verbose) printf - - int log_info(int cpu, const char *fmt, ...) - { - FILE *log; - char fn[MAX_FN_SIZE]; - char buf[MAX_BUF_SIZE]; - va_list args; - - sprintf(fn, "%d.log", cpu); - log=fopen(fn, "a+"); - if (log==NULL) { - perror("Error open:"); - return -1; - } - - va_start(args, fmt); - vprintf(fmt, args); - memset(buf, 0, MAX_BUF_SIZE); - vsprintf(buf, fmt, args); - va_end(args); - - fwrite(buf, sizeof(buf), 1, log); - fclose(log); - - return 0; - } - - typedef unsigned long u64; - typedef unsigned int u32; - - typedef union err_type_info_u { - struct { - u64 mode : 3, /* 0-2 */ - err_inj : 3, /* 3-5 */ - err_sev : 2, /* 6-7 */ - err_struct : 5, /* 8-12 */ - struct_hier : 3, /* 13-15 */ - reserved : 48; /* 16-63 */ - } err_type_info_u; - u64 err_type_info; - } err_type_info_t; - - typedef union err_struct_info_u { - struct { - u64 siv : 1, /* 0 */ - c_t : 2, /* 1-2 */ - cl_p : 3, /* 3-5 */ - cl_id : 3, /* 6-8 */ - cl_dp : 1, /* 9 */ - reserved1 : 22, /* 10-31 */ - tiv : 1, /* 32 */ - trigger : 4, /* 33-36 */ - trigger_pl : 3, /* 37-39 */ - reserved2 : 24; /* 40-63 */ - } err_struct_info_cache; - struct { - u64 siv : 1, /* 0 */ - tt : 2, /* 1-2 */ - tc_tr : 2, /* 3-4 */ - tr_slot : 8, /* 5-12 */ - reserved1 : 19, /* 13-31 */ - tiv : 1, /* 32 */ - trigger : 4, /* 33-36 */ - trigger_pl : 3, /* 37-39 */ - reserved2 : 24; /* 40-63 */ - } err_struct_info_tlb; - struct { - u64 siv : 1, /* 0 */ - regfile_id : 4, /* 1-4 */ - reg_num : 7, /* 5-11 */ - reserved1 : 20, /* 12-31 */ - tiv : 1, /* 32 */ - trigger : 4, /* 33-36 */ - trigger_pl : 3, /* 37-39 */ - reserved2 : 24; /* 40-63 */ - } err_struct_info_register; - struct { - u64 reserved; - } err_struct_info_bus_processor_interconnect; - u64 err_struct_info; - } err_struct_info_t; - - typedef union err_data_buffer_u { - struct { - u64 trigger_addr; /* 0-63 */ - u64 inj_addr; /* 64-127 */ - u64 way : 5, /* 128-132 */ - index : 20, /* 133-152 */ - : 39; /* 153-191 */ - } err_data_buffer_cache; - struct { - u64 trigger_addr; /* 0-63 */ - u64 inj_addr; /* 64-127 */ - u64 way : 5, /* 128-132 */ - index : 20, /* 133-152 */ - reserved : 39; /* 153-191 */ - } err_data_buffer_tlb; - struct { - u64 trigger_addr; /* 0-63 */ - } err_data_buffer_register; - struct { - u64 reserved; /* 0-63 */ - } err_data_buffer_bus_processor_interconnect; - u64 err_data_buffer[ERR_DATA_BUFFER_SIZE]; - } err_data_buffer_t; - - typedef union capabilities_u { - struct { - u64 i : 1, - d : 1, - rv : 1, - tag : 1, - data : 1, - mesi : 1, - dp : 1, - reserved1 : 3, - pa : 1, - va : 1, - wi : 1, - reserved2 : 20, - trigger : 1, - trigger_pl : 1, - reserved3 : 30; - } capabilities_cache; - struct { - u64 d : 1, - i : 1, - rv : 1, - tc : 1, - tr : 1, - reserved1 : 27, - trigger : 1, - trigger_pl : 1, - reserved2 : 30; - } capabilities_tlb; - struct { - u64 gr_b0 : 1, - gr_b1 : 1, - fr : 1, - br : 1, - pr : 1, - ar : 1, - cr : 1, - rr : 1, - pkr : 1, - dbr : 1, - ibr : 1, - pmc : 1, - pmd : 1, - reserved1 : 3, - regnum : 1, - reserved2 : 15, - trigger : 1, - trigger_pl : 1, - reserved3 : 30; - } capabilities_register; - struct { - u64 reserved; - } capabilities_bus_processor_interconnect; - } capabilities_t; - - typedef struct resources_s { - u64 ibr0 : 1, - ibr2 : 1, - ibr4 : 1, - ibr6 : 1, - dbr0 : 1, - dbr2 : 1, - dbr4 : 1, - dbr6 : 1, - reserved : 48; - } resources_t; - - - long get_page_size(void) - { - long page_size=sysconf(_SC_PAGESIZE); - return page_size; - } - - #define PAGE_SIZE (get_page_size()==-1?0x4000:get_page_size()) - #define SHM_SIZE (2*PAGE_SIZE*NR_CPUS) - #define SHM_VA 0x2000000100000000 - - int shmid; - void *shmaddr; - - int create_shm(void) - { - key_t key; - char fn[MAX_FN_SIZE]; - - /* cpu0 is always existing */ - sprintf(fn, PATH_FORMAT, 0); - if ((key = ftok(fn, 's')) == -1) { - perror("ftok"); - return -1; - } - - shmid = shmget(key, SHM_SIZE, 0644 | IPC_CREAT); - if (shmid == -1) { - if (errno==EEXIST) { - shmid = shmget(key, SHM_SIZE, 0); - if (shmid == -1) { - perror("shmget"); - return -1; - } - } - else { - perror("shmget"); - return -1; - } - } - vbprintf("shmid=%d", shmid); - - /* connect to the segment: */ - shmaddr = shmat(shmid, (void *)SHM_VA, 0); - if (shmaddr == (void*)-1) { - perror("shmat"); - return -1; - } - - memset(shmaddr, 0, SHM_SIZE); - mlock(shmaddr, SHM_SIZE); - - return 0; - } - - int free_shm() - { - munlock(shmaddr, SHM_SIZE); - shmdt(shmaddr); - semctl(shmid, 0, IPC_RMID); - - return 0; - } - - #ifdef _SEM_SEMUN_UNDEFINED - union semun - { - int val; - struct semid_ds *buf; - unsigned short int *array; - struct seminfo *__buf; - }; - #endif - - u32 mode=1; /* 1: physical mode; 2: virtual mode. */ - int one_lock=1; - key_t key[NR_CPUS]; - int semid[NR_CPUS]; - - int create_sem(int cpu) - { - union semun arg; - char fn[MAX_FN_SIZE]; - int sid; - - sprintf(fn, PATH_FORMAT, cpu); - sprintf(fn, "%s/%s", fn, "err_type_info"); - if ((key[cpu] = ftok(fn, 'e')) == -1) { - perror("ftok"); - return -1; - } - - if (semid[cpu]!=0) - return 0; - - /* clear old semaphore */ - if ((sid = semget(key[cpu], 1, 0)) != -1) - semctl(sid, 0, IPC_RMID); - - /* get one semaphore */ - if ((semid[cpu] = semget(key[cpu], 1, IPC_CREAT | IPC_EXCL)) == -1) { - perror("semget"); - printf("Please remove semaphore with key=0x%lx, then run the tool.\n", - (u64)key[cpu]); - return -1; - } - - vbprintf("semid[%d]=0x%lx, key[%d]=%lx\n",cpu,(u64)semid[cpu],cpu, - (u64)key[cpu]); - /* initialize the semaphore to 1: */ - arg.val = 1; - if (semctl(semid[cpu], 0, SETVAL, arg) == -1) { - perror("semctl"); - return -1; - } - - return 0; - } - - static int lock(int cpu) - { - struct sembuf lock; - - lock.sem_num = cpu; - lock.sem_op = 1; - semop(semid[cpu], &lock, 1); - - return 0; - } - - static int unlock(int cpu) - { - struct sembuf unlock; - - unlock.sem_num = cpu; - unlock.sem_op = -1; - semop(semid[cpu], &unlock, 1); - - return 0; - } - - void free_sem(int cpu) - { - semctl(semid[cpu], 0, IPC_RMID); - } - - int wr_multi(char *fn, unsigned long *data, int size) - { - int fd; - char buf[MAX_BUF_SIZE]; - int ret; - - if (size==1) - sprintf(buf, "%lx", *data); - else if (size==3) - sprintf(buf, "%lx,%lx,%lx", data[0], data[1], data[2]); - else { - fprintf(stderr,"write to file with wrong size!\n"); - return -1; - } - - fd=open(fn, O_RDWR); - if (!fd) { - perror("Error:"); - return -1; - } - ret=write(fd, buf, sizeof(buf)); - close(fd); - return ret; - } - - int wr(char *fn, unsigned long data) - { - return wr_multi(fn, &data, 1); - } - - int rd(char *fn, unsigned long *data) - { - int fd; - char buf[MAX_BUF_SIZE]; - - fd=open(fn, O_RDONLY); - if (fd<0) { - perror("Error:"); - return -1; - } - read(fd, buf, MAX_BUF_SIZE); - *data=strtoul(buf, NULL, 16); - close(fd); - return 0; - } - - int rd_status(char *path, int *status) - { - char fn[MAX_FN_SIZE]; - sprintf(fn, "%s/status", path); - if (rd(fn, (u64*)status)<0) { - perror("status reading error.\n"); - return -1; - } - - return 0; - } - - int rd_capabilities(char *path, u64 *capabilities) - { - char fn[MAX_FN_SIZE]; - sprintf(fn, "%s/capabilities", path); - if (rd(fn, capabilities)<0) { - perror("capabilities reading error.\n"); - return -1; - } - - return 0; - } - - int rd_all(char *path) - { - unsigned long err_type_info, err_struct_info, err_data_buffer; - int status; - unsigned long capabilities, resources; - char fn[MAX_FN_SIZE]; - - sprintf(fn, "%s/err_type_info", path); - if (rd(fn, &err_type_info)<0) { - perror("err_type_info reading error.\n"); - return -1; - } - printf("err_type_info=%lx\n", err_type_info); - - sprintf(fn, "%s/err_struct_info", path); - if (rd(fn, &err_struct_info)<0) { - perror("err_struct_info reading error.\n"); - return -1; - } - printf("err_struct_info=%lx\n", err_struct_info); - - sprintf(fn, "%s/err_data_buffer", path); - if (rd(fn, &err_data_buffer)<0) { - perror("err_data_buffer reading error.\n"); - return -1; - } - printf("err_data_buffer=%lx\n", err_data_buffer); - - sprintf(fn, "%s/status", path); - if (rd("status", (u64*)&status)<0) { - perror("status reading error.\n"); - return -1; - } - printf("status=%d\n", status); - - sprintf(fn, "%s/capabilities", path); - if (rd(fn,&capabilities)<0) { - perror("capabilities reading error.\n"); - return -1; - } - printf("capabilities=%lx\n", capabilities); - - sprintf(fn, "%s/resources", path); - if (rd(fn, &resources)<0) { - perror("resources reading error.\n"); - return -1; - } - printf("resources=%lx\n", resources); - - return 0; - } - - int query_capabilities(char *path, err_type_info_t err_type_info, - u64 *capabilities) - { - char fn[MAX_FN_SIZE]; - err_struct_info_t err_struct_info; - err_data_buffer_t err_data_buffer; - - err_struct_info.err_struct_info=0; - memset(err_data_buffer.err_data_buffer, -1, ERR_DATA_BUFFER_SIZE*8); - - sprintf(fn, "%s/err_type_info", path); - wr(fn, err_type_info.err_type_info); - sprintf(fn, "%s/err_struct_info", path); - wr(fn, 0x0); - sprintf(fn, "%s/err_data_buffer", path); - wr_multi(fn, err_data_buffer.err_data_buffer, ERR_DATA_BUFFER_SIZE); - - // Fire pal_mc_error_inject procedure. - sprintf(fn, "%s/call_start", path); - wr(fn, mode); - - if (rd_capabilities(path, capabilities)<0) - return -1; - - return 0; - } - - int query_all_capabilities() - { - int status; - err_type_info_t err_type_info; - int err_sev, err_struct, struct_hier; - int cap=0; - u64 capabilities; - char path[MAX_FN_SIZE]; - - err_type_info.err_type_info=0; // Initial - err_type_info.err_type_info_u.mode=0; // Query mode; - err_type_info.err_type_info_u.err_inj=0; - - printf("All capabilities implemented in pal_mc_error_inject:\n"); - sprintf(path, PATH_FORMAT ,0); - for (err_sev=0;err_sev<3;err_sev++) - for (err_struct=0;err_struct<5;err_struct++) - for (struct_hier=0;struct_hier<5;struct_hier++) - { - status=-1; - capabilities=0; - err_type_info.err_type_info_u.err_sev=err_sev; - err_type_info.err_type_info_u.err_struct=err_struct; - err_type_info.err_type_info_u.struct_hier=struct_hier; - - if (query_capabilities(path, err_type_info, &capabilities)<0) - continue; - - if (rd_status(path, &status)<0) - continue; - - if (status==0) { - cap=1; - printf("For err_sev=%d, err_struct=%d, struct_hier=%d: ", - err_sev, err_struct, struct_hier); - printf("capabilities 0x%lx\n", capabilities); - } - } - if (!cap) { - printf("No capabilities supported.\n"); - return 0; - } - - return 0; - } - - int err_inject(int cpu, char *path, err_type_info_t err_type_info, - err_struct_info_t err_struct_info, - err_data_buffer_t err_data_buffer) - { - int status; - char fn[MAX_FN_SIZE]; - - log_info(cpu, "err_type_info=%lx, err_struct_info=%lx, ", - err_type_info.err_type_info, - err_struct_info.err_struct_info); - log_info(cpu,"err_data_buffer=[%lx,%lx,%lx]\n", - err_data_buffer.err_data_buffer[0], - err_data_buffer.err_data_buffer[1], - err_data_buffer.err_data_buffer[2]); - sprintf(fn, "%s/err_type_info", path); - wr(fn, err_type_info.err_type_info); - sprintf(fn, "%s/err_struct_info", path); - wr(fn, err_struct_info.err_struct_info); - sprintf(fn, "%s/err_data_buffer", path); - wr_multi(fn, err_data_buffer.err_data_buffer, ERR_DATA_BUFFER_SIZE); - - // Fire pal_mc_error_inject procedure. - sprintf(fn, "%s/call_start", path); - wr(fn,mode); - - if (rd_status(path, &status)<0) { - vbprintf("fail: read status\n"); - return -100; - } - - if (status!=0) { - log_info(cpu, "fail: status=%d\n", status); - return status; - } - - return status; - } - - static int construct_data_buf(char *path, err_type_info_t err_type_info, - err_struct_info_t err_struct_info, - err_data_buffer_t *err_data_buffer, - void *va1) - { - char fn[MAX_FN_SIZE]; - u64 virt_addr=0, phys_addr=0; - - vbprintf("va1=%lx\n", (u64)va1); - memset(&err_data_buffer->err_data_buffer_cache, 0, ERR_DATA_BUFFER_SIZE*8); - - switch (err_type_info.err_type_info_u.err_struct) { - case 1: // Cache - switch (err_struct_info.err_struct_info_cache.cl_id) { - case 1: //Virtual addr - err_data_buffer->err_data_buffer_cache.inj_addr=(u64)va1; - break; - case 2: //Phys addr - sprintf(fn, "%s/virtual_to_phys", path); - virt_addr=(u64)va1; - if (wr(fn,virt_addr)<0) - return -1; - rd(fn, &phys_addr); - err_data_buffer->err_data_buffer_cache.inj_addr=phys_addr; - break; - default: - printf("Not supported cl_id\n"); - break; - } - break; - case 2: // TLB - break; - case 3: // Register file - break; - case 4: // Bus/system interconnect - default: - printf("Not supported err_struct\n"); - break; - } - - return 0; - } - - typedef struct { - u64 cpu; - u64 loop; - u64 interval; - u64 err_type_info; - u64 err_struct_info; - u64 err_data_buffer[ERR_DATA_BUFFER_SIZE]; - } parameters_t; - - parameters_t line_para; - int para; - - static int empty_data_buffer(u64 *err_data_buffer) - { - int empty=1; - int i; - - for (i=0;iMIN_INTERVAL - ?interval:MIN_INTERVAL; - parameters[num].err_type_info=err_type_info_conf; - parameters[num].err_struct_info=err_struct_info_conf; - memcpy(parameters[num++].err_data_buffer, - err_data_buffer_conf,ERR_DATA_BUFFER_SIZE*8) ; - - if (num>=MAX_TASK_NUM) - break; - } - } - else { - parameters[0].cpu=line_para.cpu; - parameters[0].loop=line_para.loop; - parameters[0].interval= line_para.interval>MIN_INTERVAL - ?line_para.interval:MIN_INTERVAL; - parameters[0].err_type_info=line_para.err_type_info; - parameters[0].err_struct_info=line_para.err_struct_info; - memcpy(parameters[0].err_data_buffer, - line_para.err_data_buffer,ERR_DATA_BUFFER_SIZE*8) ; - - num=1; - } - - /* Create semaphore: If one_lock, one semaphore for all processors. - Otherwise, one semaphore for each processor. */ - if (one_lock) { - if (create_sem(0)) { - printf("Can not create semaphore...exit\n"); - free_sem(0); - return -1; - } - } - else { - for (i=0;i - -Using the "epc" instruction effectively introduces a new mode of -execution to the ia64 linux kernel. We call this mode the -"fsys-mode". To recap, the normal states of execution are: - - - kernel mode: - Both the register stack and the memory stack have been - switched over to kernel memory. The user-level state is saved - in a pt-regs structure at the top of the kernel memory stack. - - - user mode: - Both the register stack and the kernel stack are in - user memory. The user-level state is contained in the - CPU registers. - - - bank 0 interruption-handling mode: - This is the non-interruptible state which all - interruption-handlers start execution in. The user-level - state remains in the CPU registers and some kernel state may - be stored in bank 0 of registers r16-r31. - -In contrast, fsys-mode has the following special properties: - - - execution is at privilege level 0 (most-privileged) - - - CPU registers may contain a mixture of user-level and kernel-level - state (it is the responsibility of the kernel to ensure that no - security-sensitive kernel-level state is leaked back to - user-level) - - - execution is interruptible and preemptible (an fsys-mode handler - can disable interrupts and avoid all other interruption-sources - to avoid preemption) - - - neither the memory-stack nor the register-stack can be trusted while - in fsys-mode (they point to the user-level stacks, which may - be invalid, or completely bogus addresses) - -In summary, fsys-mode is much more similar to running in user-mode -than it is to running in kernel-mode. Of course, given that the -privilege level is at level 0, this means that fsys-mode requires some -care (see below). - - -How to tell fsys-mode -===================== - -Linux operates in fsys-mode when (a) the privilege level is 0 (most -privileged) and (b) the stacks have NOT been switched to kernel memory -yet. For convenience, the header file provides -three macros:: - - user_mode(regs) - user_stack(task,regs) - fsys_mode(task,regs) - -The "regs" argument is a pointer to a pt_regs structure. The "task" -argument is a pointer to the task structure to which the "regs" -pointer belongs to. user_mode() returns TRUE if the CPU state pointed -to by "regs" was executing in user mode (privilege level 3). -user_stack() returns TRUE if the state pointed to by "regs" was -executing on the user-level stack(s). Finally, fsys_mode() returns -TRUE if the CPU state pointed to by "regs" was executing in fsys-mode. -The fsys_mode() macro is equivalent to the expression:: - - !user_mode(regs) && user_stack(task,regs) - -How to write an fsyscall handler -================================ - -The file arch/ia64/kernel/fsys.S contains a table of fsyscall-handlers -(fsyscall_table). This table contains one entry for each system call. -By default, a system call is handled by fsys_fallback_syscall(). This -routine takes care of entering (full) kernel mode and calling the -normal Linux system call handler. For performance-critical system -calls, it is possible to write a hand-tuned fsyscall_handler. For -example, fsys.S contains fsys_getpid(), which is a hand-tuned version -of the getpid() system call. - -The entry and exit-state of an fsyscall handler is as follows: - -Machine state on entry to fsyscall handler ------------------------------------------- - - ========= =============================================================== - r10 0 - r11 saved ar.pfs (a user-level value) - r15 system call number - r16 "current" task pointer (in normal kernel-mode, this is in r13) - r32-r39 system call arguments - b6 return address (a user-level value) - ar.pfs previous frame-state (a user-level value) - PSR.be cleared to zero (i.e., little-endian byte order is in effect) - - all other registers may contain values passed in from user-mode - ========= =============================================================== - -Required machine state on exit to fsyscall handler --------------------------------------------------- - - ========= =========================================================== - r11 saved ar.pfs (as passed into the fsyscall handler) - r15 system call number (as passed into the fsyscall handler) - r32-r39 system call arguments (as passed into the fsyscall handler) - b6 return address (as passed into the fsyscall handler) - ar.pfs previous frame-state (as passed into the fsyscall handler) - ========= =========================================================== - -Fsyscall handlers can execute with very little overhead, but with that -speed comes a set of restrictions: - - * Fsyscall-handlers MUST check for any pending work in the flags - member of the thread-info structure and if any of the - TIF_ALLWORK_MASK flags are set, the handler needs to fall back on - doing a full system call (by calling fsys_fallback_syscall). - - * Fsyscall-handlers MUST preserve incoming arguments (r32-r39, r11, - r15, b6, and ar.pfs) because they will be needed in case of a - system call restart. Of course, all "preserved" registers also - must be preserved, in accordance to the normal calling conventions. - - * Fsyscall-handlers MUST check argument registers for containing a - NaT value before using them in any way that could trigger a - NaT-consumption fault. If a system call argument is found to - contain a NaT value, an fsyscall-handler may return immediately - with r8=EINVAL, r10=-1. - - * Fsyscall-handlers MUST NOT use the "alloc" instruction or perform - any other operation that would trigger mandatory RSE - (register-stack engine) traffic. - - * Fsyscall-handlers MUST NOT write to any stacked registers because - it is not safe to assume that user-level called a handler with the - proper number of arguments. - - * Fsyscall-handlers need to be careful when accessing per-CPU variables: - unless proper safe-guards are taken (e.g., interruptions are avoided), - execution may be pre-empted and resumed on another CPU at any given - time. - - * Fsyscall-handlers must be careful not to leak sensitive kernel' - information back to user-level. In particular, before returning to - user-level, care needs to be taken to clear any scratch registers - that could contain sensitive information (note that the current - task pointer is not considered sensitive: it's already exposed - through ar.k6). - - * Fsyscall-handlers MUST NOT access user-memory without first - validating access-permission (this can be done typically via - probe.r.fault and/or probe.w.fault) and without guarding against - memory access exceptions (this can be done with the EX() macros - defined by asmmacro.h). - -The above restrictions may seem draconian, but remember that it's -possible to trade off some of the restrictions by paying a slightly -higher overhead. For example, if an fsyscall-handler could benefit -from the shadow register bank, it could temporarily disable PSR.i and -PSR.ic, switch to bank 0 (bsw.0) and then use the shadow registers as -needed. In other words, following the above rules yields extremely -fast system call execution (while fully preserving system call -semantics), but there is also a lot of flexibility in handling more -complicated cases. - -Signal handling -=============== - -The delivery of (asynchronous) signals must be delayed until fsys-mode -is exited. This is accomplished with the help of the lower-privilege -transfer trap: arch/ia64/kernel/process.c:do_notify_resume_user() -checks whether the interrupted task was in fsys-mode and, if so, sets -PSR.lp and returns immediately. When fsys-mode is exited via the -"br.ret" instruction that lowers the privilege level, a trap will -occur. The trap handler clears PSR.lp again and returns immediately. -The kernel exit path then checks for and delivers any pending signals. - -PSR Handling -============ - -The "epc" instruction doesn't change the contents of PSR at all. This -is in contrast to a regular interruption, which clears almost all -bits. Because of that, some care needs to be taken to ensure things -work as expected. The following discussion describes how each PSR bit -is handled. - -======= ======================================================================= -PSR.be Cleared when entering fsys-mode. A srlz.d instruction is used - to ensure the CPU is in little-endian mode before the first - load/store instruction is executed. PSR.be is normally NOT - restored upon return from an fsys-mode handler. In other - words, user-level code must not rely on PSR.be being preserved - across a system call. -PSR.up Unchanged. -PSR.ac Unchanged. -PSR.mfl Unchanged. Note: fsys-mode handlers must not write-registers! -PSR.mfh Unchanged. Note: fsys-mode handlers must not write-registers! -PSR.ic Unchanged. Note: fsys-mode handlers can clear the bit, if needed. -PSR.i Unchanged. Note: fsys-mode handlers can clear the bit, if needed. -PSR.pk Unchanged. -PSR.dt Unchanged. -PSR.dfl Unchanged. Note: fsys-mode handlers must not write-registers! -PSR.dfh Unchanged. Note: fsys-mode handlers must not write-registers! -PSR.sp Unchanged. -PSR.pp Unchanged. -PSR.di Unchanged. -PSR.si Unchanged. -PSR.db Unchanged. The kernel prevents user-level from setting a hardware - breakpoint that triggers at any privilege level other than - 3 (user-mode). -PSR.lp Unchanged. -PSR.tb Lazy redirect. If a taken-branch trap occurs while in - fsys-mode, the trap-handler modifies the saved machine state - such that execution resumes in the gate page at - syscall_via_break(), with privilege level 3. Note: the - taken branch would occur on the branch invoking the - fsyscall-handler, at which point, by definition, a syscall - restart is still safe. If the system call number is invalid, - the fsys-mode handler will return directly to user-level. This - return will trigger a taken-branch trap, but since the trap is - taken _after_ restoring the privilege level, the CPU has already - left fsys-mode, so no special treatment is needed. -PSR.rt Unchanged. -PSR.cpl Cleared to 0. -PSR.is Unchanged (guaranteed to be 0 on entry to the gate page). -PSR.mc Unchanged. -PSR.it Unchanged (guaranteed to be 1). -PSR.id Unchanged. Note: the ia64 linux kernel never sets this bit. -PSR.da Unchanged. Note: the ia64 linux kernel never sets this bit. -PSR.dd Unchanged. Note: the ia64 linux kernel never sets this bit. -PSR.ss Lazy redirect. If set, "epc" will cause a Single Step Trap to - be taken. The trap handler then modifies the saved machine - state such that execution resumes in the gate page at - syscall_via_break(), with privilege level 3. -PSR.ri Unchanged. -PSR.ed Unchanged. Note: This bit could only have an effect if an fsys-mode - handler performed a speculative load that gets NaTted. If so, this - would be the normal & expected behavior, so no special treatment is - needed. -PSR.bn Unchanged. Note: fsys-mode handlers may clear the bit, if needed. - Doing so requires clearing PSR.i and PSR.ic as well. -PSR.ia Unchanged. Note: the ia64 linux kernel never sets this bit. -======= ======================================================================= - -Using fast system calls -======================= - -To use fast system calls, userspace applications need simply call -__kernel_syscall_via_epc(). For example - --- example fgettimeofday() call -- - --- fgettimeofday.S -- - -:: - - #include - - GLOBAL_ENTRY(fgettimeofday) - .prologue - .save ar.pfs, r11 - mov r11 = ar.pfs - .body - - mov r2 = 0xa000000000020660;; // gate address - // found by inspection of System.map for the - // __kernel_syscall_via_epc() function. See - // below for how to do this for real. - - mov b7 = r2 - mov r15 = 1087 // gettimeofday syscall - ;; - br.call.sptk.many b6 = b7 - ;; - - .restore sp - - mov ar.pfs = r11 - br.ret.sptk.many rp;; // return to caller - END(fgettimeofday) - --- end fgettimeofday.S -- - -In reality, getting the gate address is accomplished by two extra -values passed via the ELF auxiliary vector (include/asm-ia64/elf.h) - - * AT_SYSINFO : is the address of __kernel_syscall_via_epc() - * AT_SYSINFO_EHDR : is the address of the kernel gate ELF DSO - -The ELF DSO is a pre-linked library that is mapped in by the kernel at -the gate page. It is a proper ELF shared object so, with a dynamic -loader that recognises the library, you should be able to make calls to -the exported functions within it as with any other shared library. -AT_SYSINFO points into the kernel DSO at the -__kernel_syscall_via_epc() function for historical reasons (it was -used before the kernel DSO) and as a convenience. diff --git a/Documentation/arch/ia64/ia64.rst b/Documentation/arch/ia64/ia64.rst deleted file mode 100644 index b725019a94..0000000000 --- a/Documentation/arch/ia64/ia64.rst +++ /dev/null @@ -1,49 +0,0 @@ -=========================================== -Linux kernel release for the IA-64 Platform -=========================================== - - These are the release notes for Linux since version 2.4 for IA-64 - platform. This document provides information specific to IA-64 - ONLY, to get additional information about the Linux kernel also - read the original Linux README provided with the kernel. - -Installing the Kernel -===================== - - - IA-64 kernel installation is the same as the other platforms, see - original README for details. - - -Software Requirements -===================== - - Compiling and running this kernel requires an IA-64 compliant GCC - compiler. And various software packages also compiled with an - IA-64 compliant GCC compiler. - - -Configuring the Kernel -====================== - - Configuration is the same, see original README for details. - - -Compiling the Kernel: - - - Compiling this kernel doesn't differ from other platform so read - the original README for details BUT make sure you have an IA-64 - compliant GCC compiler. - -IA-64 Specifics -=============== - - - General issues: - - * Hardly any performance tuning has been done. Obvious targets - include the library routines (IP checksum, etc.). Less - obvious targets include making sure we don't flush the TLB - needlessly, etc. - - * SMP locks cleanup/optimization - - * IA32 support. Currently experimental. It mostly works. diff --git a/Documentation/arch/ia64/index.rst b/Documentation/arch/ia64/index.rst deleted file mode 100644 index 761f2154df..0000000000 --- a/Documentation/arch/ia64/index.rst +++ /dev/null @@ -1,19 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0 - -================== -IA-64 Architecture -================== - -.. toctree:: - :maxdepth: 1 - - ia64 - aliasing - efirtc - err_inject - fsys - irq-redir - mca - serial - - features diff --git a/Documentation/arch/ia64/irq-redir.rst b/Documentation/arch/ia64/irq-redir.rst deleted file mode 100644 index 6bbbbe4f73..0000000000 --- a/Documentation/arch/ia64/irq-redir.rst +++ /dev/null @@ -1,80 +0,0 @@ -============================== -IRQ affinity on IA64 platforms -============================== - -07.01.2002, Erich Focht - - -By writing to /proc/irq/IRQ#/smp_affinity the interrupt routing can be -controlled. The behavior on IA64 platforms is slightly different from -that described in Documentation/core-api/irq/irq-affinity.rst for i386 systems. - -Because of the usage of SAPIC mode and physical destination mode the -IRQ target is one particular CPU and cannot be a mask of several -CPUs. Only the first non-zero bit is taken into account. - - -Usage examples -============== - -The target CPU has to be specified as a hexadecimal CPU mask. The -first non-zero bit is the selected CPU. This format has been kept for -compatibility reasons with i386. - -Set the delivery mode of interrupt 41 to fixed and route the -interrupts to CPU #3 (logical CPU number) (2^3=0x08):: - - echo "8" >/proc/irq/41/smp_affinity - -Set the default route for IRQ number 41 to CPU 6 in lowest priority -delivery mode (redirectable):: - - echo "r 40" >/proc/irq/41/smp_affinity - -The output of the command:: - - cat /proc/irq/IRQ#/smp_affinity - -gives the target CPU mask for the specified interrupt vector. If the CPU -mask is preceded by the character "r", the interrupt is redirectable -(i.e. lowest priority mode routing is used), otherwise its route is -fixed. - - - -Initialization and default behavior -=================================== - -If the platform features IRQ redirection (info provided by SAL) all -IO-SAPIC interrupts are initialized with CPU#0 as their default target -and the routing is the so called "lowest priority mode" (actually -fixed SAPIC mode with hint). The XTP chipset registers are used as hints -for the IRQ routing. Currently in Linux XTP registers can have three -values: - - - minimal for an idle task, - - normal if any other task runs, - - maximal if the CPU is going to be switched off. - -The IRQ is routed to the CPU with lowest XTP register value, the -search begins at the default CPU. Therefore most of the interrupts -will be handled by CPU #0. - -If the platform doesn't feature interrupt redirection IOSAPIC fixed -routing is used. The target CPUs are distributed in a round robin -manner. IRQs will be routed only to the selected target CPUs. Check -with:: - - cat /proc/interrupts - - - -Comments -======== - -On large (multi-node) systems it is recommended to route the IRQs to -the node to which the corresponding device is connected. -For systems like the NEC AzusA we get IRQ node-affinity for free. This -is because usually the chipsets on each node redirect the interrupts -only to their own CPUs (as they cannot see the XTP registers on the -other nodes). diff --git a/Documentation/arch/ia64/mca.rst b/Documentation/arch/ia64/mca.rst deleted file mode 100644 index 08270bba44..0000000000 --- a/Documentation/arch/ia64/mca.rst +++ /dev/null @@ -1,198 +0,0 @@ -============================================================= -An ad-hoc collection of notes on IA64 MCA and INIT processing -============================================================= - -Feel free to update it with notes about any area that is not clear. - ---- - -MCA/INIT are completely asynchronous. They can occur at any time, when -the OS is in any state. Including when one of the cpus is already -holding a spinlock. Trying to get any lock from MCA/INIT state is -asking for deadlock. Also the state of structures that are protected -by locks is indeterminate, including linked lists. - ---- - -The complicated ia64 MCA process. All of this is mandated by Intel's -specification for ia64 SAL, error recovery and unwind, it is not as -if we have a choice here. - -* MCA occurs on one cpu, usually due to a double bit memory error. - This is the monarch cpu. - -* SAL sends an MCA rendezvous interrupt (which is a normal interrupt) - to all the other cpus, the slaves. - -* Slave cpus that receive the MCA interrupt call down into SAL, they - end up spinning disabled while the MCA is being serviced. - -* If any slave cpu was already spinning disabled when the MCA occurred - then it cannot service the MCA interrupt. SAL waits ~20 seconds then - sends an unmaskable INIT event to the slave cpus that have not - already rendezvoused. - -* Because MCA/INIT can be delivered at any time, including when the cpu - is down in PAL in physical mode, the registers at the time of the - event are _completely_ undefined. In particular the MCA/INIT - handlers cannot rely on the thread pointer, PAL physical mode can - (and does) modify TP. It is allowed to do that as long as it resets - TP on return. However MCA/INIT events expose us to these PAL - internal TP changes. Hence curr_task(). - -* If an MCA/INIT event occurs while the kernel was running (not user - space) and the kernel has called PAL then the MCA/INIT handler cannot - assume that the kernel stack is in a fit state to be used. Mainly - because PAL may or may not maintain the stack pointer internally. - Because the MCA/INIT handlers cannot trust the kernel stack, they - have to use their own, per-cpu stacks. The MCA/INIT stacks are - preformatted with just enough task state to let the relevant handlers - do their job. - -* Unlike most other architectures, the ia64 struct task is embedded in - the kernel stack[1]. So switching to a new kernel stack means that - we switch to a new task as well. Because various bits of the kernel - assume that current points into the struct task, switching to a new - stack also means a new value for current. - -* Once all slaves have rendezvoused and are spinning disabled, the - monarch is entered. The monarch now tries to diagnose the problem - and decide if it can recover or not. - -* Part of the monarch's job is to look at the state of all the other - tasks. The only way to do that on ia64 is to call the unwinder, - as mandated by Intel. - -* The starting point for the unwind depends on whether a task is - running or not. That is, whether it is on a cpu or is blocked. The - monarch has to determine whether or not a task is on a cpu before it - knows how to start unwinding it. The tasks that received an MCA or - INIT event are no longer running, they have been converted to blocked - tasks. But (and its a big but), the cpus that received the MCA - rendezvous interrupt are still running on their normal kernel stacks! - -* To distinguish between these two cases, the monarch must know which - tasks are on a cpu and which are not. Hence each slave cpu that - switches to an MCA/INIT stack, registers its new stack using - set_curr_task(), so the monarch can tell that the _original_ task is - no longer running on that cpu. That gives us a decent chance of - getting a valid backtrace of the _original_ task. - -* MCA/INIT can be nested, to a depth of 2 on any cpu. In the case of a - nested error, we want diagnostics on the MCA/INIT handler that - failed, not on the task that was originally running. Again this - requires set_curr_task() so the MCA/INIT handlers can register their - own stack as running on that cpu. Then a recursive error gets a - trace of the failing handler's "task". - -[1] - My (Keith Owens) original design called for ia64 to separate its - struct task and the kernel stacks. Then the MCA/INIT data would be - chained stacks like i386 interrupt stacks. But that required - radical surgery on the rest of ia64, plus extra hard wired TLB - entries with its associated performance degradation. David - Mosberger vetoed that approach. Which meant that separate kernel - stacks meant separate "tasks" for the MCA/INIT handlers. - ---- - -INIT is less complicated than MCA. Pressing the nmi button or using -the equivalent command on the management console sends INIT to all -cpus. SAL picks one of the cpus as the monarch and the rest are -slaves. All the OS INIT handlers are entered at approximately the same -time. The OS monarch prints the state of all tasks and returns, after -which the slaves return and the system resumes. - -At least that is what is supposed to happen. Alas there are broken -versions of SAL out there. Some drive all the cpus as monarchs. Some -drive them all as slaves. Some drive one cpu as monarch, wait for that -cpu to return from the OS then drive the rest as slaves. Some versions -of SAL cannot even cope with returning from the OS, they spin inside -SAL on resume. The OS INIT code has workarounds for some of these -broken SAL symptoms, but some simply cannot be fixed from the OS side. - ---- - -The scheduler hooks used by ia64 (curr_task, set_curr_task) are layer -violations. Unfortunately MCA/INIT start off as massive layer -violations (can occur at _any_ time) and they build from there. - -At least ia64 makes an attempt at recovering from hardware errors, but -it is a difficult problem because of the asynchronous nature of these -errors. When processing an unmaskable interrupt we sometimes need -special code to cope with our inability to take any locks. - ---- - -How is ia64 MCA/INIT different from x86 NMI? - -* x86 NMI typically gets delivered to one cpu. MCA/INIT gets sent to - all cpus. - -* x86 NMI cannot be nested. MCA/INIT can be nested, to a depth of 2 - per cpu. - -* x86 has a separate struct task which points to one of multiple kernel - stacks. ia64 has the struct task embedded in the single kernel - stack, so switching stack means switching task. - -* x86 does not call the BIOS so the NMI handler does not have to worry - about any registers having changed. MCA/INIT can occur while the cpu - is in PAL in physical mode, with undefined registers and an undefined - kernel stack. - -* i386 backtrace is not very sensitive to whether a process is running - or not. ia64 unwind is very, very sensitive to whether a process is - running or not. - ---- - -What happens when MCA/INIT is delivered what a cpu is running user -space code? - -The user mode registers are stored in the RSE area of the MCA/INIT on -entry to the OS and are restored from there on return to SAL, so user -mode registers are preserved across a recoverable MCA/INIT. Since the -OS has no idea what unwind data is available for the user space stack, -MCA/INIT never tries to backtrace user space. Which means that the OS -does not bother making the user space process look like a blocked task, -i.e. the OS does not copy pt_regs and switch_stack to the user space -stack. Also the OS has no idea how big the user space RSE and memory -stacks are, which makes it too risky to copy the saved state to a user -mode stack. - ---- - -How do we get a backtrace on the tasks that were running when MCA/INIT -was delivered? - -mca.c:::ia64_mca_modify_original_stack(). That identifies and -verifies the original kernel stack, copies the dirty registers from -the MCA/INIT stack's RSE to the original stack's RSE, copies the -skeleton struct pt_regs and switch_stack to the original stack, fills -in the skeleton structures from the PAL minstate area and updates the -original stack's thread.ksp. That makes the original stack look -exactly like any other blocked task, i.e. it now appears to be -sleeping. To get a backtrace, just start with thread.ksp for the -original task and unwind like any other sleeping task. - ---- - -How do we identify the tasks that were running when MCA/INIT was -delivered? - -If the previous task has been verified and converted to a blocked -state, then sos->prev_task on the MCA/INIT stack is updated to point to -the previous task. You can look at that field in dumps or debuggers. -To help distinguish between the handler and the original tasks, -handlers have _TIF_MCA_INIT set in thread_info.flags. - -The sos data is always in the MCA/INIT handler stack, at offset -MCA_SOS_OFFSET. You can get that value from mca_asm.h or calculate it -as KERNEL_STACK_SIZE - sizeof(struct pt_regs) - sizeof(struct -ia64_sal_os_state), with 16 byte alignment for all structures. - -Also the comm field of the MCA/INIT task is modified to include the pid -of the original task, for humans to use. For example, a comm field of -'MCA 12159' means that pid 12159 was running when the MCA was -delivered. diff --git a/Documentation/arch/ia64/serial.rst b/Documentation/arch/ia64/serial.rst deleted file mode 100644 index 1de70c305a..0000000000 --- a/Documentation/arch/ia64/serial.rst +++ /dev/null @@ -1,165 +0,0 @@ -============== -Serial Devices -============== - -Serial Device Naming -==================== - - As of 2.6.10, serial devices on ia64 are named based on the - order of ACPI and PCI enumeration. The first device in the - ACPI namespace (if any) becomes /dev/ttyS0, the second becomes - /dev/ttyS1, etc., and PCI devices are named sequentially - starting after the ACPI devices. - - Prior to 2.6.10, there were confusing exceptions to this: - - - Firmware on some machines (mostly from HP) provides an HCDP - table[1] that tells the kernel about devices that can be used - as a serial console. If the user specified "console=ttyS0" - or the EFI ConOut path contained only UART devices, the - kernel registered the device described by the HCDP as - /dev/ttyS0. - - - If there was no HCDP, we assumed there were UARTs at the - legacy COM port addresses (I/O ports 0x3f8 and 0x2f8), so - the kernel registered those as /dev/ttyS0 and /dev/ttyS1. - - Any additional ACPI or PCI devices were registered sequentially - after /dev/ttyS0 as they were discovered. - - With an HCDP, device names changed depending on EFI configuration - and "console=" arguments. Without an HCDP, device names didn't - change, but we registered devices that might not really exist. - - For example, an HP rx1600 with a single built-in serial port - (described in the ACPI namespace) plus an MP[2] (a PCI device) has - these ports: - - ========== ========== ============ ============ ======= - Type MMIO pre-2.6.10 pre-2.6.10 2.6.10+ - address - (EFI console (EFI console - on builtin) on MP port) - ========== ========== ============ ============ ======= - builtin 0xff5e0000 ttyS0 ttyS1 ttyS0 - MP UPS 0xf8031000 ttyS1 ttyS2 ttyS1 - MP Console 0xf8030000 ttyS2 ttyS0 ttyS2 - MP 2 0xf8030010 ttyS3 ttyS3 ttyS3 - MP 3 0xf8030038 ttyS4 ttyS4 ttyS4 - ========== ========== ============ ============ ======= - -Console Selection -================= - - EFI knows what your console devices are, but it doesn't tell the - kernel quite enough to actually locate them. The DIG64 HCDP - table[1] does tell the kernel where potential serial console - devices are, but not all firmware supplies it. Also, EFI supports - multiple simultaneous consoles and doesn't tell the kernel which - should be the "primary" one. - - So how do you tell Linux which console device to use? - - - If your firmware supplies the HCDP, it is simplest to - configure EFI with a single device (either a UART or a VGA - card) as the console. Then you don't need to tell Linux - anything; the kernel will automatically use the EFI console. - - (This works only in 2.6.6 or later; prior to that you had - to specify "console=ttyS0" to get a serial console.) - - - Without an HCDP, Linux defaults to a VGA console unless you - specify a "console=" argument. - - NOTE: Don't assume that a serial console device will be /dev/ttyS0. - It might be ttyS1, ttyS2, etc. Make sure you have the appropriate - entries in /etc/inittab (for getty) and /etc/securetty (to allow - root login). - -Early Serial Console -==================== - - The kernel can't start using a serial console until it knows where - the device lives. Normally this happens when the driver enumerates - all the serial devices, which can happen a minute or more after the - kernel starts booting. - - 2.6.10 and later kernels have an "early uart" driver that works - very early in the boot process. The kernel will automatically use - this if the user supplies an argument like "console=uart,io,0x3f8", - or if the EFI console path contains only a UART device and the - firmware supplies an HCDP. - -Troubleshooting Serial Console Problems -======================================= - - No kernel output after elilo prints "Uncompressing Linux... done": - - - You specified "console=ttyS0" but Linux changed the device - to which ttyS0 refers. Configure exactly one EFI console - device[3] and remove the "console=" option. - - - The EFI console path contains both a VGA device and a UART. - EFI and elilo use both, but Linux defaults to VGA. Remove - the VGA device from the EFI console path[3]. - - - Multiple UARTs selected as EFI console devices. EFI and - elilo use all selected devices, but Linux uses only one. - Make sure only one UART is selected in the EFI console - path[3]. - - - You're connected to an HP MP port[2] but have a non-MP UART - selected as EFI console device. EFI uses the MP as a - console device even when it isn't explicitly selected. - Either move the console cable to the non-MP UART, or change - the EFI console path[3] to the MP UART. - - Long pause (60+ seconds) between "Uncompressing Linux... done" and - start of kernel output: - - - No early console because you used "console=ttyS". Remove - the "console=" option if your firmware supplies an HCDP. - - - If you don't have an HCDP, the kernel doesn't know where - your console lives until the driver discovers serial - devices. Use "console=uart,io,0x3f8" (or appropriate - address for your machine). - - Kernel and init script output works fine, but no "login:" prompt: - - - Add getty entry to /etc/inittab for console tty. Look for - the "Adding console on ttyS" message that tells you which - device is the console. - - "login:" prompt, but can't login as root: - - - Add entry to /etc/securetty for console tty. - - No ACPI serial devices found in 2.6.17 or later: - - - Turn on CONFIG_PNP and CONFIG_PNPACPI. Prior to 2.6.17, ACPI - serial devices were discovered by 8250_acpi. In 2.6.17, - 8250_acpi was replaced by the combination of 8250_pnp and - CONFIG_PNPACPI. - - - -[1] - http://www.dig64.org/specifications/agreement - The table was originally defined as the "HCDP" for "Headless - Console/Debug Port." The current version is the "PCDP" for - "Primary Console and Debug Port Devices." - -[2] - The HP MP (management processor) is a PCI device that provides - several UARTs. One of the UARTs is often used as a console; the - EFI Boot Manager identifies it as "Acpi(HWP0002,700)/Pci(...)