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Diffstat (limited to 'Documentation/arch/s390')
| -rw-r--r-- | Documentation/arch/s390/3270.ChangeLog | 44 | ||||
| -rw-r--r-- | Documentation/arch/s390/3270.rst | 298 | ||||
| -rw-r--r-- | Documentation/arch/s390/cds.rst | 530 | ||||
| -rw-r--r-- | Documentation/arch/s390/common_io.rst | 140 | ||||
| -rw-r--r-- | Documentation/arch/s390/config3270.sh | 76 | ||||
| -rw-r--r-- | Documentation/arch/s390/driver-model.rst | 328 | ||||
| -rw-r--r-- | Documentation/arch/s390/features.rst | 3 | ||||
| -rw-r--r-- | Documentation/arch/s390/index.rst | 30 | ||||
| -rw-r--r-- | Documentation/arch/s390/monreader.rst | 212 | ||||
| -rw-r--r-- | Documentation/arch/s390/pci.rst | 133 | ||||
| -rw-r--r-- | Documentation/arch/s390/qeth.rst | 64 | ||||
| -rw-r--r-- | Documentation/arch/s390/s390dbf.rst | 478 | ||||
| -rw-r--r-- | Documentation/arch/s390/text_files.rst | 11 | ||||
| -rw-r--r-- | Documentation/arch/s390/vfio-ap-locking.rst | 115 | ||||
| -rw-r--r-- | Documentation/arch/s390/vfio-ap.rst | 1069 | ||||
| -rw-r--r-- | Documentation/arch/s390/vfio-ccw.rst | 445 | ||||
| -rw-r--r-- | Documentation/arch/s390/zfcpdump.rst | 50 |
17 files changed, 4026 insertions, 0 deletions
diff --git a/Documentation/arch/s390/3270.ChangeLog b/Documentation/arch/s390/3270.ChangeLog new file mode 100644 index 0000000000..ecaf60b6c3 --- /dev/null +++ b/Documentation/arch/s390/3270.ChangeLog @@ -0,0 +1,44 @@ +ChangeLog for the UTS Global 3270-support patch + +Sep 2002: Get bootup colors right on 3270 console + * In tubttybld.c, substantially revise ESC processing so that + ESC sequences (especially coloring ones) and the strings + they affect work as right as 3270 can get them. Also, set + screen height to omit the two rows used for input area, in + tty3270_open() in tubtty.c. + +Sep 2002: Dynamically get 3270 input buffer + * Oversize 3270 screen widths may exceed GEOM_MAXINPLEN columns, + so get input-area buffer dynamically when sizing the device in + tubmakemin() in tuball.c (if it's the console) or tty3270_open() + in tubtty.c (if needed). Change tubp->tty_input to be a + pointer rather than an array, in tubio.h. + +Sep 2002: Fix tubfs kmalloc()s + * Do read and write lengths correctly in fs3270_read() + and fs3270_write(), while never asking kmalloc() + for more than 0x800 bytes. Affects tubfs.c and tubio.h. + +Sep 2002: Recognize 3270 control unit type 3174 + * Recognize control-unit type 0x3174 as well as 0x327?. + The IBM 2047 device emulates a 3174 control unit. + Modularize control-unit recognition in tuball.c by + adding and invoking new tub3270_is_ours(). + +Apr 2002: Fix 3270 console reboot loop + * (Belated log entry) Fixed reboot loop if 3270 console, + in tubtty.c:ttu3270_bh(). + +Feb 6, 2001: + * This changelog is new + * tub3270 now supports 3270 console: + Specify y for CONFIG_3270 and y for CONFIG_3270_CONSOLE. + Support for 3215 will not appear if 3270 console support + is chosen. + NOTE: The default is 3270 console support, NOT 3215. + * the components are remodularized: added source modules are + tubttybld.c and tubttyscl.c, for screen-building code and + scroll-timeout code. + * tub3270 source for this (2.4.0) version is #ifdeffed to + build with both 2.4.0 and 2.2.16.2. + * color support and minimal other ESC-sequence support is added. diff --git a/Documentation/arch/s390/3270.rst b/Documentation/arch/s390/3270.rst new file mode 100644 index 0000000000..467eace914 --- /dev/null +++ b/Documentation/arch/s390/3270.rst @@ -0,0 +1,298 @@ +=============================== +IBM 3270 Display System support +=============================== + +This file describes the driver that supports local channel attachment +of IBM 3270 devices. It consists of three sections: + + * Introduction + * Installation + * Operation + + +Introduction +============ + +This paper describes installing and operating 3270 devices under +Linux/390. A 3270 device is a block-mode rows-and-columns terminal of +which I'm sure hundreds of millions were sold by IBM and clonemakers +twenty and thirty years ago. + +You may have 3270s in-house and not know it. If you're using the +VM-ESA operating system, define a 3270 to your virtual machine by using +the command "DEF GRAF <hex-address>" This paper presumes you will be +defining four 3270s with the CP/CMS commands: + + - DEF GRAF 620 + - DEF GRAF 621 + - DEF GRAF 622 + - DEF GRAF 623 + +Your network connection from VM-ESA allows you to use x3270, tn3270, or +another 3270 emulator, started from an xterm window on your PC or +workstation. With the DEF GRAF command, an application such as xterm, +and this Linux-390 3270 driver, you have another way of talking to your +Linux box. + +This paper covers installation of the driver and operation