diff options
Diffstat (limited to 'Documentation/arch/x86')
| -rw-r--r-- | Documentation/arch/x86/amd_hsmp.rst | 7 | ||||
| -rw-r--r-- | Documentation/arch/x86/boot.rst | 3 | ||||
| -rw-r--r-- | Documentation/arch/x86/pti.rst | 6 | ||||
| -rw-r--r-- | Documentation/arch/x86/resctrl.rst | 10 | ||||
| -rw-r--r-- | Documentation/arch/x86/topology.rst | 24 | ||||
| -rw-r--r-- | Documentation/arch/x86/x86_64/fred.rst | 96 | ||||
| -rw-r--r-- | Documentation/arch/x86/x86_64/index.rst | 1 |
7 files changed, 120 insertions, 27 deletions
diff --git a/Documentation/arch/x86/amd_hsmp.rst b/Documentation/arch/x86/amd_hsmp.rst index c92bfd5535..1e499ecf5f 100644 --- a/Documentation/arch/x86/amd_hsmp.rst +++ b/Documentation/arch/x86/amd_hsmp.rst @@ -13,7 +13,8 @@ set of mailbox registers. More details on the interface can be found in chapter "7 Host System Management Port (HSMP)" of the family/model PPR -Eg: https://www.amd.com/system/files/TechDocs/55898_B1_pub_0.50.zip +Eg: https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/programmer-references/55898_B1_pub_0_50.zip + HSMP interface is supported on EPYC server CPU models only. @@ -97,8 +98,8 @@ what happened. The transaction returns 0 on success. More details on the interface and message definitions can be found in chapter "7 Host System Management Port (HSMP)" of the respective family/model PPR -eg: https://www.amd.com/system/files/TechDocs/55898_B1_pub_0.50.zip +eg: https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/programmer-references/55898_B1_pub_0_50.zip User space C-APIs are made available by linking against the esmi library, -which is provided by the E-SMS project https://developer.amd.com/e-sms/. +which is provided by the E-SMS project https://www.amd.com/en/developer/e-sms.html. See: https://github.com/amd/esmi_ib_library diff --git a/Documentation/arch/x86/boot.rst b/Documentation/arch/x86/boot.rst index c513855a54..4fd492cb49 100644 --- a/Documentation/arch/x86/boot.rst +++ b/Documentation/arch/x86/boot.rst @@ -878,7 +878,8 @@ Protocol: 2.10+ address if possible. A non-relocatable kernel will unconditionally move itself and to run - at this address. + at this address. A relocatable kernel will move itself to this address if it + loaded below this address. ============ ======= Field name: init_size diff --git a/Documentation/arch/x86/pti.rst b/Documentation/arch/x86/pti.rst index e08d35177b..57e8392f61 100644 --- a/Documentation/arch/x86/pti.rst +++ b/Documentation/arch/x86/pti.rst @@ -26,9 +26,9 @@ comments in pti.c). This approach helps to ensure that side-channel attacks leveraging the paging structures do not function when PTI is enabled. It can be -enabled by setting CONFIG_PAGE_TABLE_ISOLATION=y at compile time. -Once enabled at compile-time, it can be disabled at boot with the -'nopti' or 'pti=' kernel parameters (see kernel-parameters.txt). +enabled by setting CONFIG_MITIGATION_PAGE_TABLE_ISOLATION=y at compile +time. Once enabled at compile-time, it can be disabled at boot with +the 'nopti' or 'pti=' kernel parameters (see kernel-parameters.txt). Page Table Management ===================== diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst index a6279df64a..6c245582d8 100644 --- a/Documentation/arch/x86/resctrl.rst +++ b/Documentation/arch/x86/resctrl.rst @@ -45,7 +45,7 @@ mount options are: Enable code/data prioritization in L2 cache allocations. "mba_MBps": Enable the MBA Software Controller(mba_sc) to specify MBA - bandwidth in MBps + bandwidth in MiBps "debug": Make debug files accessible. Available debug files are annotated with "Available only with debug option". @@ -526,7 +526,7 @@ threads start using more cores in an rdtgroup, the actual bandwidth may increase or vary although user specified bandwidth percentage is same. In order to mitigate this and make the interface more user friendly, -resctrl added support for specifying the bandwidth in MBps as well. The +resctrl added support for specifying the bandwidth in MiBps as well. The kernel underneath would use a software feedback mechanism or a "Software Controller(mba_sc)" which reads the actual bandwidth using MBM counters and adjust the memory bandwidth percentages to ensure:: @@ -573,13 +573,13 @@ Memory b/w domain is L3 cache. MB:<cache_id0>=bandwidth0;<cache_id1>=bandwidth1;... -Memory bandwidth Allocation specified in MBps ---------------------------------------------- +Memory bandwidth Allocation specified in MiBps +---------------------------------------------- Memory bandwidth domain is L3 cache. :: - MB:<cache_id0>=bw_MBps0;<cache_id1>=bw_MBps1;... + MB:<cache_id0>=bw_MiBps0;<cache_id1>=bw_MiBps1;... Slow Memory Bandwidth Allocation (SMBA) --------------------------------------- diff --git a/Documentation/arch/x86/topology.rst b/Documentation/arch/x86/topology.rst index 08ebf9edbf..7352ab89a5 100644 --- a/Documentation/arch/x86/topology.rst +++ b/Documentation/arch/x86/topology.rst @@ -47,17 +47,21 @@ AMD nomenclature for package is 'Node'. Package-related topology information in the kernel: - - cpuinfo_x86.x86_max_cores: + - topology_num_threads_per_package() - The number of cores in a package. This information is retrieved via CPUID. + The number of threads in a package. - - cpuinfo_x86.x86_max_dies: + - topology_num_cores_per_package() - The number of dies in a package. This information is retrieved via CPUID. + The number of cores in a