/Uart". - The external connection is usually a 25-pin connector, and a - special dongle converts that to three 9-pin connectors, one of - which is labelled "Console." - -[3] - EFI console devices are configured using the EFI Boot Manager - "Boot option maintenance" menu. You may have to interrupt the - boot sequence to use this menu, and you will have to reset the - box after changing console configuration. diff --git a/Documentation/arch/index.rst b/Documentation/arch/index.rst index 84b80255b8..3f9962e45c 100644 --- a/Documentation/arch/index.rst +++ b/Documentation/arch/index.rst @@ -12,15 +12,14 @@ implementation. arc/index arm/index arm64/index - ia64/index loongarch/index m68k/index mips/index nios2/index openrisc/index parisc/index - ../powerpc/index - ../riscv/index + powerpc/index + riscv/index s390/index sh/index sparc/index diff --git a/Documentation/arch/loongarch/introduction.rst b/Documentation/arch/loongarch/introduction.rst index 8c568cfc21..5e6db78abe 100644 --- a/Documentation/arch/loongarch/introduction.rst +++ b/Documentation/arch/loongarch/introduction.rst @@ -375,9 +375,9 @@ Developer web site of Loongson and LoongArch (Software and Documentation): Documentation of LoongArch ISA: - https://github.com/loongson/LoongArch-Documentation/releases/latest/download/LoongArch-Vol1-v1.02-CN.pdf (in Chinese) + https://github.com/loongson/LoongArch-Documentation/releases/latest/download/LoongArch-Vol1-v1.10-CN.pdf (in Chinese) - https://github.com/loongson/LoongArch-Documentation/releases/latest/download/LoongArch-Vol1-v1.02-EN.pdf (in English) + https://github.com/loongson/LoongArch-Documentation/releases/latest/download/LoongArch-Vol1-v1.10-EN.pdf (in English) Documentation of LoongArch ELF psABI: diff --git a/Documentation/arch/powerpc/associativity.rst b/Documentation/arch/powerpc/associativity.rst new file mode 100644 index 0000000000..4d01c73685 --- /dev/null +++ b/Documentation/arch/powerpc/associativity.rst @@ -0,0 +1,105 @@ +============================ +NUMA resource associativity +============================ + +Associativity represents the groupings of the various platform resources into +domains of substantially similar mean performance relative to resources outside +of that domain. Resources subsets of a given domain that exhibit better +performance relative to each other than relative to other resources subsets +are represented as being members of a sub-grouping domain. This performance +characteristic is presented in terms of NUMA node distance within the Linux kernel. +From the platform view, these groups are also referred to as domains. + +PAPR interface currently supports different ways of communicating these resource +grouping details to the OS. These are referred to as Form 0, Form 1 and Form2 +associativity grouping. Form 0 is the oldest format and is now considered deprecated. + +Hypervisor indicates the type/form of associativity used via "ibm,architecture-vec-5 property". +Bit 0 of byte 5 in the "ibm,architecture-vec-5" property indicates usage of Form 0 or Form 1. +A value of 1 indicates the usage of Form 1 associativity. For Form 2 associativity +bit 2 of byte 5 in the "ibm,architecture-vec-5" property is used. + +Form 0 +------ +Form 0 associativity supports only two NUMA distances (LOCAL and REMOTE). + +Form 1 +------ +With Form 1 a combination of ibm,associativity-reference-points, and ibm,associativity +device tree properties are used to determine the NUMA distance between resource groups/domains. + +The “ibm,associativity” property contains a list of one or more numbers (domainID) +representing the resource’s platform grouping domains. + +The “ibm,associativity-reference-points” property contains a list of one or more numbers +(domainID index) that represents the 1 based ordinal in the associativity lists. +The list of domainID indexes represents an increasing hierarchy of resource grouping. + +ex: +{ primary domainID index, secondary domainID index, tertiary domainID index.. } + +Linux kernel uses the domainID at the primary domainID index as the NUMA node id. +Linux kernel computes NUMA distance between two domains by recursively comparing +if they belong to the same higher-level domains. For mismatch at every higher +level of the resource group, the kernel doubles the NUMA distance between the +comparing domains. + +Form 2 +------- +Form 2 associativity format adds separate device tree properties representing NUMA node distance +thereby making the node distance computation flexible. Form 2 also allows flexible primary +domain numbering. With numa distance computation now detached from the index value in +"ibm,associativity-reference-points" property, Form 2 allows a large number of primary domain +ids at the same domainID index representing resource groups of different performance/latency +characteristics. + +Hypervisor indicates the usage of FORM2 associativity using bit 2 of byte 5 in the +"ibm,architecture-vec-5" property. + +"ibm,numa-lookup-index-table" property contains a list of one or more numbers representing +the domainIDs present in the system. The offset of the domainID in this property is +used as an index while computing numa distance information via "ibm,numa-distance-table". + +prop-encoded-array: The number N of the domainIDs encoded as with encode-int, followed by +N domainID encoded as with encode-int + +For ex: +"ibm,numa-lookup-index-table" = {4, 0, 8, 250, 252}. The offset of domainID 8 (2) is used when +computing the distance of domain 8 from other domains present in the system. For the rest of +this document, this offset will be referred to as domain distance offset. + +"ibm,numa-distance-table" property contains a list of one or more numbers representing the NUMA +distance between resource groups/domains present in the system. + +prop-encoded-array: The number N of the distance values encoded as with encode-int, followed by +N distance values encoded as with encode-bytes. The max distance value we could encode is 255. +The number N must be equal to the square of m where m is the number of domainIDs in the +numa-lookup-index-table. + +For ex: +ibm,numa-lookup-index-table = <3 0 8 40>; +ibm,numa-distace-table = <9>, /bits/ 8 < 10 20 80 20 10 160 80 160 10>; + +:: + + | 0 8 40 + --|------------ + | + 0 | 10 20 80 + | + 8 | 20 10 160 + | + 40| 80 160 10 + +A possible "ibm,associativity" property for resources in node 0, 8 and 40 + +{ 3, 6, 7, 0 } +{ 3, 6, 9, 8 } +{ 3, 6, 7, 40} + +With "ibm,associativity-reference-points" { 0x3 } + +"ibm,lookup-index-table" helps in having a compact representation of distance matrix. +Since domainID can be sparse, the matrix of distances can also be effectively sparse. +With "ibm,lookup-index-table" we can achieve a compact representation of +distance information. diff --git a/Documentation/arch/powerpc/booting.rst b/Documentation/arch/powerpc/booting.rst new file mode 100644 index 0000000000..11aa440f98 --- /dev/null +++ b/Documentation/arch/powerpc/booting.rst @@ -0,0 +1,110 @@ +.. SPDX-License-Identifier: GPL-2.0 + +DeviceTree Booting +------------------ + +During the development of the Linux/ppc64 kernel, and more specifically, the +addition of new platform types outside of the old IBM pSeries/iSeries pair, it +was decided to enforce some strict rules regarding the kernel entry and +bootloader <-> kernel interfaces, in order to avoid the degeneration that had +become the ppc32 kernel entry point and the way a new platform should be added +to the kernel. The legacy iSeries platform breaks those rules as it predates +this scheme, but no new board support will be accepted in the main tree that +doesn't follow them properly. In addition, since the advent of the arch/powerpc +merged architecture for ppc32 and ppc64, new 32-bit platforms and 32-bit +platforms which move into arch/powerpc will be required to use these rules as +well. + +The main requirement that will be defined in more detail below is the presence +of a device-tree whose format is defined after Open Firmware specification. +However, in order to make life easier to embedded board vendors, the kernel +doesn't require the device-tree to represent every device in the system and only +requires some nodes and properties to be present. For example, the kernel does +not require you to create a node for every PCI device in the system. It is a +requirement to have a node for PCI host bridges in order to provide interrupt +routing information and memory/IO ranges, among others. It is also recommended +to define nodes for on chip devices and other buses that don't specifically fit +in an existing OF specification. This creates a great flexibility in the way the +kernel can then probe those and match drivers to device, without having to hard +code all sorts of tables. It also makes it more flexible for board vendors to do +minor hardware upgrades without significantly impacting the kernel code or +cluttering it with special cases. + + +Entry point +~~~~~~~~~~~ + +There is one single entry point to the kernel, at the start +of the kernel image. That entry point supports two calling +conventions: + + a) Boot from Open Firmware. If your firmware is compatible + with Open Firmware (IEEE 1275) or provides an OF compatible + client interface API (support for "interpret" callback of + forth words isn't required), you can enter the kernel with: + + r5 : OF callback pointer as defined by IEEE 1275 + bindings to powerpc. Only the 32-bit client interface + is currently supported + + r3, r4 : address & length of an initrd if any or 0 + + The MMU is either on or off; the kernel will run the + trampoline located in arch/powerpc/kernel/prom_init.c to + extract the device-tree and other information from open + firmware and build a flattened device-tree as described + in b). prom_init() will then re-enter the kernel using + the second method. This trampoline code runs in the + context of the firmware, which is supposed to handle all + exceptions during that time. + + b) Direct entry with a flattened device-tree block. This entry + point is called by a) after the OF trampoline and can also be + called directly by a bootloader that does not support the Open + Firmware client interface. It is also used by "kexec" to + implement "hot" booting of a new kernel from a previous + running one. This method is what I will describe in more + details in this document, as method a) is simply standard Open + Firmware, and thus should be implemented according to the + various standard documents defining it and its binding to the + PowerPC platform. The entry point definition then becomes: + + r3 : physical pointer to the device-tree block + (defined in chapter II) in RAM + + r4 : physical pointer to the kernel itself. This is + used by the assembly code to properly disable the MMU + in case you are entering the kernel with MMU enabled + and a non-1:1 mapping. + + r5 : NULL (as to differentiate with method a) + +Note about SMP entry: Either your firmware puts your other +CPUs in some sleep loop or spin loop in ROM where you can get +them out via a soft reset or some other means, in which case +you don't need to care, or you'll have to enter the kernel +with all CPUs. The way to do that with method b) will be +described in a later revision of this document. + +Board supports (platforms) are not exclusive config options. An +arbitrary set of board supports can be built in a single kernel +image. The kernel will "know" what set of functions to use for a +given platform based on the content of the device-tree. Thus, you +should: + + a) add your platform support as a _boolean_ option in + arch/powerpc/Kconfig, following the example of PPC_PSERIES, + PPC_PMAC and PPC_MAPLE. The latter is probably a good + example of a board support to start from. + + b) create your main platform file as + "arch/powerpc/platforms/myplatform/myboard_setup.c" and add it + to the Makefile under the condition of your ``CONFIG_`` + option. This file will define a structure of type "ppc_md" + containing the various callbacks that the generic code will + use to get to your platform specific code + +A kernel image may support multiple platforms, but only if the +platforms feature the same core architecture. A single kernel build +cannot support both configurations with Book E and configurations +with classic Powerpc architectures. diff --git a/Documentation/arch/powerpc/bootwrapper.rst b/Documentation/arch/powerpc/bootwrapper.rst new file mode 100644 index 0000000000..cdfa2bc842 --- /dev/null +++ b/Documentation/arch/powerpc/bootwrapper.rst @@ -0,0 +1,131 @@ +======================== +The PowerPC boot wrapper +======================== + +Copyright (C) Secret Lab Technologies Ltd. + +PowerPC image targets compresses and wraps the kernel image (vmlinux) with +a boot wrapper to make it usable by the system firmware. There is no +standard PowerPC firmware interface, so the boot wrapper is designed to +be adaptable for each kind of image that needs to be built. + +The boot wrapper can be found in the arch/powerpc/boot/ directory. The +Makefile in that directory has targets for all the available image types. +The different image types are used to support all of the various firmware +interfaces found on PowerPC platforms. OpenFirmware is the most commonly +used firmware type on general purpose PowerPC systems from Apple, IBM and +others. U-Boot is typically found on embedded PowerPC hardware, but there +are a handful of other firmware implementations which are also popular. Each +firmware interface requires a different image format. + +The boot wrapper is built from the makefile in arch/powerpc/boot/Makefile and +it uses the wrapper script (arch/powerpc/boot/wrapper) to generate target +image. The details of the build system is discussed in the next section. +Currently, the following image format targets exist: + + ==================== ======================================================== + cuImage.%: Backwards compatible uImage for older version of + U-Boot (for versions that don't understand the device + tree). This image embeds a device tree blob inside + the image. The boot wrapper, kernel and device tree + are all embedded inside the U-Boot uImage file format + with boot wrapper code that extracts data from the old + bd_info structure and loads the data into the device + tree before jumping into the kernel. + + Because of the series of #ifdefs found in the + bd_info structure used in the old U-Boot interfaces, + cuImages are platform specific. Each specific + U-Boot platform has a different platform init file + which populates the embedded device tree with data + from the platform specific bd_info file. The platform + specific cuImage platform init code can be found in + `arch/powerpc/boot/cuboot.*.c`. Selection of the correct + cuImage init code for a specific board can be found in + the wrapper structure. + + dtbImage.%: Similar to zImage, except device tree blob is embedded + inside the image instead of provided by firmware. The + output image file can be either an elf file or a flat + binary depending on the platform. + + dtbImages are used on systems which do not have an + interface for passing a device tree directly. + dtbImages are similar to simpleImages except that + dtbImages have platform specific code for extracting + data from the board firmware, but simpleImages do not + talk to the firmware at all. + + PlayStation 3 support uses dtbImage. So do Embedded + Planet boards using the PlanetCore firmware. Board + specific initialization code is typically found in a + file named arch/powerpc/boot/.c; but this + can be overridden by the wrapper script. + + simpleImage.%: Firmware independent compressed image that does not + depend on any particular firmware interface and embeds + a device tree blob. This image is a flat binary that + can be loaded to any location in RAM and jumped to. + Firmware cannot pass any configuration data to the + kernel with this image type and it depends entirely on + the embedded device tree for all information. + + treeImage.%; Image format for used with OpenBIOS firmware found + on some ppc4xx hardware. This image embeds a device + tree blob inside the image. + + uImage: Native image format used by U-Boot. The uImage target + does not add any boot code. It just wraps a compressed + vmlinux in the uImage data structure. This image + requires a version of U-Boot that is able to pass + a device tree to the kernel at boot. If using an older + version of U-Boot, then you need to use a cuImage + instead. + + zImage.%: Image format which does not embed a device tree. + Used by OpenFirmware and other firmware interfaces + which are able to supply a device tree. This image + expects firmware to provide the device tree at boot. + Typically, if you have general purpose PowerPC + hardware then you want this image format. + ==================== ======================================================== + +Image types which embed a device tree blob (simpleImage, dtbImage, treeImage, +and cuImage) all generate the device tree blob from a file in the +arch/powerpc/boot/dts/ directory. The Makefile selects the correct device +tree source based on the name of the target. Therefore, if the kernel is +built with 'make treeImage.walnut', then the build system will use +arch/powerpc/boot/dts/walnut.dts to build treeImage.walnut. + +Two special targets called 'zImage' and 'zImage.initrd' also exist. These +targets build all the default images as selected by the kernel configuration. +Default images are selected by the boot wrapper Makefile +(arch/powerpc/boot/Makefile) by adding targets to the $image-y variable. Look +at the Makefile to see which default image targets are available. + +How it is built +--------------- +arch/powerpc is designed to support multiplatform kernels, which means +that a single vmlinux image can be booted on many different target boards. +It also means that the boot wrapper must be able to wrap for many kinds of +images on a single build. The design decision was made to not use any +conditional compilation code (#ifdef, etc) in the boot wrapper source code. +All of the boot wrapper pieces are buildable at any time regardless of the +kernel configuration. Building all the wrapper bits on every kernel build +also ensures that obscure parts of the wrapper are at the very least compile +tested in a large variety of environments. + +The wrapper is adapted for different image types at link time by linking in +just the wrapper bits that are appropriate for the image type. The 'wrapper +script' (found in arch/powerpc/boot/wrapper) is called by the Makefile and +is responsible for selecting the correct wrapper bits for the image type. +The arguments are well documented in the script's comment block, so they +are not repeated here. However, it is worth mentioning that the script +uses the -p (platform) argument as the main method of deciding which wrapper +bits to compile in. Look for the large 'case "$platform" in' block in the +middle of the script. This is also the place where platform specific fixups +can be selected by changing the link order. + +In particular, care should be taken when working with cuImages. cuImage +wrapper bits are very board specific and care should be taken to make sure +the target you are trying to build is supported by the wrapper bits. diff --git a/Documentation/arch/powerpc/cpu_families.rst b/Documentation/arch/powerpc/cpu_families.rst new file mode 100644 index 0000000000..eb7e60649b --- /dev/null +++ b/Documentation/arch/powerpc/cpu_families.rst @@ -0,0 +1,237 @@ +============ +CPU Families +============ + +This document tries to summarise some of the different cpu families that exist +and are supported by arch/powerpc. + + +Book3S (aka sPAPR) +------------------ + +- Hash MMU (except 603 and e300) +- Radix MMU (POWER9 and later) +- Software loaded TLB (603 and e300) +- Selectable Software loaded TLB in addition to hash MMU (755, 7450, e600) +- Mix of 32 & 64 bit:: + + +--------------+ +----------------+ + | Old POWER | --------------> | RS64 (threads) | + +--------------+ +----------------+ + | + | + v + +--------------+ +----------------+ +------+ + | 601 | --------------> | 603 | ---> | e300 | + +--------------+ +----------------+ +------+ + | | + | | + v v + +--------------+ +-----+ +----------------+ +-------+ + | 604 | | 755 | <--- | 750 (G3) | ---> | 750CX | + +--------------+ +-----+ +----------------+ +-------+ + | | | + | | | + v v v + +--------------+ +----------------+ +-------+ + | 620 (64 bit) | | 7400 | | 750CL | + +--------------+ +----------------+ +-------+ + | | | + | | | + v v v + +--------------+ +----------------+ +-------+ + | POWER3/630 | | 7410 | | 750FX | + +--------------+ +----------------+ +-------+ + | | + | | + v v + +--------------+ +----------------+ + | POWER3+ | | 7450 | + +--------------+ +----------------+ + | | + | | + v v + +--------------+ +----------------+ + | POWER4 | | 7455 | + +--------------+ +----------------+ + | | + | | + v v + +--------------+ +-------+ +----------------+ + | POWER4+ | --> | 970 | | 7447 | + +--------------+ +-------+ +----------------+ + | | | + | | | + v v v + +--------------+ +-------+ +----------------+ + | POWER5 | | 970FX | | 7448 | + +--------------+ +-------+ +----------------+ + | | | + | | | + v v v + +--------------+ +-------+ +----------------+ + | POWER5+ | | 970MP | | e600 | + +--------------+ +-------+ +----------------+ + | + | + v + +--------------+ + | POWER5++ | + +--------------+ + | + | + v + +--------------+ +-------+ + | POWER6 | <-?-> | Cell | + +--------------+ +-------+ + | + | + v + +--------------+ + | POWER7 | + +--------------+ + | + | + v + +--------------+ + | POWER7+ | + +--------------+ + | + | + v + +--------------+ + | POWER8 | + +--------------+ + | + | + v + +--------------+ + | POWER9 | + +--------------+ + | + | + v + +--------------+ + | POWER10 | + +--------------+ + + + +---------------+ + | PA6T (64 bit) | + +---------------+ + + +IBM BookE +--------- + +- Software loaded TLB. +- All 32 bit:: + + +--------------+ + | 401 | + +--------------+ + | + | + v + +--------------+ + | 403 | + +--------------+ + | + | + v + +--------------+ + | 405 | + +--------------+ + | + | + v + +--------------+ + | 440 | + +--------------+ + | + | + v + +--------------+ +----------------+ + | 450 | --> | BG/P | + +--------------+ +----------------+ + | + | + v + +--------------+ + | 460 | + +--------------+ + | + | + v + +--------------+ + | 476 | + +--------------+ + + +Motorola/Freescale 8xx +---------------------- + +- Software loaded with hardware assist. +- All 32 bit:: + + +-------------+ + | MPC8xx Core | + +-------------+ + + +Freescale BookE +--------------- + +- Software loaded TLB. +- e6500 adds HW loaded indirect TLB entries. +- Mix of 32 & 64 bit:: + + +--------------+ + | e200 | + +--------------+ + + + +--------------------------------+ + | e500 | + +--------------------------------+ + | + | + v + +--------------------------------+ + | e500v2 | + +--------------------------------+ + | + | + v + +--------------------------------+ + | e500mc (Book3e) | + +--------------------------------+ + | + | + v + +--------------------------------+ + | e5500 (64 bit) | + +--------------------------------+ + | + | + v + +--------------------------------+ + | e6500 (HW TLB) (Multithreaded) | + +--------------------------------+ + + +IBM A2 core +----------- + +- Book3E, software loaded TLB + HW loaded indirect TLB entries. +- 64 bit:: + + +--------------+ +----------------+ + | A2 core | --> | WSP | + +--------------+ +----------------+ + | + | + v + +--------------+ + | BG/Q | + +--------------+ diff --git a/Documentation/arch/powerpc/cpu_features.rst b/Documentation/arch/powerpc/cpu_features.rst new file mode 100644 index 0000000000..b7bcdd2f41 --- /dev/null +++ b/Documentation/arch/powerpc/cpu_features.rst @@ -0,0 +1,60 @@ +============ +CPU Features +============ + +Hollis Blanchard +5 Jun 2002 + +This document describes the system (including self-modifying code) used in the +PPC Linux kernel to support a variety of PowerPC CPUs without requiring +compile-time selection. + +Early in the boot process the ppc32 kernel detects the current CPU type and +chooses a set of features accordingly. Some examples include Altivec support, +split instruction and data caches, and if the CPU supports the DOZE and NAP +sleep modes. + +Detection of the feature set is simple. A list of processors can be found in +arch/powerpc/kernel/cputable.c. The PVR register is masked and compared with +each value in the list. If a match is found, the cpu_features of cur_cpu_spec +is assigned to the feature bitmask for this processor and a __setup_cpu +function is called. + +C code may test 'cur_cpu_spec[smp_processor_id()]->cpu_features' for a +particular feature bit. This is done in quite a few places, for example +in ppc_setup_l2cr(). + +Implementing cpufeatures in assembly is a little more involved. There are +several paths that are performance-critical and would suffer if an array +index, structure dereference, and conditional branch were added. To avoid the +performance penalty but still allow for runtime (rather than compile-time) CPU +selection, unused code is replaced by 'nop' instructions. This nop'ing is +based on CPU 0's capabilities, so a multi-processor system with non-identical +processors will not work (but such a system would likely have other problems +anyways). + +After detecting the processor type, the kernel patches out sections of code +that shouldn't be used by writing nop's over it. Using cpufeatures requires +just 2 macros (found in arch/powerpc/include/asm/cputable.h), as seen in head.S +transfer_to_handler:: + + #ifdef CONFIG_ALTIVEC + BEGIN_FTR_SECTION + mfspr r22,SPRN_VRSAVE /* if G4, save vrsave register value */ + stw r22,THREAD_VRSAVE(r23) + END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC) + #endif /* CONFIG_ALTIVEC */ + +If CPU 0 supports Altivec, the code is left untouched. If it doesn't, both +instructions are replaced with nop's. + +The END_FTR_SECTION macro has two simpler variations: END_FTR_SECTION_IFSET +and END_FTR_SECTION_IFCLR. These simply test if a flag is set (in +cur_cpu_spec[0]->cpu_features) or is cleared, respectively. These two macros +should be used in the majority of cases. + +The END_FTR_SECTION macros are implemented by storing information about this +code in the '__ftr_fixup' ELF section. When do_cpu_ftr_fixups +(arch/powerpc/kernel/misc.S) is invoked, it will iterate over the records in +__ftr_fixup, and if the required feature is not present it will loop writing +nop's from each BEGIN_FTR_SECTION to END_FTR_SECTION. diff --git a/Documentation/arch/powerpc/cxl.rst b/Documentation/arch/powerpc/cxl.rst new file mode 100644 index 0000000000..d2d7705761 --- /dev/null +++ b/Documentation/arch/powerpc/cxl.rst @@ -0,0 +1,469 @@ +==================================== +Coherent Accelerator Interface (CXL) +==================================== + +Introduction +============ + + The coherent accelerator interface is designed to allow the + coherent connection of accelerators (FPGAs and other devices) to a + POWER system. These devices need to adhere to the Coherent + Accelerator Interface Architecture (CAIA). + + IBM refers to this as the Coherent Accelerator Processor Interface + or CAPI. In the kernel it's referred to by the name CXL to avoid + confusion with the ISDN CAPI subsystem. + + Coherent in this context means that the accelerator and CPUs can + both access system memory directly and with the same effective + addresses. + + +Hardware overview +================= + + :: + + POWER8/9 FPGA + +----------+ +---------+ + | | | | + | CPU | | AFU | + | | | | + | | | | + | | | | + +----------+ +---------+ + | PHB | | | + | +------+ | PSL | + | | CAPP |<------>| | + +---+------+ PCIE +---------+ + + The POWER8/9 chip has a Coherently Attached Processor Proxy (CAPP) + unit which is part of the PCIe Host Bridge (PHB). This is managed + by Linux by calls into OPAL. Linux doesn't directly program the + CAPP. + + The FPGA (or coherently attached device) consists of two parts. + The POWER Service Layer (PSL) and the Accelerator Function Unit + (AFU). The AFU is used to implement specific functionality behind + the PSL. The PSL, among other things, provides memory address + translation services to allow each AFU direct access to userspace + memory. + + The AFU is the core part of the accelerator (eg. the compression, + crypto etc function). The kernel has no knowledge of the function + of the AFU. Only userspace interacts directly with the AFU. + + The PSL provides the translation and interrupt services that the + AFU needs. This is what the kernel interacts with. For example, if + the AFU needs to read a particular effective address, it sends + that address to the PSL, the PSL then translates it, fetches the + data from memory and returns it to the AFU. If the PSL has a + translation miss, it interrupts the kernel and the kernel services + the fault. The context to which this fault is serviced is based on + who owns that acceleration function. + + - POWER8 and PSL Version 8 are compliant to the CAIA Version 1.0. + - POWER9 and PSL Version 9 are compliant to the CAIA Version 2.0. + + This PSL Version 9 provides new features such as: + + * Interaction with the nest MMU on the P9 chip. + * Native DMA support. + * Supports sending ASB_Notify messages for host thread wakeup. + * Supports Atomic operations. + * etc. + + Cards with a PSL9 won't work on a POWER8 system and cards with a + PSL8 won't work on a POWER9 system. + +AFU Modes +========= + + There are two programming modes supported by the AFU. Dedicated + and AFU directed. AFU may support one or both modes. + + When using dedicated mode only one MMU context is supported. In + this mode, only one userspace process can use the accelerator at + time. + + When using AFU directed mode, up to 16K simultaneous contexts can + be supported. This means up to 16K simultaneous userspace + applications may use the accelerator (although specific AFUs may + support fewer). In this mode, the AFU sends a 16 bit context ID + with each of its requests. This tells the PSL which context is + associated with each operation. If the PSL can't translate an + operation, the ID can also be accessed by the kernel so it can + determine the userspace context associated with an operation. + + +MMIO space +========== + + A portion of the accelerator MMIO space can be directly mapped + from the AFU to userspace. Either the whole space can be mapped or + just a per context portion. The hardware is self describing, hence + the kernel can determine the offset and size of the per context + portion. + + +Interrupts +========== + + AFUs may generate interrupts that are destined for userspace. These + are received by the kernel as hardware interrupts and passed onto + userspace by a read syscall documented below. + + Data storage faults and error interrupts are handled by the kernel + driver. + + +Work Element Descriptor (WED) +============================= + + The WED is a 64-bit parameter passed to the AFU when a context is + started. Its format is up to the AFU hence the kernel has no + knowledge of what it represents. Typically it will be the + effective address of a work queue or status block where the AFU + and userspace can share control and status information. + + + + +User API +======== + +1. AFU character devices +^^^^^^^^^^^^^^^^^^^^^^^^ + + For AFUs operating in AFU directed mode, two character device + files will be created. /dev/cxl/afu0.0m will correspond to a + master context and /dev/cxl/afu0.0s will correspond to a slave + context. Master contexts have access to the full MMIO space an + AFU provides. Slave contexts have access to only the per process + MMIO space an AFU provides. + + For AFUs operating in dedicated process mode, the driver will + only create a single character device per AFU called + /dev/cxl/afu0.0d. This will have access to the entire MMIO space + that the AFU provides (like master contexts in AFU directed). + + The types described below are defined in include/uapi/misc/cxl.h + + The following file operations are supported on both slave and + master devices. + + A userspace library libcxl is available here: + + https://github.com/ibm-capi/libcxl + + This provides a C interface to this kernel API. + +open +---- + + Opens the device and allocates a file descriptor to be used with + the rest of the API. + + A dedicated mode AFU only has one context and only allows the + device to be opened once. + + An AFU directed mode AFU can have many contexts, the device can be + opened once for each context that is available. + + When all available contexts are allocated the open call will fail + and return -ENOSPC. + + Note: + IRQs need to be allocated for each context, which may limit + the number of contexts that can be created, and therefore + how many times the device can be opened. The POWER8 CAPP + supports 2040 IRQs and 3 are used by the kernel, so 2037 are + left. If 1 IRQ is needed per context, then only 2037 + contexts can be allocated. If 4 IRQs are needed per context, + then only 2037/4 = 509 contexts can be allocated. + + +ioctl +----- + + CXL_IOCTL_START_WORK: + Starts the AFU context and associates it with the current + process. Once this ioctl is successfully executed, all memory + mapped into this process is accessible to this AFU context + using the same effective addresses. No additional calls are + required to map/unmap memory. The AFU memory context will be + updated as userspace allocates and frees memory. This ioctl + returns once the AFU context is started. + + Takes a pointer to a struct cxl_ioctl_start_work + + :: + + struct cxl_ioctl_start_work { + __u64 flags; + __u64 work_element_descriptor; + __u64 amr; + __s16 num_interrupts; + __s16 reserved1; + __s32 reserved2; + __u64 reserved3; + __u64 reserved4; + __u64 reserved5; + __u64 reserved6; + }; + + flags: + Indicates which optional fields in the structure are + valid. + + work_element_descriptor: + The Work Element Descriptor (WED) is a 64-bit argument + defined by the AFU. Typically this is an effective + address pointing to an AFU specific structure + describing what work to perform. + + amr: + Authority Mask Register (AMR), same as the powerpc + AMR. This field is only used by the kernel when the + corresponding CXL_START_WORK_AMR value is specified in + flags. If not specified the kernel will use a default + value of 0. + + num_interrupts: + Number of userspace interrupts to request. This field + is only used by the kernel when the corresponding + CXL_START_WORK_NUM_IRQS value is specified in flags. + If not specified the minimum number required by the + AFU will be allocated. The min and max number can be + obtained from sysfs. + + reserved fields: + For ABI padding and future extensions + + CXL_IOCTL_GET_PROCESS_ELEMENT: + Get the current context id, also known as the process element. + The value is returned from the kernel as a __u32. + + +mmap +---- + + An AFU may have an MMIO space to facilitate communication with the + AFU. If it does, the MMIO space can be accessed via mmap. The size + and contents of this area are specific to the particular AFU. The + size can be discovered via sysfs. + + In AFU directed mode, master contexts are allowed to map all of + the MMIO space and slave contexts are allowed to only map the per + process MMIO space associated with the context. In dedicated + process mode the entire MMIO space can always be mapped. + + This mmap call must be done after the START_WORK ioctl. + + Care should be taken when accessing MMIO space. Only 32 and 64-bit + accesses are supported by POWER8. Also, the AFU will be designed + with a specific endianness, so all MMIO accesses should consider + endianness (recommend endian(3) variants like: le64toh(), + be64toh() etc). These endian issues equally apply to shared memory + queues the WED may describe. + + +read +---- + + Reads events from the AFU. Blocks if no events are pending + (unless O_NONBLOCK is supplied). Returns -EIO in the case of an + unrecoverable error or if the card is removed. + + read() will always return an integral number of events. + + The buffer passed to read() must be at least 4K bytes. + + The result of the read will be a buffer of one or more events, + each event is of type struct cxl_event, of varying size:: + + struct cxl_event { + struct cxl_event_header header; + union { + struct cxl_event_afu_interrupt irq; + struct cxl_event_data_storage fault; + struct cxl_event_afu_error afu_error; + }; + }; + + The struct cxl_event_header is defined as + + :: + + struct cxl_event_header { + __u16 type; + __u16 size; + __u16 process_element; + __u16 reserved1; + }; + + type: + This defines the type of event. The type determines how + the rest of the event is structured. These types are + described below and defined by enum cxl_event_type. + + size: + This is the size of the event in bytes including the + struct cxl_event_header. The start of the next event can + be found at this offset from the start of the current + event. + + process_element: + Context ID of the event. + + reserved field: + For future extensions and padding. + + If the event type is CXL_EVENT_AFU_INTERRUPT then the event + structure is defined as + + :: + + struct cxl_event_afu_interrupt { + __u16 flags; + __u16 irq; /* Raised AFU interrupt number */ + __u32 reserved1; + }; + + flags: + These flags indicate which optional fields are present + in this struct. Currently all fields are mandatory. + + irq: + The IRQ number sent by the AFU. + + reserved field: + For future extensions and padding. + + If the event type is CXL_EVENT_DATA_STORAGE then the event + structure is defined as + + :: + + struct cxl_event_data_storage { + __u16 flags; + __u16 reserved1; + __u32 reserved2; + __u64 addr; + __u64 dsisr; + __u64 reserved3; + }; + + flags: + These flags indicate which optional fields are present in + this struct. Currently all fields are mandatory. + + address: + The address that the AFU unsuccessfully attempted to + access. Valid accesses will be handled transparently by the + kernel but invalid accesses will generate this event. + + dsisr: + This field gives information on the type of fault. It is a + copy of the DSISR from the PSL hardware when the address + fault occurred. The form of the DSISR is as defined in the + CAIA. + + reserved fields: + For future extensions + + If the event type is CXL_EVENT_AFU_ERROR then the event structure + is defined as + + :: + + struct cxl_event_afu_error { + __u16 flags; + __u16 reserved1; + __u32 reserved2; + __u64 error; + }; + + flags: + These flags indicate which optional fields are present in + this struct. Currently all fields are Mandatory. + + error: + Error status from the AFU. Defined by the AFU. + + reserved fields: + For future extensions and padding + + +2. Card character device (powerVM guest only) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + + In a powerVM guest, an extra character device is created for the + card. The device is only used to write (flash) a new image on the + FPGA accelerator. Once the image is written and verified, the + device tree is updated and the card is reset to reload the updated + image. + +open +---- + + Opens the device and allocates a file descriptor to be used with + the rest of the API. The device can only be opened once. + +ioctl +----- + +CXL_IOCTL_DOWNLOAD_IMAGE / CXL_IOCTL_VALIDATE_IMAGE: + Starts and controls flashing a new FPGA image. Partial + reconfiguration is not supported (yet), so the image must contain + a copy of the PSL and AFU(s). Since an image can be quite large, + the caller may have to iterate, splitting the image in smaller + chunks. + + Takes a pointer to a struct cxl_adapter_image:: + + struct cxl_adapter_image { + __u64 flags; + __u64 data; + __u64 len_data; + __u64 len_image; + __u64 reserved1; + __u64 reserved2; + __u64 reserved3; + __u64 reserved4; + }; + + flags: + These flags indicate which optional fields are present in + this struct. Currently all fields are mandatory. + + data: + Pointer to a buffer with part of the image to write to the + card. + + len_data: + Size of the buffer pointed to by data. + + len_image: + Full size of the image. + + +Sysfs Class +=========== + + A cxl sysfs class is added under /sys/class/cxl to facilitate + enumeration and tuning of the accelerators. Its layout is + described in Documentation/ABI/testing/sysfs-class-cxl + + +Udev rules +========== + + The following udev rules could be used to create a symlink to the + most logical chardev to use in any programming mode (afuX.Yd for + dedicated, afuX.Ys for afu directed), since the API is virtually + identical for each:: + + SUBSYSTEM=="cxl", ATTRS{mode}=="dedicated_process", SYMLINK="cxl/%b" + SUBSYSTEM=="cxl", ATTRS{mode}=="afu_directed", \ + KERNEL=="afu[0-9]*.[0-9]*s", SYMLINK="cxl/%b" diff --git a/Documentation/arch/powerpc/cxlflash.rst b/Documentation/arch/powerpc/cxlflash.rst new file mode 100644 index 0000000000..e8f488acfa --- /dev/null +++ b/Documentation/arch/powerpc/cxlflash.rst @@ -0,0 +1,433 @@ +================================ +Coherent Accelerator (CXL) Flash +================================ + +Introduction +============ + + The IBM Power architecture provides support for CAPI (Coherent + Accelerator Power Interface), which is available to certain PCIe slots + on Power 8 systems. CAPI can be thought of as a special tunneling + protocol through PCIe that allow PCIe adapters to look like special + purpose co-processors which can read or write an application's + memory and generate page faults. As a result, the host interface to + an adapter running in CAPI mode does not require the data buffers to + be mapped to the device's memory (IOMMU bypass) nor does it require + memory to be pinned. + + On Linux, Coherent Accelerator (CXL) kernel services present CAPI + devices as a PCI device by implementing a virtual PCI host bridge. + This abstraction simplifies the infrastructure and programming + model, allowing for drivers to look similar to other native PCI + device drivers. + + CXL provides a mechanism by which user space applications can + directly talk to a device (network or storage) bypassing the typical + kernel/device driver stack. The CXL Flash Adapter Driver enables a + user space application direct access to Flash storage. + + The CXL Flash Adapter Driver is a kernel module that sits in the + SCSI stack as a low level device driver (below the SCSI disk and + protocol drivers) for the IBM CXL Flash Adapter. This driver is + responsible for the initialization of the adapter, setting up the + special path for user space access, and performing error recovery. It + communicates directly the Flash Accelerator Functional Unit (AFU) + as described in Documentation/arch/powerpc/cxl.rst. + + The cxlflash driver supports two, mutually exclusive, modes of + operation at the device (LUN) level: + + - Any flash device (LUN) can be configured to be accessed as a + regular disk device (i.e.: /dev/sdc). This is the default mode. + + - Any flash device (LUN) can be configured to be accessed from + user space with a special block library. This mode further + specifies the means of accessing the device and provides for + either raw access to the entire LUN (referred to as direct + or physical LUN access) or access to a kernel/AFU-mediated + partition of the LUN (referred to as virtual LUN access). The + segmentation of a disk device into virtual LUNs is assisted + by special translation services provided by the Flash AFU. + +Overview +======== + + The Coherent Accelerator Interface Architecture (CAIA) introduces a + concept of a master context. A master typically has special privileges + granted to it by the kernel or hypervisor allowing it to perform AFU + wide management and control. The master may or may not be involved + directly in each user I/O, but at the minimum is involved in the + initial setup before the user application is allowed to send requests + directly to the AFU. + + The CXL Flash Adapter Driver establishes a master context with the + AFU. It uses memory mapped I/O (MMIO) for this control and setup. The + Adapter Problem Space Memory Map looks like this:: + + +-------------------------------+ + | 512 * 64 KB User MMIO | + | (per context) | + | User Accessible | + +-------------------------------+ + | 512 * 128 B per context | + | Provisioning and Control | + | Trusted Process accessible | + +-------------------------------+ + | 64 KB Global | + | Trusted Process accessible | + +-------------------------------+ + + This driver configures itself into the SCSI software stack as an + adapter driver. The driver is the only entity that is considered a + Trusted Process to program the Provisioning and Control and Global + areas in the MMIO Space shown above. The master context driver + discovers all LUNs attached to the CXL Flash adapter and instantiates + scsi block devices (/dev/sdb, /dev/sdc etc.) for each unique LUN + seen from each path. + + Once these scsi block devices are instantiated, an application + written to a specification provided by the block library may get + access to the Flash from user space (without requiring a system call). + + This master context driver also provides a series of ioctls for this + block library to enable this user space access. The driver supports + two modes for accessing the block device. + + The first mode is called a virtual mode. In this mode a single scsi + block device (/dev/sdb) may be carved up into any number of distinct + virtual LUNs. The virtual LUNs may be resized as long as the sum of + the sizes of all the virtual LUNs, along with the meta-data associated + with it does not exceed the physical capacity. + + The second mode is called the physical mode. In this mode a single + block device (/dev/sdb) may be opened directly by the block library + and the entire space for the LUN is available to the application. + + Only the physical mode provides persistence of the data. i.e. The + data written to the block device will survive application exit and + restart and also reboot. The virtual LUNs do not persist (i.e. do + not survive after the application terminates or the system reboots). + + +Block library API +================= + + Applications intending to get access to the CXL Flash from user + space should use the block library, as it abstracts the details of + interfacing directly with the cxlflash driver that are necessary for + performing administrative actions (i.e.: setup, tear down, resize). + The block library can be thought of as a 'user' of services, + implemented as IOCTLs, that are provided by the cxlflash driver + specifically for devices (LUNs) operating in user space access + mode. While it is not a requirement that applications understand + the interface between the block library and the cxlflash driver, + a high-level overview of each supported service (IOCTL) is provided + below. + + The block library can be found on GitHub: + http://github.com/open-power/capiflash + + +CXL Flash Driver LUN IOCTLs +=========================== + + Users, such as the block library, that wish to interface with a flash + device (LUN) via user space access need to use the services provided + by the cxlflash driver. As these services are implemented as ioctls, + a file descriptor handle must first be obtained in order to establish + the communication channel between a user and the kernel. This file + descriptor is obtained by opening the device special file associated + with the scsi disk device (/dev/sdb) that was created during LUN + discovery. As per the location of the cxlflash driver within the + SCSI protocol stack, this open is actually not seen by the cxlflash + driver. Upon successful open, the user receives a file descriptor + (herein referred to as fd1) that should be used for issuing the + subsequent ioctls listed below. + + The structure definitions for these IOCTLs are available in: + uapi/scsi/cxlflash_ioctl.h + +DK_CXLFLASH_ATTACH +------------------ + + This ioctl obtains, initializes, and starts a context using the CXL + kernel services. These services specify a context id (u16) by which + to uniquely identify the context and its allocated resources. The + services additionally provide a second file descriptor (herein + referred to as fd2) that is used by the block library to initiate + memory mapped I/O (via mmap()) to the CXL flash device and poll for + completion events. This file descriptor is intentionally installed by + this driver and not the CXL kernel services to allow for intermediary + notification and access in the event of a non-user-initiated close(), + such as a killed process. This design point is described in further + detail in the description for the DK_CXLFLASH_DETACH ioctl. + + There are a few important aspects regarding the "tokens" (context id + and fd2) that are provided back to the user: + + - These tokens are only valid for the process under which they + were created. The child of a forked process cannot continue + to use the context id or file descriptor created by its parent + (see DK_CXLFLASH_VLUN_CLONE for further details). + + - These tokens are only valid for the lifetime of the context and + the process under which they were created. Once either is + destroyed, the tokens are to be considered stale and subsequent + usage will result in errors. + + - A valid adapter file descriptor (fd2 >= 0) is only returned on + the initial attach for a context. Subsequent attaches to an + existing context (DK_CXLFLASH_ATTACH_REUSE_CONTEXT flag present) + do not provide the adapter file descriptor as it was previously + made known to the application. + + - When a context is no longer needed, the user shall detach from + the context via the DK_CXLFLASH_DETACH ioctl. When this ioctl + returns with a valid adapter file descriptor and the return flag + DK_CXLFLASH_APP_CLOSE_ADAP_FD is present, the application _must_ + close the adapter file descriptor following a successful detach. + + - When this ioctl returns with a valid fd2 and the return flag + DK_CXLFLASH_APP_CLOSE_ADAP_FD is present, the application _must_ + close fd2 in the following circumstances: + + + Following a successful detach of the last user of the context + + Following a successful recovery on the context's original fd2 + + In the child process of a fork(), following a clone ioctl, + on the fd2 associated with the source context + + - At any time, a close on fd2 will invalidate the tokens. Applications + should exercise caution to only close fd2 when appropriate (outlined + in the previous bullet) to avoid premature loss of I/O. + +DK_CXLFLASH_USER_DIRECT +----------------------- + This ioctl is responsible for transitioning the LUN to direct + (physical) mode access and configuring the AFU for direct access from + user space on a per-context basis. Additionally, the block size and + last logical block address (LBA) are returned to the user. + + As mentioned previously, when operating in user space access mode, + LUNs may be accessed in whole or in part. Only one mode is allowed + at a time and if one mode is active (outstanding references exist), + requests to use the LUN in a different mode are denied. + + The AFU is configured for direct access from user space by adding an + entry to the AFU's resource handle table. The index of the entry is + treated as a resource handle that is returned to the user. The user + is then able to use the handle to reference the LUN during I/O. + +DK_CXLFLASH_USER_VIRTUAL +------------------------ + This ioctl is responsible for transitioning the LUN to virtual mode + of access and configuring the AFU for virtual access from user space + on a per-context basis. Additionally, the block size and last logical + block address (LBA) are returned to the user. + + As mentioned previously, when operating in user space access mode, + LUNs may be accessed in whole or in part. Only one mode is allowed + at a time and if one mode is active (outstanding references exist), + requests to use the LUN in a different mode are denied. + + The AFU is configured for virtual access from user space by adding + an entry to the AFU's resource handle table. The index of the entry + is treated as a resource handle that is returned to the user. The + user is then able to use the handle to reference the LUN during I/O. + + By default, the virtual LUN is created with a size of 0. The user + would need to use the DK_CXLFLASH_VLUN_RESIZE ioctl to adjust the grow + the virtual LUN to a desired size. To avoid having to perform this + resize for the initial creation of the virtual LUN, the user has the + option of specifying a size as part of the DK_CXLFLASH_USER_VIRTUAL + ioctl, such that when success is returned to the user, the + resource handle that is provided is already referencing provisioned + storage. This is reflected by the last LBA being a non-zero value. + + When a LUN is accessible from more than one port, this ioctl will + return with the DK_CXLFLASH_ALL_PORTS_ACTIVE return flag set. This + provides the user with a hint that I/O can be retried in the event + of an I/O error as the LUN can be reached over multiple paths. + +DK_CXLFLASH_VLUN_RESIZE +----------------------- + This ioctl is responsible for resizing a previously created virtual + LUN and will fail if invoked upon a LUN that is not in virtual + mode. Upon success, an updated last LBA is returned to the user + indicating the new size of the virtual LUN associated with the + resource handle. + + The partitioning of virtual LUNs is jointly mediated by the cxlflash + driver and the AFU. An allocation table is kept for each LUN that is + operating in the virtual mode and used to program a LUN translation + table that the AFU references when provided with a resource handle. + + This ioctl can return -EAGAIN if an AFU sync operation takes too long. + In addition to returning a failure to user, cxlflash will also schedule + an asynchronous AFU reset. Should the user choose to retry the operation, + it is expected to succeed. If this ioctl fails with -EAGAIN, the user + can either retry the operation or treat it as a failure. + +DK_CXLFLASH_RELEASE +------------------- + This ioctl is responsible for releasing a previously obtained + reference to either a physical or virtual LUN. This can be + thought of as the inverse of the DK_CXLFLASH_USER_DIRECT or + DK_CXLFLASH_USER_VIRTUAL ioctls. Upon success, the resource handle + is no longer valid and the entry in the resource handle table is + made available to be used again. + + As part of the release process for virtual LUNs, the virtual LUN + is first resized to 0 to clear out and free the translation tables + associated with the virtual LUN reference. + +DK_CXLFLASH_DETACH +------------------ + This ioctl is responsible for unregistering a context with the + cxlflash driver and release outstanding resources that were + not explicitly released via the DK_CXLFLASH_RELEASE ioctl. Upon + success, all "tokens" which had been provided to the user from the + DK_CXLFLASH_ATTACH onward are no longer valid. + + When the DK_CXLFLASH_APP_CLOSE_ADAP_FD flag was returned on a successful + attach, the application _must_ close the fd2 associated with the context + following the detach of the final user of the context. + +DK_CXLFLASH_VLUN_CLONE +---------------------- + This ioctl is responsible for cloning a previously created + context to a more recently created context. It exists solely to + support maintaining user space access to storage after a process + forks. Upon success, the child process (which invoked the ioctl) + will have access to the same LUNs via the same resource handle(s) + as the parent, but under a different context. + + Context sharing across processes is not supported with CXL and + therefore each fork must be met with establishing a new context + for the child process. This ioctl simplifies the state management + and playback required by a user in such a scenario. When a process + forks, child process can clone the parents context by first creating + a context (via DK_CXLFLASH_ATTACH) and then using this ioctl to + perform the clone from the parent to the child. + + The clone itself is fairly simple. The resource handle and lun + translation tables are copied from the parent context to the child's + and then synced with the AFU. + + When the DK_CXLFLASH_APP_CLOSE_ADAP_FD flag was returned on a successful + attach, the application _must_ close the fd2 associated with the source + context (still resident/accessible in the parent process) following the + clone. This is to avoid a stale entry in the file descriptor table of the + child process. + + This ioctl can return -EAGAIN if an AFU sync operation takes too long. + In addition to returning a failure to user, cxlflash will also schedule + an asynchronous AFU reset. Should the user choose to retry the operation, + it is expected to succeed. If this ioctl fails with -EAGAIN, the user + can either retry the operation or treat it as a failure. + +DK_CXLFLASH_VERIFY +------------------ + This ioctl is used to detect various changes such as the capacity of + the disk changing, the number of LUNs visible changing, etc. In cases + where the changes affect the application (such as a LUN resize), the + cxlflash driver will report the changed state to the application. + + The user calls in when they want to validate that a LUN hasn't been + changed in response to a check condition. As the user is operating out + of band from the kernel, they will see these types of events without + the kernel's knowledge. When encountered, the user's architected + behavior is to call in to this ioctl, indicating what they want to + verify and passing along any appropriate information. For now, only + verifying a LUN change (ie: size different) with sense data is + supported. + +DK_CXLFLASH_RECOVER_AFU +----------------------- + This ioctl is used to drive recovery (if such an action is warranted) + of a specified user context. Any state associated with the user context + is re-established upon successful recovery. + + User contexts are put into an error condition when the device needs to + be reset or is terminating. Users are notified of this error condition + by seeing all 0xF's on an MMIO read. Upon encountering this, the + architected behavior for a user is to call into this ioctl to recover + their context. A user may also call into this ioctl at any time to + check if the device is operating normally. If a failure is returned + from this ioctl, the user is expected to gracefully clean up their + context via release/detach ioctls. Until they do, the context they + hold is not relinquished. The user may also optionally exit the process + at which time the context/resources they held will be freed as part of + the release fop. + + When the DK_CXLFLASH_APP_CLOSE_ADAP_FD flag was returned on a successful + attach, the application _must_ unmap and close the fd2 associated with the + original context following this ioctl returning success and indicating that + the context was recovered (DK_CXLFLASH_RECOVER_AFU_CONTEXT_RESET). + +DK_CXLFLASH_MANAGE_LUN +---------------------- + This ioctl is used to switch a LUN from a mode where it is available + for file-system access (legacy), to a mode where it is set aside for + exclusive user space access (superpipe). In case a LUN is visible + across multiple ports and adapters, this ioctl is used to uniquely + identify each LUN by its World Wide Node Name (WWNN). + + +CXL Flash Driver Host IOCTLs +============================ + + Each host adapter instance that is supported by the cxlflash driver + has a special character device associated with it to enable a set of + host management function. These character devices are hosted in a + class dedicated for cxlflash and can be accessed via `/dev/cxlflash/*`. + + Applications can be written to perform various functions using the + host ioctl APIs below. + + The structure definitions for these IOCTLs are available in: + uapi/scsi/cxlflash_ioctl.h + +HT_CXLFLASH_LUN_PROVISION +------------------------- + This ioctl is used to create and delete persistent LUNs on cxlflash + devices that lack an external LUN management interface. It is only + valid when used with AFUs that support the LUN provision capability. + + When sufficient space is available, LUNs can be created by specifying + the target port to host the LUN and a desired size in 4K blocks. Upon + success, the LUN ID and WWID of the created LUN will be returned and + the SCSI bus can be scanned to detect the change in LUN topology. Note + that partial allocations are not supported. Should a creation fail due + to a space issue, the target port can be queried for its current LUN + geometry. + + To remove a LUN, the device must first be disassociated from the Linux + SCSI subsystem. The LUN deletion can then be initiated by specifying a + target port and LUN ID. Upon success, the LUN geometry associated with + the port will be updated to reflect new number of provisioned LUNs and + available capacity. + + To query the LUN geometry of a port, the target port is specified and + upon success, the following information is presented: + + - Maximum number of provisioned LUNs allowed for the port + - Current number of provisioned LUNs for the port + - Maximum total capacity of provisioned LUNs for the port (4K blocks) + - Current total capacity of provisioned LUNs for the port (4K blocks) + + With this information, the number of available LUNs and capacity can be + can be calculated. + +HT_CXLFLASH_AFU_DEBUG +--------------------- + This ioctl is used to debug AFUs by supporting a command pass-through + interface. It is only valid when used with AFUs that support the AFU + debug capability. + + With exception of buffer management, AFU debug commands are opaque to + cxlflash and treated as pass-through. For debug commands that do require + data transfer, the user supplies an adequately sized data buffer and must + specify the data transfer direction with respect to the host. There is a + maximum transfer size of 256K imposed. Note that partial read completions + are not supported - when errors are experienced with a host read data + transfer, the data buffer is not copied back to the user. diff --git a/Documentation/arch/powerpc/dawr-power9.rst b/Documentation/arch/powerpc/dawr-power9.rst new file mode 100644 index 0000000000..310f2e0cea --- /dev/null +++ b/Documentation/arch/powerpc/dawr-power9.rst @@ -0,0 +1,101 @@ +===================== +DAWR issues on POWER9 +===================== + +On older POWER9 processors, the Data Address Watchpoint Register (DAWR) can +cause a checkstop if it points to cache inhibited (CI) memory. Currently Linux +has no way to distinguish CI memory when configuring the DAWR, so on affected +systems, the DAWR is disabled. + +Affected processor revisions +============================ + +This issue is only present on processors prior to v2.3. The revision can be +found in /proc/cpuinfo:: + + processor : 0 + cpu : POWER9, altivec supported + clock : 3800.000000MHz + revision : 2.3 (pvr 004e 1203) + +On a system with the issue, the DAWR is disabled as detailed below. + +Technical Details: +================== + +DAWR has 6 different ways of being set. +1) ptrace +2) h_set_mode(DAWR) +3) h_set_dabr() +4) kvmppc_set_one_reg() +5) xmon + +For ptrace, we now advertise zero breakpoints on POWER9 via the +PPC_PTRACE_GETHWDBGINFO call. This results in GDB falling back to +software emulation of the watchpoint (which is slow). + +h_set_mode(DAWR) and h_set_dabr() will now return an error to the +guest on a POWER9 host. Current Linux guests ignore this error, so +they will silently not get the DAWR. + +kvmppc_set_one_reg() will store the value in the vcpu but won't +actually set it on POWER9 hardware. This is done so we don't break +migration from POWER8 to POWER9, at the cost of silently losing the +DAWR on the migration. + +For xmon, the 'bd' command will return an error on P9. + +Consequences for users +====================== + +For GDB watchpoints (ie 'watch' command) on POWER9 bare metal , GDB +will accept the command. Unfortunately since there is no hardware +support for the watchpoint, GDB will software emulate the watchpoint +making it run very slowly. + +The same will also be true for any guests started on a POWER9 +host. The watchpoint will fail and GDB will fall back to software +emulation. + +If a guest is started on a POWER8 host, GDB will accept the watchpoint +and configure the hardware to use the DAWR. This will run at full +speed since it can use the hardware emulation. Unfortunately if this +guest is migrated to a POWER9 host, the watchpoint will be lost on the +POWER9. Loads and stores to the watchpoint locations will not be +trapped in GDB. The watchpoint is remembered, so if the guest is +migrated back to the POWER8 host, it will start working again. + +Force enabling the DAWR +======================= +Kernels (since ~v5.2) have an option to force enable the DAWR via:: + + echo Y > /sys/kernel/debug/powerpc/dawr_enable_dangerous + +This enables the DAWR even on POWER9. + +This is a dangerous setting, USE AT YOUR OWN RISK. + +Some users may not care about a bad user crashing their box +(ie. single user/desktop systems) and really want the DAWR. This +allows them to force enable DAWR. + +This flag can also be used to disable DAWR access. Once this is +cleared, all DAWR access should be cleared immediately and your +machine once again safe from crashing. + +Userspace may get confused by toggling this. If DAWR is force +enabled/disabled between getting the number of breakpoints (via +PTRACE_GETHWDBGINFO) and setting the breakpoint, userspace will get an +inconsistent view of what's available. Similarly for guests. + +For the DAWR to be enabled in a KVM guest, the DAWR needs to be force +enabled in the host AND the guest. For this reason, this won't work on +POWERVM as it doesn't allow the HCALL to work. Writes of 'Y' to the +dawr_enable_dangerous file will fail if the hypervisor doesn't support +writing the DAWR. + +To double check the DAWR is working, run this kernel selftest: + + tools/testing/selftests/powerpc/ptrace/ptrace-hwbreak.c + +Any errors/failures/skips mean something is wrong. diff --git a/Documentation/arch/powerpc/dexcr.rst b/Documentation/arch/powerpc/dexcr.rst new file mode 100644 index 0000000000..615a631f51 --- /dev/null +++ b/Documentation/arch/powerpc/dexcr.rst @@ -0,0 +1,58 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +========================================== +DEXCR (Dynamic Execution Control Register) +========================================== + +Overview +======== + +The DEXCR is a privileged special purpose register (SPR) introduced in +PowerPC ISA 3.1B (Power10) that allows per-cpu control over several dynamic +execution behaviours. These behaviours include speculation (e.g., indirect +branch target prediction) and enabling return-oriented programming (ROP) +protection instructions. + +The execution control is exposed in hardware as up to 32 bits ('aspects') in +the DEXCR. Each aspect controls a certain behaviour, and can be set or cleared +to enable/disable the aspect. There are several variants of the DEXCR for +different purposes: + +DEXCR + A privileged SPR that can control aspects for userspace and kernel space +HDEXCR + A hypervisor-privileged SPR that can control aspects for the hypervisor and + enforce aspects for the kernel and userspace. +UDEXCR + An optional ultravisor-privileged SPR that can control aspects for the ultravisor. + +Userspace can examine the current DEXCR state using a dedicated SPR that +provides a non-privileged read-only view of the userspace DEXCR aspects. +There is also an SPR that provides a read-only view of the hypervisor enforced +aspects, which ORed with the userspace DEXCR view gives the effective DEXCR +state for a process. + + +Configuration +============= + +The DEXCR is currently unconfigurable. All threads are run with the +NPHIE aspect enabled. + + +coredump and ptrace +=================== + +The userspace values of the DEXCR and HDEXCR (in this order) are exposed under +``NT_PPC_DEXCR``. These are each 64 bits and readonly, and are intended to +assist with core dumps. The DEXCR may be made writable in future. The top 32 +bits of both registers (corresponding to the non-userspace bits) are masked off. + +If the kernel config ``CONFIG_CHECKPOINT_RESTORE`` is enabled, then +``NT_PPC_HASHKEYR`` is available and exposes the HASHKEYR value of the process +for reading and writing. This is a tradeoff between increased security and +checkpoint/restore support: a process should normally have no need to know its +secret key, but restoring a process requires setting its original key. The key +therefore appears in core dumps, and an attacker may be able to retrieve it from +a coredump and effectively bypass ROP protection on any threads that share this +key (potentially all threads from the same parent that have not run ``exec()``). diff --git a/Documentation/arch/powerpc/dscr.rst b/Documentation/arch/powerpc/dscr.rst new file mode 100644 index 0000000000..f735ec5375 --- /dev/null +++ b/Documentation/arch/powerpc/dscr.rst @@ -0,0 +1,87 @@ +=================================== +DSCR (Data Stream Control Register) +=================================== + +DSCR register in powerpc allows user to have some control of prefetch of data +stream in the processor. Please refer to the ISA documents or related manual +for more detailed information regarding how to use this DSCR to attain this +control of the prefetches . This document here provides an overview of kernel +support for DSCR, related kernel objects, its functionalities and exported +user interface. + +(A) Data Structures: + + (1) thread_struct:: + + dscr /* Thread DSCR value */ + dscr_inherit /* Thread has changed default DSCR */ + + (2) PACA:: + + dscr_default /* per-CPU DSCR default value */ + + (3) sysfs.c:: + + dscr_default /* System DSCR default value */ + +(B) Scheduler Changes: + + Scheduler will write the per-CPU DSCR default which is stored in the + CPU's PACA value into the register if the thread has dscr_inherit value + cleared which means that it has not changed the default DSCR till now. + If the dscr_inherit value is set which means that it has changed the + default DSCR value, scheduler will write the changed value which will + now be contained in thread struct's dscr into the register instead of + the per-CPU default PACA based DSCR value. + + NOTE: Please note here that the system wide global DSCR value never + gets used directly in the scheduler process context switch at all. + +(C) SYSFS Interface: + + - Global DSCR default: /sys/devices/system/cpu/dscr_default + - CPU specific DSCR default: /sys/devices/system/cpu/cpuN/dscr + + Changing the global DSCR default in the sysfs will change all the CPU + specific DSCR defaults immediately in their PACA structures. Again if + the current process has the dscr_inherit clear, it also writes the new + value into every CPU's DSCR register right away and updates the current + thread's DSCR value as well. + + Changing the CPU specific DSCR default value in the sysfs does exactly + the same thing as above but unlike the global one above, it just changes + stuff for that particular CPU instead for all the CPUs on the system. + +(D) User Space Instructions: + + The DSCR register can be accessed in the user space using any of these + two SPR numbers available for that purpose. + + (1) Problem state SPR: 0x03 (Un-privileged, POWER8 only) + (2) Privileged state SPR: 0x11 (Privileged) + + Accessing DSCR through privileged SPR number (0x11) from user space + works, as it is emulated following an illegal instruction exception + inside the kernel. Both mfspr and mtspr instructions are emulated. + + Accessing DSCR through user level SPR (0x03) from user space will first + create a facility unavailable exception. Inside this exception handler + all mfspr instruction based read attempts will get emulated and returned + where as the first mtspr instruction based write attempts will enable + the DSCR facility for the next time around (both for read and write) by + setting DSCR facility in the FSCR register. + +(E) Specifics about 'dscr_inherit': + + The thread struct element 'dscr_inherit' represents whether the thread + in question has attempted and changed the DSCR itself using any of the + following methods. This element signifies whether the thread wants to + use the CPU default DSCR value or its own changed DSCR value in the + kernel. + + (1) mtspr instruction (SPR number 0x03) + (2) mtspr instruction (SPR number 0x11) + (3) ptrace interface (Explicitly set user DSCR value) + + Any child of the process created after this event in the process inherits + this same behaviour as well. diff --git a/Documentation/arch/powerpc/eeh-pci-error-recovery.rst b/Documentation/arch/powerpc/eeh-pci-error-recovery.rst new file mode 100644 index 0000000000..d6643a91bd --- /dev/null +++ b/Documentation/arch/powerpc/eeh-pci-error-recovery.rst @@ -0,0 +1,336 @@ +========================== +PCI Bus EEH Error Recovery +========================== + +Linas Vepstas + +12 January 2005 + + +Overview: +--------- +The IBM POWER-based pSeries and iSeries computers include PCI bus +controller chips that have extended capabilities for detecting and +reporting a large variety of PCI bus error conditions. These features +go under the name of "EEH", for "Enhanced Error Handling". The EEH +hardware features allow PCI bus errors to be cleared and a PCI +card to be "rebooted", without also having to reboot the operating +system. + +This is in contrast to traditional PCI error handling, where the +PCI chip is wired directly to the CPU, and an error would cause +a CPU machine-check/check-stop condition, halting the CPU entirely. +Another "traditional" technique is to ignore such errors, which +can lead to data corruption, both of user data or of kernel data, +hung/unresponsive adapters, or system crashes/lockups. Thus, +the idea behind EEH is that the operating system can become more +reliable and robust by protecting it from PCI errors, and giving +the OS the ability to "reboot"/recover individual PCI devices. + +Future systems from other vendors, based on the PCI-E specification, +may contain similar features. + + +Causes of EEH Errors +-------------------- +EEH was originally designed to guard against hardware failure, such +as PCI cards dying from heat, humidity, dust, vibration and bad +electrical connections. The vast majority of EEH errors seen in +"real life" are due to either poorly seated PCI cards, or, +unfortunately quite commonly, due to device driver bugs, device firmware +bugs, and sometimes PCI card hardware bugs. + +The most common software bug, is one that causes the device to +attempt to DMA to a location in system memory that has not been +reserved for DMA access for that card. This is a powerful feature, +as it prevents what; otherwise, would have been silent memory +corruption caused by the bad DMA. A number of device driver +bugs have been found and fixed in this way over the past few +years. Other possible causes of EEH errors include data or +address line parity errors (for example, due to poor electrical +connectivity due to a poorly seated card), and PCI-X split-completion +errors (due to software, device firmware, or device PCI hardware bugs). +The vast majority of "true hardware failures" can be cured by +physically removing and re-seating the PCI card. + + +Detection and Recovery +---------------------- +In the following discussion, a generic overview of how to detect +and recover from EEH errors will be presented. This is followed +by an overview of how the current implementation in the Linux +kernel does it. The actual implementation is subject to change, +and some of the finer points are still being debated. These +may in turn be swayed if or when other architectures implement +similar functionality. + +When a PCI Host Bridge (PHB, the bus controller connecting the +PCI bus to the system CPU electronics complex) detects a PCI error +condition, it will "isolate" the affected PCI card. Isolation +will block all writes (either to the card from the system, or +from the card to the system), and it will cause all reads to +return all-ff's (0xff, 0xffff, 0xffffffff for 8/16/32-bit reads). +This value was chosen because it is the same value you would +get if the device was physically unplugged from the slot. +This includes access to PCI memory, I/O space, and PCI config +space. Interrupts; however, will continue to be delivered. + +Detection and recovery are performed with the aid of ppc64 +firmware. The programming interfaces in the Linux kernel +into the firmware are referred to as RTAS (Run-Time Abstraction +Services). The Linux kernel does not (should not) access +the EEH function in the PCI chipsets directly, primarily because +there are a number of different chipsets out there, each with +different interfaces and quirks. The firmware provides a +uniform abstraction layer that will work with all pSeries +and iSeries hardware (and be forwards-compatible). + +If the OS or device driver suspects that a PCI slot has been +EEH-isolated, there is a firmware call it can make to determine if +this is the case. If so, then the device driver should put itself +into a consistent state (given that it won't be able to complete any +pending work) and start recovery of the card. Recovery normally +would consist of resetting the PCI device (holding the PCI #RST +line high for two seconds), followed by setting up the device +config space (the base address registers (BAR's), latency timer, +cache line size, interrupt line, and so on). This is followed by a +reinitialization of the device driver. In a worst-case scenario, +the power to the card can be toggled, at least on hot-plug-capable +slots. In principle, layers far above the device driver probably +do not need to know that the PCI card has been "rebooted" in this +way; ideally, there should be at most a pause in Ethernet/disk/USB +I/O while the card is being reset. + +If the card cannot be recovered after three or four resets, the +kernel/device driver should assume the worst-case scenario, that the +card has died completely, and report this error to the sysadmin. +In addition, error messages are reported through RTAS and also through +syslogd (/var/log/messages) to alert the sysadmin of PCI resets. +The correct way to deal with failed adapters is to use the standard +PCI hotplug tools to remove and replace the dead card. + + +Current PPC64 Linux EEH Implementation +-------------------------------------- +At this time, a generic EEH recovery mechanism has been implemented, +so that individual device drivers do not need to be modified to support +EEH recovery. This generic mechanism piggy-backs on the PCI hotplug +infrastructure, and percolates events up through the userspace/udev +infrastructure. Following is a detailed description of how this is +accomplished. + +EEH must be enabled in the PHB's very early during the boot process, +and if a PCI slot is hot-plugged. The former is performed by +eeh_init() in arch/powerpc/platforms/pseries/eeh.c, and the later by +drivers/pci/hotplug/pSeries_pci.c calling in to the eeh.c code. +EEH must be enabled before a PCI scan of the device can proceed. +Current Power5 hardware will not work unless EEH is enabled; +although older Power4 can run with it disabled. Effectively, +EEH can no longer be turned off. PCI devices *must* be +registered with the EEH code; the EEH code needs to know about +the I/O address ranges of the PCI device in order to detect an +error. Given an arbitrary address, the routine +pci_get_device_by_addr() will find the pci device associated +with that address (if any). + +The default arch/powerpc/include/asm/io.h macros readb(), inb(), insb(), +etc. include a check to see if the i/o read returned all-0xff's. +If so, these make a call to eeh_dn_check_failure(), which in turn +asks the firmware if the all-ff's value is the sign of a true EEH +error. If it is not, processing continues as normal. The grand +total number of these false alarms or "false positives" can be +seen in /proc/ppc64/eeh (subject to change). Normally, almost +all of these occur during boot, when the PCI bus is scanned, where +a large number of 0xff reads are part of the bus scan procedure. + +If a frozen slot is detected, code in +arch/powerpc/platforms/pseries/eeh.c will print a stack trace to +syslog (/var/log/messages). This stack trace has proven to be very +useful to device-driver authors for finding out at what point the EEH +error was detected, as the error itself usually occurs slightly +beforehand. + +Next, it uses the Linux kernel notifier chain/work queue mechanism to +allow any interested parties to find out about the failure. Device +drivers, or other parts of the kernel, can use +`eeh_register_notifier(struct notifier_block *)` to find out about EEH +events. The event will include a pointer to the pci device, the +device node and some state info. Receivers of the event can "do as +they wish"; the default handler will be described further in this +section. + +To assist in the recovery of the device, eeh.c exports the +following functions: + +rtas_set_slot_reset() + assert the PCI #RST line for 1/8th of a second +rtas_configure_bridge() + ask firmware to configure any PCI bridges + located topologically under the pci slot. +eeh_save_bars() and eeh_restore_bars(): + save and restore the PCI + config-space info for a device and any devices under it. + + +A handler for the EEH notifier_block events is implemented in +drivers/pci/hotplug/pSeries_pci.c, called handle_eeh_events(). +It saves the device BAR's and then calls rpaphp_unconfig_pci_adapter(). +This last call causes the device driver for the card to be stopped, +which causes uevents to go out to user space. This triggers +user-space scripts that might issue commands such as "ifdown eth0" +for ethernet cards, and so on. This handler then sleeps for 5 seconds, +hoping to give the user-space scripts enough time to complete. +It then resets the PCI card, reconfigures the device BAR's, and +any bridges underneath. It then calls rpaphp_enable_pci_slot(), +which restarts the device driver and triggers more user-space +events (for example, calling "ifup eth0" for ethernet cards). + + +Device Shutdown and User-Space Events +------------------------------------- +This section documents what happens when a pci slot is unconfigured, +focusing on how the device driver gets shut down, and on how the +events get delivered to user-space scripts. + +Following is an example sequence of events that cause a device driver +close function to be called during the first phase of an EEH reset. +The following sequence is an example of the pcnet32 device driver:: + + rpa_php_unconfig_pci_adapter (struct slot *) // in rpaphp_pci.c + { + calls + pci_remove_bus_device (struct pci_dev *) // in /drivers/pci/remove.c + { + calls + pci_destroy_dev (struct pci_dev *) + { + calls + device_unregister (&dev->dev) // in /drivers/base/core.c + { + calls + device_del (struct device *) + { + calls + bus_remove_device() // in /drivers/base/bus.c + { + calls + device_release_driver() + { + calls + struct device_driver->remove() which is just + pci_device_remove() // in /drivers/pci/pci_driver.c + { + calls + struct pci_driver->remove() which is just + pcnet32_remove_one() // in /drivers/net/pcnet32.c + { + calls + unregister_netdev() // in /net/core/dev.c + { + calls + dev_close() // in /net/core/dev.c + { + calls dev->stop(); + which is just pcnet32_close() // in pcnet32.c + { + which does what you wanted + to stop the device + } + } + } + which + frees pcnet32 device driver memory + } + }}}}}} + + +in drivers/pci/pci_driver.c, +struct device_driver->remove() is just pci_device_remove() +which calls struct pci_driver->remove() which is pcnet32_remove_one() +which calls unregister_netdev() (in net/core/dev.c) +which calls dev_close() (in net/core/dev.c) +which calls dev->stop() which is pcnet32_close() +which then does the appropriate shutdown. + +--- + +Following is the analogous stack trace for events sent to user-space +when the pci device is unconfigured:: + + rpa_php_unconfig_pci_adapter() { // in rpaphp_pci.c + calls + pci_remove_bus_device (struct pci_dev *) { // in /drivers/pci/remove.c + calls + pci_destroy_dev (struct pci_dev *) { + calls + device_unregister (&dev->dev) { // in /drivers/base/core.c + calls + device_del(struct device * dev) { // in /drivers/base/core.c + calls + kobject_del() { //in /libs/kobject.c + calls + kobject_uevent() { // in /libs/kobject.c + calls + kset_uevent() { // in /lib/kobject.c + calls + kset->uevent_ops->uevent() // which is really just + a call to + dev_uevent() { // in /drivers/base/core.c + calls + dev->bus->uevent() which is really just a call to + pci_uevent () { // in drivers/pci/hotplug.c + which prints device name, etc.... + } + } + then kobject_uevent() sends a netlink uevent to userspace + --> userspace uevent + (during early boot, nobody listens to netlink events and + kobject_uevent() executes uevent_helper[], which runs the + event process /sbin/hotplug) + } + } + kobject_del() then calls sysfs_remove_dir(), which would + trigger any user-space daemon that was watching /sysfs, + and notice the delete event. + + +Pro's and Con's of the Current Design +------------------------------------- +There are several issues with the current EEH software recovery design, +which may be addressed in future revisions. But first, note that the +big plus of the current design is that no changes need to be made to +individual device drivers, so that the current design throws a wide net. +The biggest negative of the design is that it potentially disturbs +network daemons and file systems that didn't need to be disturbed. + +- A minor complaint is that resetting the network card causes + user-space back-to-back ifdown/ifup burps that potentially disturb + network daemons, that didn't need to even know that the pci + card was being rebooted. + +- A more serious concern is that the same reset, for SCSI devices, + causes havoc to mounted file systems. Scripts cannot post-facto + unmount a file system without flushing pending buffers, but this + is impossible, because I/O has already been stopped. Thus, + ideally, the reset should happen at or below the block layer, + so that the file systems are not disturbed. + + Reiserfs does not tolerate errors returned from the block device. + Ext3fs seems to be tolerant, retrying reads/writes until it does + succeed. Both have been only lightly tested in this scenario. + + The SCSI-generic subsystem already has built-in code for performing + SCSI device resets, SCSI bus resets, and SCSI host-bus-adapter + (HBA) resets. These are cascaded into a chain of attempted + resets if a SCSI command fails. These are completely hidden + from the block layer. It would be very natural to add an EEH + reset into this chain of events. + +- If a SCSI error occurs for the root device, all is lost unless + the sysadmin had the foresight to run /bin, /sbin, /etc, /var + and so on, out of ramdisk/tmpfs. + + +Conclusions +----------- +There's forward progress ... diff --git a/Documentation/arch/powerpc/elf_hwcaps.rst b/Documentation/arch/powerpc/elf_hwcaps.rst new file mode 100644 index 0000000000..4c896cf077 --- /dev/null +++ b/Documentation/arch/powerpc/elf_hwcaps.rst @@ -0,0 +1,231 @@ +.. _elf_hwcaps_powerpc: + +================== +POWERPC ELF HWCAPs +================== + +This document describes the usage and semantics of the powerpc ELF HWCAPs. + + +1. Introduction +--------------- + +Some hardware or software features are only available on some CPU +implementations, and/or with certain kernel configurations, but have no other +discovery mechanism available to userspace code. The kernel exposes the +presence of these features to userspace through a set of flags called HWCAPs, +exposed in the auxiliary vector. + +Userspace software can test for features by acquiring the AT_HWCAP or +AT_HWCAP2 entry of the auxiliary vector, and testing whether the relevant +flags are set, e.g.:: + + bool floating_point_is_present(void) + { + unsigned long HWCAPs = getauxval(AT_HWCAP); + if (HWCAPs & PPC_FEATURE_HAS_FPU) + return true; + + return false; + } + +Where software relies on a feature described by a HWCAP, it should check the +relevant HWCAP flag to verify that the feature is present before attempting to +make use of the feature. + +HWCAP is the preferred method to test for the presence of a feature rather +than probing through other means, which may not be reliable or may cause +unpredictable behaviour. + +Software that targets a particular platform does not necessarily have to +test for required or implied features. For example if the program requires +FPU, VMX, VSX, it is not necessary to test those HWCAPs, and it may be +impossible to do so if the compiler generates code requiring those features. + +2. Facilities +------------- + +The Power ISA uses the term "facility" to describe a class of instructions, +registers, interrupts, etc. The presence or absence of a facility indicates +whether this class is available to be used, but the specifics depend on the +ISA version. For example, if the VSX facility is available, the VSX +instructions that can be used differ between the v3.0B and v3.1B ISA +versions. + +3. Categories +------------- + +The Power ISA before v3.0 uses the term "category" to describe certain +classes of instructions and operating modes which may be optional or +mutually exclusive, the exact meaning of the HWCAP flag may depend on +context, e.g., the presence of the BOOKE feature implies that the server +category is not implemented. + +4. HWCAP allocation +------------------- + +HWCAPs are allocated as described in Power Architecture 64-Bit ELF V2 ABI +Specification (which will be reflected in the kernel's uapi headers). + +5. The HWCAPs exposed in AT_HWCAP +--------------------------------- + +PPC_FEATURE_32 + 32-bit CPU + +PPC_FEATURE_64 + 64-bit CPU (userspace may be running in 32-bit mode). + +PPC_FEATURE_601_INSTR + The processor is PowerPC 601. + Unused in the kernel since f0ed73f3fa2c ("powerpc: Remove PowerPC 601") + +PPC_FEATURE_HAS_ALTIVEC + Vector (aka Altivec, VMX) facility is available. + +PPC_FEATURE_HAS_FPU + Floating point facility is available. + +PPC_FEATURE_HAS_MMU + Memory management unit is present and enabled. + +PPC_FEATURE_HAS_4xxMAC + The processor is 40x or 44x family. + +PPC_FEATURE_UNIFIED_CACHE + The processor has a unified L1 cache for instructions and data, as + found in NXP e200. + Unused in the kernel since 39c8bf2b3cc1 ("powerpc: Retire e200 core (mpc555x processor)") + +PPC_FEATURE_HAS_SPE + Signal Processing Engine facility is available. + +PPC_FEATURE_HAS_EFP_SINGLE + Embedded Floating Point single precision operations are available. + +PPC_FEATURE_HAS_EFP_DOUBLE + Embedded Floating Point double precision operations are available. + +PPC_FEATURE_NO_TB + The timebase facility (mftb instruction) is not available. + This is a 601 specific HWCAP, so if it is known that the processor + running is not a 601, via other HWCAPs or other means, it is not + required to test this bit before using the timebase. + Unused in the kernel since f0ed73f3fa2c ("powerpc: Remove PowerPC 601") + +PPC_FEATURE_POWER4 + The processor is POWER4 or PPC970/FX/MP. + POWER4 support dropped from the kernel since 471d7ff8b51b ("powerpc/64s: Remove POWER4 support") + +PPC_FEATURE_POWER5 + The processor is POWER5. + +PPC_FEATURE_POWER5_PLUS + The processor is POWER5+. + +PPC_FEATURE_CELL + The processor is Cell. + +PPC_FEATURE_BOOKE + The processor implements the embedded category ("BookE") architecture. + +PPC_FEATURE_SMT + The processor implements SMT. + +PPC_FEATURE_ICACHE_SNOOP + The processor icache is coherent with the dcache, and instruction storage + can be made consistent with data storage for the purpose of executing + instructions with the sequence (as described in, e.g., POWER9 Processor + User's Manual, 4.6.2.2 Instruction Cache Block Invalidate (icbi)):: + + sync + icbi (to any address) + isync + +PPC_FEATURE_ARCH_2_05 + The processor supports the v2.05 userlevel architecture. Processors + supporting later architectures DO NOT set this feature. + +PPC_FEATURE_PA6T + The processor is PA6T. + +PPC_FEATURE_HAS_DFP + DFP facility is available. + +PPC_FEATURE_POWER6_EXT + The processor is POWER6. + +PPC_FEATURE_ARCH_2_06 + The processor supports the v2.06 userlevel architecture. Processors + supporting later architectures also set this feature. + +PPC_FEATURE_HAS_VSX + VSX facility is available. + +PPC_FEATURE_PSERIES_PERFMON_COMPAT + The processor supports architected PMU events in the range 0xE0-0xFF. + +PPC_FEATURE_TRUE_LE + The processor supports true little-endian mode. + +PPC_FEATURE_PPC_LE + The processor supports "PowerPC Little-Endian", that uses address + munging to make storage access appear to be little-endian, but the + data is stored in a different format that is unsuitable to be + accessed by other agents not running in this mode. + +6. The HWCAPs exposed in AT_HWCAP2 +---------------------------------- + +PPC_FEATURE2_ARCH_2_07 + The processor supports the v2.07 userlevel architecture. Processors + supporting later architectures also set this feature. + +PPC_FEATURE2_HTM + Transactional Memory feature is available. + +PPC_FEATURE2_DSCR + DSCR facility is available. + +PPC_FEATURE2_EBB + EBB facility is available. + +PPC_FEATURE2_ISEL + isel instruction is available. This is superseded by ARCH_2_07 and + later. + +PPC_FEATURE2_TAR + TAR facility is available. + +PPC_FEATURE2_VEC_CRYPTO + v2.07 crypto instructions are available. + +PPC_FEATURE2_HTM_NOSC + System calls fail if called in a transactional state, see + Documentation/arch/powerpc/syscall64-abi.rst + +PPC_FEATURE2_ARCH_3_00 + The processor supports the v3.0B / v3.0C userlevel architecture. Processors + supporting later architectures also set this feature. + +PPC_FEATURE2_HAS_IEEE128 + IEEE 128-bit binary floating point is supported with VSX + quad-precision instructions and data types. + +PPC_FEATURE2_DARN + darn instruction is available. + +PPC_FEATURE2_SCV + The scv 0 instruction may be used for system calls, see + Documentation/arch/powerpc/syscall64-abi.rst. + +PPC_FEATURE2_HTM_NO_SUSPEND + A limited Transactional Memory facility that does not support suspend is + available, see Documentation/arch/powerpc/transactional_memory.rst. + +PPC_FEATURE2_ARCH_3_1 + The processor supports the v3.1 userlevel architecture. Processors + supporting later architectures also set this feature. + +PPC_FEATURE2_MMA + MMA facility is available. diff --git a/Documentation/arch/powerpc/elfnote.rst b/Documentation/arch/powerpc/elfnote.rst new file mode 100644 index 0000000000..3ec8d61e9a --- /dev/null +++ b/Documentation/arch/powerpc/elfnote.rst @@ -0,0 +1,41 @@ +========================== +ELF Note PowerPC Namespace +========================== + +The PowerPC namespace in an ELF Note of the kernel binary is used to store +capabilities and information which can be used by a bootloader or userland. + +Types and Descriptors +--------------------- + +The types to be used with the "PowerPC" namespace are defined in [#f1]_. + + 1) PPC_ELFNOTE_CAPABILITIES + +Define the capabilities supported/required by the kernel. This type uses a +bitmap as "descriptor" field. Each bit is described below: + +- Ultravisor-capable bit (PowerNV only). + +.. code-block:: c + + #define PPCCAP_ULTRAVISOR_BIT (1 << 0) + +Indicate that the powerpc kernel binary knows how to run in an +ultravisor-enabled system. + +In an ultravisor-enabled system, some machine resources are now controlled +by the ultravisor. If the kernel is not ultravisor-capable, but it ends up +being run on a machine with ultravisor, the kernel will probably crash +trying to access ultravisor resources. For instance, it may crash in early +boot trying to set the partition table entry 0. + +In an ultravisor-enabled system, a bootloader could warn the user or prevent +the kernel from being run if the PowerPC ultravisor capability doesn't exist +or the Ultravisor-capable bit is not set. + +References +---------- + +.. [#f1] arch/powerpc/include/asm/elfnote.h + diff --git a/Documentation/arch/powerpc/features.rst b/Documentation/arch/powerpc/features.rst new file mode 100644 index 0000000000..ee4b95e042 --- /dev/null +++ b/Documentation/arch/powerpc/features.rst @@ -0,0 +1,3 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. kernel-feat:: features powerpc diff --git a/Documentation/arch/powerpc/firmware-assisted-dump.rst b/Documentation/arch/powerpc/firmware-assisted-dump.rst new file mode 100644 index 0000000000..e363fc4852 --- /dev/null +++ b/Documentation/arch/powerpc/firmware-assisted-dump.rst @@ -0,0 +1,381 @@ +====================== +Firmware-Assisted Dump +====================== + +July 2011 + +The goal of firmware-assisted dump is to enable the dump of +a crashed system, and to do so from a fully-reset system, and +to minimize the total elapsed time until the system is back +in production use. + +- Firmware-Assisted Dump (FADump) infrastructure is intended to replace + the existing phyp assisted dump. +- Fadump uses the same firmware interfaces and memory reservation model + as phyp assisted dump. +- Unlike phyp dump, FADump exports the memory dump through /proc/vmcore + in the ELF format in the same way as kdump. This helps us reuse the + kdump infrastructure for dump capture and filtering. +- Unlike phyp dump, userspace tool does not need to refer any sysfs + interface while reading /proc/vmcore. +- Unlike phyp dump, FADump allows user to release all the memory reserved + for dump, with a single operation of echo 1 > /sys/kernel/fadump_release_mem. +- Once enabled through kernel boot parameter, FADump can be + started/stopped through /sys/kernel/fadump_registered interface (see + sysfs files section below) and can be easily integrated with kdump + service start/stop init scripts. + +Comparing with kdump or other strategies, firmware-assisted +dump offers several strong, practical advantages: + +- Unlike kdump, the system has been reset, and loaded + with a fresh copy of the kernel. In particular, + PCI and I/O devices have been reinitialized and are + in a clean, consistent state. +- Once the dump is copied out, the memory that held the dump + is immediately available to the running kernel. And therefore, + unlike kdump, FADump doesn't need a 2nd reboot to get back + the system to the production configuration. + +The above can only be accomplished by coordination with, +and assistance from the Power firmware. The procedure is +as follows: + +- The first kernel registers the sections of memory with the + Power firmware for dump preservation during OS initialization. + These registered sections of memory are reserved by the first + kernel during early boot. + +- When system crashes, the Power firmware will copy the registered + low memory regions (boot memory) from source to destination area. + It will also save hardware PTE's. + + NOTE: + The term 'boot memory' means size of the low memory chunk + that is required for a kernel to boot successfully when + booted with restricted memory. By default, the boot memory + size will be the larger of 5% of system RAM or 256MB. + Alternatively, user can also specify boot memory size + through boot parameter 'crashkernel=' which will override + the default calculated size. Use this option if default + boot memory size is not sufficient for second kernel to + boot successfully. For syntax of crashkernel= parameter, + refer to Documentation/admin-guide/kdump/kdump.rst. If any + offset is provided in crashkernel= parameter, it will be + ignored as FADump uses a predefined offset to reserve memory + for boot memory dump preservation in case of a crash. + +- After the low memory (boot memory) area has been saved, the + firmware will reset PCI and other hardware state. It will + *not* clear the RAM. It will then launch the bootloader, as + normal. + +- The freshly booted kernel will notice that there is a new node + (rtas/ibm,kernel-dump on pSeries or ibm,opal/dump/mpipl-boot + on OPAL platform) in the device tree, indicating that + there is crash data available from a previous boot. During + the early boot OS will reserve rest of the memory above + boot memory size effectively booting with restricted memory + size. This will make sure that this kernel (also, referred + to as second kernel or capture kernel) will not touch any + of the dump memory area. + +- User-space tools will read /proc/vmcore to obtain the contents + of memory, which holds the previous crashed kernel dump in ELF + format. The userspace tools may copy this info to disk, or + network, nas, san, iscsi, etc. as desired. + +- Once the userspace tool is done saving dump, it will echo + '1' to /sys/kernel/fadump_release_mem to release the reserved + memory back to general use, except the memory required for + next firmware-assisted dump registration. + + e.g.:: + + # echo 1 > /sys/kernel/fadump_release_mem + +Please note that the firmware-assisted dump feature +is only available on POWER6 and above systems on pSeries +(PowerVM) platform and POWER9 and above systems with OP940 +or later firmware versions on PowerNV (OPAL) platform. +Note that, OPAL firmware exports ibm,opal/dump node when +FADump is supported on PowerNV platform. + +On OPAL based machines, system first boots into an intermittent +kernel (referred to as petitboot kernel) before booting into the +capture kernel. This kernel would have minimal kernel and/or +userspace support to process crash data. Such kernel needs to +preserve previously crash'ed kernel's memory for the subsequent +capture kernel boot to process this crash data. Kernel config +option CONFIG_PRESERVE_FA_DUMP has to be enabled on such kernel +to ensure that crash data is preserved to process later. + +-- On OPAL based machines (PowerNV), if the kernel is build with + CONFIG_OPAL_CORE=y, OPAL memory at the time of crash is also + exported as /sys/firmware/opal/mpipl/core file. This procfs file is + helpful in debugging OPAL crashes with GDB. The kernel memory + used for exporting this procfs file can be released by echo'ing + '1' to /sys/firmware/opal/mpipl/release_core node. + + e.g. + # echo 1 > /sys/firmware/opal/mpipl/release_core + +Implementation details: +----------------------- + +During boot, a check is made to see if firmware supports +this feature on that particular machine. If it does, then +we check to see if an active dump is waiting for us. If yes +then everything but boot memory size of RAM is reserved during +early boot (See Fig. 2). This area is released once we finish +collecting the dump from user land scripts (e.g. kdump scripts) +that are run. If there is dump data, then the +/sys/kernel/fadump_release_mem file is created, and the reserved +memory is held. + +If there is no waiting dump data, then only the memory required to +hold CPU state, HPTE region, boot memory dump, FADump header and +elfcore header, is usually reserved at an offset greater than boot +memory size (see Fig. 1). This area is *not* released: this region +will be kept permanently reserved, so that it can act as a receptacle +for a copy of the boot memory content in addition to CPU state and +HPTE region, in the case a crash does occur. + +Since this reserved memory area is used only after the system crash, +there is no point in blocking this significant chunk of memory from +production kernel. Hence, the implementation uses the Linux kernel's +Contiguous Memory Allocator (CMA) for memory reservation if CMA is +configured for kernel. With CMA reservation this memory will be +available for applications to use it, while kernel is prevented from +using it. With this FADump will still be able to capture all of the +kernel memory and most of the user space memory except the user pages +that were present in CMA region:: + + o Memory Reservation during first kernel + + Low memory Top of memory + 0 boot memory size |<--- Reserved dump area --->| | + | | | Permanent Reservation | | + V V | | V + +-----------+-----/ /---+---+----+-------+-----+-----+----+--+ + | | |///|////| DUMP | HDR | ELF |////| | + +-----------+-----/ /---+---+----+-------+-----+-----+----+--+ + | ^ ^ ^ ^ ^ + | | | | | | + \ CPU HPTE / | | + ------------------------------ | | + Boot memory content gets transferred | | + to reserved area by firmware at the | | + time of crash. | | + FADump Header | + (meta area) | + | + | + Metadata: This area holds a metadata structure whose + address is registered with f/w and retrieved in the + second kernel after crash, on platforms that support + tags (OPAL). Having such structure with info needed + to process the crashdump eases dump capture process. + + Fig. 1 + + + o Memory Reservation during second kernel after crash + + Low memory Top of memory + 0 boot memory size | + | |<------------ Crash preserved area ------------>| + V V |<--- Reserved dump area --->| | + +-----------+-----/ /---+---+----+-------+-----+-----+----+--+ + | | |///|////| DUMP | HDR | ELF |////| | + +-----------+-----/ /---+---+----+-------+-----+-----+----+--+ + | | + V V + Used by second /proc/vmcore + kernel to boot + + +---+ + |///| -> Regions (CPU, HPTE & Metadata) marked like this in the above + +---+ figures are not always present. For example, OPAL platform + does not have CPU & HPTE regions while Metadata region is + not supported on pSeries currently. + + Fig. 2 + + +Currently the dump will be copied from /proc/vmcore to a new file upon +user intervention. The dump data available through /proc/vmcore will be +in ELF format. Hence the existing kdump infrastructure (kdump scripts) +to save the dump works fine with minor modifications. KDump scripts on +major Distro releases have already been modified to work seamlessly (no +user intervention in saving the dump) when FADump is used, instead of +KDump, as dump mechanism. + +The tools to examine the dump will be same as the ones +used for kdump. + +How to enable firmware-assisted dump (FADump): +---------------------------------------------- + +1. Set config option CONFIG_FA_DUMP=y and build kernel. +2. Boot into linux kernel with 'fadump=on' kernel cmdline option. + By default, FADump reserved memory will be initialized as CMA area. + Alternatively, user can boot linux kernel with 'fadump=nocma' to + prevent FADump to use CMA. +3. Optionally, user can also set 'crashkernel=' kernel cmdline + to specify size of the memory to reserve for boot memory dump + preservation. + +NOTE: + 1. 