package. + + - topology_max_dies_per_package() + + The maximum number of dies in a package. - cpuinfo_x86.topo.die_id: - The physical ID of the die. This information is retrieved via CPUID. + The physical ID of the die. - cpuinfo_x86.topo.pkg_id: @@ -96,16 +100,6 @@ are SMT- or CMT-type threads. AMDs nomenclature for a CMT core is "Compute Unit". The kernel always uses "core". -Core-related topology information in the kernel: - - - smp_num_siblings: - - The number of threads in a core. The number of threads in a package can be - calculated by:: - - threads_per_package = cpuinfo_x86.x86_max_cores * smp_num_siblings - - Threads ======= A thread is a single scheduling unit. It's the equivalent to a logical Linux diff --git a/Documentation/arch/x86/x86_64/fred.rst b/Documentation/arch/x86/x86_64/fred.rst new file mode 100644 index 0000000000..9f57e7b91f --- /dev/null +++ b/Documentation/arch/x86/x86_64/fred.rst @@ -0,0 +1,96 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================================= +Flexible Return and Event Delivery (FRED) +========================================= + +Overview +======== + +The FRED architecture defines simple new transitions that change +privilege level (ring transitions). The FRED architecture was +designed with the following goals: + +1) Improve overall performance and response time by replacing event + delivery through the interrupt descriptor table (IDT event + delivery) and event return by the IRET instruction with lower + latency transitions. + +2) Improve software robustness by ensuring that event delivery + establishes the full supervisor context and that event return + establishes the full user context. + +The new transitions defined by the FRED architecture are FRED event +delivery and, for returning from events, two FRED return instructions. +FRED event delivery can effect a transition from ring 3 to ring 0, but +it is used also to deliver events incident to ring 0. One FRED +instruction (ERETU) effects a return from ring 0 to ring 3, while the +other (ERETS) returns while remaining in ring 0. Collectively, FRED +event delivery and the FRED return instructions are FRED transitions. + +In addition to these transitions, the FRED architecture defines a new +instruction (LKGS) for managing the state of the GS segment register. +The LKGS instruction can be used by 64-bit operating systems that do +not use the new FRED transitions. + +Furthermore, the FRED architecture is easy to extend for future CPU +architectures. + +Software based event dispatching +================================ + +FRED operates differently from IDT in terms of event handling. Instead +of directly dispatching an event to its handler based on the event +vector, FRED requires the software to dispatch an event to its handler +based on both the event's type and vector. Therefore, an event dispatch +framework must be implemented to facilitate the event-to-handler +dispatch process. The FRED event dispatch framework takes control +once an event is delivered, and employs a two-level dispatch. + +The first level dispatching is event type based, and the second level +dispatching is event vector based. + +Full supervisor/user context +============================ + +FRED event delivery atomically save and restore full supervisor/user +context upon event delivery and return. Thus it avoids the problem of +transient states due to %cr2 and/or %dr6, and it is no longer needed +to handle all the ugly corner cases caused by half baked entry states. + +FRED allows explicit unblock of NMI with new event return instructions +ERETS/ERETU, avoiding the mess caused by IRET which unconditionally +unblocks NMI, e.g., when an exception happens during NMI handling. + +FRED always restores the full value of %rsp, thus ESPFIX is no longer +needed when FRED is enabled. + +LKGS +==== + +LKGS behaves like the MOV to GS instruction except that it loads the +base address into the IA32_KERNEL_GS_BASE MSR instead of the GS +segment’s descriptor cache. With LKGS, it ends up with avoiding +mucking with kernel GS, i.e., an operating system can always operate +with its own GS base address. + +Because FRED event delivery from ring 3 and ERETU both swap the value +of the GS base address and that of the IA32_KERNEL_GS_BASE MSR, plus +the introduction of LKGS instruction, the SWAPGS instruction is no +longer needed when FRED is enabled, thus is disallowed (#UD). + +Stack levels +============ + +4 stack levels 0~3 are introduced to replace the nonreentrant IST for +event handling, and each stack level should be configured to use a +dedicated stack. + +The current stack level could be unchanged or go higher upon FRED +event delivery. If unchanged, the CPU keeps using the current event +stack. If higher, the CPU switches to a new event stack specified by +the MSR of the new stack level, i.e., MSR_IA32_FRED_RSP[123]. + +Only execution of a FRED return instruction ERET[US], could lower the +current stack level, causing the CPU to switch back to the stack it was +on before a previous event delivery that promoted the stack level. diff --git a/Documentation/arch/x86/x86_64/index.rst b/Documentation/arch/x86/x86_64/index.rst index a56070fc8e..ad15e9bd62 100644 --- a/Documentation/arch/x86/x86_64/index.rst +++ b/Documentation/arch/x86/x86_64/index.rst @@ -15,3 +15,4 @@ x86_64 Support cpu-hotplug-spec machinecheck fsgs + fred |