'fadump_reserve_mem=' parameter has been deprecated. Instead + use 'crashkernel=' to specify size of the memory to reserve + for boot memory dump preservation. + 2. If firmware-assisted dump fails to reserve memory then it + will fallback to existing kdump mechanism if 'crashkernel=' + option is set at kernel cmdline. + 3. if user wants to capture all of user space memory and ok with + reserved memory not available to production system, then + 'fadump=nocma' kernel parameter can be used to fallback to + old behaviour. + +Sysfs/debugfs files: +-------------------- + +Firmware-assisted dump feature uses sysfs file system to hold +the control files and debugfs file to display memory reserved region. + +Here is the list of files under kernel sysfs: + + /sys/kernel/fadump_enabled + This is used to display the FADump status. + + - 0 = FADump is disabled + - 1 = FADump is enabled + + This interface can be used by kdump init scripts to identify if + FADump is enabled in the kernel and act accordingly. + + /sys/kernel/fadump_registered + This is used to display the FADump registration status as well + as to control (start/stop) the FADump registration. + + - 0 = FADump is not registered. + - 1 = FADump is registered and ready to handle system crash. + + To register FADump echo 1 > /sys/kernel/fadump_registered and + echo 0 > /sys/kernel/fadump_registered for un-register and stop the + FADump. Once the FADump is un-registered, the system crash will not + be handled and vmcore will not be captured. This interface can be + easily integrated with kdump service start/stop. + + /sys/kernel/fadump/mem_reserved + + This is used to display the memory reserved by FADump for saving the + crash dump. + + /sys/kernel/fadump_release_mem + This file is available only when FADump is active during + second kernel. This is used to release the reserved memory + region that are held for saving crash dump. To release the + reserved memory echo 1 to it:: + + echo 1 > /sys/kernel/fadump_release_mem + + After echo 1, the content of the /sys/kernel/debug/powerpc/fadump_region + file will change to reflect the new memory reservations. + + The existing userspace tools (kdump infrastructure) can be easily + enhanced to use this interface to release the memory reserved for + dump and continue without 2nd reboot. + +Note: /sys/kernel/fadump_release_opalcore sysfs has moved to + /sys/firmware/opal/mpipl/release_core + + /sys/firmware/opal/mpipl/release_core + + This file is available only on OPAL based machines when FADump is + active during capture kernel. This is used to release the memory + used by the kernel to export /sys/firmware/opal/mpipl/core file. To + release this memory, echo '1' to it: + + echo 1 > /sys/firmware/opal/mpipl/release_core + +Note: The following FADump sysfs files are deprecated. + ++----------------------------------+--------------------------------+ +| Deprecated | Alternative | ++----------------------------------+--------------------------------+ +| /sys/kernel/fadump_enabled | /sys/kernel/fadump/enabled | ++----------------------------------+--------------------------------+ +| /sys/kernel/fadump_registered | /sys/kernel/fadump/registered | ++----------------------------------+--------------------------------+ +| /sys/kernel/fadump_release_mem | /sys/kernel/fadump/release_mem | ++----------------------------------+--------------------------------+ + +Here is the list of files under powerpc debugfs: +(Assuming debugfs is mounted on /sys/kernel/debug directory.) + + /sys/kernel/debug/powerpc/fadump_region + This file shows the reserved memory regions if FADump is + enabled otherwise this file is empty. The output format + is:: + + : [-] bytes, Dumped: + + and for kernel DUMP region is: + + DUMP: Src: , Dest: , Size: , Dumped: # bytes + + e.g. + Contents when FADump is registered during first kernel:: + + # cat /sys/kernel/debug/powerpc/fadump_region + CPU : [0x0000006ffb0000-0x0000006fff001f] 0x40020 bytes, Dumped: 0x0 + HPTE: [0x0000006fff0020-0x0000006fff101f] 0x1000 bytes, Dumped: 0x0 + DUMP: [0x0000006fff1020-0x0000007fff101f] 0x10000000 bytes, Dumped: 0x0 + + Contents when FADump is active during second kernel:: + + # cat /sys/kernel/debug/powerpc/fadump_region + CPU : [0x0000006ffb0000-0x0000006fff001f] 0x40020 bytes, Dumped: 0x40020 + HPTE: [0x0000006fff0020-0x0000006fff101f] 0x1000 bytes, Dumped: 0x1000 + DUMP: [0x0000006fff1020-0x0000007fff101f] 0x10000000 bytes, Dumped: 0x10000000 + : [0x00000010000000-0x0000006ffaffff] 0x5ffb0000 bytes, Dumped: 0x5ffb0000 + + +NOTE: + Please refer to Documentation/filesystems/debugfs.rst on + how to mount the debugfs filesystem. + + +TODO: +----- + - Need to come up with the better approach to find out more + accurate boot memory size that is required for a kernel to + boot successfully when booted with restricted memory. + - The FADump implementation introduces a FADump crash info structure + in the scratch area before the ELF core header. The idea of introducing + this structure is to pass some important crash info data to the second + kernel which will help second kernel to populate ELF core header with + correct data before it gets exported through /proc/vmcore. The current + design implementation does not address a possibility of introducing + additional fields (in future) to this structure without affecting + compatibility. Need to come up with the better approach to address this. + + The possible approaches are: + + 1. Introduce version field for version tracking, bump up the version + whenever a new field is added to the structure in future. The version + field can be used to find out what fields are valid for the current + version of the structure. + 2. Reserve the area of predefined size (say PAGE_SIZE) for this + structure and have unused area as reserved (initialized to zero) + for future field additions. + + The advantage of approach 1 over 2 is we don't need to reserve extra space. + +Author: Mahesh Salgaonkar + +This document is based on the original documentation written for phyp + +assisted dump by Linas Vepstas and Manish Ahuja. diff --git a/Documentation/arch/powerpc/hvcs.rst b/Documentation/arch/powerpc/hvcs.rst new file mode 100644 index 0000000000..6808acde67 --- /dev/null +++ b/Documentation/arch/powerpc/hvcs.rst @@ -0,0 +1,581 @@ +=============================================================== +HVCS IBM "Hypervisor Virtual Console Server" Installation Guide +=============================================================== + +for Linux Kernel 2.6.4+ + +Copyright (C) 2004 IBM Corporation + +.. =========================================================================== +.. NOTE:Eight space tabs are the optimum editor setting for reading this file. +.. =========================================================================== + + +Author(s): Ryan S. Arnold + +Date Created: March, 02, 2004 +Last Changed: August, 24, 2004 + +.. Table of contents: + + 1. Driver Introduction: + 2. System Requirements + 3. Build Options: + 3.1 Built-in: + 3.2 Module: + 4. Installation: + 5. Connection: + 6. Disconnection: + 7. Configuration: + 8. Questions & Answers: + 9. Reporting Bugs: + +1. Driver Introduction: +======================= + +This is the device driver for the IBM Hypervisor Virtual Console Server, +"hvcs". The IBM hvcs provides a tty driver interface to allow Linux user +space applications access to the system consoles of logically partitioned +operating systems (Linux and AIX) running on the same partitioned Power5 +ppc64 system. Physical hardware consoles per partition are not practical +on this hardware so system consoles are accessed by this driver using +firmware interfaces to virtual terminal devices. + +2. System Requirements: +======================= + +This device driver was written using 2.6.4 Linux kernel APIs and will only +build and run on kernels of this version or later. + +This driver was written to operate solely on IBM Power5 ppc64 hardware +though some care was taken to abstract the architecture dependent firmware +calls from the driver code. + +Sysfs must be mounted on the system so that the user can determine which +major and minor numbers are associated with each vty-server. Directions +for sysfs mounting are outside the scope of this document. + +3. Build Options: +================= + +The hvcs driver registers itself as a tty driver. The tty layer +dynamically allocates a block of major and minor numbers in a quantity +requested by the registering driver. The hvcs driver asks the tty layer +for 64 of these major/minor numbers by default to use for hvcs device node +entries. + +If the default number of device entries is adequate then this driver can be +built into the kernel. If not, the default can be over-ridden by inserting +the driver as a module with insmod parameters. + +3.1 Built-in: +------------- + +The following menuconfig example demonstrates selecting to build this +driver into the kernel:: + + Device Drivers ---> + Character devices ---> + <*> IBM Hypervisor Virtual Console Server Support + +Begin the kernel make process. + +3.2 Module: +----------- + +The following menuconfig example demonstrates selecting to build this +driver as a kernel module:: + + Device Drivers ---> + Character devices ---> + IBM Hypervisor Virtual Console Server Support + +The make process will build the following kernel modules: + + - hvcs.ko + - hvcserver.ko + +To insert the module with the default allocation execute the following +commands in the order they appear:: + + insmod hvcserver.ko + insmod hvcs.ko + +The hvcserver module contains architecture specific firmware calls and must +be inserted first, otherwise the hvcs module will not find some of the +symbols it expects. + +To override the default use an insmod parameter as follows (requesting 4 +tty devices as an example):: + + insmod hvcs.ko hvcs_parm_num_devs=4 + +There is a maximum number of dev entries that can be specified on insmod. +We think that 1024 is currently a decent maximum number of server adapters +to allow. This can always be changed by modifying the constant in the +source file before building. + +NOTE: The length of time it takes to insmod the driver seems to be related +to the number of tty interfaces the registering driver requests. + +In order to remove the driver module execute the following command:: + + rmmod hvcs.ko + +The recommended method for installing hvcs as a module is to use depmod to +build a current modules.dep file in /lib/modules/`uname -r` and then +execute:: + + modprobe hvcs hvcs_parm_num_devs=4 + +The modules.dep file indicates that hvcserver.ko needs to be inserted +before hvcs.ko and modprobe uses this file to smartly insert the modules in +the proper order. + +The following modprobe command is used to remove hvcs and hvcserver in the +proper order:: + + modprobe -r hvcs + +4. Installation: +================ + +The tty layer creates sysfs entries which contain the major and minor +numbers allocated for the hvcs driver. The following snippet of "tree" +output of the sysfs directory shows where these numbers are presented:: + + sys/ + |-- *other sysfs base dirs* + | + |-- class + | |-- *other classes of devices* + | | + | `-- tty + | |-- *other tty devices* + | | + | |-- hvcs0 + | | `-- dev + | |-- hvcs1 + | | `-- dev + | |-- hvcs2 + | | `-- dev + | |-- hvcs3 + | | `-- dev + | | + | |-- *other tty devices* + | + |-- *other sysfs base dirs* + +For the above examples the following output is a result of cat'ing the +"dev" entry in the hvcs directory:: + + Pow5:/sys/class/tty/hvcs0/ # cat dev + 254:0 + + Pow5:/sys/class/tty/hvcs1/ # cat dev + 254:1 + + Pow5:/sys/class/tty/hvcs2/ # cat dev + 254:2 + + Pow5:/sys/class/tty/hvcs3/ # cat dev + 254:3 + +The output from reading the "dev" attribute is the char device major and +minor numbers that the tty layer has allocated for this driver's use. Most +systems running hvcs will already have the device entries created or udev +will do it automatically. + +Given the example output above, to manually create a /dev/hvcs* node entry +mknod can be used as follows:: + + mknod /dev/hvcs0 c 254 0 + mknod /dev/hvcs1 c 254 1 + mknod /dev/hvcs2 c 254 2 + mknod /dev/hvcs3 c 254 3 + +Using mknod to manually create the device entries makes these device nodes +persistent. Once created they will exist prior to the driver insmod. + +Attempting to connect an application to /dev/hvcs* prior to insertion of +the hvcs module will result in an error message similar to the following:: + + "/dev/hvcs*: No such device". + +NOTE: Just because there is a device node present doesn't mean that there +is a vty-server device configured for that node. + +5. Connection +============= + +Since this driver controls devices that provide a tty interface a user can +interact with the device node entries using any standard tty-interactive +method (e.g. "cat", "dd", "echo"). The intent of this driver however, is +to provide real time console interaction with a Linux partition's console, +which requires the use of applications that provide bi-directional, +interactive I/O with a tty device. + +Applications (e.g. "minicom" and "screen") that act as terminal emulators +or perform terminal type control sequence conversion on the data being +passed through them are NOT acceptable for providing interactive console +I/O. These programs often emulate antiquated terminal types (vt100 and +ANSI) and expect inbound data to take the form of one of these supported +terminal types but they either do not convert, or do not _adequately_ +convert, outbound data into the terminal type of the terminal which invoked +them (though screen makes an attempt and can apparently be configured with +much termcap wrestling.) + +For this reason kermit and cu are two of the recommended applications for +interacting with a Linux console via an hvcs device. These programs simply +act as a conduit for data transfer to and from the tty device. They do not +require inbound data to take the form of a particular terminal type, nor do +they cook outbound data to a particular terminal type. + +In order to ensure proper functioning of console applications one must make +sure that once connected to a /dev/hvcs console that the console's $TERM +env variable is set to the exact terminal type of the terminal emulator +used to launch the interactive I/O application. If one is using xterm and +kermit to connect to /dev/hvcs0 when the console prompt becomes available +one should "export TERM=xterm" on the console. This tells ncurses +applications that are invoked from the console that they should output +control sequences that xterm can understand. + +As a precautionary measure an hvcs user should always "exit" from their +session before disconnecting an application such as kermit from the device +node. If this is not done, the next user to connect to the console will +continue using the previous user's logged in session which includes +using the $TERM variable that the previous user supplied. + +Hotplug add and remove of vty-server adapters affects which /dev/hvcs* node +is used to connect to each vty-server adapter. In order to determine which +vty-server adapter is associated with which /dev/hvcs* node a special sysfs +attribute has been added to each vty-server sysfs entry. This entry is +called "index" and showing it reveals an integer that refers to the +/dev/hvcs* entry to use to connect to that device. For instance cating the +index attribute of vty-server adapter 30000004 shows the following:: + + Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat index + 2 + +This index of '2' means that in order to connect to vty-server adapter +30000004 the user should interact with /dev/hvcs2. + +It should be noted that due to the system hotplug I/O capabilities of a +system the /dev/hvcs* entry that interacts with a particular vty-server +adapter is not guaranteed to remain the same across system reboots. Look +in the Q & A section for more on this issue. + +6. Disconnection +================ + +As a security feature to prevent the delivery of stale data to an +unintended target the Power5 system firmware disables the fetching of data +and discards that data when a connection between a vty-server and a vty has +been severed. As an example, when a vty-server is immediately disconnected +from a vty following output of data to the vty the vty adapter may not have +enough time between when it received the data interrupt and when the +connection was severed to fetch the data from firmware before the fetch is +disabled by firmware. + +When hvcs is being used to serve consoles this behavior is not a huge issue +because the adapter stays connected for large amounts of time following +almost all data writes. When hvcs is being used as a tty conduit to tunnel +data between two partitions [see Q & A below] this is a huge problem +because the standard Linux behavior when cat'ing or dd'ing data to a device +is to open the tty, send the data, and then close the tty. If this driver +manually terminated vty-server connections on tty close this would close +the vty-server and vty connection before the target vty has had a chance to +fetch the data. + +Additionally, disconnecting a vty-server and vty only on module removal or +adapter removal is impractical because other vty-servers in other +partitions may require the usage of the target vty at any time. + +Due to this behavioral restriction disconnection of vty-servers from the +connected vty is a manual procedure using a write to a sysfs attribute +outlined below, on the other hand the initial vty-server connection to a +vty is established automatically by this driver. Manual vty-server +connection is never required. + +In order to terminate the connection between a vty-server and vty the +"vterm_state" sysfs attribute within each vty-server's sysfs entry is used. +Reading this attribute reveals the current connection state of the +vty-server adapter. A zero means that the vty-server is not connected to a +vty. A one indicates that a connection is active. + +Writing a '0' (zero) to the vterm_state attribute will disconnect the VTERM +connection between the vty-server and target vty ONLY if the vterm_state +previously read '1'. The write directive is ignored if the vterm_state +read '0' or if any value other than '0' was written to the vterm_state +attribute. The following example will show the method used for verifying +the vty-server connection status and disconnecting a vty-server connection:: + + Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat vterm_state + 1 + + Pow5:/sys/bus/vio/drivers/hvcs/30000004 # echo 0 > vterm_state + + Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat vterm_state + 0 + +All vty-server connections are automatically terminated when the device is +hotplug removed and when the module is removed. + +7. Configuration +================ + +Each vty-server has a sysfs entry in the /sys/devices/vio directory, which +is symlinked in several other sysfs tree directories, notably under the +hvcs driver entry, which looks like the following example:: + + Pow5:/sys/bus/vio/drivers/hvcs # ls + . .. 30000003 30000004 rescan + +By design, firmware notifies the hvcs driver of vty-server lifetimes and +partner vty removals but not the addition of partner vtys. Since an HMC +Super Admin can add partner info dynamically we have provided the hvcs +driver sysfs directory with the "rescan" update attribute which will query +firmware and update the partner info for all the vty-servers that this +driver manages. Writing a '1' to the attribute triggers the update. An +explicit example follows: + + Pow5:/sys/bus/vio/drivers/hvcs # echo 1 > rescan + +Reading the attribute will indicate a state of '1' or '0'. A one indicates +that an update is in process. A zero indicates that an update has +completed or was never executed. + +Vty-server entries in this directory are a 32 bit partition unique unit +address that is created by firmware. An example vty-server sysfs entry +looks like the following:: + + Pow5:/sys/bus/vio/drivers/hvcs/30000004 # ls + . current_vty devspec name partner_vtys + .. index partner_clcs vterm_state + +Each entry is provided, by default with a "name" attribute. Reading the +"name" attribute will reveal the device type as shown in the following +example:: + + Pow5:/sys/bus/vio/drivers/hvcs/30000003 # cat name + vty-server + +Each entry is also provided, by default, with a "devspec" attribute which +reveals the full device specification when read, as shown in the following +example:: + + Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat devspec + /vdevice/vty-server@30000004 + +Each vty-server sysfs dir is provided with two read-only attributes that +provide lists of easily parsed partner vty data: "partner_vtys" and +"partner_clcs":: + + Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat partner_vtys + 30000000 + 30000001 + 30000002 + 30000000 + 30000000 + + Pow5:/sys/bus/vio/drivers/hvcs/30000004 # cat partner_clcs + U5112.428.103048A-V3-C0 + U5112.428.103048A-V3-C2 + U5112.428.103048A-V3-C3 + U5112.428.103048A-V4-C0 + U5112.428.103048A-V5-C0 + +Reading partner_vtys returns a list of partner vtys. Vty unit address +numbering is only per-partition-unique so entries will frequently repeat. + +Reading partner_clcs returns a list of "converged location codes" which are +composed of a system serial number followed by "-V*", where the '*' is the +target partition number, and "-C*", where the '*' is the slot of the +adapter. The first vty partner corresponds to the first clc item, the +second vty partner to the second clc item, etc. + +A vty-server can only be connected to a single vty at a time. The entry, +"current_vty" prints the clc of the currently selected partner vty when +read. + +The current_vty can be changed by writing a valid partner clc to the entry +as in the following example:: + + Pow5:/sys/bus/vio/drivers/hvcs/30000004 # echo U5112.428.10304 + 8A-V4-C0 > current_vty + +Changing the current_vty when a vty-server is already connected to a vty +does not affect the current connection. The change takes effect when the +currently open connection is freed. + +Information on the "vterm_state" attribute was covered earlier on the +chapter entitled "disconnection". + +8. Questions & Answers: +======================= + +Q: What are the security concerns involving hvcs? + +A: There are three main security concerns: + + 1. The creator of the /dev/hvcs* nodes has the ability to restrict + the access of the device entries to certain users or groups. It + may be best to create a special hvcs group privilege for providing + access to system consoles. + + 2. To provide network security when grabbing the console it is + suggested that the user connect to the console hosting partition + using a secure method, such as SSH or sit at a hardware console. + + 3. Make sure to exit the user session when done with a console or + the next vty-server connection (which may be from another + partition) will experience the previously logged in session. + +--------------------------------------------------------------------------- + +Q: How do I multiplex a console that I grab through hvcs so that other +people can see it: + +A: You can use "screen" to directly connect to the /dev/hvcs* device and +setup a session on your machine with the console group privileges. As +pointed out earlier by default screen doesn't provide the termcap settings +for most terminal emulators to provide adequate character conversion from +term type "screen" to others. This means that curses based programs may +not display properly in screen sessions. + +--------------------------------------------------------------------------- + +Q: Why are the colors all messed up? +Q: Why are the control characters acting strange or not working? +Q: Why is the console output all strange and unintelligible? + +A: Please see the preceding section on "Connection" for a discussion of how +applications can affect the display of character control sequences. +Additionally, just because you logged into the console using and xterm +doesn't mean someone else didn't log into the console with the HMC console +(vt320) before you and leave the session logged in. The best thing to do +is to export TERM to the terminal type of your terminal emulator when you +get the console. Additionally make sure to "exit" the console before you +disconnect from the console. This will ensure that the next user gets +their own TERM type set when they login. + +--------------------------------------------------------------------------- + +Q: When I try to CONNECT kermit to an hvcs device I get: +"Sorry, can't open connection: /dev/hvcs*"What is happening? + +A: Some other Power5 console mechanism has a connection to the vty and +isn't giving it up. You can try to force disconnect the consoles from the +HMC by right clicking on the partition and then selecting "close terminal". +Otherwise you have to hunt down the people who have console authority. It +is possible that you already have the console open using another kermit +session and just forgot about it. Please review the console options for +Power5 systems to determine the many ways a system console can be held. + +OR + +A: Another user may not have a connectivity method currently attached to a +/dev/hvcs device but the vterm_state may reveal that they still have the +vty-server connection established. They need to free this using the method +outlined in the section on "Disconnection" in order for others to connect +to the target vty. + +OR + +A: The user profile you are using to execute kermit probably doesn't have +permissions to use the /dev/hvcs* device. + +OR + +A: You probably haven't inserted the hvcs.ko module yet but the /dev/hvcs* +entry still exists (on systems without udev). + +OR + +A: There is not a corresponding vty-server device that maps to an existing +/dev/hvcs* entry. + +--------------------------------------------------------------------------- + +Q: When I try to CONNECT kermit to an hvcs device I get: +"Sorry, write access to UUCP lockfile directory denied." + +A: The /dev/hvcs* entry you have specified doesn't exist where you said it +does? Maybe you haven't inserted the module (on systems with udev). + +--------------------------------------------------------------------------- + +Q: If I already have one Linux partition installed can I use hvcs on said +partition to provide the console for the install of a second Linux +partition? + +A: Yes granted that your are connected to the /dev/hvcs* device using +kermit or cu or some other program that doesn't provide terminal emulation. + +--------------------------------------------------------------------------- + +Q: Can I connect to more than one partition's console at a time using this +driver? + +A: Yes. Of course this means that there must be more than one vty-server +configured for this partition and each must point to a disconnected vty. + +--------------------------------------------------------------------------- + +Q: Does the hvcs driver support dynamic (hotplug) addition of devices? + +A: Yes, if you have dlpar and hotplug enabled for your system and it has +been built into the kernel the hvcs drivers is configured to dynamically +handle additions of new devices and removals of unused devices. + +--------------------------------------------------------------------------- + +Q: For some reason /dev/hvcs* doesn't map to the same vty-server adapter +after a reboot. What happened? + +A: Assignment of vty-server adapters to /dev/hvcs* entries is always done +in the order that the adapters are exposed. Due to hotplug capabilities of +this driver assignment of hotplug added vty-servers may be in a different +order than how they would be exposed on module load. Rebooting or +reloading the module after dynamic addition may result in the /dev/hvcs* +and vty-server coupling changing if a vty-server adapter was added in a +slot between two other vty-server adapters. Refer to the section above +on how to determine which vty-server goes with which /dev/hvcs* node. +Hint; look at the sysfs "index" attribute for the vty-server. + +--------------------------------------------------------------------------- + +Q: Can I use /dev/hvcs* as a conduit to another partition and use a tty +device on that partition as the other end of the pipe? + +A: Yes, on Power5 platforms the hvc_console driver provides a tty interface +for extra /dev/hvc* devices (where /dev/hvc0 is most likely the console). +In order to get a tty conduit working between the two partitions the HMC +Super Admin must create an additional "serial server" for the target +partition with the HMC gui which will show up as /dev/hvc* when the target +partition is rebooted. + +The HMC Super Admin then creates an additional "serial client" for the +current partition and points this at the target partition's newly created +"serial server" adapter (remember the slot). This shows up as an +additional /dev/hvcs* device. + +Now a program on the target system can be configured to read or write to +/dev/hvc* and another program on the current partition can be configured to +read or write to /dev/hvcs*. Now you have a tty conduit between two +partitions. + +--------------------------------------------------------------------------- + +9. Reporting Bugs: +================== + +The proper channel for reporting bugs is either through the Linux OS +distribution company that provided your OS or by posting issues to the +PowerPC development mailing list at: + +linuxppc-dev@lists.ozlabs.org + +This request is to provide a documented and searchable public exchange +of the problems and solutions surrounding this driver for the benefit of +all users. diff --git a/Documentation/arch/powerpc/imc.rst b/Documentation/arch/powerpc/imc.rst new file mode 100644 index 0000000000..633bcee7dc --- /dev/null +++ b/Documentation/arch/powerpc/imc.rst @@ -0,0 +1,199 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. _imc: + +=================================== +IMC (In-Memory Collection Counters) +=================================== + +Anju T Sudhakar, 10 May 2019 + +.. contents:: + :depth: 3 + + +Basic overview +============== + +IMC (In-Memory collection counters) is a hardware monitoring facility that +collects large numbers of hardware performance events at Nest level (these are +on-chip but off-core), Core level and Thread level. + +The Nest PMU counters are handled by a Nest IMC microcode which runs in the OCC +(On-Chip Controller) complex. The microcode collects the counter data and moves +the nest IMC counter data to memory. + +The Core and Thread IMC PMU counters are handled in the core. Core level PMU +counters give us the IMC counters' data per core and thread level PMU counters +give us the IMC counters' data per CPU thread. + +OPAL obtains the IMC PMU and supported events information from the IMC Catalog +and passes on to the kernel via the device tree. The event's information +contains: + +- Event name +- Event Offset +- Event description + +and possibly also: + +- Event scale +- Event unit + +Some PMUs may have a common scale and unit values for all their supported +events. For those cases, the scale and unit properties for those events must be +inherited from the PMU. + +The event offset in the memory is where the counter data gets accumulated. + +IMC catalog is available at: + https://github.com/open-power/ima-catalog + +The kernel discovers the IMC counters information in the device tree at the +`imc-counters` device node which has a compatible field +`ibm,opal-in-memory-counters`. From the device tree, the kernel parses the PMUs +and their event's information and register the PMU and its attributes in the +kernel. + +IMC example usage +================= + +.. code-block:: sh + + # perf list + [...] + nest_mcs01/PM_MCS01_64B_RD_DISP_PORT01/ [Kernel PMU event] + nest_mcs01/PM_MCS01_64B_RD_DISP_PORT23/ [Kernel PMU event] + [...] + core_imc/CPM_0THRD_NON_IDLE_PCYC/ [Kernel PMU event] + core_imc/CPM_1THRD_NON_IDLE_INST/ [Kernel PMU event] + [...] + thread_imc/CPM_0THRD_NON_IDLE_PCYC/ [Kernel PMU event] + thread_imc/CPM_1THRD_NON_IDLE_INST/ [Kernel PMU event] + +To see per chip data for nest_mcs0/PM_MCS_DOWN_128B_DATA_XFER_MC0/: + +.. code-block:: sh + + # ./perf stat -e "nest_mcs01/PM_MCS01_64B_WR_DISP_PORT01/" -a --per-socket + +To see non-idle instructions for core 0: + +.. code-block:: sh + + # ./perf stat -e "core_imc/CPM_NON_IDLE_INST/" -C 0 -I 1000 + +To see non-idle instructions for a "make": + +.. code-block:: sh + + # ./perf stat -e "thread_imc/CPM_NON_IDLE_PCYC/" make + + +IMC Trace-mode +=============== + +POWER9 supports two modes for IMC which are the Accumulation mode and Trace +mode. In Accumulation mode, event counts are accumulated in system Memory. +Hypervisor then reads the posted counts periodically or when requested. In IMC +Trace mode, the 64 bit trace SCOM value is initialized with the event +information. The CPMCxSEL and CPMC_LOAD in the trace SCOM, specifies the event +to be monitored and the sampling duration. On each overflow in the CPMCxSEL, +hardware snapshots the program counter along with event counts and writes into +memory pointed by LDBAR. + +LDBAR is a 64 bit special purpose per thread register, it has bits to indicate +whether hardware is configured for accumulation or trace mode. + +LDBAR Register Layout +--------------------- + + +-------+----------------------+ + | 0 | Enable/Disable | + +-------+----------------------+ + | 1 | 0: Accumulation Mode | + | +----------------------+ + | | 1: Trace Mode | + +-------+----------------------+ + | 2:3 | Reserved | + +-------+----------------------+ + | 4-6 | PB scope | + +-------+----------------------+ + | 7 | Reserved | + +-------+----------------------+ + | 8:50 | Counter Address | + +-------+----------------------+ + | 51:63 | Reserved | + +-------+----------------------+ + +TRACE_IMC_SCOM bit representation +--------------------------------- + + +-------+------------+ + | 0:1 | SAMPSEL | + +-------+------------+ + | 2:33 | CPMC_LOAD | + +-------+------------+ + | 34:40 | CPMC1SEL | + +-------+------------+ + | 41:47 | CPMC2SEL | + +-------+------------+ + | 48:50 | BUFFERSIZE | + +-------+------------+ + | 51:63 | RESERVED | + +-------+------------+ + +CPMC_LOAD contains the sampling duration. SAMPSEL and CPMCxSEL determines the +event to count. BUFFERSIZE indicates the memory range. On each overflow, +hardware snapshots the program counter along with event counts and updates the +memory and reloads the CMPC_LOAD value for the next sampling duration. IMC +hardware does not support exceptions, so it quietly wraps around if memory +buffer reaches the end. + +*Currently the event monitored for trace-mode is fixed as cycle.* + +Trace IMC example usage +======================= + +.. code-block:: sh + + # perf list + [....] + trace_imc/trace_cycles/ [Kernel PMU event] + +To record an application/process with trace-imc event: + +.. code-block:: sh + + # perf record -e trace_imc/trace_cycles/ yes > /dev/null + [ perf record: Woken up 1 times to write data ] + [ perf record: Captured and wrote 0.012 MB perf.data (21 samples) ] + +The `perf.data` generated, can be read using perf report. + +Benefits of using IMC trace-mode +================================ + +PMI (Performance Monitoring Interrupts) interrupt handling is avoided, since IMC +trace mode snapshots the program counter and updates to the memory. And this +also provide a way for the operating system to do instruction sampling in real +time without PMI processing overhead. + +Performance data using `perf top` with and without trace-imc event. + +PMI interrupts count when `perf top` command is executed without trace-imc event. + +.. code-block:: sh + + # grep PMI /proc/interrupts + PMI: 0 0 0 0 Performance monitoring interrupts + # ./perf top + ... + # grep PMI /proc/interrupts + PMI: 39735 8710 17338 17801 Performance monitoring interrupts + # ./perf top -e trace_imc/trace_cycles/ + ... + # grep PMI /proc/interrupts + PMI: 39735 8710 17338 17801 Performance monitoring interrupts + + +That is, the PMI interrupt counts do not increment when using the `trace_imc` event. diff --git a/Documentation/arch/powerpc/index.rst b/Documentation/arch/powerpc/index.rst new file mode 100644 index 0000000000..9749f6dc25 --- /dev/null +++ b/Documentation/arch/powerpc/index.rst @@ -0,0 +1,49 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======= +powerpc +======= + +.. toctree:: + :maxdepth: 1 + + associativity + booting + bootwrapper + cpu_families + cpu_features + cxl + cxlflash + dawr-power9 + dexcr + dscr + eeh-pci-error-recovery + elf_hwcaps + elfnote + firmware-assisted-dump + hvcs + imc + isa-versions + kaslr-booke32 + mpc52xx + kvm-nested + papr_hcalls + pci_iov_resource_on_powernv + pmu-ebb + ptrace + qe_firmware + syscall64-abi + transactional_memory + ultravisor + vas-api + vcpudispatch_stats + vmemmap_dedup + + features + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/arch/powerpc/isa-versions.rst b/Documentation/arch/powerpc/isa-versions.rst new file mode 100644 index 0000000000..a8d6b6028b --- /dev/null +++ b/Documentation/arch/powerpc/isa-versions.rst @@ -0,0 +1,101 @@ +========================== +CPU to ISA Version Mapping +========================== + +Mapping of some CPU versions to relevant ISA versions. + +Note Power4 and Power4+ are not supported. + +========= ==================================================================== +CPU Architecture version +========= ==================================================================== +Power10 Power ISA v3.1 +Power9 Power ISA v3.0B +Power8 Power ISA v2.07 +e6500 Power ISA v2.06 with some exceptions +e5500 Power ISA v2.06 with some exceptions, no Altivec +Power7 Power ISA v2.06 +Power6 Power ISA v2.05 +PA6T Power ISA v2.04 +Cell PPU - Power ISA v2.02 with some minor exceptions + - Plus Altivec/VMX ~= 2.03 +Power5++ Power ISA v2.04 (no VMX) +Power5+ Power ISA v2.03 +Power5 - PowerPC User Instruction Set Architecture Book I v2.02 + - PowerPC Virtual Environment Architecture Book II v2.02 + - PowerPC Operating Environment Architecture Book III v2.02 +PPC970 - PowerPC User Instruction Set Architecture Book I v2.01 + - PowerPC Virtual Environment Architecture Book II v2.01 + - PowerPC Operating Environment Architecture Book III v2.01 + - Plus Altivec/VMX ~= 2.03 +Power4+ - PowerPC User Instruction Set Architecture Book I v2.01 + - PowerPC Virtual Environment Architecture Book II v2.01 + - PowerPC Operating Environment Architecture Book III v2.01 +Power4 - PowerPC User Instruction Set Architecture Book I v2.00 + - PowerPC Virtual Environment Architecture Book II v2.00 + - PowerPC Operating Environment Architecture Book III v2.00 +========= ==================================================================== + + +Key Features +------------ + +========== ================== +CPU VMX (aka. Altivec) +========== ================== +Power10 Yes +Power9 Yes +Power8 Yes +e6500 Yes +e5500 No +Power7 Yes +Power6 Yes +PA6T Yes +Cell PPU Yes +Power5++ No +Power5+ No +Power5 No +PPC970 Yes +Power4+ No +Power4 No +========== ================== + +========== ==== +CPU VSX +========== ==== +Power10 Yes +Power9 Yes +Power8 Yes +e6500 No +e5500 No +Power7 Yes +Power6 No +PA6T No +Cell PPU No +Power5++ No +Power5+ No +Power5 No +PPC970 No +Power4+ No +Power4 No +========== ==== + +========== ==================================== +CPU Transactional Memory +========== ==================================== +Power10 No (* see Power ISA v3.1, "Appendix A. Notes on the Removal of Transactional Memory from the Architecture") +Power9 Yes (* see transactional_memory.txt) +Power8 Yes +e6500 No +e5500 No +Power7 No +Power6 No +PA6T No +Cell PPU No +Power5++ No +Power5+ No +Power5 No +PPC970 No +Power4+ No +Power4 No +========== ==================================== diff --git a/Documentation/arch/powerpc/kasan.txt b/Documentation/arch/powerpc/kasan.txt new file mode 100644 index 0000000000..a4f647e4ff --- /dev/null +++ b/Documentation/arch/powerpc/kasan.txt @@ -0,0 +1,58 @@ +KASAN is supported on powerpc on 32-bit and Radix 64-bit only. + +32 bit support +============== + +KASAN is supported on both hash and nohash MMUs on 32-bit. + +The shadow area sits at the top of the kernel virtual memory space above the +fixmap area and occupies one eighth of the total kernel virtual memory space. + +Instrumentation of the vmalloc area is optional, unless built with modules, +in which case it is required. + +64 bit support +============== + +Currently, only the radix MMU is supported. There have been versions for hash +and Book3E processors floating around on the mailing list, but nothing has been +merged. + +KASAN support on Book3S is a bit tricky to get right: + + - It would be good to support inline instrumentation so as to be able to catch + stack issues that cannot be caught with outline mode. + + - Inline instrumentation requires a fixed offset. + + - Book3S runs code with translations off ("real mode") during boot, including a + lot of generic device-tree parsing code which is used to determine MMU + features. + + - Some code - most notably a lot of KVM code - also runs with translations off + after boot. + + - Therefore any offset has to point to memory that is valid with + translations on or off. + +One approach is just to give up on inline instrumentation. This way boot-time +checks can be delayed until after the MMU is set is up, and we can just not +instrument any code that runs with translations off after booting. This is the +current approach. + +To avoid this limitation, the KASAN shadow would have to be placed inside the +linear mapping, using the same high-bits trick we use for the rest of the linear +mapping. This is tricky: + + - We'd like to place it near the start of physical memory. In theory we can do + this at run-time based on how much physical memory we have, but this requires + being able to arbitrarily relocate the kernel, which is basically the tricky + part of KASLR. Not being game to implement both tricky things at once, this + is hopefully something we can revisit once we get KASLR for Book3S. + + - Alternatively, we can place the shadow at the _end_ of memory, but this + requires knowing how much contiguous physical memory a system has _at compile + time_. This is a big hammer, and has some unfortunate consequences: inablity + to handle discontiguous physical memory, total failure to boot on machines + with less memory than specified, and that machines with more memory than + specified can't use it. This was deemed unacceptable. diff --git a/Documentation/arch/powerpc/kaslr-booke32.rst b/Documentation/arch/powerpc/kaslr-booke32.rst new file mode 100644 index 0000000000..5681c1d1b6 --- /dev/null +++ b/Documentation/arch/powerpc/kaslr-booke32.rst @@ -0,0 +1,42 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================== +KASLR for Freescale BookE32 +=========================== + +The word KASLR stands for Kernel Address Space Layout Randomization. + +This document tries to explain the implementation of the KASLR for +Freescale BookE32. KASLR is a security feature that deters exploit +attempts relying on knowledge of the location of kernel internals. + +Since CONFIG_RELOCATABLE has already supported, what we need to do is +map or copy kernel to a proper place and relocate. Freescale Book-E +parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1 +entries are not suitable to map the kernel directly in a randomized +region, so we chose to copy the kernel to a proper place and restart to +relocate. + +Entropy is derived from the banner and timer base, which will change every +build and boot. This not so much safe so additionally the bootloader may +pass entropy via the /chosen/kaslr-seed node in device tree. + +We will use the first 512M of the low memory to randomize the kernel +image. The memory will be split in 64M zones. We will use the lower 8 +bit of the entropy to decide the index of the 64M zone. Then we chose a +16K aligned offset inside the 64M zone to put the kernel in:: + + KERNELBASE + + |--> 64M <--| + | | + +---------------+ +----------------+---------------+ + | |....| |kernel| | | + +---------------+ +----------------+---------------+ + | | + |-----> offset <-----| + + kernstart_virt_addr + +To enable KASLR, set CONFIG_RANDOMIZE_BASE = y. If KASLR is enabled and you +want to disable it at runtime, add "nokaslr" to the kernel cmdline. diff --git a/Documentation/arch/powerpc/kvm-nested.rst b/Documentation/arch/powerpc/kvm-nested.rst new file mode 100644 index 0000000000..630602a8aa --- /dev/null +++ b/Documentation/arch/powerpc/kvm-nested.rst @@ -0,0 +1,634 @@ +.. SPDX-License-Identifier: GPL-2.0 + +==================================== +Nested KVM on POWER +==================================== + +Introduction +============ + +This document explains how a guest operating system can act as a +hypervisor and run nested guests through the use of hypercalls, if the +hypervisor has implemented them. The terms L0, L1, and L2 are used to +refer to different software entities. L0 is the hypervisor mode entity +that would normally be called the "host" or "hypervisor". L1 is a +guest virtual machine that is directly run under L0 and is initiated +and controlled by L0. L2 is a guest virtual machine that is initiated +and controlled by L1 acting as a hypervisor. + +Existing API +============ + +Linux/KVM has had support for Nesting as an L0 or L1 since 2018 + +The L0 code was added:: + + commit 8e3f5fc1045dc49fd175b978c5457f5f51e7a2ce + Author: Paul Mackerras + Date: Mon Oct 8 16:31:03 2018 +1100 + KVM: PPC: Book3S HV: Framework and hcall stubs for nested virtualization + +The L1 code was added:: + + commit 360cae313702cdd0b90f82c261a8302fecef030a + Author: Paul Mackerras + Date: Mon Oct 8 16:31:04 2018 +1100 + KVM: PPC: Book3S HV: Nested guest entry via hypercall + +This API works primarily using a single hcall h_enter_nested(). This +call made by the L1 to tell the L0 to start an L2 vCPU with the given +state. The L0 then starts this L2 and runs until an L2 exit condition +is reached. Once the L2 exits, the state of the L2 is given back to +the L1 by the L0. The full L2 vCPU state is always transferred from +and to L1 when the L2 is run. The L0 doesn't keep any state on the L2 +vCPU (except in the short sequence in the L0 on L1 -> L2 entry and L2 +-> L1 exit). + +The only state kept by the L0 is the partition table. The L1 registers +it's partition table using the h_set_partition_table() hcall. All +other state held by the L0 about the L2s is cached state (such as +shadow page tables). + +The L1 may run any L2 or vCPU without first informing the L0. It +simply starts the vCPU using h_enter_nested(). The creation of L2s and +vCPUs is done implicitly whenever h_enter_nested() is called. + +In this document, we call this existing API the v1 API. + +New PAPR API +=============== + +The new PAPR API changes from the v1 API such that the creating L2 and +associated vCPUs is explicit. In this document, we call this the v2 +API. + +h_enter_nested() is replaced with H_GUEST_VCPU_RUN(). Before this can +be called the L1 must explicitly create the L2 using h_guest_create() +and any associated vCPUs() created with h_guest_create_vCPU(). Getting +and setting vCPU state can also be performed using h_guest_{g|s}et +hcall. + +The basic execution flow is for an L1 to create an L2, run it, and +delete it is: + +- L1 and L0 negotiate capabilities with H_GUEST_{G,S}ET_CAPABILITIES() + (normally at L1 boot time). + +- L1 requests the L0 create an L2 with H_GUEST_CREATE() and receives a token + +- L1 requests the L0 create an L2 vCPU with H_GUEST_CREATE_VCPU() + +- L1 and L0 communicate the vCPU state using the H_GUEST_{G,S}ET() hcall + +- L1 requests the L0 runs the vCPU running H_GUEST_VCPU_RUN() hcall + +- L1 deletes L2 with H_GUEST_DELETE() + +More details of the individual hcalls follows: + +HCALL Details +============= + +This documentation is provided to give an overall understating of the +API. It doesn't aim to provide all the details required to implement +an L1 or L0. Latest version of PAPR can be referred to for more details. + +All these HCALLs are made by the L1 to the L0. + +H_GUEST_GET_CAPABILITIES() +-------------------------- + +This is called to get the capabilities of the L0 nested +hypervisor. This includes capabilities such the CPU versions (eg +POWER9, POWER10) that are supported as L2s:: + + H_GUEST_GET_CAPABILITIES(uint64 flags) + + Parameters: + Input: + flags: Reserved + Output: + R3: Return code + R4: Hypervisor Supported Capabilities bitmap 1 + +H_GUEST_SET_CAPABILITIES() +-------------------------- + +This is called to inform the L0 of the capabilities of the L1 +hypervisor. The set of flags passed here are the same as +H_GUEST_GET_CAPABILITIES() + +Typically, GET will be called first and then SET will be called with a +subset of the flags returned from GET. This process allows the L0 and +L1 to negotiate an agreed set of capabilities:: + + H_GUEST_SET_CAPABILITIES(uint64 flags, + uint64 capabilitiesBitmap1) + Parameters: + Input: + flags: Reserved + capabilitiesBitmap1: Only capabilities advertised through + H_GUEST_GET_CAPABILITIES + Output: + R3: Return code + R4: If R3 = H_P2: The number of invalid bitmaps + R5: If R3 = H_P2: The index of first invalid bitmap + +H_GUEST_CREATE() +---------------- + +This is called to create an L2. A unique ID of the L2 created +(similar to an LPID) is returned, which can be used on subsequent HCALLs to +identify the L2:: + + H_GUEST_CREATE(uint64 flags, + uint64 continueToken); + Parameters: + Input: + flags: Reserved + continueToken: Initial call set to -1. Subsequent calls, + after H_Busy or H_LongBusyOrder has been + returned, value that was returned in R4. + Output: + R3: Return code. Notable: + H_Not_Enough_Resources: Unable to create Guest VCPU due to not + enough Hypervisor memory. See H_GUEST_CREATE_GET_STATE(flags = + takeOwnershipOfVcpuState) + R4: If R3 = H_Busy or_H_LongBusyOrder -> continueToken + +H_GUEST_CREATE_VCPU() +--------------------- + +This is called to create a vCPU associated with an L2. The L2 id +(returned from H_GUEST_CREATE()) should be passed it. Also passed in +is a unique (for this L2) vCPUid. This vCPUid is allocated by the +L1:: + + H_GUEST_CREATE_VCPU(uint64 flags, + uint64 guestId, + uint64 vcpuId); + Parameters: + Input: + flags: Reserved + guestId: ID obtained from H_GUEST_CREATE + vcpuId: ID of the vCPU to be created. This must be within the + range of 0 to 2047 + Output: + R3: Return code. Notable: + H_Not_Enough_Resources: Unable to create Guest VCPU due to not + enough Hypervisor memory. See H_GUEST_CREATE_GET_STATE(flags = + takeOwnershipOfVcpuState) + +H_GUEST_GET_STATE() +------------------- + +This is called to get state associated with an L2 (Guest-wide or vCPU specific). +This info is passed via the Guest State Buffer (GSB), a standard format as +explained later in this doc, necessary details below: + +This can get either L2 wide or vcpu specific information. Examples of +L2 wide is the timebase offset or process scoped page table +info. Examples of vCPU specific are GPRs or VSRs. A bit in the flags +parameter specifies if this call is L2 wide or vCPU specific and the +IDs in the GSB must match this. + +The L1 provides a pointer to the GSB as a parameter to this call. Also +provided is the L2 and vCPU IDs associated with the state to set. + +The L1 writes only the IDs and sizes in the GSB. L0 writes the +associated values for each ID in the GSB:: + + H_GUEST_GET_STATE(uint64 flags, + uint64 guestId, + uint64 vcpuId, + uint64 dataBuffer, + uint64 dataBufferSizeInBytes); + Parameters: + Input: + flags: + Bit 0: getGuestWideState: Request state of the Guest instead + of an individual VCPU. + Bit 1: takeOwnershipOfVcpuState Indicate the L1 is taking + over ownership of the VCPU state and that the L0 can free + the storage holding the state. The VCPU state will need to + be returned to the Hypervisor via H_GUEST_SET_STATE prior + to H_GUEST_RUN_VCPU being called for this VCPU. The data + returned in the dataBuffer is in a Hypervisor internal + format. + Bits 2-63: Reserved + guestId: ID obtained from H_GUEST_CREATE + vcpuId: ID of the vCPU pass to H_GUEST_CREATE_VCPU + dataBuffer: A L1 real address of the GSB. + If takeOwnershipOfVcpuState, size must be at least the size + returned by ID=0x0001 + dataBufferSizeInBytes: Size of dataBuffer + Output: + R3: Return code + R4: If R3 = H_Invalid_Element_Id: The array index of the bad + element ID. + If R3 = H_Invalid_Element_Size: The array index of the bad + element size. + If R3 = H_Invalid_Element_Value: The array index of the bad + element value. + +H_GUEST_SET_STATE() +------------------- + +This is called to set L2 wide or vCPU specific L2 state. This info is +passed via the Guest State Buffer (GSB), necessary details below: + +This can set either L2 wide or vcpu specific information. Examples of +L2 wide is the timebase offset or process scoped page table +info. Examples of vCPU specific are GPRs or VSRs. A bit in the flags +parameter specifies if this call is L2 wide or vCPU specific and the +IDs in the GSB must match this. + +The L1 provides a pointer to the GSB as a parameter to this call. Also +provided is the L2 and vCPU IDs associated with the state to set. + +The L1 writes all values in the GSB and the L0 only reads the GSB for +this call:: + + H_GUEST_SET_STATE(uint64 flags, + uint64 guestId, + uint64 vcpuId, + uint64 dataBuffer, + uint64 dataBufferSizeInBytes); + Parameters: + Input: + flags: + Bit 0: getGuestWideState: Request state of the Guest instead + of an individual VCPU. + Bit 1: returnOwnershipOfVcpuState Return Guest VCPU state. See + GET_STATE takeOwnershipOfVcpuState + Bits 2-63: Reserved + guestId: ID obtained from H_GUEST_CREATE + vcpuId: ID of the vCPU pass to H_GUEST_CREATE_VCPU + dataBuffer: A L1 real address of the GSB. + If takeOwnershipOfVcpuState, size must be at least the size + returned by ID=0x0001 + dataBufferSizeInBytes: Size of dataBuffer + Output: + R3: Return code + R4: If R3 = H_Invalid_Element_Id: The array index of the bad + element ID. + If R3 = H_Invalid_Element_Size: The array index of the bad + element size. + If R3 = H_Invalid_Element_Value: The array index of the bad + element value. + +H_GUEST_RUN_VCPU() +------------------ + +This is called to run an L2 vCPU. The L2 and vCPU IDs are passed in as +parameters. The vCPU runs with the state set previously using +H_GUEST_SET_STATE(). When the L2 exits, the L1 will resume from this +hcall. + +This hcall also has associated input and output GSBs. Unlike +H_GUEST_{S,G}ET_STATE(), these GSB pointers are not passed in as +parameters to the hcall (This was done in the interest of +performance). The locations of these GSBs must be preregistered using +the H_GUEST_SET_STATE() call with ID 0x0c00 and 0x0c01 (see table +below). + +The input GSB may contain only VCPU specific elements to be set. This +GSB may also contain zero elements (ie 0 in the first 4 bytes of the +GSB) if nothing needs to be set. + +On exit from the hcall, the output buffer is filled with elements +determined by the L0. The reason for the exit is contained in GPR4 (ie +NIP is put in GPR4). The elements returned depend on the exit +type. For example, if the exit reason is the L2 doing a hcall (GPR4 = +0xc00), then GPR3-12 are provided in the output GSB as this is the +state likely needed to service the hcall. If additional state is +needed, H_GUEST_GET_STATE() may be called by the L1. + +To synthesize interrupts in the L2, when calling H_GUEST_RUN_VCPU() +the L1 may set a flag (as a hcall parameter) and the L0 will +synthesize the interrupt in the L2. Alternatively, the L1 may +synthesize the interrupt itself using H_GUEST_SET_STATE() or the +H_GUEST_RUN_VCPU() input GSB to set the state appropriately:: + + H_GUEST_RUN_VCPU(uint64 flags, + uint64 guestId, + uint64 vcpuId, + uint64 dataBuffer, + uint64 dataBufferSizeInBytes); + Parameters: + Input: + flags: + Bit 0: generateExternalInterrupt: Generate an external interrupt + Bit 1: generatePrivilegedDoorbell: Generate a Privileged Doorbell + Bit 2: sendToSystemReset”: Generate a System Reset Interrupt + Bits 3-63: Reserved + guestId: ID obtained from H_GUEST_CREATE + vcpuId: ID of the vCPU pass to H_GUEST_CREATE_VCPU + Output: + R3: Return code + R4: If R3 = H_Success: The reason L1 VCPU exited (ie. NIA) + 0x000: The VCPU stopped running for an unspecified reason. An + example of this is the Hypervisor stopping a VCPU running + due to an outstanding interrupt for the Host Partition. + 0x980: HDEC + 0xC00: HCALL + 0xE00: HDSI + 0xE20: HISI + 0xE40: HEA + 0xF80: HV Fac Unavail + If R3 = H_Invalid_Element_Id, H_Invalid_Element_Size, or + H_Invalid_Element_Value: R4 is offset of the invalid element + in the input buffer. + +H_GUEST_DELETE() +---------------- + +This is called to delete an L2. All associated vCPUs are also +deleted. No specific vCPU delete call is provided. + +A flag may be provided to delete all guests. This is used to reset the +L0 in the case of kdump/kexec:: + + H_GUEST_DELETE(uint64 flags, + uint64 guestId) + Parameters: + Input: + flags: + Bit 0: deleteAllGuests: deletes all guests + Bits 1-63: Reserved + guestId: ID obtained from H_GUEST_CREATE + Output: + R3: Return code + +Guest State Buffer +================== + +The Guest State Buffer (GSB) is the main method of communicating state +about the L2 between the L1 and L0 via H_GUEST_{G,S}ET() and +H_GUEST_VCPU_RUN() calls. + +State may be associated with a whole L2 (eg timebase offset) or a +specific L2 vCPU (eg. GPR state). Only L2 VCPU state maybe be set by +H_GUEST_VCPU_RUN(). + +All data in the GSB is big endian (as is standard in PAPR) + +The Guest state buffer has a header which gives the number of +elements, followed by the GSB elements themselves. + +GSB header: + ++----------+----------+-------------------------------------------+ +| Offset | Size | Purpose | +| Bytes | Bytes | | ++==========+==========+===========================================+ +| 0 | 4 | Number of elements | ++----------+----------+-------------------------------------------+ +| 4 | | Guest state buffer elements | ++----------+----------+-------------------------------------------+ + +GSB element: + ++----------+----------+-------------------------------------------+ +| Offset | Size | Purpose | +| Bytes | Bytes | | ++==========+==========+===========================================+ +| 0 | 2 | ID | ++----------+----------+-------------------------------------------+ +| 2 | 2 | Size of Value | ++----------+----------+-------------------------------------------+ +| 4 | As above | Value | ++----------+----------+-------------------------------------------+ + +The ID in the GSB element specifies what is to be set. This includes +archtected state like GPRs, VSRs, SPRs, plus also some meta data about +the partition like the timebase offset and partition scoped page +table information. + ++--------+-------+----+--------+----------------------------------+ +| ID | Size | RW | Thread | Details | +| | Bytes | | Guest | | +| | | | Scope | | ++========+=======+====+========+==================================+ +| 0x0000 | | RW | TG | NOP element | ++--------+-------+----+--------+----------------------------------+ +| 0x0001 | 0x08 | R | G | Size of L0 vCPU state. See: | +| | | | | H_GUEST_GET_STATE: | +| | | | | flags = takeOwnershipOfVcpuState | ++--------+-------+----+--------+----------------------------------+ +| 0x0002 | 0x08 | R | G | Size Run vCPU out buffer | ++--------+-------+----+--------+----------------------------------+ +| 0x0003 | 0x04 | RW | G | Logical PVR | ++--------+-------+----+--------+----------------------------------+ +| 0x0004 | 0x08 | RW | G | TB Offset (L1 relative) | ++--------+-------+----+--------+----------------------------------+ +| 0x0005 | 0x18 | RW | G |Partition scoped page tbl info: | +| | | | | | +| | | | |- 0x00 Addr part scope table | +| | | | |- 0x08 Num addr bits | +| | | | |- 0x10 Size root dir | ++--------+-------+----+--------+----------------------------------+ +| 0x0006 | 0x10 | RW | G |Process Table Information: | +| | | | | | +| | | | |- 0x0 Addr proc scope table | +| | | | |- 0x8 Table size. | ++--------+-------+----+--------+----------------------------------+ +| 0x0007-| | | | Reserved | +| 0x0BFF | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0x0C00 | 0x10 | RW | T |Run vCPU Input Buffer: | +| | | | | | +| | | | |- 0x0 Addr of buffer | +| | | | |- 0x8 Buffer Size. | ++--------+-------+----+--------+----------------------------------+ +| 0x0C01 | 0x10 | RW | T |Run vCPU Output Buffer: | +| | | | | | +| | | | |- 0x0 Addr of buffer | +| | | | |- 0x8 Buffer Size. | ++--------+-------+----+--------+----------------------------------+ +| 0x0C02 | 0x08 | RW | T | vCPU VPA Address | ++--------+-------+----+--------+----------------------------------+ +| 0x0C03-| | | | Reserved | +| 0x0FFF | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0x1000-| 0x08 | RW | T | GPR 0-31 | +| 0x101F | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0x1020 | 0x08 | T | T | HDEC expiry TB | ++--------+-------+----+--------+----------------------------------+ +| 0x1021 | 0x08 | RW | T | NIA | ++--------+-------+----+--------+----------------------------------+ +| 0x1022 | 0x08 | RW | T | MSR | ++--------+-------+----+--------+----------------------------------+ +| 0x1023 | 0x08 | RW | T | LR | ++--------+-------+----+--------+----------------------------------+ +| 0x1024 | 0x08 | RW | T | XER | ++--------+-------+----+--------+----------------------------------+ +| 0x1025 | 0x08 | RW | T | CTR | ++--------+-------+----+--------+----------------------------------+ +| 0x1026 | 0x08 | RW | T | CFAR | ++--------+-------+----+--------+----------------------------------+ +| 0x1027 | 0x08 | RW | T | SRR0 | ++--------+-------+----+--------+----------------------------------+ +| 0x1028 | 0x08 | RW | T | SRR1 | ++--------+-------+----+--------+----------------------------------+ +| 0x1029 | 0x08 | RW | T | DAR | ++--------+-------+----+--------+----------------------------------+ +| 0x102A | 0x08 | RW | T | DEC expiry TB | ++--------+-------+----+--------+----------------------------------+ +| 0x102B | 0x08 | RW | T | VTB | ++--------+-------+----+--------+----------------------------------+ +| 0x102C | 0x08 | RW | T | LPCR | ++--------+-------+----+--------+----------------------------------+ +| 0x102D | 0x08 | RW | T | HFSCR | ++--------+-------+----+--------+----------------------------------+ +| 0x102E | 0x08 | RW | T | FSCR | ++--------+-------+----+--------+----------------------------------+ +| 0x102F | 0x08 | RW | T | FPSCR | ++--------+-------+----+--------+----------------------------------+ +| 0x1030 | 0x08 | RW | T | DAWR0 | ++--------+-------+----+--------+----------------------------------+ +| 0x1031 | 0x08 | RW | T | DAWR1 | ++--------+-------+----+--------+----------------------------------+ +| 0x1032 | 0x08 | RW | T | CIABR | ++--------+-------+----+--------+----------------------------------+ +| 0x1033 | 0x08 | RW | T | PURR | ++--------+-------+----+--------+----------------------------------+ +| 0x1034 | 0x08 | RW | T | SPURR | ++--------+-------+----+--------+----------------------------------+ +| 0x1035 | 0x08 | RW | T | IC | ++--------+-------+----+--------+----------------------------------+ +| 0x1036-| 0x08 | RW | T | SPRG 0-3 | +| 0x1039 | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0x103A | 0x08 | W | T | PPR | ++--------+-------+----+--------+----------------------------------+ +| 0x103B | 0x08 | RW | T | MMCR 0-3 | +| 0x103E | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0x103F | 0x08 | RW | T | MMCRA | ++--------+-------+----+--------+----------------------------------+ +| 0x1040 | 0x08 | RW | T | SIER | ++--------+-------+----+--------+----------------------------------+ +| 0x1041 | 0x08 | RW | T | SIER 2 | ++--------+-------+----+--------+----------------------------------+ +| 0x1042 | 0x08 | RW | T | SIER 3 | ++--------+-------+----+--------+----------------------------------+ +| 0x1043 | 0x08 | RW | T | BESCR | ++--------+-------+----+--------+----------------------------------+ +| 0x1044 | 0x08 | RW | T | EBBHR | ++--------+-------+----+--------+----------------------------------+ +| 0x1045 | 0x08 | RW | T | EBBRR | ++--------+-------+----+--------+----------------------------------+ +| 0x1046 | 0x08 | RW | T | AMR | ++--------+-------+----+--------+----------------------------------+ +| 0x1047 | 0x08 | RW | T | IAMR | ++--------+-------+----+--------+----------------------------------+ +| 0x1048 | 0x08 | RW | T | AMOR | ++--------+-------+----+--------+----------------------------------+ +| 0x1049 | 0x08 | RW | T | UAMOR | ++--------+-------+----+--------+----------------------------------+ +| 0x104A | 0x08 | RW | T | SDAR | ++--------+-------+----+--------+----------------------------------+ +| 0x104B | 0x08 | RW | T | SIAR | ++--------+-------+----+--------+----------------------------------+ +| 0x104C | 0x08 | RW | T | DSCR | ++--------+-------+----+--------+----------------------------------+ +| 0x104D | 0x08 | RW | T | TAR | ++--------+-------+----+--------+----------------------------------+ +| 0x104E | 0x08 | RW | T | DEXCR | ++--------+-------+----+--------+----------------------------------+ +| 0x104F | 0x08 | RW | T | HDEXCR | ++--------+-------+----+--------+----------------------------------+ +| 0x1050 | 0x08 | RW | T | HASHKEYR | ++--------+-------+----+--------+----------------------------------+ +| 0x1051 | 0x08 | RW | T | HASHPKEYR | ++--------+-------+----+--------+----------------------------------+ +| 0x1052 | 0x08 | RW | T | CTRL | ++--------+-------+----+--------+----------------------------------+ +| 0x1053-| | | | Reserved | +| 0x1FFF | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0x2000 | 0x04 | RW | T | CR | ++--------+-------+----+--------+----------------------------------+ +| 0x2001 | 0x04 | RW | T | PIDR | ++--------+-------+----+--------+----------------------------------+ +| 0x2002 | 0x04 | RW | T | DSISR | ++--------+-------+----+--------+----------------------------------+ +| 0x2003 | 0x04 | RW | T | VSCR | ++--------+-------+----+--------+----------------------------------+ +| 0x2004 | 0x04 | RW | T | VRSAVE | ++--------+-------+----+--------+----------------------------------+ +| 0x2005 | 0x04 | RW | T | DAWRX0 | ++--------+-------+----+--------+----------------------------------+ +| 0x2006 | 0x04 | RW | T | DAWRX1 | ++--------+-------+----+--------+----------------------------------+ +| 0x2007-| 0x04 | RW | T | PMC 1-6 | +| 0x200c | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0x200D | 0x04 | RW | T | WORT | ++--------+-------+----+--------+----------------------------------+ +| 0x200E | 0x04 | RW | T | PSPB | ++--------+-------+----+--------+----------------------------------+ +| 0x200F-| | | | Reserved | +| 0x2FFF | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0x3000-| 0x10 | RW | T | VSR 0-63 | +| 0x303F | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0x3040-| | | | Reserved | +| 0xEFFF | | | | | ++--------+-------+----+--------+----------------------------------+ +| 0xF000 | 0x08 | R | T | HDAR | ++--------+-------+----+--------+----------------------------------+ +| 0xF001 | 0x04 | R | T | HDSISR | ++--------+-------+----+--------+----------------------------------+ +| 0xF002 | 0x04 | R | T | HEIR | ++--------+-------+----+--------+----------------------------------+ +| 0xF003 | 0x08 | R | T | ASDR | ++--------+-------+----+--------+----------------------------------+ + + +Miscellaneous info +================== + +State not in ptregs/hvregs +-------------------------- + +In the v1 API, some state is not in the ptregs/hvstate. This includes +the vector register and some SPRs. For the L1 to set this state for +the L2, the L1 loads up these hardware registers before the +h_enter_nested() call and the L0 ensures they end up as the L2 state +(by not touching them). + +The v2 API removes this and explicitly sets this state via the GSB. + +L1 Implementation details: Caching state +---------------------------------------- + +In the v1 API, all state is sent from the L1 to the L0 and vice versa +on every h_enter_nested() hcall. If the L0 is not currently running +any L2s, the L0 has no state information about them. The only +exception to this is the location of the partition table, registered +via h_set_partition_table(). + +The v2 API changes this so that the L0 retains the L2 state even when +it's vCPUs are no longer running. This means that the L1 only needs to +communicate with the L0 about L2 state when it needs to modify the L2 +state, or when it's value is out of date. This provides an opportunity +for performance optimisation. + +When a vCPU exits from a H_GUEST_RUN_VCPU() call, the L1 internally +marks all L2 state as invalid. This means that if the L1 wants to know +the L2 state (say via a kvm_get_one_reg() call), it needs call +H_GUEST_GET_STATE() to get that state. Once it's read, it's marked as +valid in L1 until the L2 is run again. + +Also, when an L1 modifies L2 vcpu state, it doesn't need to write it +to the L0 until that L2 vcpu runs again. Hence when the L1 updates +state (say via a kvm_set_one_reg() call), it writes to an internal L1 +copy and only flushes this copy to the L0 when the L2 runs again via +the H_GUEST_VCPU_RUN() input buffer. + +This lazy updating of state by the L1 avoids unnecessary +H_GUEST_{G|S}ET_STATE() calls. diff --git a/Documentation/arch/powerpc/mpc52xx.rst b/Documentation/arch/powerpc/mpc52xx.rst new file mode 100644 index 0000000000..5243b1763f --- /dev/null +++ b/Documentation/arch/powerpc/mpc52xx.rst @@ -0,0 +1,43 @@ +============================= +Linux 2.6.x on MPC52xx family +============================= + +For the latest info, go to https://www.246tNt.com/mpc52xx/ + +To compile/use : + + - U-Boot:: + + # tftpboot 200000 uImage + => tftpboot 400000 pRamdisk + => bootm 200000 400000 + + - DBug:: + + # dn -i zImage.initrd.lite5200 + + +Some remarks: + + - The port is named mpc52xxx, and config options are PPC_MPC52xx. The MGT5100 + is not supported, and I'm not sure anyone is interested in working on it + so. I didn't took 5xxx because there's apparently a lot of 5xxx that have + nothing to do with the MPC5200. I also included the 'MPC' for the same + reason. + - Of course, I inspired myself from the 2.4 port. If you think I forgot to + mention you/your company in the copyright of some code, I'll correct it + ASAP. diff --git a/Documentation/arch/powerpc/papr_hcalls.rst b/Documentation/arch/powerpc/papr_hcalls.rst new file mode 100644 index 0000000000..80d2c0aada --- /dev/null +++ b/Documentation/arch/powerpc/papr_hcalls.rst @@ -0,0 +1,302 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================== +Hypercall Op-codes (hcalls) +=========================== + +Overview +========= + +Virtualization on 64-bit Power Book3S Platforms is based on the PAPR +specification [1]_ which describes the run-time environment for a guest +operating system and how it should interact with the hypervisor for +privileged operations. Currently there are two PAPR compliant hypervisors: + +- **IBM PowerVM (PHYP)**: IBM's proprietary hypervisor that supports AIX, + IBM-i and Linux as supported guests (termed as Logical Partitions + or LPARS). It supports the full PAPR specification. + +- **Qemu/KVM**: Supports PPC64 linux guests running on a PPC64 linux host. + Though it only implements a subset of PAPR specification called LoPAPR [2]_. + +On PPC64 arch a guest kernel running on top of a PAPR hypervisor is called +a *pSeries guest*. A pseries guest runs in a supervisor mode (HV=0) and must +issue hypercalls to the hypervisor whenever it needs to perform an action +that is hypervisor privileged [3]_ or for other services managed by the +hypervisor. + +Hence a Hypercall (hcall) is essentially a request by the pseries guest +asking hypervisor to perform a privileged operation on behalf of the guest. The +guest issues a with necessary input operands. The hypervisor after performing +the privilege operation returns a status code and output operands back to the +guest. + +HCALL ABI +========= +The ABI specification for a hcall between a pseries guest and PAPR hypervisor +is covered in section 14.5.3 of ref [2]_. Switch to the Hypervisor context is +done via the instruction **HVCS** that expects the Opcode for hcall is set in *r3* +and any in-arguments for the hcall are provided in registers *r4-r12*. If values +have to be passed through a memory buffer, the data stored in that buffer should be +in Big-endian byte order. + +Once control returns back to the guest after hypervisor has serviced the +'HVCS' instruction the return value of the hcall is available in *r3* and any +out values are returned in registers *r4-r12*. Again like in case of in-arguments, +any out values stored in a memory buffer will be in Big-endian byte order. + +Powerpc arch code provides convenient wrappers named **plpar_hcall_xxx** defined +in a arch specific header [4]_ to issue hcalls from the linux kernel +running as pseries guest. + +Register Conventions +==================== + +Any hcall should follow same register convention as described in section 2.2.1.1 +of "64-Bit ELF V2 ABI Specification: Power Architecture"[5]_. Table below +summarizes these conventions: + ++----------+----------+-------------------------------------------+ +| Register |Volatile | Purpose | +| Range |(Y/N) | | ++==========+==========+===========================================+ +| r0 | Y | Optional-usage | ++----------+----------+-------------------------------------------+ +| r1 | N | Stack Pointer | ++----------+----------+-------------------------------------------+ +| r2 | N | TOC | ++----------+----------+-------------------------------------------+ +| r3 | Y | hcall opcode/return value | ++----------+----------+-------------------------------------------+ +| r4-r10 | Y | in and out values | ++----------+----------+-------------------------------------------+ +| r11 | Y | Optional-usage/Environmental pointer | ++----------+----------+-------------------------------------------+ +| r12 | Y | Optional-usage/Function entry address at | +| | | global entry point | ++----------+----------+-------------------------------------------+ +| r13 | N | Thread-Pointer | ++----------+----------+-------------------------------------------+ +| r14-r31 | N | Local Variables | ++----------+----------+-------------------------------------------+ +| LR | Y | Link Register | ++----------+----------+-------------------------------------------+ +| CTR | Y | Loop Counter | ++----------+----------+-------------------------------------------+ +| XER | Y | Fixed-point exception register. | ++----------+----------+-------------------------------------------+ +| CR0-1 | Y | Condition register fields. | ++----------+----------+-------------------------------------------+ +| CR2-4 | N | Condition register fields. | ++----------+----------+-------------------------------------------+ +| CR5-7 | Y | Condition register fields. | ++----------+----------+-------------------------------------------+ +| Others | N | | ++----------+----------+-------------------------------------------+ + +DRC & DRC Indexes +================= +:: + + DR1 Guest + +--+ +------------+ +---------+ + | | <----> | | | User | + +--+ DRC1 | | DRC | Space | + | PAPR | Index +---------+ + DR2 | Hypervisor | | | + +--+ | | <-----> | Kernel | + | | <----> | | Hcall | | + +--+ DRC2 +------------+ +---------+ + +PAPR hypervisor terms shared hardware resources like PCI devices, NVDIMMs etc +available for use by LPARs as Dynamic Resource (DR). When a DR is allocated to +an LPAR, PHYP creates a data-structure called Dynamic Resource Connector (DRC) +to manage LPAR access. An LPAR refers to a DRC via an opaque 32-bit number +called DRC-Index. The DRC-index value is provided to the LPAR via device-tree +where its present as an attribute in the device tree node associated with the +DR. + +HCALL Return-values +=================== + +After servicing the hcall, hypervisor sets the return-value in *r3* indicating +success or failure of the hcall. In case of a failure an error code indicates +the cause for error. These codes are defined and documented in arch specific +header [4]_. + +In some cases a hcall can potentially take a long time and need to be issued +multiple times in order to be completely serviced. These hcalls will usually +accept an opaque value *continue-token* within there argument list and a +return value of *H_CONTINUE* indicates that hypervisor hasn't still finished +servicing the hcall yet. + +To make such hcalls the guest need to set *continue-token == 0* for the +initial call and use the hypervisor returned value of *continue-token* +for each subsequent hcall until hypervisor returns a non *H_CONTINUE* +return value. + +HCALL Op-codes +============== + +Below is a partial list of HCALLs that are supported by PHYP. For the +corresponding opcode values please look into the arch specific header [4]_: + +**H_SCM_READ_METADATA** + +| Input: *drcIndex, offset, buffer-address, numBytesToRead* +| Out: *numBytesRead* +| Return Value: *H_Success, H_Parameter, H_P2, H_P3, H_Hardware* + +Given a DRC Index of an NVDIMM, read N-bytes from the metadata area +associated with it, at a specified offset and copy it to provided buffer. +The metadata area stores configuration information such as label information, +bad-blocks etc. The metadata area is located out-of-band of NVDIMM storage +area hence a separate access semantics is provided. + +**H_SCM_WRITE_METADATA** + +| Input: *drcIndex, offset, data, numBytesToWrite* +| Out: *None* +| Return Value: *H_Success, H_Parameter, H_P2, H_P4, H_Hardware* + +Given a DRC Index of an NVDIMM, write N-bytes to the metadata area +associated with it, at the specified offset and from the provided buffer. + +**H_SCM_BIND_MEM** + +| Input: *drcIndex, startingScmBlockIndex, numScmBlocksToBind,* +| *targetLogicalMemoryAddress, continue-token* +| Out: *continue-token, targetLogicalMemoryAddress, numScmBlocksToBound* +| Return Value: *H_Success, H_Parameter, H_P2, H_P3, H_P4, H_Overlap,* +| *H_Too_Big, H_P5, H_Busy* + +Given a DRC-Index of an NVDIMM, map a continuous SCM blocks range +*(startingScmBlockIndex, startingScmBlockIndex+numScmBlocksToBind)* to the guest +at *targetLogicalMemoryAddress* within guest physical address space. In +case *targetLogicalMemoryAddress == 0xFFFFFFFF_FFFFFFFF* then hypervisor +assigns a target address to the guest. The HCALL can fail if the Guest has +an active PTE entry to the SCM block being bound. + +**H_SCM_UNBIND_MEM** +| Input: drcIndex, startingScmLogicalMemoryAddress, numScmBlocksToUnbind +| Out: numScmBlocksUnbound +| Return Value: *H_Success, H_Parameter, H_P2, H_P3, H_In_Use, H_Overlap,* +| *H_Busy, H_LongBusyOrder1mSec, H_LongBusyOrder10mSec* + +Given a DRC-Index of an NVDimm, unmap *numScmBlocksToUnbind* SCM blocks starting +at *startingScmLogicalMemoryAddress* from guest physical address space. The +HCALL can fail if the Guest has an active PTE entry to the SCM block being +unbound. + +**H_SCM_QUERY_BLOCK_MEM_BINDING** + +| Input: *drcIndex, scmBlockIndex* +| Out: *Guest-Physical-Address* +| Return Value: *H_Success, H_Parameter, H_P2, H_NotFound* + +Given a DRC-Index and an SCM Block index return the guest physical address to +which the SCM block is mapped to. + +**H_SCM_QUERY_LOGICAL_MEM_BINDING** + +| Input: *Guest-Physical-Address* +| Out: *drcIndex, scmBlockIndex* +| Return Value: *H_Success, H_Parameter, H_P2, H_NotFound* + +Given a guest physical address return which DRC Index and SCM block is mapped +to that address. + +**H_SCM_UNBIND_ALL** + +| Input: *scmTargetScope, drcIndex* +| Out: *None* +| Return Value: *H_Success, H_Parameter, H_P2, H_P3, H_In_Use, H_Busy,* +| *H_LongBusyOrder1mSec, H_LongBusyOrder10mSec* + +Depending on the Target scope unmap all SCM blocks belonging to all NVDIMMs +or all SCM blocks belonging to a single NVDIMM identified by its drcIndex +from the LPAR memory. + +**H_SCM_HEALTH** + +| Input: drcIndex +| Out: *health-bitmap (r4), health-bit-valid-bitmap (r5)* +| Return Value: *H_Success, H_Parameter, H_Hardware* + +Given a DRC Index return the info on predictive failure and overall health of +the PMEM device. The asserted bits in the health-bitmap indicate one or more states +(described in table below) of the PMEM device and health-bit-valid-bitmap indicate +which bits in health-bitmap are valid. The bits are reported in +reverse bit ordering for example a value of 0xC400000000000000 +indicates bits 0, 1, and 5 are valid. + +Health Bitmap Flags: + ++------+-----------------------------------------------------------------------+ +| Bit | Definition | ++======+=======================================================================+ +| 00 | PMEM device is unable to persist memory contents. | +| | If the system is powered down, nothing will be saved. | ++------+-----------------------------------------------------------------------+ +| 01 | PMEM device failed to persist memory contents. Either contents were | +| | not saved successfully on power down or were not restored properly on | +| | power up. | ++------+-----------------------------------------------------------------------+ +| 02 | PMEM device contents are persisted from previous IPL. The data from | +| | the last boot were successfully restored. | ++------+-----------------------------------------------------------------------+ +| 03 | PMEM device contents are not persisted from previous IPL. There was no| +| | data to restore from the last boot. | ++------+-----------------------------------------------------------------------+ +| 04 | PMEM device memory life remaining is critically low | ++------+-----------------------------------------------------------------------+ +| 05 | PMEM device will be garded off next IPL due to failure | ++------+-----------------------------------------------------------------------+ +| 06 | PMEM device contents cannot persist due to current platform health | +| | status. A hardware failure may prevent data from being saved or | +| | restored. | ++------+-----------------------------------------------------------------------+ +| 07 | PMEM device is unable to persist memory contents in certain conditions| ++------+-----------------------------------------------------------------------+ +| 08 | PMEM device is encrypted | ++------+-----------------------------------------------------------------------+ +| 09 | PMEM device has successfully completed a requested erase or secure | +| | erase procedure. | ++------+-----------------------------------------------------------------------+ +|10:63 | Reserved / Unused | ++------+-----------------------------------------------------------------------+ + +**H_SCM_PERFORMANCE_STATS** + +| Input: drcIndex, resultBuffer Addr +| Out: None +| Return Value: *H_Success, H_Parameter, H_Unsupported, H_Hardware, H_Authority, H_Privilege* + +Given a DRC Index collect the performance statistics for NVDIMM and copy them +to the resultBuffer. + +**H_SCM_FLUSH** + +| Input: *drcIndex, continue-token* +| Out: *continue-token* +| Return Value: *H_SUCCESS, H_Parameter, H_P2, H_BUSY* + +Given a DRC Index Flush the data to backend NVDIMM device. + +The hcall returns H_BUSY when the flush takes longer time and the hcall needs +to be issued multiple times in order to be completely serviced. The +*continue-token* from the output to be passed in the argument list of +subsequent hcalls to the hypervisor until the hcall is completely serviced +at which point H_SUCCESS or other error is returned by the hypervisor. + +References +========== +.. [1] "Power Architecture Platform Reference" + https://en.wikipedia.org/wiki/Power_Architecture_Platform_Reference +.. [2] "Linux on Power Architecture Platform Reference" + https://members.openpowerfoundation.org/document/dl/469 +.. [3] "Definitions and Notation" Book III-Section 14.5.3 + https://openpowerfoundation.org/?resource_lib=power-isa-version-3-0 +.. [4] arch/powerpc/include/asm/hvcall.h +.. [5] "64-Bit ELF V2 ABI Specification: Power Architecture" + https://openpowerfoundation.org/?resource_lib=64-bit-elf-v2-abi-specification-power-architecture diff --git a/Documentation/arch/powerpc/pci_iov_resource_on_powernv.rst b/Documentation/arch/powerpc/pci_iov_resource_on_powernv.rst new file mode 100644 index 0000000000..f5a5793e16 --- /dev/null +++ b/Documentation/arch/powerpc/pci_iov_resource_on_powernv.rst @@ -0,0 +1,312 @@ +=================================================== +PCI Express I/O Virtualization Resource on Powerenv +=================================================== + +Wei Yang + +Benjamin Herrenschmidt + +Bjorn Helgaas + +26 Aug 2014 + +This document describes the requirement from hardware for PCI MMIO resource +sizing and assignment on PowerKVM and how generic PCI code handles this +requirement. The first two sections describe the concepts of Partitionable +Endpoints and the implementation on P8 (IODA2). The next two sections talks +about considerations on enabling SRIOV on IODA2. + +1. Introduction to Partitionable Endpoints +========================================== + +A Partitionable Endpoint (PE) is a way to group the various resources +associated with a device or a set of devices to provide isolation between +partitions (i.e., filtering of DMA, MSIs etc.) and to provide a mechanism +to freeze a device that is causing errors in order to limit the possibility +of propagation of bad data. + +There is thus, in HW, a table of PE states that contains a pair of "frozen" +state bits (one for MMIO and one for DMA, they get set together but can be +cleared independently) for each PE. + +When a PE is frozen, all stores in any direction are dropped and all loads +return all 1's value. MSIs are also blocked. There's a bit more state that +captures things like the details of the error that caused the freeze etc., but +that's not critical. + +The interesting part is how the various PCIe transactions (MMIO, DMA, ...) +are matched to their corresponding PEs. + +The following section provides a rough description of what we have on P8 +(IODA2). Keep in mind that this is all per PHB (PCI host bridge). Each PHB +is a completely separate HW entity that replicates the entire logic, so has +its own set of PEs, etc. + +2. Implementation of Partitionable Endpoints on P8 (IODA2) +========================================================== + +P8 supports up to 256 Partitionable Endpoints per PHB. + + * Inbound + + For DMA, MSIs and inbound PCIe error messages, we have a table (in + memory but accessed in HW by the chip) that provides a direct + correspondence between a PCIe RID (bus/dev/fn) with a PE number. + We call this the RTT. + + - For DMA we then provide an entire address space for each PE that can + contain two "windows", depending on the value of PCI address bit 59. + Each window can be configured to be remapped via a "TCE table" (IOMMU + translation table), which has various configurable characteristics + not described here. + + - For MSIs, we have two windows in the address space (one at the top of + the 32-bit space and one much higher) which, via a combination of the + address and MSI value, will result in one of the 2048 interrupts per + bridge being triggered. There's a PE# in the interrupt controller + descriptor table as well which is compared with the PE# obtained from + the RTT to "authorize" the device to emit that specific interrupt. + + - Error messages just use the RTT. + + * Outbound. That's where the tricky part is. + + Like other PCI host bridges, the Power8 IODA2 PHB supports "windows" + from the CPU address space to the PCI address space. There is one M32 + window and sixteen M64 windows. They have different characteristics. + First what they have in common: they forward a configurable portion of + the CPU address space to the PCIe bus and must be naturally aligned + power of two in size. The rest is different: + + - The M32 window: + + * Is limited to 4GB in size. + + * Drops the top bits of the address (above the size) and replaces + them with a configurable value. This is typically used to generate + 32-bit PCIe accesses. We configure that window at boot from FW and + don't touch it from Linux; it's usually set to forward a 2GB + portion of address space from the CPU to PCIe + 0x8000_0000..0xffff_ffff. (Note: The top 64KB are actually + reserved for MSIs but this is not a problem at this point; we just + need to ensure Linux doesn't assign anything there, the M32 logic + ignores that however and will forward in that space if we try). + + * It is divided into 256 segments of equal size. A table in the chip + maps each segment to a PE#. That allows portions of the MMIO space + to be assigned to PEs on a segment granularity. For a 2GB window, + the segment granularity is 2GB/256 = 8MB. + + Now, this is the "main" window we use in Linux today (excluding + SR-IOV). We basically use the trick of forcing the bridge MMIO windows + onto a segment alignment/granularity so that the space behind a bridge + can be assigned to a PE. + + Ideally we would like to be able to have individual functions in PEs + but that would mean using a completely different address allocation + scheme where individual function BARs can be "grouped" to fit in one or + more segments. + + - The M64 windows: + + * Must be at least 256MB in size. + + * Do not translate addresses (the address on PCIe is the same as the + address on the PowerBus). There is a way to also set the top 14 + bits which are not conveyed by PowerBus but we don't use this. + + * Can be configured to be segmented. When not segmented, we can + specify the PE# for the entire window. When segmented, a window + has 256 segments; however, there is no table for mapping a segment + to a PE#. The segment number *is* the PE#. + + * Support overlaps. If an address is covered by multiple windows, + there's a defined ordering for which window applies. + + We have code (fairly new compared to the M32 stuff) that exploits that + for large BARs in 64-bit space: + + We configure an M64 window to cover the entire region of address space + that has been assigned by FW for the PHB (about 64GB, ignore the space + for the M32, it comes out of a different "reserve"). We configure it + as segmented. + + Then we do the same thing as with M32, using the bridge alignment + trick, to match to those giant segments. + + Since we cannot remap, we have two additional constraints: + + - We do the PE# allocation *after* the 64-bit space has been assigned + because the addresses we use directly determine the PE#. We then + update the M32 PE# for the devices that use both 32-bit and 64-bit + spaces or assign the remaining PE# to 32-bit only devices. + + - We cannot "group" segments in HW, so if a device ends up using more + than one segment, we end up with more than one PE#. There is a HW + mechanism to make the freeze state cascade to "companion" PEs but + that only works for PCIe error messages (typically used so that if + you freeze a switch, it freezes all its children). So we do it in + SW. We lose a bit of effectiveness of EEH in that case, but that's + the best we found. So when any of the PEs freezes, we freeze the + other ones for that "domain". We thus introduce the concept of + "master PE" which is the one used for DMA, MSIs, etc., and "secondary + PEs" that are used for the remaining M64 segments. + + We would like to investigate using additional M64 windows in "single + PE" mode to overlay over specific BARs to work around some of that, for + example for devices with very large BARs, e.g., GPUs. It would make + sense, but we haven't done it yet. + +3. Considerations for SR-IOV on PowerKVM +======================================== + + * SR-IOV Background + + The PCIe SR-IOV feature allows a single Physical Function (PF) to + support several Virtual Functions (VFs). Registers in the PF's SR-IOV + Capability control the number of VFs and whether they are enabled. + + When VFs are enabled, they appear in Configuration Space like normal + PCI devices, but the BARs in VF config space headers are unusual. For + a non-VF device, software uses BARs in the config space header to + discover the BAR sizes and assign addresses for them. For VF devices, + software uses VF BAR registers in the *PF* SR-IOV Capability to + discover sizes and assign addresses. The BARs in the VF's config space + header are read-only zeros. + + When a VF BAR in the PF SR-IOV Capability is programmed, it sets the + base address for all the corresponding VF(n) BARs. For example, if the + PF SR-IOV Capability is programmed to enable eight VFs, and it has a + 1MB VF BAR0, the address in that VF BAR sets the base of an 8MB region. + This region is divided into eight contiguous 1MB regions, each of which + is a BAR0 for one of the VFs. Note that even though the VF BAR + describes an 8MB region, the alignment requirement is for a single VF, + i.e., 1MB in this example. + + There are several strategies for isolating VFs in PEs: + + - M32 window: There's one M32 window, and it is split into 256 + equally-sized segments. The finest granularity possible is a 256MB + window with 1MB segments. VF BARs that are 1MB or larger could be + mapped to separate PEs in this window. Each segment can be + individually mapped to a PE via the lookup table, so this is quite + flexible, but it works best when all the VF BARs are the same size. If + they are different sizes, the entire window has to be small enough that + the segment size matches the smallest VF BAR, which means larger VF + BARs span several segments. + + - Non-segmented M64 window: A non-segmented M64 window is mapped entirely + to a single PE, so it could only isolate one VF. + + - Single segmented M64 windows: A segmented M64 window could be used just + like the M32 window, but the segments can't be individually mapped to + PEs (the segment number is the PE#), so there isn't as much + flexibility. A VF with multiple BARs would have to be in a "domain" of + multiple PEs, which is not as well isolated as a single PE. + + - Multiple segmented M64 windows: As usual, each window is split into 256 + equally-sized segments, and the segment number is the PE#. But if we + use several M64 windows, they can be set to different base addresses + and different segment sizes. If we have VFs that each have a 1MB BAR + and a 32MB BAR, we could use one M64 window to assign 1MB segments and + another M64 window to assign 32MB segments. + + Finally, the plan to use M64 windows for SR-IOV, which will be described + more in the next two sections. For a given VF BAR, we need to + effectively reserve the entire 256 segments (256 * VF BAR size) and + position the VF BAR to start at the beginning of a free range of + segments/PEs inside that M64 window. + + The goal is of course to be able to give a separate PE for each VF. + + The IODA2 platform has 16 M64 windows, which are used to map MMIO + range to PE#. Each M64 window defines one MMIO range and this range is + divided into 256 segments, with each segment corresponding to one PE. + + We decide to leverage this M64 window to map VFs to individual PEs, since + SR-IOV VF BARs are all the same size. + + But doing so introduces another problem: total_VFs is usually smaller + than the number of M64 window segments, so if we map one VF BAR directly + to one M64 window, some part of the M64 window will map to another + device's MMIO range. + + IODA supports 256 PEs, so segmented windows contain 256 segments, so if + total_VFs is less than 256, we have the situation in Figure 1.0, where + segments [total_VFs, 255] of the M64 window may map to some MMIO range on + other devices:: + + 0 1 total_VFs - 1 + +------+------+- -+------+------+ + | | | ... | | | + +------+------+- -+------+------+ + + VF(n) BAR space + + 0 1 total_VFs - 1 255 + +------+------+- -+------+------+- -+------+------+ + | | | ... | | | ... | | | + +------+------+- -+------+------+- -+------+------+ + + M64 window + + Figure 1.0 Direct map VF(n) BAR space + + Our current solution is to allocate 256 segments even if the VF(n) BAR + space doesn't need that much, as shown in Figure 1.1:: + + 0 1 total_VFs - 1 255 + +------+------+- -+------+------+- -+------+------+ + | | | ... | | | ... | | | + +------+------+- -+------+------+- -+------+------+ + + VF(n) BAR space + extra + + 0 1 total_VFs - 1 255 + +------+------+- -+------+------+- -+------+------+ + | | | ... | | | ... | | | + +------+------+- -+------+------+- -+------+------+ + + M64 window + + Figure 1.1 Map VF(n) BAR space + extra + + Allocating the extra space ensures that the entire M64 window will be + assigned to this one SR-IOV device and none of the space will be + available for other devices. Note that this only expands the space + reserved in software; there are still only total_VFs VFs, and they only + respond to segments [0, total_VFs - 1]. There's nothing in hardware that + responds to segments [total_VFs, 255]. + +4. Implications for the Generic PCI Code +======================================== + +The PCIe SR-IOV spec requires that the base of the VF(n) BAR space be +aligned to the size of an individual VF BAR. + +In IODA2, the MMIO address determines the PE#. If the address is in an M32 +window, we can set the PE# by updating the table that translates segments +to PE#s. Similarly, if the address is in an unsegmented M64 window, we can +set the PE# for the window. But if it's in a segmented M64 window, the +segment number is the PE#. + +Therefore, the only way to control the PE# for a VF is to change the base +of the VF(n) BAR space in the VF BAR. If the PCI core allocates the exact +amount of space required for the VF(n) BAR space, the VF BAR value is fixed +and cannot be changed. + +On the other hand, if the PCI core allocates additional space, the VF BAR +value can be changed as long as the entire VF(n) BAR space remains inside +the space allocated by the core. + +Ideally the segment size will be the same as an individual VF BAR size. +Then each VF will be in its own PE. The VF BARs (and therefore the PE#s) +are contiguous. If VF0 is in PE(x), then VF(n) is in PE(x+n). If we +allocate 256 segments, there are (256 - numVFs) choices for the PE# of VF0. + +If the segment size is smaller than the VF BAR size, it will take several +segments to cover a VF BAR, and a VF will be in several PEs. This is +possible, but the isolation isn't as good, and it reduces the number of PE# +choices because instead of consuming only numVFs segments, the VF(n) BAR +space will consume (numVFs * n) segments. That means there aren't as many +available segments for adjusting base of the VF(n) BAR space. diff --git a/Documentation/arch/powerpc/pmu-ebb.rst b/Documentation/arch/powerpc/pmu-ebb.rst new file mode 100644 index 0000000000..4f474758eb --- /dev/null +++ b/Documentation/arch/powerpc/pmu-ebb.rst @@ -0,0 +1,138 @@ +======================== +PMU Event Based Branches +======================== + +Event Based Branches (EBBs) are a feature which allows the hardware to +branch directly to a specified user space address when certain events occur. + +The full specification is available in Power ISA v2.07: + + https://www.power.org/documentation/power-isa-version-2-07/ + +One type of event for which EBBs can be configured is PMU exceptions. This +document describes the API for configuring the Power PMU to generate EBBs, +using the Linux perf_events API. + + +Terminology +----------- + +Throughout this document we will refer to an "EBB event" or "EBB events". This +just refers to a struct perf_event which has set the "EBB" flag in its +attr.config. All events which can be configured on the hardware PMU are +possible "EBB events". + + +Background +---------- + +When a PMU EBB occurs it is delivered to the currently running process. As such +EBBs can only sensibly be used by programs for self-monitoring. + +It is a feature of the perf_events API that events can be created on other +processes, subject to standard permission checks. This is also true of EBB +events, however unless the target process enables EBBs (via mtspr(BESCR)) no +EBBs will ever be delivered. + +This makes it possible for a process to enable EBBs for itself, but not +actually configure any events. At a later time another process can come along +and attach an EBB event to the process, which will then cause EBBs to be +delivered to the first process. It's not clear if this is actually useful. + + +When the PMU is configured for EBBs, all PMU interrupts are delivered to the +user process. This means once an EBB event is scheduled on the PMU, no non-EBB +events can be configured. This means that EBB events can not be run +concurrently with regular 'perf' commands, or any other perf events. + +It is however safe to run 'perf' commands on a process which is using EBBs. The +kernel will in general schedule the EBB event, and perf will be notified that +its events could not run. + +The exclusion between EBB events and regular events is implemented using the +existing "pinned" and "exclusive" attributes of perf_events. This means EBB +events will be given priority over other events, unless they are also pinned. +If an EBB event and a regular event are both pinned, then whichever is enabled +first will be scheduled and the other will be put in error state. See the +section below titled "Enabling an EBB event" for more information. + + +Creating an EBB event +--------------------- + +To request that an event is counted using EBB, the event code should have bit +63 set. + +EBB events must be created with a particular, and restrictive, set of +attributes - this is so that they interoperate correctly with the rest of the +perf_events subsystem. + +An EBB event must be created with the "pinned" and "exclusive" attributes set. +Note that if you are creating a group of EBB events, only the leader can have +these attributes set. + +An EBB event must NOT set any of the "inherit", "sample_period", "freq" or +"enable_on_exec" attributes. + +An EBB event must be attached to a task. This is specified to perf_event_open() +by passing a pid value, typically 0 indicating the current task. + +All events in a group must agree on whether they want EBB. That is all events +must request EBB, or none may request EBB. + +EBB events must specify the PMC they are to be counted on. This ensures +userspace is able to reliably determine which PMC the event is scheduled on. + + +Enabling an EBB event +--------------------- + +Once an EBB event has been successfully opened, it must be enabled with the +perf_events API. This can be achieved either via the ioctl() interface, or the +prctl() interface. + +However, due to the design of the perf_events API, enabling an event does not +guarantee that it has been scheduled on the PMU. To ensure that the EBB event +has been scheduled on the PMU, you must perform a read() on the event. If the +read() returns EOF, then the event has not been scheduled and EBBs are not +enabled. + +This behaviour occurs because the EBB event is pinned and exclusive. When the +EBB event is enabled it will force all other non-pinned events off the PMU. In +this case the enable will be successful. However if there is already an event +pinned on the PMU then the enable will not be successful. + + +Reading an EBB event +-------------------- + +It is possible to read() from an EBB event. However the results are +meaningless. Because interrupts are being delivered to the user process the +kernel is not able to count the event, and so will return a junk value. + + +Closing an EBB event +-------------------- + +When an EBB event is finished with, you can close it using close() as for any +regular event. If this is the last EBB event the PMU will be deconfigured and +no further PMU EBBs will be delivered. + + +EBB Handler +----------- + +The EBB handler is just regular userspace code, however it must be written in +the style of an interrupt handler. When the handler is entered all registers +are live (possibly) and so must be saved somehow before the handler can invoke +other code. + +It's up to the program how to handle this. For C programs a relatively simple +option is to create an interrupt frame on the stack and save registers there. + +Fork +---- + +EBB events are not inherited across fork. If the child process wishes to use +EBBs it should open a new event for itself. Similarly the EBB state in +BESCR/EBBHR/EBBRR is cleared across fork(). diff --git a/Documentation/arch/powerpc/ptrace.rst b/Documentation/arch/powerpc/ptrace.rst new file mode 100644 index 0000000000..5629edf4d5 --- /dev/null +++ b/Documentation/arch/powerpc/ptrace.rst @@ -0,0 +1,157 @@ +====== +Ptrace +====== + +GDB intends to support the following hardware debug features of BookE +processors: + +4 hardware breakpoints (IAC) +2 hardware watchpoints (read, write and read-write) (DAC) +2 value conditions for the hardware watchpoints (DVC) + +For that, we need to extend ptrace so that GDB can query and set these +resources. Since we're extending, we're trying to create an interface +that's extendable and that covers both BookE and server processors, so +that GDB doesn't need to special-case each of them. We added the +following 3 new ptrace requests. + +1. PPC_PTRACE_GETHWDBGINFO +============================ + +Query for GDB to discover the hardware debug features. The main info to +be returned here is the minimum alignment for the hardware watchpoints. +BookE processors don't have restrictions here, but server processors have +an 8-byte alignment restriction for hardware watchpoints. We'd like to avoid +adding special cases to GDB based on what it sees in AUXV. + +Since we're at it, we added other useful info that the kernel can return to +GDB: this query will return the number of hardware breakpoints, hardware +watchpoints and whether it supports a range of addresses and a condition. +The query will fill the following structure provided by the requesting process:: + + struct ppc_debug_info { + unit32_t version; + unit32_t num_instruction_bps; + unit32_t num_data_bps; + unit32_t num_condition_regs; + unit32_t data_bp_alignment; + unit32_t sizeof_condition; /* size of the DVC register */ + uint64_t features; /* bitmask of the individual flags */ + }; + +features will have bits indicating whether there is support for:: + + #define PPC_DEBUG_FEATURE_INSN_BP_RANGE 0x1 + #define PPC_DEBUG_FEATURE_INSN_BP_MASK 0x2 + #define PPC_DEBUG_FEATURE_DATA_BP_RANGE 0x4 + #define PPC_DEBUG_FEATURE_DATA_BP_MASK 0x8 + #define PPC_DEBUG_FEATURE_DATA_BP_DAWR 0x10 + #define PPC_DEBUG_FEATURE_DATA_BP_ARCH_31 0x20 + +2. PPC_PTRACE_SETHWDEBUG + +Sets a hardware breakpoint or watchpoint, according to the provided structure:: + + struct ppc_hw_breakpoint { + uint32_t version; + #define PPC_BREAKPOINT_TRIGGER_EXECUTE 0x1 + #define PPC_BREAKPOINT_TRIGGER_READ 0x2 + #define PPC_BREAKPOINT_TRIGGER_WRITE 0x4 + uint32_t trigger_type; /* only some combinations allowed */ + #define PPC_BREAKPOINT_MODE_EXACT 0x0 + #define PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE 0x1 + #define PPC_BREAKPOINT_MODE_RANGE_EXCLUSIVE 0x2 + #define PPC_BREAKPOINT_MODE_MASK 0x3 + uint32_t addr_mode; /* address match mode */ + + #define PPC_BREAKPOINT_CONDITION_MODE 0x3 + #define PPC_BREAKPOINT_CONDITION_NONE 0x0 + #define PPC_BREAKPOINT_CONDITION_AND 0x1 + #define PPC_BREAKPOINT_CONDITION_EXACT 0x1 /* different name for the same thing as above */ + #define PPC_BREAKPOINT_CONDITION_OR 0x2 + #define PPC_BREAKPOINT_CONDITION_AND_OR 0x3 + #define PPC_BREAKPOINT_CONDITION_BE_ALL 0x00ff0000 /* byte enable bits */ + #define PPC_BREAKPOINT_CONDITION_BE(n) (1<<((n)+16)) + uint32_t condition_mode; /* break/watchpoint condition flags */ + + uint64_t addr; + uint64_t addr2; + uint64_t condition_value; + }; + +A request specifies one event, not necessarily just one register to be set. +For instance, if the request is for a watchpoint with a condition, both the +DAC and DVC registers will be set in the same request. + +With this GDB can ask for all kinds of hardware breakpoints and watchpoints +that the BookE supports. COMEFROM breakpoints available in server processors +are not contemplated, but that is out of the scope of this work. + +ptrace will return an integer (handle) uniquely identifying the breakpoint or +watchpoint just created. This integer will be used in the PPC_PTRACE_DELHWDEBUG +request to ask for its removal. Return -ENOSPC if the requested breakpoint +can't be allocated on the registers. + +Some examples of using the structure to: + +- set a breakpoint in the first breakpoint register:: + + p.version = PPC_DEBUG_CURRENT_VERSION; + p.trigger_type = PPC_BREAKPOINT_TRIGGER_EXECUTE; + p.addr_mode = PPC_BREAKPOINT_MODE_EXACT; + p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE; + p.addr = (uint64_t) address; + p.addr2 = 0; + p.condition_value = 0; + +- set a watchpoint which triggers on reads in the second watchpoint register:: + + p.version = PPC_DEBUG_CURRENT_VERSION; + p.trigger_type = PPC_BREAKPOINT_TRIGGER_READ; + p.addr_mode = PPC_BREAKPOINT_MODE_EXACT; + p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE; + p.addr = (uint64_t) address; + p.addr2 = 0; + p.condition_value = 0; + +- set a watchpoint which triggers only with a specific value:: + + p.version = PPC_DEBUG_CURRENT_VERSION; + p.trigger_type = PPC_BREAKPOINT_TRIGGER_READ; + p.addr_mode = PPC_BREAKPOINT_MODE_EXACT; + p.condition_mode = PPC_BREAKPOINT_CONDITION_AND | PPC_BREAKPOINT_CONDITION_BE_ALL; + p.addr = (uint64_t) address; + p.addr2 = 0; + p.condition_value = (uint64_t) condition; + +- set a ranged hardware breakpoint:: + + p.version = PPC_DEBUG_CURRENT_VERSION; + p.trigger_type = PPC_BREAKPOINT_TRIGGER_EXECUTE; + p.addr_mode = PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE; + p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE; + p.addr = (uint64_t) begin_range; + p.addr2 = (uint64_t) end_range; + p.condition_value = 0; + +- set a watchpoint in server processors (BookS):: + + p.version = 1; + p.trigger_type = PPC_BREAKPOINT_TRIGGER_RW; + p.addr_mode = PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE; + or + p.addr_mode = PPC_BREAKPOINT_MODE_EXACT; + + p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE; + p.addr = (uint64_t) begin_range; + /* For PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE addr2 needs to be specified, where + * addr2 - addr <= 8 Bytes. + */ + p.addr2 = (uint64_t) end_range; + p.condition_value = 0; + +3. PPC_PTRACE_DELHWDEBUG + +Takes an integer which identifies an existing breakpoint or watchpoint +(i.e., the value returned from PTRACE_SETHWDEBUG), and deletes the +corresponding breakpoint or watchpoint.. diff --git a/Documentation/arch/powerpc/qe_firmware.rst b/Documentation/arch/powerpc/qe_firmware.rst new file mode 100644 index 0000000000..a358f152b7 --- /dev/null +++ b/Documentation/arch/powerpc/qe_firmware.rst @@ -0,0 +1,296 @@ +========================================= +Freescale QUICC Engine Firmware Uploading +========================================= + +(c) 2007 Timur Tabi , + Freescale Semiconductor + +.. Table of Contents + + I - Software License for Firmware + + II - Microcode Availability + + III - Description and Terminology + + IV - Microcode Programming Details + + V - Firmware Structure Layout + + VI - Sample Code for Creating Firmware Files + +Revision Information +==================== + +November 30, 2007: Rev 1.0 - Initial version + +I - Software License for Firmware +================================= + +Each firmware file comes with its own software license. For information on +the particular license, please see the license text that is distributed with +the firmware. + +II - Microcode Availability +=========================== + +Firmware files are distributed through various channels. Some are available on +http://opensource.freescale.com. For other firmware files, please contact +your Freescale representative or your operating system vendor. + +III - Description and Terminology +================================= + +In this document, the term 'microcode' refers to the sequence of 32-bit +integers that compose the actual QE microcode. + +The term 'firmware' refers to a binary blob that contains the microcode as +well as other data that + + 1) describes the microcode's purpose + 2) describes how and where to upload the microcode + 3) specifies the values of various registers + 4) includes additional data for use by specific device drivers + +Firmware files are binary files that contain only a firmware. + +IV - Microcode Programming Details +=================================== + +The QE architecture allows for only one microcode present in I-RAM for each +RISC processor. To replace any current microcode, a full QE reset (which +disables the microcode) must be performed first. + +QE microcode is uploaded using the following procedure: + +1) The microcode is placed into I-RAM at a specific location, using the + IRAM.IADD and IRAM.IDATA registers. + +2) The CERCR.CIR bit is set to 0 or 1, depending on whether the firmware + needs split I-RAM. Split I-RAM is only meaningful for SOCs that have + QEs with multiple RISC processors, such as the 8360. Splitting the I-RAM + allows each processor to run a different microcode, effectively creating an + asymmetric multiprocessing (AMP) system. + +3) The TIBCR trap registers are loaded with the addresses of the trap handlers + in the microcode. + +4) The RSP.ECCR register is programmed with the value provided. + +5) If necessary, device drivers that need the virtual traps and extended mode + data will use them. + +Virtual Microcode Traps + +These virtual traps are conditional branches in the microcode. These are +"soft" provisional introduced in the ROMcode in order to enable higher +flexibility and save h/w traps If new features are activated or an issue is +being fixed in the RAM package utilizing they should be activated. This data +structure signals the microcode which of these virtual traps is active. + +This structure contains 6 words that the application should copy to some +specific been defined. This table describes the structure:: + + --------------------------------------------------------------- + | Offset in | | Destination Offset | Size of | + | array | Protocol | within PRAM | Operand | + --------------------------------------------------------------| + | 0 | Ethernet | 0xF8 | 4 bytes | + | | interworking | | | + --------------------------------------------------------------- + | 4 | ATM | 0xF8 | 4 bytes | + | | interworking | | | + --------------------------------------------------------------- + | 8 | PPP | 0xF8 | 4 bytes | + | | interworking | | | + --------------------------------------------------------------- + | 12 | Ethernet RX | 0x22 | 1 byte | + | | Distributor Page | | | + --------------------------------------------------------------- + | 16 | ATM Globtal | 0x28 | 1 byte | + | | Params Table | | | + --------------------------------------------------------------- + | 20 | Insert Frame | 0xF8 | 4 bytes | + --------------------------------------------------------------- + + +Extended Modes + +This is a double word bit array (64 bits) that defines special functionality +which has an impact on the software drivers. Each bit has its own impact +and has special instructions for the s/w associated with it. This structure is +described in this table:: + + ----------------------------------------------------------------------- + | Bit # | Name | Description | + ----------------------------------------------------------------------- + | 0 | General | Indicates that prior to each host command | + | | push command | given by the application, the software must | + | | | assert a special host command (push command)| + | | | CECDR = 0x00800000. | + | | | CECR = 0x01c1000f. | + ----------------------------------------------------------------------- + | 1 | UCC ATM | Indicates that after issuing ATM RX INIT | + | | RX INIT | command, the host must issue another special| + | | push command | command (push command) and immediately | + | | | following that re-issue the ATM RX INIT | + | | | command. (This makes the sequence of | + | | | initializing the ATM receiver a sequence of | + | | | three host commands) | + | | | CECDR = 0x00800000. | + | | | CECR = 0x01c1000f. | + ----------------------------------------------------------------------- + | 2 | Add/remove | Indicates that following the specific host | + | | command | command: "Add/Remove entry in Hash Lookup | + | | validation | Table" used in Interworking setup, the user | + | | | must issue another command. | + | | | CECDR = 0xce000003. | + | | | CECR = 0x01c10f58. | + ----------------------------------------------------------------------- + | 3 | General push | Indicates that the s/w has to initialize | + | | command | some pointers in the Ethernet thread pages | + | | | which are used when Header Compression is | + | | | activated. The full details of these | + | | | pointers is located in the software drivers.| + ----------------------------------------------------------------------- + | 4 | General push | Indicates that after issuing Ethernet TX | + | | command | INIT command, user must issue this command | + | | | for each SNUM of Ethernet TX thread. | + | | | CECDR = 0x00800003. | + | | | CECR = 0x7'b{0}, 8'b{Enet TX thread SNUM}, | + | | | 1'b{1}, 12'b{0}, 4'b{1} | + ----------------------------------------------------------------------- + | 5 - 31 | N/A | Reserved, set to zero. | + ----------------------------------------------------------------------- + +V - Firmware Structure Layout +============================== + +QE microcode from Freescale is typically provided as a header file. This +header file contains macros that define the microcode binary itself as well as +some other data used in uploading that microcode. The format of these files +do not lend themselves to simple inclusion into other code. Hence, +the need for a more portable format. This section defines that format. + +Instead of distributing a header file, the microcode and related data are +embedded into a binary blob. This blob is passed to the qe_upload_firmware() +function, which parses the blob and performs everything necessary to upload +the microcode. + +All integers are big-endian. See the comments for function +qe_upload_firmware() for up-to-date implementation information. + +This structure supports versioning, where the version of the structure is +embedded into the structure itself. To ensure forward and backwards +compatibility, all versions of the structure must use the same 'qe_header' +structure at the beginning. + +'header' (type: struct qe_header): + The 'length' field is the size, in bytes, of the entire structure, + including all the microcode embedded in it, as well as the CRC (if + present). + + The 'magic' field is an array of three bytes that contains the letters + 'Q', 'E', and 'F'. This is an identifier that indicates that this + structure is a QE Firmware structure. + + The 'version' field is a single byte that indicates the version of this + structure. If the layout of the structure should ever need to be + changed to add support for additional types of microcode, then the + version number should also be changed. + +The 'id' field is a null-terminated string(suitable for printing) that +identifies the firmware. + +The 'count' field indicates the number of 'microcode' structures. There +must be one and only one 'microcode' structure for each RISC processor. +Therefore, this field also represents the number of RISC processors for this +SOC. + +The 'soc' structure contains the SOC numbers and revisions used to match +the microcode to the SOC itself. Normally, the microcode loader should +check the data in this structure with the SOC number and revisions, and +only upload the microcode if there's a match. However, this check is not +made on all platforms. + +Although it is not recommended, you can specify '0' in the soc.model +field to skip matching SOCs altogether. + +The 'model' field is a 16-bit number that matches the actual SOC. The +'major' and 'minor' fields are the major and minor revision numbers, +respectively, of the SOC. + +For example, to match the 8323, revision 1.0:: + + soc.model = 8323 + soc.major = 1 + soc.minor = 0 + +'padding' is necessary for structure alignment. This field ensures that the +'extended_modes' field is aligned on a 64-bit boundary. + +'extended_modes' is a bitfield that defines special functionality which has an +impact on the device drivers. Each bit has its own impact and has special +instructions for the driver associated with it. This field is stored in +the QE library and available to any driver that calls qe_get_firmware_info(). + +'vtraps' is an array of 8 words that contain virtual trap values for each +virtual traps. As with 'extended_modes', this field is stored in the QE +library and available to any driver that calls qe_get_firmware_info(). + +'microcode' (type: struct qe_microcode): + For each RISC processor there is one 'microcode' structure. The first + 'microcode' structure is for the first RISC, and so on. + + The 'id' field is a null-terminated string suitable for printing that + identifies this particular microcode. + + 'traps' is an array of 16 words that contain hardware trap values + for each of the 16 traps. If trap[i] is 0, then this particular + trap is to be ignored (i.e. not written to TIBCR[i]). The entire value + is written as-is to the TIBCR[i] register, so be sure to set the EN + and T_IBP bits if necessary. + + 'eccr' is the value to program into the ECCR register. + + 'iram_offset' is the offset into IRAM to start writing the + microcode. + + 'count' is the number of 32-bit words in the microcode. + + 'code_offset' is the offset, in bytes, from the beginning of this + structure where the microcode itself can be found. The first + microcode binary should be located immediately after the 'microcode' + array. + + 'major', 'minor', and 'revision' are the major, minor, and revision + version numbers, respectively, of the microcode. If all values are 0, + then these fields are ignored. + + 'reserved' is necessary for structure alignment. Since 'microcode' + is an array, the 64-bit 'extended_modes' field needs to be aligned + on a 64-bit boundary, and this can only happen if the size of + 'microcode' is a multiple of 8 bytes. To ensure that, we add + 'reserved'. + +After the last microcode is a 32-bit CRC. It can be calculated using +this algorithm:: + + u32 crc32(const u8 *p, unsigned int len) + { + unsigned int i; + u32 crc = 0; + + while (len--) { + crc ^= *p++; + for (i = 0; i < 8; i++) + crc = (crc >> 1) ^ ((crc & 1) ? 0xedb88320 : 0); + } + return crc; + } + +VI - Sample Code for Creating Firmware Files +============================================ + +A Python program that creates firmware binaries from the header files normally +distributed by Freescale can be found on http://opensource.freescale.com. diff --git a/Documentation/arch/powerpc/syscall64-abi.rst b/Documentation/arch/powerpc/syscall64-abi.rst new file mode 100644 index 0000000000..56490c4c0c --- /dev/null +++ b/Documentation/arch/powerpc/syscall64-abi.rst @@ -0,0 +1,153 @@ +=============================================== +Power Architecture 64-bit Linux system call ABI +=============================================== + +syscall +======= + +Invocation +---------- +The syscall is made with the sc instruction, and returns with execution +continuing at the instruction following the sc instruction. + +If PPC_FEATURE2_SCV appears in the AT_HWCAP2 ELF auxiliary vector, the +scv 0 instruction is an alternative that may provide better performance, +with some differences to calling sequence. + +syscall calling sequence\ [1]_ matches the Power Architecture 64-bit ELF ABI +specification C function calling sequence, including register preservation +rules, with the following differences. + +.. [1] Some syscalls (typically low-level management functions) may have + different calling sequences (e.g., rt_sigreturn). + +Parameters +---------- +The system call number is specified in r0. + +There is a maximum of 6 integer parameters to a syscall, passed in r3-r8. + +Return value +------------ +- For the sc instruction, both a value and an error condition are returned. + cr0.SO is the error condition, and r3 is the return value. When cr0.SO is + clear, the syscall succeeded and r3 is the return value. When cr0.SO is set, + the syscall failed and r3 is the error value (that normally corresponds to + errno). + +- For the scv 0 instruction, the return value indicates failure if it is + -4095..-1 (i.e., it is >= -MAX_ERRNO (-4095) as an unsigned comparison), + in which case the error value is the negated return value. + +Stack +----- +System calls do not modify the caller's stack frame. For example, the caller's +stack frame LR and CR save fields are not used. + +Register preservation rules +--------------------------- +Register preservation rules match the ELF ABI calling sequence with some +differences. + +For the sc instruction, the differences from the ELF ABI are as follows: + ++--------------+--------------------+-----------------------------------------+ +| Register | Preservation Rules | Purpose | ++==============+====================+=========================================+ +| r0 | Volatile | (System call number.) | ++--------------+--------------------+-----------------------------------------+ +| r3 | Volatile | (Parameter 1, and return value.) | ++--------------+--------------------+-----------------------------------------+ +| r4-r8 | Volatile | (Parameters 2-6.) | ++--------------+--------------------+-----------------------------------------+ +| cr0 | Volatile | (cr0.SO is the return error condition.) | ++--------------+--------------------+-----------------------------------------+ +| cr1, cr5-7 | Nonvolatile | | ++--------------+--------------------+-----------------------------------------+ +| lr | Nonvolatile | | ++--------------+--------------------+-----------------------------------------+ + +For the scv 0 instruction, the differences from the ELF ABI are as follows: + ++--------------+--------------------+-----------------------------------------+ +| Register | Preservation Rules | Purpose | ++==============+====================+=========================================+ +| r0 | Volatile | (System call number.) | ++--------------+--------------------+-----------------------------------------+ +| r3 | Volatile | (Parameter 1, and return value.) | ++--------------+--------------------+-----------------------------------------+ +| r4-r8 | Volatile | (Parameters 2-6.) | ++--------------+--------------------+-----------------------------------------+ + +All floating point and vector data registers as well as control and status +registers are nonvolatile. + +Transactional Memory +-------------------- +Syscall behavior can change if the processor is in transactional or suspended +transaction state, and the syscall can affect the behavior of the transaction. + +If the processor is in suspended state when a syscall is made, the syscall +will be performed as normal, and will return as normal. The syscall will be +performed in suspended state, so its side effects will be persistent according +to the usual transactional memory semantics. A syscall may or may not result +in the transaction being doomed by hardware. + +If the processor is in transactional state when a syscall is made, then the +behavior depends on the presence of PPC_FEATURE2_HTM_NOSC in the AT_HWCAP2 ELF +auxiliary vector. + +- If present, which is the case for newer kernels, then the syscall will not + be performed and the transaction will be doomed by the kernel with the + failure code TM_CAUSE_SYSCALL | TM_CAUSE_PERSISTENT in the TEXASR SPR. + +- If not present (older kernels), then the kernel will suspend the + transactional state and the syscall will proceed as in the case of a + suspended state syscall, and will resume the transactional state before + returning to the caller. This case is not well defined or supported, so this + behavior should not be relied upon. + +scv 0 syscalls will always behave as PPC_FEATURE2_HTM_NOSC. + +ptrace +------ +When ptracing system calls (PTRACE_SYSCALL), the pt_regs.trap value contains +the system call type that can be used to distinguish between sc and scv 0 +system calls, and the different register conventions can be accounted for. + +If the value of (pt_regs.trap & 0xfff0) is 0xc00 then the system call was +performed with the sc instruction, if it is 0x3000 then the system call was +performed with the scv 0 instruction. + +vsyscall +======== + +vsyscall calling sequence matches the syscall calling sequence, with the +following differences. Some vsyscalls may have different calling sequences. + +Parameters and return value +--------------------------- +r0 is not used as an input. The vsyscall is selected by its address. + +Stack +----- +The vsyscall may or may not use the caller's stack frame save areas. + +Register preservation rules +--------------------------- + +=========== ======== +r0 Volatile +cr1, cr5-7 Volatile +lr Volatile +=========== ======== + +Invocation +---------- +The vsyscall is performed with a branch-with-link instruction to the vsyscall +function address. + +Transactional Memory +-------------------- +vsyscalls will run in the same transactional state as the caller. A vsyscall +may or may not result in the transaction being doomed by hardware. diff --git a/Documentation/arch/powerpc/transactional_memory.rst b/Documentation/arch/powerpc/transactional_memory.rst new file mode 100644 index 0000000000..040a20675f --- /dev/null +++ b/Documentation/arch/powerpc/transactional_memory.rst @@ -0,0 +1,274 @@ +============================ +Transactional Memory support +============================ + +POWER kernel support for this feature is currently limited to supporting +its use by user programs. It is not currently used by the kernel itself. + +This file aims to sum up how it is supported by Linux and what behaviour you +can expect from your user programs. + + +Basic overview +============== + +Hardware Transactional Memory is supported on POWER8 processors, and is a +feature that enables a different form of atomic memory access. Several new +instructions are presented to delimit transactions; transactions are +guaranteed to either complete atomically or roll back and undo any partial +changes. + +A simple transaction looks like this:: + + begin_move_money: + tbegin + beq abort_handler + + ld r4, SAVINGS_ACCT(r3) + ld r5, CURRENT_ACCT(r3) + subi r5, r5, 1 + addi r4, r4, 1 + std r4, SAVINGS_ACCT(r3) + std r5, CURRENT_ACCT(r3) + + tend + + b continue + + abort_handler: + ... test for odd failures ... + + /* Retry the transaction if it failed because it conflicted with + * someone else: */ + b begin_move_money + + +The 'tbegin' instruction denotes the start point, and 'tend' the end point. +Between these points the processor is in 'Transactional' state; any memory +references will complete in one go if there are no conflicts with other +transactional or non-transactional accesses within the system. In this +example, the transaction completes as though it were normal straight-line code +IF no other processor has touched SAVINGS_ACCT(r3) or CURRENT_ACCT(r3); an +atomic move of money from the current account to the savings account has been +performed. Even though the normal ld/std instructions are used (note no +lwarx/stwcx), either *both* SAVINGS_ACCT(r3) and CURRENT_ACCT(r3) will be +updated, or neither will be updated. + +If, in the meantime, there is a conflict with the locations accessed by the +transaction, the transaction will be aborted by the CPU. Register and memory +state will roll back to that at the 'tbegin', and control will continue from +'tbegin+4'. The branch to abort_handler will be taken this second time; the +abort handler can check the cause of the failure, and retry. + +Checkpointed registers include all GPRs, FPRs, VRs/VSRs, LR, CCR/CR, CTR, FPCSR +and a few other status/flag regs; see the ISA for details. + +Causes of transaction aborts +============================ + +- Conflicts with cache lines used by other processors +- Signals +- Context switches +- See the ISA for full documentation of everything that will abort transactions. + + +Syscalls +======== + +Syscalls made from within an active transaction will not be performed and the +transaction will be doomed by the kernel with the failure code TM_CAUSE_SYSCALL +| TM_CAUSE_PERSISTENT. + +Syscalls made from within a suspended transaction are performed as normal and +the transaction is not explicitly doomed by the kernel. However, what the +kernel does to perform the syscall may result in the transaction being doomed +by the hardware. The syscall is performed in suspended mode so any side +effects will be persistent, independent of transaction success or failure. No +guarantees are provided by the kernel about which syscalls will affect +transaction success. + +Care must be taken when relying on syscalls to abort during active transactions +if the calls are made via a library. Libraries may cache values (which may +give the appearance of success) or perform operations that cause transaction +failure before entering the kernel (which may produce different failure codes). +Examples are glibc's getpid() and lazy symbol resolution. + + +Signals +======= + +Delivery of signals (both sync and async) during transactions provides a second +thread state (ucontext/mcontext) to represent the second transactional register +state. Signal delivery 'treclaim's to capture both register states, so signals +abort transactions. The usual ucontext_t passed to the signal handler +represents the checkpointed/original register state; the signal appears to have +arisen at 'tbegin+4'. + +If the sighandler ucontext has uc_link set, a second ucontext has been +delivered. For future compatibility the MSR.TS field should be checked to +determine the transactional state -- if so, the second ucontext in uc->uc_link +represents the active transactional registers at the point of the signal. + +For 64-bit processes, uc->uc_mcontext.regs->msr is a full 64-bit MSR and its TS +field shows the transactional mode. + +For 32-bit processes, the mcontext's MSR register is only 32 bits; the top 32 +bits are stored in the MSR of the second ucontext, i.e. in +uc->uc_link->uc_mcontext.regs->msr. The top word contains the transactional +state TS. + +However, basic signal handlers don't need to be aware of transactions +and simply returning from the handler will deal with things correctly: + +Transaction-aware signal handlers can read the transactional register state +from the second ucontext. This will be necessary for crash handlers to +determine, for example, the address of the instruction causing the SIGSEGV. + +Example signal handler:: + + void crash_handler(int sig, siginfo_t *si, void *uc) + { + ucontext_t *ucp = uc; + ucontext_t *transactional_ucp = ucp->uc_link; + + if (ucp_link) { + u64 msr = ucp->uc_mcontext.regs->msr; + /* May have transactional ucontext! */ + #ifndef __powerpc64__ + msr |= ((u64)transactional_ucp->uc_mcontext.regs->msr) << 32; + #endif + if (MSR_TM_ACTIVE(msr)) { + /* Yes, we crashed during a transaction. Oops. */ + fprintf(stderr, "Transaction to be restarted at 0x%llx, but " + "crashy instruction was at 0x%llx\n", + ucp->uc_mcontext.regs->nip, + transactional_ucp->uc_mcontext.regs->nip); + } + } + + fix_the_problem(ucp->dar); + } + +When in an active transaction that takes a signal, we need to be careful with +the stack. It's possible that the stack has moved back up after the tbegin. +The obvious case here is when the tbegin is called inside a function that +returns before a tend. In this case, the stack is part of the checkpointed +transactional memory state. If we write over this non transactionally or in +suspend, we are in trouble because if we get a tm abort, the program counter and +stack pointer will be back at the tbegin but our in memory stack won't be valid +anymore. + +To avoid this, when taking a signal in an active transaction, we need to use +the stack pointer from the checkpointed state, rather than the speculated +state. This ensures that the signal context (written tm suspended) will be +written below the stack required for the rollback. The transaction is aborted +because of the treclaim, so any memory written between the tbegin and the +signal will be rolled back anyway. + +For signals taken in non-TM or suspended mode, we use the +normal/non-checkpointed stack pointer. + +Any transaction initiated inside a sighandler and suspended on return +from the sighandler to the kernel will get reclaimed and discarded. + +Failure cause codes used by kernel +================================== + +These are defined in , and distinguish different reasons why the +kernel aborted a transaction: + + ====================== ================================ + TM_CAUSE_RESCHED Thread was rescheduled. + TM_CAUSE_TLBI Software TLB invalid. + TM_CAUSE_FAC_UNAV FP/VEC/VSX unavailable trap. + TM_CAUSE_SYSCALL Syscall from active transaction. + TM_CAUSE_SIGNAL Signal delivered. + TM_CAUSE_MISC Currently unused. + TM_CAUSE_ALIGNMENT Alignment fault. + TM_CAUSE_EMULATE Emulation that touched memory. + ====================== ================================ + +These can be checked by the user program's abort handler as TEXASR[0:7]. If +bit 7 is set, it indicates that the error is considered persistent. For example +a TM_CAUSE_ALIGNMENT will be persistent while a TM_CAUSE_RESCHED will not. + +GDB +=== + +GDB and ptrace are not currently TM-aware. If one stops during a transaction, +it looks like the transaction has just started (the checkpointed state is +presented). The transaction cannot then be continued and will take the failure +handler route. Furthermore, the transactional 2nd register state will be +inaccessible. GDB can currently be used on programs using TM, but not sensibly +in parts within transactions. + +POWER9 +====== + +TM on POWER9 has issues with storing the complete register state. This +is described in this commit:: + + commit 4bb3c7a0208fc13ca70598efd109901a7cd45ae7 + Author: Paul Mackerras + Date: Wed Mar 21 21:32:01 2018 +1100 + KVM: PPC: Book3S HV: Work around transactional memory bugs in POWER9 + +To account for this different POWER9 chips have TM enabled in +different ways. + +On POWER9N DD2.01 and below, TM is disabled. ie +HWCAP2[PPC_FEATURE2_HTM] is not set. + +On POWER9N DD2.1 TM is configured by firmware to always abort a +transaction when tm suspend occurs. So tsuspend will cause a +transaction to be aborted and rolled back. Kernel exceptions will also +cause the transaction to be aborted and rolled back and the exception +will not occur. If userspace constructs a sigcontext that enables TM +suspend, the sigcontext will be rejected by the kernel. This mode is +advertised to users with HWCAP2[PPC_FEATURE2_HTM_NO_SUSPEND] set. +HWCAP2[PPC_FEATURE2_HTM] is not set in this mode. + +On POWER9N DD2.2 and above, KVM and POWERVM emulate TM for guests (as +described in commit 4bb3c7a0208f), hence TM is enabled for guests +ie. HWCAP2[PPC_FEATURE2_HTM] is set for guest userspace. Guests that +makes heavy use of TM suspend (tsuspend or kernel suspend) will result +in traps into the hypervisor and hence will suffer a performance +degradation. Host userspace has TM disabled +ie. HWCAP2[PPC_FEATURE2_HTM] is not set. (although we make enable it +at some point in the future if we bring the emulation into host +userspace context switching). + +POWER9C DD1.2 and above are only available with POWERVM and hence +Linux only runs as a guest. On these systems TM is emulated like on +POWER9N DD2.2. + +Guest migration from POWER8 to POWER9 will work with POWER9N DD2.2 and +POWER9C DD1.2. Since earlier POWER9 processors don't support TM +emulation, migration from POWER8 to POWER9 is not supported there. + +Kernel implementation +===================== + +h/rfid mtmsrd quirk +------------------- + +As defined in the ISA, rfid has a quirk which is useful in early +exception handling. When in a userspace transaction and we enter the +kernel via some exception, MSR will end up as TM=0 and TS=01 (ie. TM +off but TM suspended). Regularly the kernel will want change bits in +the MSR and will perform an rfid to do this. In this case rfid can +have SRR0 TM = 0 and TS = 00 (ie. TM off and non transaction) and the +resulting MSR will retain TM = 0 and TS=01 from before (ie. stay in +suspend). This is a quirk in the architecture as this would normally +be a transition from TS=01 to TS=00 (ie. suspend -> non transactional) +which is an illegal transition. + +This quirk is described the architecture in the definition of rfid +with these lines: + + if (MSR 29:31 ¬ = 0b010 | SRR1 29:31 ¬ = 0b000) then + MSR 29:31 <- SRR1 29:31 + +hrfid and mtmsrd have the same quirk. + +The Linux kernel uses this quirk in its early exception handling. diff --git a/Documentation/arch/powerpc/ultravisor.rst b/Documentation/arch/powerpc/ultravisor.rst new file mode 100644 index 0000000000..ba6b1bf1cc --- /dev/null +++ b/Documentation/arch/powerpc/ultravisor.rst @@ -0,0 +1,1117 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. _ultravisor: + +============================ +Protected Execution Facility +============================ + +.. contents:: + :depth: 3 + +Introduction +############ + + Protected Execution Facility (PEF) is an architectural change for + POWER 9 that enables Secure Virtual Machines (SVMs). DD2.3 chips + (PVR=0x004e1203) or greater will be PEF-capable. A new ISA release + will include the PEF RFC02487 changes. + + When enabled, PEF adds a new higher privileged mode, called Ultravisor + mode, to POWER architecture. Along with the new mode there is new + firmware called the Protected Execution Ultravisor (or Ultravisor + for short). Ultravisor mode is the highest privileged mode in POWER + architecture. + + +------------------+ + | Privilege States | + +==================+ + | Problem | + +------------------+ + | Supervisor | + +------------------+ + | Hypervisor | + +------------------+ + | Ultravisor | + +------------------+ + + PEF protects SVMs from the hypervisor, privileged users, and other + VMs in the system. SVMs are protected while at rest and can only be + executed by an authorized machine. All virtual machines utilize + hypervisor services. The Ultravisor filters calls between the SVMs + and the hypervisor to assure that information does not accidentally + leak. All hypercalls except H_RANDOM are reflected to the hypervisor. + H_RANDOM is not reflected to prevent the hypervisor from influencing + random values in the SVM. + + To support this there is a refactoring of the ownership of resources + in the CPU. Some of the resources which were previously hypervisor + privileged are now ultravisor privileged. + +Hardware +======== + + The hardware changes include the following: + + * There is a new bit in the MSR that determines whether the current + process is running in secure mode, MSR(S) bit 41. MSR(S)=1, process + is in secure mode, MSR(s)=0 process is in normal mode. + + * The MSR(S) bit can only be set by the Ultravisor. + + * HRFID cannot be used to set the MSR(S) bit. If the hypervisor needs + to return to a SVM it must use an ultracall. It can determine if + the VM it is returning to is secure. + + * There is a new Ultravisor privileged register, SMFCTRL, which has an + enable/disable bit SMFCTRL(E). + + * The privilege of a process is now determined by three MSR bits, + MSR(S, HV, PR). In each of the tables below the modes are listed + from least privilege to highest privilege. The higher privilege + modes can access all the resources of the lower privilege modes. + + **Secure Mode MSR Settings** + + +---+---+---+---------------+ + | S | HV| PR|Privilege | + +===+===+===+===============+ + | 1 | 0 | 1 | Problem | + +---+---+---+---------------+ + | 1 | 0 | 0 | Privileged(OS)| + +---+---+---+---------------+ + | 1 | 1 | 0 | Ultravisor | + +---+---+---+---------------+ + | 1 | 1 | 1 | Reserved | + +---+---+---+---------------+ + + **Normal Mode MSR Settings** + + +---+---+---+---------------+ + | S | HV| PR|Privilege | + +===+===+===+===============+ + | 0 | 0 | 1 | Problem | + +---+---+---+---------------+ + | 0 | 0 | 0 | Privileged(OS)| + +---+---+---+---------------+ + | 0 | 1 | 0 | Hypervisor | + +---+---+---+---------------+ + | 0 | 1 | 1 | Problem (Host)| + +---+---+---+---------------+ + + * Memory is partitioned into secure and normal memory. Only processes + that are running in secure mode can access secure memory. + + * The hardware does not allow anything that is not running secure to + access secure memory. This means that the Hypervisor cannot access + the memory of the SVM without using an ultracall (asking the + Ultravisor). The Ultravisor will only allow the hypervisor to see + the SVM memory encrypted. + + * I/O systems are not allowed to directly address secure memory. This + limits the SVMs to virtual I/O only. + + * The architecture allows the SVM to share pages of memory with the + hypervisor that are not protected with encryption. However, this + sharing must be initiated by the SVM. + + * When a process is running in secure mode all hypercalls + (syscall lev=1) go to the Ultravisor. + + * When a process is in secure mode all interrupts go to the + Ultravisor. + + * The following resources have become Ultravisor privileged and + require an Ultravisor interface to manipulate: + + * Processor configurations registers (SCOMs). + + * Stop state information. + + * The debug registers CIABR, DAWR, and DAWRX when SMFCTRL(D) is set. + If SMFCTRL(D) is not set they do not work in secure mode. When set, + reading and writing requires an Ultravisor call, otherwise that + will cause a Hypervisor Emulation Assistance interrupt. + + * PTCR and partition table entries (partition table is in secure + memory). An attempt to write to PTCR will cause a Hypervisor + Emulation Assitance interrupt. + + * LDBAR (LD Base Address Register) and IMC (In-Memory Collection) + non-architected registers. An attempt to write to them will cause a + Hypervisor Emulation Assistance interrupt. + + * Paging for an SVM, sharing of memory with Hypervisor for an SVM. + (Including Virtual Processor Area (VPA) and virtual I/O). + + +Software/Microcode +================== + + The software changes include: + + * SVMs are created from normal VM using (open source) tooling supplied + by IBM. + + * All SVMs start as normal VMs and utilize an ultracall, UV_ESM + (Enter Secure Mode), to make the transition. + + * When the UV_ESM ultracall is made the Ultravisor copies the VM into + secure memory, decrypts the verification information, and checks the + integrity of the SVM. If the integrity check passes the Ultravisor + passes control in secure mode. + + * The verification information includes the pass phrase for the + encrypted disk associated with the SVM. This pass phrase is given + to the SVM when requested. + + * The Ultravisor is not involved in protecting the encrypted disk of + the SVM while at rest. + + * For external interrupts the Ultravisor saves the state of the SVM, + and reflects the interrupt to the hypervisor for processing. + For hypercalls, the Ultravisor inserts neutral state into all + registers not needed for the hypercall then reflects the call to + the hypervisor for processing. The H_RANDOM hypercall is performed + by the Ultravisor and not reflected. + + * For virtual I/O to work bounce buffering must be done. + + * The Ultravisor uses AES (IAPM) for protection of SVM memory. IAPM + is a mode of AES that provides integrity and secrecy concurrently. + + * The movement of data between normal and secure pages is coordinated + with the Ultravisor by a new HMM plug-in in the Hypervisor. + + The Ultravisor offers new services to the hypervisor and SVMs. These + are accessed through ultracalls. + +Terminology +=========== + + * Hypercalls: special system calls used to request services from + Hypervisor. + + * Normal memory: Memory that is accessible to Hypervisor. + + * Normal page: Page backed by normal memory and available to + Hypervisor. + + * Shared page: A page backed by normal memory and available to both + the Hypervisor/QEMU and the SVM (i.e page has mappings in SVM and + Hypervisor/QEMU). + + * Secure memory: Memory that is accessible only to Ultravisor and + SVMs. + + * Secure page: Page backed by secure memory and only available to + Ultravisor and SVM. + + * SVM: Secure Virtual Machine. + + * Ultracalls: special system calls used to request services from + Ultravisor. + + +Ultravisor calls API +#################### + + This section describes Ultravisor calls (ultracalls) needed to + support Secure Virtual Machines (SVM)s and Paravirtualized KVM. The + ultracalls allow the SVMs and Hypervisor to request services from the + Ultravisor such as accessing a register or memory region that can only + be accessed when running in Ultravisor-privileged mode. + + The specific service needed from an ultracall is specified in register + R3 (the first parameter to the ultracall). Other parameters to the + ultracall, if any, are specified in registers R4 through R12. + + Return value of all ultracalls is in register R3. Other output values + from the ultracall, if any, are returned in registers R4 through R12. + The only exception to this register usage is the ``UV_RETURN`` + ultracall described below. + + Each ultracall returns specific error codes, applicable in the context + of the ultracall. However, like with the PowerPC Architecture Platform + Reference (PAPR), if no specific error code is defined for a + particular situation, then the ultracall will fallback to an erroneous + parameter-position based code. i.e U_PARAMETER, U_P2, U_P3 etc + depending on the ultracall parameter that may have caused the error. + + Some ultracalls involve transferring a page of data between Ultravisor + and Hypervisor. Secure pages that are transferred from secure memory + to normal memory may be encrypted using dynamically generated keys. + When the secure pages are transferred back to secure memory, they may + be decrypted using the same dynamically generated keys. Generation and + management of these keys will be covered in a separate document. + + For now this only covers ultracalls currently implemented and being + used by Hypervisor and SVMs but others can be added here when it + makes sense. + + The full specification for all hypercalls/ultracalls will eventually + be made available in the public/OpenPower version of the PAPR + specification. + + .. note:: + + If PEF is not enabled, the ultracalls will be redirected to the + Hypervisor which must handle/fail the calls. + +Ultracalls used by Hypervisor +============================= + + This section describes the virtual memory management ultracalls used + by the Hypervisor to manage SVMs. + +UV_PAGE_OUT +----------- + + Encrypt and move the contents of a page from secure memory to normal + memory. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_PAGE_OUT, + uint16_t lpid, /* LPAR ID */ + uint64_t dest_ra, /* real address of destination page */ + uint64_t src_gpa, /* source guest-physical-address */ + uint8_t flags, /* flags */ + uint64_t order) /* page size order */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_PARAMETER if ``lpid`` is invalid. + * U_P2 if ``dest_ra`` is invalid. + * U_P3 if the ``src_gpa`` address is invalid. + * U_P4 if any bit in the ``flags`` is unrecognized + * U_P5 if the ``order`` parameter is unsupported. + * U_FUNCTION if functionality is not supported. + * U_BUSY if page cannot be currently paged-out. + +Description +~~~~~~~~~~~ + + Encrypt the contents of a secure-page and make it available to + Hypervisor in a normal page. + + By default, the source page is unmapped from the SVM's partition- + scoped page table. But the Hypervisor can provide a hint to the + Ultravisor to retain the page mapping by setting the ``UV_SNAPSHOT`` + flag in ``flags`` parameter. + + If the source page is already a shared page the call returns + U_SUCCESS, without doing anything. + +Use cases +~~~~~~~~~ + + #. QEMU attempts to access an address belonging to the SVM but the + page frame for that address is not mapped into QEMU's address + space. In this case, the Hypervisor will allocate a page frame, + map it into QEMU's address space and issue the ``UV_PAGE_OUT`` + call to retrieve the encrypted contents of the page. + + #. When Ultravisor runs low on secure memory and it needs to page-out + an LRU page. In this case, Ultravisor will issue the + ``H_SVM_PAGE_OUT`` hypercall to the Hypervisor. The Hypervisor will + then allocate a normal page and issue the ``UV_PAGE_OUT`` ultracall + and the Ultravisor will encrypt and move the contents of the secure + page into the normal page. + + #. When Hypervisor accesses SVM data, the Hypervisor requests the + Ultravisor to transfer the corresponding page into a insecure page, + which the Hypervisor can access. The data in the normal page will + be encrypted though. + +UV_PAGE_IN +---------- + + Move the contents of a page from normal memory to secure memory. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_PAGE_IN, + uint16_t lpid, /* the LPAR ID */ + uint64_t src_ra, /* source real address of page */ + uint64_t dest_gpa, /* destination guest physical address */ + uint64_t flags, /* flags */ + uint64_t order) /* page size order */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_BUSY if page cannot be currently paged-in. + * U_FUNCTION if functionality is not supported + * U_PARAMETER if ``lpid`` is invalid. + * U_P2 if ``src_ra`` is invalid. + * U_P3 if the ``dest_gpa`` address is invalid. + * U_P4 if any bit in the ``flags`` is unrecognized + * U_P5 if the ``order`` parameter is unsupported. + +Description +~~~~~~~~~~~ + + Move the contents of the page identified by ``src_ra`` from normal + memory to secure memory and map it to the guest physical address + ``dest_gpa``. + + If `dest_gpa` refers to a shared address, map the page into the + partition-scoped page-table of the SVM. If `dest_gpa` is not shared, + copy the contents of the page into the corresponding secure page. + Depending on the context, decrypt the page before being copied. + + The caller provides the attributes of the page through the ``flags`` + parameter. Valid values for ``flags`` are: + + * CACHE_INHIBITED + * CACHE_ENABLED + * WRITE_PROTECTION + + The Hypervisor must pin the page in memory before making + ``UV_PAGE_IN`` ultracall. + +Use cases +~~~~~~~~~ + + #. When a normal VM switches to secure mode, all its pages residing + in normal memory, are moved into secure memory. + + #. When an SVM requests to share a page with Hypervisor the Hypervisor + allocates a page and informs the Ultravisor. + + #. When an SVM accesses a secure page that has been paged-out, + Ultravisor invokes the Hypervisor to locate the page. After + locating the page, the Hypervisor uses UV_PAGE_IN to make the + page available to Ultravisor. + +UV_PAGE_INVAL +------------- + + Invalidate the Ultravisor mapping of a page. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_PAGE_INVAL, + uint16_t lpid, /* the LPAR ID */ + uint64_t guest_pa, /* destination guest-physical-address */ + uint64_t order) /* page size order */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_PARAMETER if ``lpid`` is invalid. + * U_P2 if ``guest_pa`` is invalid (or corresponds to a secure + page mapping). + * U_P3 if the ``order`` is invalid. + * U_FUNCTION if functionality is not supported. + * U_BUSY if page cannot be currently invalidated. + +Description +~~~~~~~~~~~ + + This ultracall informs Ultravisor that the page mapping in Hypervisor + corresponding to the given guest physical address has been invalidated + and that the Ultravisor should not access the page. If the specified + ``guest_pa`` corresponds to a secure page, Ultravisor will ignore the + attempt to invalidate the page and return U_P2. + +Use cases +~~~~~~~~~ + + #. When a shared page is unmapped from the QEMU's page table, possibly + because it is paged-out to disk, Ultravisor needs to know that the + page should not be accessed from its side too. + + +UV_WRITE_PATE +------------- + + Validate and write the partition table entry (PATE) for a given + partition. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_WRITE_PATE, + uint32_t lpid, /* the LPAR ID */ + uint64_t dw0 /* the first double word to write */ + uint64_t dw1) /* the second double word to write */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_BUSY if PATE cannot be currently written to. + * U_FUNCTION if functionality is not supported. + * U_PARAMETER if ``lpid`` is invalid. + * U_P2 if ``dw0`` is invalid. + * U_P3 if the ``dw1`` address is invalid. + * U_PERMISSION if the Hypervisor is attempting to change the PATE + of a secure virtual machine or if called from a + context other than Hypervisor. + +Description +~~~~~~~~~~~ + + Validate and write a LPID and its partition-table-entry for the given + LPID. If the LPID is already allocated and initialized, this call + results in changing the partition table entry. + +Use cases +~~~~~~~~~ + + #. The Partition table resides in Secure memory and its entries, + called PATE (Partition Table Entries), point to the partition- + scoped page tables for the Hypervisor as well as each of the + virtual machines (both secure and normal). The Hypervisor + operates in partition 0 and its partition-scoped page tables + reside in normal memory. + + #. This ultracall allows the Hypervisor to register the partition- + scoped and process-scoped page table entries for the Hypervisor + and other partitions (virtual machines) with the Ultravisor. + + #. If the value of the PATE for an existing partition (VM) changes, + the TLB cache for the partition is flushed. + + #. The Hypervisor is responsible for allocating LPID. The LPID and + its PATE entry are registered together. The Hypervisor manages + the PATE entries for a normal VM and can change the PATE entry + anytime. Ultravisor manages the PATE entries for an SVM and + Hypervisor is not allowed to modify them. + +UV_RETURN +--------- + + Return control from the Hypervisor back to the Ultravisor after + processing an hypercall or interrupt that was forwarded (aka + *reflected*) to the Hypervisor. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_RETURN) + +Return values +~~~~~~~~~~~~~ + + This call never returns to Hypervisor on success. It returns + U_INVALID if ultracall is not made from a Hypervisor context. + +Description +~~~~~~~~~~~ + + When an SVM makes an hypercall or incurs some other exception, the + Ultravisor usually forwards (aka *reflects*) the exceptions to the + Hypervisor. After processing the exception, Hypervisor uses the + ``UV_RETURN`` ultracall to return control back to the SVM. + + The expected register state on entry to this ultracall is: + + * Non-volatile registers are restored to their original values. + * If returning from an hypercall, register R0 contains the return + value (**unlike other ultracalls**) and, registers R4 through R12 + contain any output values of the hypercall. + * R3 contains the ultracall number, i.e UV_RETURN. + * If returning with a synthesized interrupt, R2 contains the + synthesized interrupt number. + +Use cases +~~~~~~~~~ + + #. Ultravisor relies on the Hypervisor to provide several services to + the SVM such as processing hypercall and other exceptions. After + processing the exception, Hypervisor uses UV_RETURN to return + control back to the Ultravisor. + + #. Hypervisor has to use this ultracall to return control to the SVM. + + +UV_REGISTER_MEM_SLOT +-------------------- + + Register an SVM address-range with specified properties. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_REGISTER_MEM_SLOT, + uint64_t lpid, /* LPAR ID of the SVM */ + uint64_t start_gpa, /* start guest physical address */ + uint64_t size, /* size of address range in bytes */ + uint64_t flags /* reserved for future expansion */ + uint16_t slotid) /* slot identifier */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_PARAMETER if ``lpid`` is invalid. + * U_P2 if ``start_gpa`` is invalid. + * U_P3 if ``size`` is invalid. + * U_P4 if any bit in the ``flags`` is unrecognized. + * U_P5 if the ``slotid`` parameter is unsupported. + * U_PERMISSION if called from context other than Hypervisor. + * U_FUNCTION if functionality is not supported. + + +Description +~~~~~~~~~~~ + + Register a memory range for an SVM. The memory range starts at the + guest physical address ``start_gpa`` and is ``size`` bytes long. + +Use cases +~~~~~~~~~ + + + #. When a virtual machine goes secure, all the memory slots managed by + the Hypervisor move into secure memory. The Hypervisor iterates + through each of memory slots, and registers the slot with + Ultravisor. Hypervisor may discard some slots such as those used + for firmware (SLOF). + + #. When new memory is hot-plugged, a new memory slot gets registered. + + +UV_UNREGISTER_MEM_SLOT +---------------------- + + Unregister an SVM address-range that was previously registered using + UV_REGISTER_MEM_SLOT. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_UNREGISTER_MEM_SLOT, + uint64_t lpid, /* LPAR ID of the SVM */ + uint64_t slotid) /* reservation slotid */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_FUNCTION if functionality is not supported. + * U_PARAMETER if ``lpid`` is invalid. + * U_P2 if ``slotid`` is invalid. + * U_PERMISSION if called from context other than Hypervisor. + +Description +~~~~~~~~~~~ + + Release the memory slot identified by ``slotid`` and free any + resources allocated towards the reservation. + +Use cases +~~~~~~~~~ + + #. Memory hot-remove. + + +UV_SVM_TERMINATE +---------------- + + Terminate an SVM and release its resources. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_SVM_TERMINATE, + uint64_t lpid, /* LPAR ID of the SVM */) + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_FUNCTION if functionality is not supported. + * U_PARAMETER if ``lpid`` is invalid. + * U_INVALID if VM is not secure. + * U_PERMISSION if not called from a Hypervisor context. + +Description +~~~~~~~~~~~ + + Terminate an SVM and release all its resources. + +Use cases +~~~~~~~~~ + + #. Called by Hypervisor when terminating an SVM. + + +Ultracalls used by SVM +====================== + +UV_SHARE_PAGE +------------- + + Share a set of guest physical pages with the Hypervisor. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_SHARE_PAGE, + uint64_t gfn, /* guest page frame number */ + uint64_t num) /* number of pages of size PAGE_SIZE */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_FUNCTION if functionality is not supported. + * U_INVALID if the VM is not secure. + * U_PARAMETER if ``gfn`` is invalid. + * U_P2 if ``num`` is invalid. + +Description +~~~~~~~~~~~ + + Share the ``num`` pages starting at guest physical frame number ``gfn`` + with the Hypervisor. Assume page size is PAGE_SIZE bytes. Zero the + pages before returning. + + If the address is already backed by a secure page, unmap the page and + back it with an insecure page, with the help of the Hypervisor. If it + is not backed by any page yet, mark the PTE as insecure and back it + with an insecure page when the address is accessed. If it is already + backed by an insecure page, zero the page and return. + +Use cases +~~~~~~~~~ + + #. The Hypervisor cannot access the SVM pages since they are backed by + secure pages. Hence an SVM must explicitly request Ultravisor for + pages it can share with Hypervisor. + + #. Shared pages are needed to support virtio and Virtual Processor Area + (VPA) in SVMs. + + +UV_UNSHARE_PAGE +--------------- + + Restore a shared SVM page to its initial state. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_UNSHARE_PAGE, + uint64_t gfn, /* guest page frame number */ + uint73 num) /* number of pages of size PAGE_SIZE*/ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_FUNCTION if functionality is not supported. + * U_INVALID if VM is not secure. + * U_PARAMETER if ``gfn`` is invalid. + * U_P2 if ``num`` is invalid. + +Description +~~~~~~~~~~~ + + Stop sharing ``num`` pages starting at ``gfn`` with the Hypervisor. + Assume that the page size is PAGE_SIZE. Zero the pages before + returning. + + If the address is already backed by an insecure page, unmap the page + and back it with a secure page. Inform the Hypervisor to release + reference to its shared page. If the address is not backed by a page + yet, mark the PTE as secure and back it with a secure page when that + address is accessed. If it is already backed by an secure page zero + the page and return. + +Use cases +~~~~~~~~~ + + #. The SVM may decide to unshare a page from the Hypervisor. + + +UV_UNSHARE_ALL_PAGES +-------------------- + + Unshare all pages the SVM has shared with Hypervisor. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_UNSHARE_ALL_PAGES) + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success. + * U_FUNCTION if functionality is not supported. + * U_INVAL if VM is not secure. + +Description +~~~~~~~~~~~ + + Unshare all shared pages from the Hypervisor. All unshared pages are + zeroed on return. Only pages explicitly shared by the SVM with the + Hypervisor (using UV_SHARE_PAGE ultracall) are unshared. Ultravisor + may internally share some pages with the Hypervisor without explicit + request from the SVM. These pages will not be unshared by this + ultracall. + +Use cases +~~~~~~~~~ + + #. This call is needed when ``kexec`` is used to boot a different + kernel. It may also be needed during SVM reset. + +UV_ESM +------ + + Secure the virtual machine (*enter secure mode*). + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t ultracall(const uint64_t UV_ESM, + uint64_t esm_blob_addr, /* location of the ESM blob */ + unint64_t fdt) /* Flattened device tree */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * U_SUCCESS on success (including if VM is already secure). + * U_FUNCTION if functionality is not supported. + * U_INVALID if VM is not secure. + * U_PARAMETER if ``esm_blob_addr`` is invalid. + * U_P2 if ``fdt`` is invalid. + * U_PERMISSION if any integrity checks fail. + * U_RETRY insufficient memory to create SVM. + * U_NO_KEY symmetric key unavailable. + +Description +~~~~~~~~~~~ + + Secure the virtual machine. On successful completion, return + control to the virtual machine at the address specified in the + ESM blob. + +Use cases +~~~~~~~~~ + + #. A normal virtual machine can choose to switch to a secure mode. + +Hypervisor Calls API +#################### + + This document describes the Hypervisor calls (hypercalls) that are + needed to support the Ultravisor. Hypercalls are services provided by + the Hypervisor to virtual machines and Ultravisor. + + Register usage for these hypercalls is identical to that of the other + hypercalls defined in the Power Architecture Platform Reference (PAPR) + document. i.e on input, register R3 identifies the specific service + that is being requested and registers R4 through R11 contain + additional parameters to the hypercall, if any. On output, register + R3 contains the return value and registers R4 through R9 contain any + other output values from the hypercall. + + This document only covers hypercalls currently implemented/planned + for Ultravisor usage but others can be added here when it makes sense. + + The full specification for all hypercalls/ultracalls will eventually + be made available in the public/OpenPower version of the PAPR + specification. + +Hypervisor calls to support Ultravisor +====================================== + + Following are the set of hypercalls needed to support Ultravisor. + +H_SVM_INIT_START +---------------- + + Begin the process of converting a normal virtual machine into an SVM. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t hypercall(const uint64_t H_SVM_INIT_START) + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * H_SUCCESS on success. + * H_STATE if the VM is not in a position to switch to secure. + +Description +~~~~~~~~~~~ + + Initiate the process of securing a virtual machine. This involves + coordinating with the Ultravisor, using ultracalls, to allocate + resources in the Ultravisor for the new SVM, transferring the VM's + pages from normal to secure memory etc. When the process is + completed, Ultravisor issues the H_SVM_INIT_DONE hypercall. + +Use cases +~~~~~~~~~ + + #. Ultravisor uses this hypercall to inform Hypervisor that a VM + has initiated the process of switching to secure mode. + + +H_SVM_INIT_DONE +--------------- + + Complete the process of securing an SVM. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t hypercall(const uint64_t H_SVM_INIT_DONE) + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * H_SUCCESS on success. + * H_UNSUPPORTED if called from the wrong context (e.g. + from an SVM or before an H_SVM_INIT_START + hypercall). + * H_STATE if the hypervisor could not successfully + transition the VM to Secure VM. + +Description +~~~~~~~~~~~ + + Complete the process of securing a virtual machine. This call must + be made after a prior call to ``H_SVM_INIT_START`` hypercall. + +Use cases +~~~~~~~~~ + + On successfully securing a virtual machine, the Ultravisor informs + Hypervisor about it. Hypervisor can use this call to finish setting + up its internal state for this virtual machine. + + +H_SVM_INIT_ABORT +---------------- + + Abort the process of securing an SVM. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t hypercall(const uint64_t H_SVM_INIT_ABORT) + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * H_PARAMETER on successfully cleaning up the state, + Hypervisor will return this value to the + **guest**, to indicate that the underlying + UV_ESM ultracall failed. + + * H_STATE if called after a VM has gone secure (i.e + H_SVM_INIT_DONE hypercall was successful). + + * H_UNSUPPORTED if called from a wrong context (e.g. from a + normal VM). + +Description +~~~~~~~~~~~ + + Abort the process of securing a virtual machine. This call must + be made after a prior call to ``H_SVM_INIT_START`` hypercall and + before a call to ``H_SVM_INIT_DONE``. + + On entry into this hypercall the non-volatile GPRs and FPRs are + expected to contain the values they had at the time the VM issued + the UV_ESM ultracall. Further ``SRR0`` is expected to contain the + address of the instruction after the ``UV_ESM`` ultracall and ``SRR1`` + the MSR value with which to return to the VM. + + This hypercall will cleanup any partial state that was established for + the VM since the prior ``H_SVM_INIT_START`` hypercall, including paging + out pages that were paged-into secure memory, and issue the + ``UV_SVM_TERMINATE`` ultracall to terminate the VM. + + After the partial state is cleaned up, control returns to the VM + (**not Ultravisor**), at the address specified in ``SRR0`` with the + MSR values set to the value in ``SRR1``. + +Use cases +~~~~~~~~~ + + If after a successful call to ``H_SVM_INIT_START``, the Ultravisor + encounters an error while securing a virtual machine, either due + to lack of resources or because the VM's security information could + not be validated, Ultravisor informs the Hypervisor about it. + Hypervisor should use this call to clean up any internal state for + this virtual machine and return to the VM. + +H_SVM_PAGE_IN +------------- + + Move the contents of a page from normal memory to secure memory. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t hypercall(const uint64_t H_SVM_PAGE_IN, + uint64_t guest_pa, /* guest-physical-address */ + uint64_t flags, /* flags */ + uint64_t order) /* page size order */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * H_SUCCESS on success. + * H_PARAMETER if ``guest_pa`` is invalid. + * H_P2 if ``flags`` is invalid. + * H_P3 if ``order`` of page is invalid. + +Description +~~~~~~~~~~~ + + Retrieve the content of the page, belonging to the VM at the specified + guest physical address. + + Only valid value(s) in ``flags`` are: + + * H_PAGE_IN_SHARED which indicates that the page is to be shared + with the Ultravisor. + + * H_PAGE_IN_NONSHARED indicates that the UV is not anymore + interested in the page. Applicable if the page is a shared page. + + The ``order`` parameter must correspond to the configured page size. + +Use cases +~~~~~~~~~ + + #. When a normal VM becomes a secure VM (using the UV_ESM ultracall), + the Ultravisor uses this hypercall to move contents of each page of + the VM from normal memory to secure memory. + + #. Ultravisor uses this hypercall to ask Hypervisor to provide a page + in normal memory that can be shared between the SVM and Hypervisor. + + #. Ultravisor uses this hypercall to page-in a paged-out page. This + can happen when the SVM touches a paged-out page. + + #. If SVM wants to disable sharing of pages with Hypervisor, it can + inform Ultravisor to do so. Ultravisor will then use this hypercall + and inform Hypervisor that it has released access to the normal + page. + +H_SVM_PAGE_OUT +--------------- + + Move the contents of the page to normal memory. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t hypercall(const uint64_t H_SVM_PAGE_OUT, + uint64_t guest_pa, /* guest-physical-address */ + uint64_t flags, /* flags (currently none) */ + uint64_t order) /* page size order */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * H_SUCCESS on success. + * H_PARAMETER if ``guest_pa`` is invalid. + * H_P2 if ``flags`` is invalid. + * H_P3 if ``order`` is invalid. + +Description +~~~~~~~~~~~ + + Move the contents of the page identified by ``guest_pa`` to normal + memory. + + Currently ``flags`` is unused and must be set to 0. The ``order`` + parameter must correspond to the configured page size. + +Use cases +~~~~~~~~~ + + #. If Ultravisor is running low on secure pages, it can move the + contents of some secure pages, into normal pages using this + hypercall. The content will be encrypted. + +References +########## + +- `Supporting Protected Computing on IBM Power Architecture `_ diff --git a/Documentation/arch/powerpc/vas-api.rst b/Documentation/arch/powerpc/vas-api.rst new file mode 100644 index 0000000000..a9625a2fa0 --- /dev/null +++ b/Documentation/arch/powerpc/vas-api.rst @@ -0,0 +1,305 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. _VAS-API: + +=================================================== +Virtual Accelerator Switchboard (VAS) userspace API +=================================================== + +Introduction +============ + +Power9 processor introduced Virtual Accelerator Switchboard (VAS) which +allows both userspace and kernel communicate to co-processor +(hardware accelerator) referred to as the Nest Accelerator (NX). The NX +unit comprises of one or more hardware engines or co-processor types +such as 842 compression, GZIP compression and encryption. On power9, +userspace applications will have access to only GZIP Compression engine +which supports ZLIB and GZIP compression algorithms in the hardware. + +To communicate with NX, kernel has to establish a channel or window and +then requests can be submitted directly without kernel involvement. +Requests to the GZIP engine must be formatted as a co-processor Request +Block (CRB) and these CRBs must be submitted to the NX using COPY/PASTE +instructions to paste the CRB to hardware address that is associated with +the engine's request queue. + +The GZIP engine provides two priority levels of requests: Normal and +High. Only Normal requests are supported from userspace right now. + +This document explains userspace API that is used to interact with +kernel to setup channel / window which can be used to send compression +requests directly to NX accelerator. + + +Overview +======== + +Application access to the GZIP engine is provided through +/dev/crypto/nx-gzip device node implemented by the VAS/NX device driver. +An application must open the /dev/crypto/nx-gzip device to obtain a file +descriptor (fd). Then should issue VAS_TX_WIN_OPEN ioctl with this fd to +establish connection to the engine. It means send window is opened on GZIP +engine for this process. Once a connection is established, the application +should use the mmap() system call to map the hardware address of engine's +request queue into the application's virtual address space. + +The application can then submit one or more requests to the engine by +using copy/paste instructions and pasting the CRBs to the virtual address +(aka paste_address) returned by mmap(). User space can close the +established connection or send window by closing the file descriptor +(close(fd)) or upon the process exit. + +Note that applications can send several requests with the same window or +can establish multiple windows, but one window for each file descriptor. + +Following sections provide additional details and references about the +individual steps. + +NX-GZIP Device Node +=================== + +There is one /dev/crypto/nx-gzip node in the system and it provides +access to all GZIP engines in the system. The only valid operations on +/dev/crypto/nx-gzip are: + + * open() the device for read and write. + * issue VAS_TX_WIN_OPEN ioctl + * mmap() the engine's request queue into application's virtual + address space (i.e. get a paste_address for the co-processor + engine). + * close the device node. + +Other file operations on this device node are undefined. + +Note that the copy and paste operations go directly to the hardware and +do not go through this device. Refer COPY/PASTE document for more +details. + +Although a system may have several instances of the NX co-processor +engines (typically, one per P9 chip) there is just one +/dev/crypto/nx-gzip device node in the system. When the nx-gzip device +node is opened, Kernel opens send window on a suitable instance of NX +accelerator. It finds CPU on which the user process is executing and +determine the NX instance for the corresponding chip on which this CPU +belongs. + +Applications may chose a specific instance of the NX co-processor using +the vas_id field in the VAS_TX_WIN_OPEN ioctl as detailed below. + +A userspace library libnxz is available here but still in development: + + https://github.com/abalib/power-gzip + +Applications that use inflate / deflate calls can link with libnxz +instead of libz and use NX GZIP compression without any modification. + +Open /dev/crypto/nx-gzip +======================== + +The nx-gzip device should be opened for read and write. No special +privileges are needed to open the device. Each window corresponds to one +file descriptor. So if the userspace process needs multiple windows, +several open calls have to be issued. + +See open(2) system call man pages for other details such as return values, +error codes and restrictions. + +VAS_TX_WIN_OPEN ioctl +===================== + +Applications should use the VAS_TX_WIN_OPEN ioctl as follows to establish +a connection with NX co-processor engine: + + :: + + struct vas_tx_win_open_attr { + __u32 version; + __s16 vas_id; /* specific instance of vas or -1 + for default */ + __u16 reserved1; + __u64 flags; /* For future use */ + __u64 reserved2[6]; + }; + + version: + The version field must be currently set to 1. + vas_id: + If '-1' is passed, kernel will make a best-effort attempt + to assign an optimal instance of NX for the process. To + select the specific VAS instance, refer + "Discovery of available VAS engines" section below. + + flags, reserved1 and reserved2[6] fields are for future extension + and must be set to 0. + + The attributes attr for the VAS_TX_WIN_OPEN ioctl are defined as + follows:: + + #define VAS_MAGIC 'v' + #define VAS_TX_WIN_OPEN _IOW(VAS_MAGIC, 1, + struct vas_tx_win_open_attr) + + struct vas_tx_win_open_attr attr; + rc = ioctl(fd, VAS_TX_WIN_OPEN, &attr); + + The VAS_TX_WIN_OPEN ioctl returns 0 on success. On errors, it + returns -1 and sets the errno variable to indicate the error. + + Error conditions: + + ====== ================================================ + EINVAL fd does not refer to a valid VAS device. + EINVAL Invalid vas ID + EINVAL version is not set with proper value + EEXIST Window is already opened for the given fd + ENOMEM Memory is not available to allocate window + ENOSPC System has too many active windows (connections) + opened + EINVAL reserved fields are not set to 0. + ====== ================================================ + + See the ioctl(2) man page for more details, error codes and + restrictions. + +mmap() NX-GZIP device +===================== + +The mmap() system call for a NX-GZIP device fd returns a paste_address +that the application can use to copy/paste its CRB to the hardware engines. + + :: + + paste_addr = mmap(addr, size, prot, flags, fd, offset); + + Only restrictions on mmap for a NX-GZIP device fd are: + + * size should be PAGE_SIZE + * offset parameter should be 0ULL + + Refer to mmap(2) man page for additional details/restrictions. + In addition to the error conditions listed on the mmap(2) man + page, can also fail with one of the following error codes: + + ====== ============================================= + EINVAL fd is not associated with an open window + (i.e mmap() does not follow a successful call + to the VAS_TX_WIN_OPEN ioctl). + EINVAL offset field is not 0ULL. + ====== ============================================= + +Discovery of available VAS engines +================================== + +Each available VAS instance in the system will have a device tree node +like /proc/device-tree/vas@* or /proc/device-tree/xscom@*/vas@*. +Determine the chip or VAS instance and use the corresponding ibm,vas-id +property value in this node to select specific VAS instance. + +Copy/Paste operations +===================== + +Applications should use the copy and paste instructions to send CRB to NX. +Refer section 4.4 in PowerISA for Copy/Paste instructions: +https://openpowerfoundation.org/?resource_lib=power-isa-version-3-0 + +CRB Specification and use NX +============================ + +Applications should format requests to the co-processor using the +co-processor Request Block (CRBs). Refer NX-GZIP user's manual for the format +of CRB and use NX from userspace such as sending requests and checking +request status. + +NX Fault handling +================= + +Applications send requests to NX and wait for the status by polling on +co-processor Status Block (CSB) flags. NX updates status in CSB after each +request is processed. Refer NX-GZIP user's manual for the format of CSB and +status flags. + +In case if NX encounters translation error (called NX page fault) on CSB +address or any request buffer, raises an interrupt on the CPU to handle the +fault. Page fault can happen if an application passes invalid addresses or +request buffers are not in memory. The operating system handles the fault by +updating CSB with the following data:: + + csb.flags = CSB_V; + csb.cc = CSB_CC_FAULT_ADDRESS; + csb.ce = CSB_CE_TERMINATION; + csb.address = fault_address; + +When an application receives translation error, it can touch or access +the page that has a fault address so that this page will be in memory. Then +the application can resend this request to NX. + +If the OS can not update CSB due to invalid CSB address, sends SEGV signal +to the process who opened the send window on which the original request was +issued. This signal returns with the following siginfo struct:: + + siginfo.si_signo = SIGSEGV; + siginfo.si_errno = EFAULT; + siginfo.si_code = SEGV_MAPERR; + siginfo.si_addr = CSB address; + +In the case of multi-thread applications, NX send windows can be shared +across all threads. For example, a child thread can open a send window, +but other threads can send requests to NX using this window. These +requests will be successful even in the case of OS handling faults as long +as CSB address is valid. If the NX request contains an invalid CSB address, +the signal will be sent to the child thread that opened the window. But if +the thread is exited without closing the window and the request is issued +using this window. the signal will be issued to the thread group leader +(tgid). It is up to the application whether to ignore or handle these +signals. + +NX-GZIP User's Manual: +https://github.com/libnxz/power-gzip/blob/master/doc/power_nx_gzip_um.pdf + +Simple example +============== + + :: + + int use_nx_gzip() + { + int rc, fd; + void *addr; + struct vas_setup_attr txattr; + + fd = open("/dev/crypto/nx-gzip", O_RDWR); + if (fd < 0) { + fprintf(stderr, "open nx-gzip failed\n"); + return -1; + } + memset(&txattr, 0, sizeof(txattr)); + txattr.version = 1; + txattr.vas_id = -1 + rc = ioctl(fd, VAS_TX_WIN_OPEN, + (unsigned long)&txattr); + if (rc < 0) { + fprintf(stderr, "ioctl() n %d, error %d\n", + rc, errno); + return rc; + } + addr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, + MAP_SHARED, fd, 0ULL); + if (addr == MAP_FAILED) { + fprintf(stderr, "mmap() failed, errno %d\n", + errno); + return -errno; + } + do { + //Format CRB request with compression or + //uncompression + // Refer tests for vas_copy/vas_paste + vas_copy((&crb, 0, 1); + vas_paste(addr, 0, 1); + // Poll on csb.flags with timeout + // csb address is listed in CRB + } while (true) + close(fd) or window can be closed upon process exit + } + + Refer https://github.com/libnxz/power-gzip for tests or more + use cases. diff --git a/Documentation/arch/powerpc/vcpudispatch_stats.rst b/Documentation/arch/powerpc/vcpudispatch_stats.rst new file mode 100644 index 0000000000..5704657a59 --- /dev/null +++ b/Documentation/arch/powerpc/vcpudispatch_stats.rst @@ -0,0 +1,75 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================== +VCPU Dispatch Statistics +======================== + +For Shared Processor LPARs, the POWER Hypervisor maintains a relatively +static mapping of the LPAR processors (vcpus) to physical processor +chips (representing the "home" node) and tries to always dispatch vcpus +on their associated physical processor chip. However, under certain +scenarios, vcpus may be dispatched on a different processor chip (away +from its home node). + +/proc/powerpc/vcpudispatch_stats can be used to obtain statistics +related to the vcpu dispatch behavior. Writing '1' to this file enables +collecting the statistics, while writing '0' disables the statistics. +By default, the DTLB log for each vcpu is processed 50 times a second so +as not to miss any entries. This processing frequency can be changed +through /proc/powerpc/vcpudispatch_stats_freq. + +The statistics themselves are available by reading the procfs file +/proc/powerpc/vcpudispatch_stats. Each line in the output corresponds to +a vcpu as represented by the first field, followed by 8 numbers. + +The first number corresponds to: + +1. total vcpu dispatches since the beginning of statistics collection + +The next 4 numbers represent vcpu dispatch dispersions: + +2. number of times this vcpu was dispatched on the same processor as last + time +3. number of times this vcpu was dispatched on a different processor core + as last time, but within the same chip +4. number of times this vcpu was dispatched on a different chip +5. number of times this vcpu was dispatches on a different socket/drawer + (next numa boundary) + +The final 3 numbers represent statistics in relation to the home node of +the vcpu: + +6. number of times this vcpu was dispatched in its home node (chip) +7. number of times this vcpu was dispatched in a different node +8. number of times this vcpu was dispatched in a node further away (numa + distance) + +An example output:: + + $ sudo cat /proc/powerpc/vcpudispatch_stats + cpu0 6839 4126 2683 30 0 6821 18 0 + cpu1 2515 1274 1229 12 0 2509 6 0 + cpu2 2317 1198 1109 10 0 2312 5 0 + cpu3 2259 1165 1088 6 0 2256 3 0 + cpu4 2205 1143 1056 6 0 2202 3 0 + cpu5 2165 1121 1038 6 0 2162 3 0 + cpu6 2183 1127 1050 6 0 2180 3 0 + cpu7 2193 1133 1052 8 0 2187 6 0 + cpu8 2165 1115 1032 18 0 2156 9 0 + cpu9 2301 1252 1033 16 0 2293 8 0 + cpu10 2197 1138 1041 18 0 2187 10 0 + cpu11 2273 1185 1062 26 0 2260 13 0 + cpu12 2186 1125 1043 18 0 2177 9 0 + cpu13 2161 1115 1030 16 0 2153 8 0 + cpu14 2206 1153 1033 20 0 2196 10 0 + cpu15 2163 1115 1032 16 0 2155 8 0 + +In the output above, for vcpu0, there have been 6839 dispatches since +statistics were enabled. 4126 of those dispatches were on the same +physical cpu as the last time. 2683 were on a different core, but within +the same chip, while 30 dispatches were on a different chip compared to +its last dispatch. + +Also, out of the total of 6839 dispatches, we see that there have been +6821 dispatches on the vcpu's home node, while 18 dispatches were +outside its home node, on a neighbouring chip. diff --git a/Documentation/arch/powerpc/vmemmap_dedup.rst b/Documentation/arch/powerpc/vmemmap_dedup.rst new file mode 100644 index 0000000000..dc4db59fdf --- /dev/null +++ b/Documentation/arch/powerpc/vmemmap_dedup.rst @@ -0,0 +1,101 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========== +Device DAX +========== + +The device-dax interface uses the tail deduplication technique explained in +Documentation/mm/vmemmap_dedup.rst + +On powerpc, vmemmap deduplication is only used with radix MMU translation. Also +with a 64K page size, only the devdax namespace with 1G alignment uses vmemmap +deduplication. + +With 2M PMD level mapping, we require 32 struct pages and a single 64K vmemmap +page can contain 1024 struct pages (64K/sizeof(struct page)). Hence there is no +vmemmap deduplication possible. + +With 1G PUD level mapping, we require 16384 struct pages and a single 64K +vmemmap page can contain 1024 struct pages (64K/sizeof(struct page)). Hence we +require 16 64K pages in vmemmap to map the struct page for 1G PUD level mapping. + +Here's how things look like on device-dax after the sections are populated:: + +-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+ + | | | 0 | -------------> | 0 | + | | +-----------+ +-----------+ + | | | 1 | -------------> | 1 | + | | +-----------+ +-----------+ + | | | 2 | ----------------^ ^ ^ ^ ^ ^ + | | +-----------+ | | | | | + | | | 3 | ------------------+ | | | | + | | +-----------+ | | | | + | | | 4 | --------------------+ | | | + | PUD | +-----------+ | | | + | level | | . | ----------------------+ | | + | mapping | +-----------+ | | + | | | . | ------------------------+ | + | | +-----------+ | + | | | 15 | --------------------------+ + | | +-----------+ + | | + | | + | | + +-----------+ + + +With 4K page size, 2M PMD level mapping requires 512 struct pages and a single +4K vmemmap page contains 64 struct pages(4K/sizeof(struct page)). Hence we +require 8 4K pages in vmemmap to map the struct page for 2M pmd level mapping. + +Here's how things look like on device-dax after the sections are populated:: + + +-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+ + | | | 0 | -------------> | 0 | + | | +-----------+ +-----------+ + | | | 1 | -------------> | 1 | + | | +-----------+ +-----------+ + | | | 2 | ----------------^ ^ ^ ^ ^ ^ + | | +-----------+ | | | | | + | | | 3 | ------------------+ | | | | + | | +-----------+ | | | | + | | | 4 | --------------------+ | | | + | PMD | +-----------+ | | | + | level | | 5 | ----------------------+ | | + | mapping | +-----------+ | | + | | | 6 | ------------------------+ | + | | +-----------+ | + | | | 7 | --------------------------+ + | | +-----------+ + | | + | | + | | + +-----------+ + +With 1G PUD level mapping, we require 262144 struct pages and a single 4K +vmemmap page can contain 64 struct pages (4K/sizeof(struct page)). Hence we +require 4096 4K pages in vmemmap to map the struct pages for 1G PUD level +mapping. + +Here's how things look like on device-dax after the sections are populated:: + + +-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+ + | | | 0 | -------------> | 0 | + | | +-----------+ +-----------+ + | | | 1 | -------------> | 1 | + | | +-----------+ +-----------+ + | | | 2 | ----------------^ ^ ^ ^ ^ ^ + | | +-----------+ | | | | | + | | | 3 | ------------------+ | | | | + | | +-----------+ | | | | + | | | 4 | --------------------+ | | | + | PUD | +-----------+ | | | + | level | | . | ----------------------+ | | + | mapping | +-----------+ | | + | | | . | ------------------------+ | + | | +-----------+ | + | | | 4095 | --------------------------+ + | | +-----------+ + | | + | | + | | + +-----------+ diff --git a/Documentation/arch/riscv/acpi.rst b/Documentation/arch/riscv/acpi.rst new file mode 100644 index 0000000000..9870a28281 --- /dev/null +++ b/Documentation/arch/riscv/acpi.rst @@ -0,0 +1,10 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============== +ACPI on RISC-V +============== + +The ISA string parsing rules for ACPI are defined by `Version ASCIIDOC +Conversion, 12/2022 of the RISC-V specifications, as defined by tag +"riscv-isa-release-1239329-2023-05-23" (commit 1239329 +) `_ diff --git a/Documentation/arch/riscv/boot-image-header.rst b/Documentation/arch/riscv/boot-image-header.rst new file mode 100644 index 0000000000..df2ffc173e --- /dev/null +++ b/Documentation/arch/riscv/boot-image-header.rst @@ -0,0 +1,59 @@ +================================= +Boot image header in RISC-V Linux +================================= + +:Author: Atish Patra +:Date: 20 May 2019 + +This document only describes the boot image header details for RISC-V Linux. + +The following 64-byte header is present in decompressed Linux kernel image:: + + u32 code0; /* Executable code */ + u32 code1; /* Executable code */ + u64 text_offset; /* Image load offset, little endian */ + u64 image_size; /* Effective Image size, little endian */ + u64 flags; /* kernel flags, little endian */ + u32 version; /* Version of this header */ + u32 res1 = 0; /* Reserved */ + u64 res2 = 0; /* Reserved */ + u64 magic = 0x5643534952; /* Magic number, little endian, "RISCV" */ + u32 magic2 = 0x05435352; /* Magic number 2, little endian, "RSC\x05" */ + u32 res3; /* Reserved for PE COFF offset */ + +This header format is compliant with PE/COFF header and largely inspired from +ARM64 header. Thus, both ARM64 & RISC-V header can be combined into one common +header in future. + +Notes +===== + +- This header is also reused to support EFI stub for RISC-V. EFI specification + needs PE/COFF image header in the beginning of the kernel image in order to + load it as an EFI application. In order to support EFI stub, code0 is replaced + with "MZ" magic string and res3(at offset 0x3c) points to the rest of the + PE/COFF header. + +- version field indicate header version number + + ========== ============= + Bits 0:15 Minor version + Bits 16:31 Major version + ========== ============= + + This preserves compatibility across newer and older version of the header. + The current version is defined as 0.2. + +- The "magic" field is deprecated as of version 0.2. In a future + release, it may be removed. This originally should have matched up + with the ARM64 header "magic" field, but unfortunately does not. + The "magic2" field replaces it, matching up with the ARM64 header. + +- In current header, the flags field has only one field. + + ===== ==================================== + Bit 0 Kernel endianness. 1 if BE, 0 if LE. + ===== ==================================== + +- Image size is mandatory for boot loader to load kernel image. Booting will + fail otherwise. diff --git a/Documentation/arch/riscv/boot.rst b/Documentation/arch/riscv/boot.rst new file mode 100644 index 0000000000..6077b587a8 --- /dev/null +++ b/Documentation/arch/riscv/boot.rst @@ -0,0 +1,169 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============================================== +RISC-V Kernel Boot Requirements and Constraints +=============================================== + +:Author: Alexandre Ghiti +:Date: 23 May 2023 + +This document describes what the RISC-V kernel expects from bootloaders and +firmware, and also the constraints that any developer must have in mind when +touching the early boot process. For the purposes of this document, the +``early boot process`` refers to any code that runs before the final virtual +mapping is set up. + +Pre-kernel Requirements and Constraints +======================================= + +The RISC-V kernel expects the following of bootloaders and platform firmware: + +Register state +-------------- + +The RISC-V kernel expects: + + * ``$a0`` to contain the hartid of the current core. + * ``$a1`` to contain the address of the devicetree in memory. + +CSR state +--------- + +The RISC-V kernel expects: + + * ``$satp = 0``: the MMU, if present, must be disabled. + +Reserved memory for resident firmware +------------------------------------- + +The RISC-V kernel must not map any resident memory, or memory protected with +PMPs, in the direct mapping, so the firmware must correctly mark those regions +as per the devicetree specification and/or the UEFI specification. + +Kernel location +--------------- + +The RISC-V kernel expects to be placed at a PMD boundary (2MB aligned for rv64 +and 4MB aligned for rv32). Note that the EFI stub will physically relocate the +kernel if that's not the case. + +Hardware description +-------------------- + +The firmware can pass either a devicetree or ACPI tables to the RISC-V kernel. + +The devicetree is either passed directly to the kernel from the previous stage +using the ``$a1`` register, or when booting with UEFI, it can be passed using the +EFI configuration table. + +The ACPI tables are passed to the kernel using the EFI configuration table. In +this case, a tiny devicetree is still created by the EFI stub. Please refer to +"EFI stub and devicetree" section below for details about this devicetree. + +Kernel entry +------------ + +On SMP systems, there are 2 methods to enter the kernel: + +- ``RISCV_BOOT_SPINWAIT``: the firmware releases all harts in the kernel, one hart + wins a lottery and executes the early boot code while the other harts are + parked waiting for the initialization to finish. This method is mostly used to + support older firmwares without SBI HSM extension and M-mode RISC-V kernel. +- ``Ordered booting``: the firmware releases only one hart that will execute the + initialization phase and then will start all other harts using the SBI HSM + extension. The ordered booting method is the preferred booting method for + booting the RISC-V kernel because it can support CPU hotplug and kexec. + +UEFI +---- + +UEFI memory map +~~~~~~~~~~~~~~~ + +When booting with UEFI, the RISC-V kernel will use only the EFI memory map to +populate the system memory. + +The UEFI firmware must parse the subnodes of the ``/reserved-memory`` devicetree +node and abide by the devicetree specification to convert the attributes of +those subnodes (``no-map`` and ``reusable``) into their correct EFI equivalent +(refer to section "3.5.4 /reserved-memory and UEFI" of the devicetree +specification v0.4-rc1). + +RISCV_EFI_BOOT_PROTOCOL +~~~~~~~~~~~~~~~~~~~~~~~ + +When booting with UEFI, the EFI stub requires the boot hartid in order to pass +it to the RISC-V kernel in ``$a1``. The EFI stub retrieves the boot hartid using +one of the following methods: + +- ``RISCV_EFI_BOOT_PROTOCOL`` (**preferred**). +- ``boot-hartid`` devicetree subnode (**deprecated**). + +Any new firmware must implement ``RISCV_EFI_BOOT_PROTOCOL`` as the devicetree +based approach is deprecated now. + +Early Boot Requirements and Constraints +======================================= + +The RISC-V kernel's early boot process operates under the following constraints: + +EFI stub and devicetree +----------------------- + +When booting with UEFI, the devicetree is supplemented (or created) by the EFI +stub with the same parameters as arm64 which are described at the paragraph +"UEFI kernel support on ARM" in Documentation/arch/arm/uefi.rst. + +Virtual mapping installation +---------------------------- + +The installation of the virtual mapping is done in 2 steps in the RISC-V kernel: + +1. ``setup_vm()`` installs a temporary kernel mapping in ``early_pg_dir`` which + allows discovery of the system memory. Only the kernel text/data are mapped + at this point. When establishing this mapping, no allocation can be done + (since the system memory is not known yet), so ``early_pg_dir`` page table is + statically allocated (using only one table for each level). + +2. ``setup_vm_final()`` creates the final kernel mapping in ``swapper_pg_dir`` + and takes advantage of the discovered system memory to create the linear + mapping. When establishing this mapping, the kernel can allocate memory but + cannot access it directly (since the direct mapping is not present yet), so + it uses temporary mappings in the fixmap region to be able to access the + newly allocated page table levels. + +For ``virt_to_phys()`` and ``phys_to_virt()`` to be able to correctly convert +direct mapping addresses to physical addresses, they need to know the start of +the DRAM. This happens after step 1, right before step 2 installs the direct +mapping (see ``setup_bootmem()`` function in arch/riscv/mm/init.c). Any usage of +those macros before the final virtual mapping is installed must be carefully +examined. + +Devicetree mapping via fixmap +----------------------------- + +As the ``reserved_mem`` array is initialized with virtual addresses established +by ``setup_vm()``, and used with the mapping established by +``setup_vm_final()``, the RISC-V kernel uses the fixmap region to map the +devicetree. This ensures that the devicetree remains accessible by both virtual +mappings. + +Pre-MMU execution +----------------- + +A few pieces of code need to run before even the first virtual mapping is +established. These are the installation of the first virtual mapping itself, +patching of early alternatives and the early parsing of the kernel command line. +That code must be very carefully compiled as: + +- ``-fno-pie``: This is needed for relocatable kernels which use ``-fPIE``, + since otherwise, any access to a global symbol would go through the GOT which + is only relocated virtually. +- ``-mcmodel=medany``: Any access to a global symbol must be PC-relative to + avoid any relocations to happen before the MMU is setup. +- *all* instrumentation must also be disabled (that includes KASAN, ftrace and + others). + +As using a symbol from a different compilation unit requires this unit to be +compiled with those flags, we advise, as much as possible, not to use external +symbols. diff --git a/Documentation/arch/riscv/features.rst b/Documentation/arch/riscv/features.rst new file mode 100644 index 0000000000..36e90144ad --- /dev/null +++ b/Documentation/arch/riscv/features.rst @@ -0,0 +1,3 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. kernel-feat:: features riscv diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst new file mode 100644 index 0000000000..7b2384de47 --- /dev/null +++ b/Documentation/arch/riscv/hwprobe.rst @@ -0,0 +1,104 @@ +.. SPDX-License-Identifier: GPL-2.0 + +RISC-V Hardware Probing Interface +--------------------------------- + +The RISC-V hardware probing interface is based around a single syscall, which +is defined in :: + + struct riscv_hwprobe { + __s64 key; + __u64 value; + }; + + long sys_riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count, + size_t cpu_count, cpu_set_t *cpus, + unsigned int flags); + +The arguments are split into three groups: an array of key-value pairs, a CPU +set, and some flags. The key-value pairs are supplied with a count. Userspace +must prepopulate the key field for each element, and the kernel will fill in the +value if the key is recognized. If a key is unknown to the kernel, its key field +will be cleared to -1, and its value set to 0. The CPU set is defined by +CPU_SET(3). For value-like keys (eg. vendor/arch/impl), the returned value will +be only be valid if all CPUs in the given set have the same value. Otherwise -1 +will be returned. For boolean-like keys, the value returned will be a logical +AND of the values for the specified CPUs. Usermode can supply NULL for cpus and +0 for cpu_count as a shortcut for all online CPUs. There are currently no flags, +this value must be zero for future compatibility. + +On success 0 is returned, on failure a negative error code is returned. + +The following keys are defined: + +* :c:macro:`RISCV_HWPROBE_KEY_MVENDORID`: Contains the value of ``mvendorid``, + as defined by the RISC-V privileged architecture specification. + +* :c:macro:`RISCV_HWPROBE_KEY_MARCHID`: Contains the value of ``marchid``, as + defined by the RISC-V privileged architecture specification. + +* :c:macro:`RISCV_HWPROBE_KEY_MIMPLID`: Contains the value of ``mimplid``, as + defined by the RISC-V privileged architecture specification. + +* :c:macro:`RISCV_HWPROBE_KEY_BASE_BEHAVIOR`: A bitmask containing the base + user-visible behavior that this kernel supports. The following base user ABIs + are defined: + + * :c:macro:`RISCV_HWPROBE_BASE_BEHAVIOR_IMA`: Support for rv32ima or + rv64ima, as defined by version 2.2 of the user ISA and version 1.10 of the + privileged ISA, with the following known exceptions (more exceptions may be + added, but only if it can be demonstrated that the user ABI is not broken): + + * The ``fence.i`` instruction cannot be directly executed by userspace + programs (it may still be executed in userspace via a + kernel-controlled mechanism such as the vDSO). + +* :c:macro:`RISCV_HWPROBE_KEY_IMA_EXT_0`: A bitmask containing the extensions + that are compatible with the :c:macro:`RISCV_HWPROBE_BASE_BEHAVIOR_IMA`: + base system behavior. + + * :c:macro:`RISCV_HWPROBE_IMA_FD`: The F and D extensions are supported, as + defined by commit cd20cee ("FMIN/FMAX now implement + minimumNumber/maximumNumber, not minNum/maxNum") of the RISC-V ISA manual. + + * :c:macro:`RISCV_HWPROBE_IMA_C`: The C extension is supported, as defined + by version 2.2 of the RISC-V ISA manual. + + * :c:macro:`RISCV_HWPROBE_IMA_V`: The V extension is supported, as defined by + version 1.0 of the RISC-V Vector extension manual. + + * :c:macro:`RISCV_HWPROBE_EXT_ZBA`: The Zba address generation extension is + supported, as defined in version 1.0 of the Bit-Manipulation ISA + extensions. + + * :c:macro:`RISCV_HWPROBE_EXT_ZBB`: The Zbb extension is supported, as defined + in version 1.0 of the Bit-Manipulation ISA extensions. + + * :c:macro:`RISCV_HWPROBE_EXT_ZBS`: The Zbs extension is supported, as defined + in version 1.0 of the Bit-Manipulation ISA extensions. + + * :c:macro:`RISCV_HWPROBE_EXT_ZICBOZ`: The Zicboz extension is supported, as + ratified in commit 3dd606f ("Create cmobase-v1.0.pdf") of riscv-CMOs. + +* :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance + information about the selected set of processors. + + * :c:macro:`RISCV_HWPROBE_MISALIGNED_UNKNOWN`: The performance of misaligned + accesses is unknown. + + * :c:macro:`RISCV_HWPROBE_MISALIGNED_EMULATED`: Misaligned accesses are + emulated via software, either in or below the kernel. These accesses are + always extremely slow. + + * :c:macro:`RISCV_HWPROBE_MISALIGNED_SLOW`: Misaligned accesses are slower + than equivalent byte accesses. Misaligned accesses may be supported + directly in hardware, or trapped and emulated by software. + + * :c:macro:`RISCV_HWPROBE_MISALIGNED_FAST`: Misaligned accesses are faster + than equivalent byte accesses. + + * :c:macro:`RISCV_HWPROBE_MISALIGNED_UNSUPPORTED`: Misaligned accesses are + not supported at all and will generate a misaligned address fault. + +* :c:macro:`RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE`: An unsigned int which + represents the size of the Zicboz block in bytes. diff --git a/Documentation/arch/riscv/index.rst b/Documentation/arch/riscv/index.rst new file mode 100644 index 0000000000..4dab0cb4b9 --- /dev/null +++ b/Documentation/arch/riscv/index.rst @@ -0,0 +1,24 @@ +=================== +RISC-V architecture +=================== + +.. toctree:: + :maxdepth: 1 + + acpi + boot + boot-image-header + vm-layout + hwprobe + patch-acceptance + uabi + vector + + features + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/arch/riscv/patch-acceptance.rst b/Documentation/arch/riscv/patch-acceptance.rst new file mode 100644 index 0000000000..634aa222b4 --- /dev/null +++ b/Documentation/arch/riscv/patch-acceptance.rst @@ -0,0 +1,59 @@ +.. SPDX-License-Identifier: GPL-2.0 + +arch/riscv maintenance guidelines for developers +================================================ + +Overview +-------- +The RISC-V instruction set architecture is developed in the open: +in-progress drafts are available for all to review and to experiment +with implementations. New module or extension drafts can change +during the development process - sometimes in ways that are +incompatible with previous drafts. This flexibility can present a +challenge for RISC-V Linux maintenance. Linux maintainers disapprove +of churn, and the Linux development process prefers well-reviewed and +tested code over experimental code. We wish to extend these same +principles to the RISC-V-related code that will be accepted for +inclusion in the kernel. + +Patchwork +--------- + +RISC-V has a patchwork instance, where the status of patches can be checked: + + https://patchwork.kernel.org/project/linux-riscv/list/ + +If your patch does not appear in the default view, the RISC-V maintainers have +likely either requested changes, or expect it to be applied to another tree. + +Automation runs against this patchwork instance, building/testing patches as +they arrive. The automation applies patches against the current HEAD of the +RISC-V `for-next` and `fixes` branches, depending on whether the patch has been +detected as a fix. Failing those, it will use the RISC-V `master` branch. +The exact commit to which a series has been applied will be noted on patchwork. +Patches for which any of the checks fail are unlikely to be applied and in most +cases will need to be resubmitted. + +Submit Checklist Addendum +------------------------- +We'll only accept patches for new modules or extensions if the +specifications for those modules or extensions are listed as being +unlikely to be incompatibly changed in the future. For +specifications from the RISC-V foundation this means "Frozen" or +"Ratified", for the UEFI forum specifications this means a published +ECR. (Developers may, of course, maintain their own Linux kernel trees +that contain code for any draft extensions that they wish.) + +Additionally, the RISC-V specification allows implementers to create +their own custom extensions. These custom extensions aren't required +to go through any review or ratification process by the RISC-V +Foundation. To avoid the maintenance complexity and potential +performance impact of adding kernel code for implementor-specific +RISC-V extensions, we'll only consider patches for extensions that either: + +- Have been officially frozen or ratified by the RISC-V Foundation, or +- Have been implemented in hardware that is widely available, per standard + Linux practice. + +(Implementers, may, of course, maintain their own Linux kernel trees containing +code for any custom extensions that they wish.) diff --git a/Documentation/arch/riscv/uabi.rst b/Documentation/arch/riscv/uabi.rst new file mode 100644 index 0000000000..54d199dce7 --- /dev/null +++ b/Documentation/arch/riscv/uabi.rst @@ -0,0 +1,68 @@ +.. SPDX-License-Identifier: GPL-2.0 + +RISC-V Linux User ABI +===================== + +ISA string ordering in /proc/cpuinfo +------------------------------------ + +The canonical order of ISA extension names in the ISA string is defined in +chapter 27 of the unprivileged specification. +The specification uses vague wording, such as should, when it comes to ordering, +so for our purposes the following rules apply: + +#. Single-letter extensions come first, in canonical order. + The canonical order is "IMAFDQLCBKJTPVH". + +#. All multi-letter extensions will be separated from other extensions by an + underscore. + +#. Additional standard extensions (starting with 'Z') will be sorted after + single-letter extensions and before any higher-privileged extensions. + +#. For additional standard extensions, the first letter following the 'Z' + conventionally indicates the most closely related alphabetical + extension category. If multiple 'Z' extensions are named, they will be + ordered first by category, in canonical order, as listed above, then + alphabetically within a category. + +#. Standard supervisor-level extensions (starting with 'S') will be listed + after standard unprivileged extensions. If multiple supervisor-level + extensions are listed, they will be ordered alphabetically. + +#. Standard machine-level extensions (starting with 'Zxm') will be listed + after any lower-privileged, standard extensions. If multiple machine-level + extensions are listed, they will be ordered alphabetically. + +#. Non-standard extensions (starting with 'X') will be listed after all standard + extensions. If multiple non-standard extensions are listed, they will be + ordered alphabetically. + +An example string following the order is:: + + rv64imadc_zifoo_zigoo_zafoo_sbar_scar_zxmbaz_xqux_xrux + +"isa" and "hart isa" lines in /proc/cpuinfo +------------------------------------------- + +The "isa" line in /proc/cpuinfo describes the lowest common denominator of +RISC-V ISA extensions recognized by the kernel and implemented on all harts. The +"hart isa" line, in contrast, describes the set of extensions recognized by the +kernel on the particular hart being described, even if those extensions may not +be present on all harts in the system. + +In both lines, the presence of an extension guarantees only that the hardware +has the described capability. Additional kernel support or policy changes may be +required before an extension's capability is fully usable by userspace programs. +Similarly, for S-mode extensions, presence in one of these lines does not +guarantee that the kernel is taking advantage of the extension, or that the +feature will be visible in guest VMs managed by this kernel. + +Inversely, the absence of an extension in these lines does not necessarily mean +the hardware does not support that feature. The running kernel may not recognize +the extension, or may have deliberately removed it from the listing. + +Misaligned accesses +------------------- + +Misaligned accesses are supported in userspace, but they may perform poorly. diff --git a/Documentation/arch/riscv/vector.rst b/Documentation/arch/riscv/vector.rst new file mode 100644 index 0000000000..75dd88a62e --- /dev/null +++ b/Documentation/arch/riscv/vector.rst @@ -0,0 +1,140 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================================= +Vector Extension Support for RISC-V Linux +========================================= + +This document briefly outlines the interface provided to userspace by Linux in +order to support the use of the RISC-V Vector Extension. + +1. prctl() Interface +--------------------- + +Two new prctl() calls are added to allow programs to manage the enablement +status for the use of Vector in userspace. The intended usage guideline for +these interfaces is to give init systems a way to modify the availability of V +for processes running under its domain. Calling these interfaces is not +recommended in libraries routines because libraries should not override policies +configured from the parant process. Also, users must noted that these interfaces +are not portable to non-Linux, nor non-RISC-V environments, so it is discourage +to use in a portable code. To get the availability of V in an ELF program, +please read :c:macro:`COMPAT_HWCAP_ISA_V` bit of :c:macro:`ELF_HWCAP` in the +auxiliary vector. + +* prctl(PR_RISCV_V_SET_CONTROL, unsigned long arg) + + Sets the Vector enablement status of the calling thread, where the control + argument consists of two 2-bit enablement statuses and a bit for inheritance + mode. Other threads of the calling process are unaffected. + + Enablement status is a tri-state value each occupying 2-bit of space in + the control argument: + + * :c:macro:`PR_RISCV_V_VSTATE_CTRL_DEFAULT`: Use the system-wide default + enablement status on execve(). The system-wide default setting can be + controlled via sysctl interface (see sysctl section below). + + * :c:macro:`PR_RISCV_V_VSTATE_CTRL_ON`: Allow Vector to be run for the + thread. + + * :c:macro:`PR_RISCV_V_VSTATE_CTRL_OFF`: Disallow Vector. Executing Vector + instructions under such condition will trap and casuse the termination of the thread. + + arg: The control argument is a 5-bit value consisting of 3 parts, and + accessed by 3 masks respectively. + + The 3 masks, PR_RISCV_V_VSTATE_CTRL_CUR_MASK, + PR_RISCV_V_VSTATE_CTRL_NEXT_MASK, and PR_RISCV_V_VSTATE_CTRL_INHERIT + represents bit[1:0], bit[3:2], and bit[4]. bit[1:0] accounts for the + enablement status of current thread, and the setting at bit[3:2] takes place + at next execve(). bit[4] defines the inheritance mode of the setting in + bit[3:2]. + + * :c:macro:`PR_RISCV_V_VSTATE_CTRL_CUR_MASK`: bit[1:0]: Account for the + Vector enablement status for the calling thread. The calling thread is + not able to turn off Vector once it has been enabled. The prctl() call + fails with EPERM if the value in this mask is PR_RISCV_V_VSTATE_CTRL_OFF + but the current enablement status is not off. Setting + PR_RISCV_V_VSTATE_CTRL_DEFAULT here takes no effect but to set back + the original enablement status. + + * :c:macro:`PR_RISCV_V_VSTATE_CTRL_NEXT_MASK`: bit[3:2]: Account for the + Vector enablement setting for the calling thread at the next execve() + system call. If PR_RISCV_V_VSTATE_CTRL_DEFAULT is used in this mask, + then the enablement status will be decided by the system-wide + enablement status when execve() happen. + + * :c:macro:`PR_RISCV_V_VSTATE_CTRL_INHERIT`: bit[4]: the inheritance + mode for the setting at PR_RISCV_V_VSTATE_CTRL_NEXT_MASK. If the bit + is set then the following execve() will not clear the setting in both + PR_RISCV_V_VSTATE_CTRL_NEXT_MASK and PR_RISCV_V_VSTATE_CTRL_INHERIT. + This setting persists across changes in the system-wide default value. + + Return value: + * 0 on success; + * EINVAL: Vector not supported, invalid enablement status for current or + next mask; + * EPERM: Turning off Vector in PR_RISCV_V_VSTATE_CTRL_CUR_MASK if Vector + was enabled for the calling thread. + + On success: + * A valid setting for PR_RISCV_V_VSTATE_CTRL_CUR_MASK takes place + immediately. The enablement status specified in + PR_RISCV_V_VSTATE_CTRL_NEXT_MASK happens at the next execve() call, or + all following execve() calls if PR_RISCV_V_VSTATE_CTRL_INHERIT bit is + set. + * Every successful call overwrites a previous setting for the calling + thread. + +* prctl(PR_RISCV_V_GET_CONTROL) + + Gets the same Vector enablement status for the calling thread. Setting for + next execve() call and the inheritance bit are all OR-ed together. + + Note that ELF programs are able to get the availability of V for itself by + reading :c:macro:`COMPAT_HWCAP_ISA_V` bit of :c:macro:`ELF_HWCAP` in the + auxiliary vector. + + Return value: + * a nonnegative value on success; + * EINVAL: Vector not supported. + +2. System runtime configuration (sysctl) +----------------------------------------- + +To mitigate the ABI impact of expansion of the signal stack, a +policy mechanism is provided to the administrators, distro maintainers, and +developers to control the default Vector enablement status for userspace +processes in form of sysctl knob: + +* /proc/sys/abi/riscv_v_default_allow + + Writing the text representation of 0 or 1 to this file sets the default + system enablement status for new starting userspace programs. Valid values + are: + + * 0: Do not allow Vector code to be executed as the default for new processes. + * 1: Allow Vector code to be executed as the default for new processes. + + Reading this file returns the current system default enablement status. + + At every execve() call, a new enablement status of the new process is set to + the system default, unless: + + * PR_RISCV_V_VSTATE_CTRL_INHERIT is set for the calling process, and the + setting in PR_RISCV_V_VSTATE_CTRL_NEXT_MASK is not + PR_RISCV_V_VSTATE_CTRL_DEFAULT. Or, + + * The setting in PR_RISCV_V_VSTATE_CTRL_NEXT_MASK is not + PR_RISCV_V_VSTATE_CTRL_DEFAULT. + + Modifying the system default enablement status does not affect the enablement + status of any existing process of thread that do not make an execve() call. + +3. Vector Register State Across System Calls +--------------------------------------------- + +As indicated by version 1.0 of the V extension [1], vector registers are +clobbered by system calls. + +1: https://github.com/riscv/riscv-v-spec/blob/master/calling-convention.adoc diff --git a/Documentation/arch/riscv/vm-layout.rst b/Documentation/arch/riscv/vm-layout.rst new file mode 100644 index 0000000000..69ff6da1db --- /dev/null +++ b/Documentation/arch/riscv/vm-layout.rst @@ -0,0 +1,157 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================================== +Virtual Memory Layout on RISC-V Linux +===================================== + +:Author: Alexandre Ghiti +:Date: 12 February 2021 + +This document describes the virtual memory layout used by the RISC-V Linux +Kernel. + +RISC-V Linux Kernel 32bit +========================= + +RISC-V Linux Kernel SV32 +------------------------ + +TODO + +RISC-V Linux Kernel 64bit +========================= + +The RISC-V privileged architecture document states that the 64bit addresses +"must have bits 63–48 all equal to bit 47, or else a page-fault exception will +occur.": that splits the virtual address space into 2 halves separated by a very +big hole, the lower half is where the userspace resides, the upper half is where +the RISC-V Linux Kernel resides. + +RISC-V Linux Kernel SV39 +------------------------ + +:: + + ======================================================================================================================== + Start addr | Offset | End addr | Size | VM area description + ======================================================================================================================== + | | | | + 0000000000000000 | 0 | 0000003fffffffff | 256 GB | user-space virtual memory, different per mm + __________________|____________|__________________|_________|___________________________________________________________ + | | | | + 0000004000000000 | +256 GB | ffffffbfffffffff | ~16M TB | ... huge, almost 64 bits wide hole of non-canonical + | | | | virtual memory addresses up to the -256 GB + | | | | starting offset of kernel mappings. + __________________|____________|__________________|_________|___________________________________________________________ + | + | Kernel-space virtual memory, shared between all processes: + ____________________________________________________________|___________________________________________________________ + | | | | + ffffffc6fea00000 | -228 GB | ffffffc6feffffff | 6 MB | fixmap + ffffffc6ff000000 | -228 GB | ffffffc6ffffffff | 16 MB | PCI io + ffffffc700000000 | -228 GB | ffffffc7ffffffff | 4 GB | vmemmap + ffffffc800000000 | -224 GB | ffffffd7ffffffff | 64 GB | vmalloc/ioremap space + ffffffd800000000 | -160 GB | fffffff6ffffffff | 124 GB | direct mapping of all physical memory + fffffff700000000 | -36 GB | fffffffeffffffff | 32 GB | kasan + __________________|____________|__________________|_________|____________________________________________________________ + | + | + ____________________________________________________________|____________________________________________________________ + | | | | + ffffffff00000000 | -4 GB | ffffffff7fffffff | 2 GB | modules, BPF + ffffffff80000000 | -2 GB | ffffffffffffffff | 2 GB | kernel + __________________|____________|__________________|_________|____________________________________________________________ + + +RISC-V Linux Kernel SV48 +------------------------ + +:: + + ======================================================================================================================== + Start addr | Offset | End addr | Size | VM area description + ======================================================================================================================== + | | | | + 0000000000000000 | 0 | 00007fffffffffff | 128 TB | user-space virtual memory, different per mm + __________________|____________|__________________|_________|___________________________________________________________ + | | | | + 0000800000000000 | +128 TB | ffff7fffffffffff | ~16M TB | ... huge, almost 64 bits wide hole of non-canonical + | | | | virtual memory addresses up to the -128 TB + | | | | starting offset of kernel mappings. + __________________|____________|__________________|_________|___________________________________________________________ + | + | Kernel-space virtual memory, shared between all processes: + ____________________________________________________________|___________________________________________________________ + | | | | + ffff8d7ffea00000 | -114.5 TB | ffff8d7ffeffffff | 6 MB | fixmap + ffff8d7fff000000 | -114.5 TB | ffff8d7fffffffff | 16 MB | PCI io + ffff8d8000000000 | -114.5 TB | ffff8f7fffffffff | 2 TB | vmemmap + ffff8f8000000000 | -112.5 TB | ffffaf7fffffffff | 32 TB | vmalloc/ioremap space + ffffaf8000000000 | -80.5 TB | ffffef7fffffffff | 64 TB | direct mapping of all physical memory + ffffef8000000000 | -16.5 TB | fffffffeffffffff | 16.5 TB | kasan + __________________|____________|__________________|_________|____________________________________________________________ + | + | Identical layout to the 39-bit one from here on: + ____________________________________________________________|____________________________________________________________ + | | | | + ffffffff00000000 | -4 GB | ffffffff7fffffff | 2 GB | modules, BPF + ffffffff80000000 | -2 GB | ffffffffffffffff | 2 GB | kernel + __________________|____________|__________________|_________|____________________________________________________________ + + +RISC-V Linux Kernel SV57 +------------------------ + +:: + + ======================================================================================================================== + Start addr | Offset | End addr | Size | VM area description + ======================================================================================================================== + | | | | + 0000000000000000 | 0 | 00ffffffffffffff | 64 PB | user-space virtual memory, different per mm + __________________|____________|__________________|_________|___________________________________________________________ + | | | | + 0100000000000000 | +64 PB | feffffffffffffff | ~16K PB | ... huge, almost 64 bits wide hole of non-canonical + | | | | virtual memory addresses up to the -64 PB + | | | | starting offset of kernel mappings. + __________________|____________|__________________|_________|___________________________________________________________ + | + | Kernel-space virtual memory, shared between all processes: + ____________________________________________________________|___________________________________________________________ + | | | | + ff1bfffffea00000 | -57 PB | ff1bfffffeffffff | 6 MB | fixmap + ff1bffffff000000 | -57 PB | ff1bffffffffffff | 16 MB | PCI io + ff1c000000000000 | -57 PB | ff1fffffffffffff | 1 PB | vmemmap + ff20000000000000 | -56 PB | ff5fffffffffffff | 16 PB | vmalloc/ioremap space + ff60000000000000 | -40 PB | ffdeffffffffffff | 32 PB | direct mapping of all physical memory + ffdf000000000000 | -8 PB | fffffffeffffffff | 8 PB | kasan + __________________|____________|__________________|_________|____________________________________________________________ + | + | Identical layout to the 39-bit one from here on: + ____________________________________________________________|____________________________________________________________ + | | | | + ffffffff00000000 | -4 GB | ffffffff7fffffff | 2 GB | modules, BPF + ffffffff80000000 | -2 GB | ffffffffffffffff | 2 GB | kernel + __________________|____________|__________________|_________|____________________________________________________________ + + +Userspace VAs +-------------------- +To maintain compatibility with software that relies on the VA space with a +maximum of 48 bits the kernel will, by default, return virtual addresses to +userspace from a 48-bit range (sv48). This default behavior is achieved by +passing 0 into the hint address parameter of mmap. On CPUs with an address space +smaller than sv48, the CPU maximum supported address space will be the default. + +Software can "opt-in" to receiving VAs from another VA space by providing +a hint address to mmap. A hint address passed to mmap will cause the largest +address space that fits entirely into the hint to be used, unless there is no +space left in the address space. If there is no space available in the requested +address space, an address in the next smallest available address space will be +returned. + +For example, in order to obtain 48-bit VA space, a hint address greater than +:code:`1 << 47` must be provided. Note that this is 47 due to sv48 userspace +ending at :code:`1 << 47` and the addresses beyond this are reserved for the +kernel. Similarly, to obtain 57-bit VA space addresses, a hint address greater +than or equal to :code:`1 << 56` must be provided. diff --git a/Documentation/arch/sh/index.rst b/Documentation/arch/sh/index.rst index c64776738c..01fce7c131 100644 --- a/Documentation/arch/sh/index.rst +++ b/Documentation/arch/sh/index.rst @@ -43,12 +43,6 @@ mach-x3proto Busses ====== -SuperHyway ----------- - -.. kernel-doc:: drivers/sh/superhyway/superhyway.c - :export: - Maple ----- diff --git a/Documentation/arch/x86/amd-memory-encryption.rst b/Documentation/arch/x86/amd-memory-encryption.rst index 934310ce72..07caa8fff8 100644 --- a/Documentation/arch/x86/amd-memory-encryption.rst +++ b/Documentation/arch/x86/amd-memory-encryption.rst @@ -130,4 +130,4 @@ SNP feature support. More details in AMD64 APM[1] Vol 2: 15.34.10 SEV_STATUS MSR -[1] https://www.amd.com/system/files/TechDocs/40332.pdf +[1] https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/24593.pdf diff --git a/Documentation/arch/x86/amd_hsmp.rst b/Documentation/arch/x86/amd_hsmp.rst index 440e4b645a..c92bfd5535 100644 --- a/Documentation/arch/x86/amd_hsmp.rst +++ b/Documentation/arch/x86/amd_hsmp.rst @@ -41,6 +41,24 @@ In-kernel integration: * Locking across callers is taken care by the driver. +HSMP sysfs interface +==================== + +1. Metrics table binary sysfs + +AMD MI300A MCM provides GET_METRICS_TABLE message to retrieve +most of the system management information from SMU in one go. + +The metrics table is made available as hexadecimal sysfs binary file +under per socket sysfs directory created at +/sys/devices/platform/amd_hsmp/socket%d/metrics_bin + +Note: lseek() is not supported as entire metrics table is read. + +Metrics table definitions will be documented as part of Public PPR. +The same is defined in the amd_hsmp.h header. + + An example ========== diff --git a/Documentation/arch/x86/boot.rst b/Documentation/arch/x86/boot.rst index f5d2f2414d..22cc7a040d 100644 --- a/Documentation/arch/x86/boot.rst +++ b/Documentation/arch/x86/boot.rst @@ -77,7 +77,7 @@ Protocol 2.14 BURNT BY INCORRECT COMMIT Protocol 2.15 (Kernel 5.5) Added the kernel_info and kernel_info.setup_type_max. ============= ============================================================ -.. note:: + .. note:: The protocol version number should be changed only if the setup header is changed. There is no need to update the version number if boot_params or kernel_info are changed. Additionally, it is recommended to use diff --git a/Documentation/arch/x86/iommu.rst b/Documentation/arch/x86/iommu.rst index 42c7a6faa3..41fbadfe22 100644 --- a/Documentation/arch/x86/iommu.rst +++ b/Documentation/arch/x86/iommu.rst @@ -5,7 +5,7 @@ x86 IOMMU Support The architecture specs can be obtained from the below locations. - Intel: http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/vt-directed-io-spec.pdf -- AMD: https://www.amd.com/system/files/TechDocs/48882_IOMMU.pdf +- AMD: https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/specifications/48882_3_07_PUB.pdf This guide gives a quick cheat sheet for some basic understanding. diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst index cb05d90111..a6279df64a 100644 --- a/Documentation/arch/x86/resctrl.rst +++ b/Documentation/arch/x86/resctrl.rst @@ -35,7 +35,7 @@ about the feature from resctrl's info directory. To use the feature mount the file system:: - # mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps]] /sys/fs/resctrl + # mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps][,debug]] /sys/fs/resctrl mount options are: @@ -46,6 +46,9 @@ mount options are: "mba_MBps": Enable the MBA Software Controller(mba_sc) to specify MBA bandwidth in MBps +"debug": + Make debug files accessible. Available debug files are annotated with + "Available only with debug option". L2 and L3 CDP are controlled separately. @@ -124,6 +127,13 @@ related to allocation: "P": Corresponding region is pseudo-locked. No sharing allowed. +"sparse_masks": + Indicates if non-contiguous 1s value in CBM is supported. + + "0": + Only contiguous 1s value in CBM is supported. + "1": + Non-contiguous 1s value in CBM is supported. Memory bandwidth(MB) subdirectory contains the following files with respect to allocation: @@ -299,7 +309,14 @@ All groups contain the following files: "tasks": Reading this file shows the list of all tasks that belong to this group. Writing a task id to the file will add a task to the - group. If the group is a CTRL_MON group the task is removed from + group. Multiple tasks can be added by separating the task ids + with commas. Tasks will be assigned sequentially. Multiple + failures are not supported. A single failure encountered while + attempting to assign a task will cause the operation to abort and + already added tasks before the failure will remain in the group. + Failures will be logged to /sys/fs/resctrl/info/last_cmd_status. + + If the group is a CTRL_MON group the task is removed from whichever previous CTRL_MON group owned the task and also from any MON group that owned the task. If the group is a MON group, then the task must already belong to the CTRL_MON parent of this @@ -342,6 +359,10 @@ When control is enabled all CTRL_MON groups will also contain: file. On successful pseudo-locked region creation the mode will automatically change to "pseudo-locked". +"ctrl_hw_id": + Available only with debug option. The identifier used by hardware + for the control group. On x86 this is the CLOSID. + When monitoring is enabled all MON groups will also contain: "mon_data": @@ -355,6 +376,10 @@ When monitoring is enabled all MON groups will also contain: the sum for all tasks in the CTRL_MON group and all tasks in MON groups. Please see example section for more details on usage. +"mon_hw_id": + Available only with debug option. The identifier used by hardware + for the monitor group. On x86 this is the RMID. + Resource allocation rules ------------------------- @@ -445,12 +470,13 @@ For cache resources we describe the portion of the cache that is available for allocation using a bitmask. The maximum value of the mask is defined by each cpu model (and may be different for different cache levels). It is found using CPUID, but is also provided in the "info" directory of -the resctrl file system in "info/{resource}/cbm_mask". Intel hardware +the resctrl file system in "info/{resource}/cbm_mask". Some Intel hardware requires that these masks have all the '1' bits in a contiguous block. So 0x3, 0x6 and 0xC are legal 4-bit masks with two bits set, but 0x5, 0x9 -and 0xA are not. On a system with a 20-bit mask each bit represents 5% -of the capacity of the cache. You could partition the cache into four -equal parts with masks: 0x1f, 0x3e0, 0x7c00, 0xf8000. +and 0xA are not. Check /sys/fs/resctrl/info/{resource}/sparse_masks +if non-contiguous 1s value is supported. On a system with a 20-bit mask +each bit represents 5% of the capacity of the cache. You could partition +the cache into four equal parts with masks: 0x1f, 0x3e0, 0x7c00, 0xf8000. Memory bandwidth Allocation and monitoring ========================================== diff --git a/Documentation/arch/x86/topology.rst b/Documentation/arch/x86/topology.rst index 7f58010ea8..08ebf9edbf 100644 --- a/Documentation/arch/x86/topology.rst +++ b/Documentation/arch/x86/topology.rst @@ -55,19 +55,19 @@ Package-related topology information in the kernel: The number of dies in a package. This information is retrieved via CPUID. - - cpuinfo_x86.cpu_die_id: + - cpuinfo_x86.topo.die_id: The physical ID of the die. This information is retrieved via CPUID. - - cpuinfo_x86.phys_proc_id: + - cpuinfo_x86.topo.pkg_id: The physical ID of the package. This information is retrieved via CPUID and deduced from the APIC IDs of the cores in the package. Modern systems use this value for the socket. There may be multiple - packages within a socket. This value may differ from cpu_die_id. + packages within a socket. This value may differ from topo.die_id. - - cpuinfo_x86.logical_proc_id: + - cpuinfo_x86.topo.logical_pkg_id: The logical ID of the package. As we do not trust BIOSes to enumerate the packages in a consistent way, we introduced the concept of logical package @@ -79,9 +79,7 @@ Package-related topology information in the kernel: The maximum possible number of packages in the system. Helpful for per package facilities to preallocate per package information. - - cpu_llc_id: - - A per-CPU variable containing: + - cpuinfo_x86.topo.llc_id: - On Intel, the first APIC ID of the list of CPUs sharing the Last Level Cache -- cgit v1.2.3