of a +dialed-in x3270. + + +Installation +============ + +You install the driver by installing a patch, doing a kernel build, and +running the configuration script (config3270.sh, in this directory). + +WARNING: If you are using 3270 console support, you must rerun the +configuration script every time you change the console's address (perhaps +by using the condev= parameter in silo's /boot/parmfile). More precisely, +you should rerun the configuration script every time your set of 3270s, +including the console 3270, changes subchannel identifier relative to +one another. ReIPL as soon as possible after running the configuration +script and the resulting /tmp/mkdev3270. + +If you have chosen to make tub3270 a module, you add a line to a +configuration file under /etc/modprobe.d/. If you are working on a VM +virtual machine, you can use DEF GRAF to define virtual 3270 devices. + +You may generate both 3270 and 3215 console support, or one or the +other, or neither. If you generate both, the console type under VM is +not changed. Use #CP Q TERM to see what the current console type is. +Use #CP TERM CONMODE 3270 to change it to 3270. If you generate only +3270 console support, then the driver automatically converts your console +at boot time to a 3270 if it is a 3215. + +In brief, these are the steps: + + 1. Install the tub3270 patch + 2. (If a module) add a line to a file in `/etc/modprobe.d/*.conf` + 3. (If VM) define devices with DEF GRAF + 4. Reboot + 5. Configure + +To test that everything works, assuming VM and x3270, + + 1. Bring up an x3270 window. + 2. Use the DIAL command in that window. + 3. You should immediately see a Linux login screen. + +Here are the installation steps in detail: + + 1. The 3270 driver is a part of the official Linux kernel + source. Build a tree with the kernel source and any necessary + patches. Then do:: + + make oldconfig + (If you wish to disable 3215 console support, edit + .config; change CONFIG_TN3215's value to "n"; + and rerun "make oldconfig".) + make image + make modules + make modules_install + + 2. (Perform this step only if you have configured tub3270 as a + module.) Add a line to a file `/etc/modprobe.d/*.conf` to automatically + load the driver when it's needed. With this line added, you will see + login prompts appear on your 3270s as soon as boot is complete (or + with emulated 3270s, as soon as you dial into your vm guest using the + command "DIAL <vmguestname>"). Since the line-mode major number is + 227, the line to add should be:: + + alias char-major-227 tub3270 + + 3. Define graphic devices to your vm guest machine, if you + haven't already. Define them before you reboot (reipl): + + - DEFINE GRAF 620 + - DEFINE GRAF 621 + - DEFINE GRAF 622 + - DEFINE GRAF 623 + + 4. Reboot. The reboot process scans hardware devices, including + 3270s, and this enables the tub3270 driver once loaded to respond + correctly to the configuration requests of the next step. If + you have chosen 3270 console support, your console now behaves + as a 3270, not a 3215. + + 5. Run the 3270 configuration script config3270. It is + distributed in this same directory, Documentation/arch/s390, as + config3270.sh. Inspect the output script it produces, + /tmp/mkdev3270, and then run that script. This will create the + necessary character special device files and make the necessary + changes to /etc/inittab. + + Then notify /sbin/init that /etc/inittab has changed, by issuing + the telinit command with the q operand:: + + cd Documentation/arch/s390 + sh config3270.sh + sh /tmp/mkdev3270 + telinit q + + This should be sufficient for your first time. If your 3270 + configuration has changed and you're reusing config3270, you + should follow these steps:: + + Change 3270 configuration + Reboot + Run config3270 and /tmp/mkdev3270 + Reboot + +Here are the testing steps in detail: + + 1. Bring up an x3270 window, or use an actual hardware 3278 or + 3279, or use the 3270 emulator of your choice. You would be + running the emulator on your PC or workstation. You would use + the command, for example:: + + x3270 vm-esa-domain-name & + + if you wanted a 3278 Model 4 with 43 rows of 80 columns, the + default model number. The driver does not take advantage of + extended attributes. + + The screen you should now see contains a VM logo with input + lines near the bottom. Use TAB to move to the bottom line, + probably labeled "COMMAND ===>". + + 2. Use the DIAL command instead of the LOGIN command to connect + to one of the virtual 3270s you defined with the DEF GRAF + commands:: + + dial my-vm-guest-name + + 3. You should immediately see a login prompt from your + Linux-390 operating system. If that does not happen, you would + see instead the line "DIALED TO my-vm-guest-name 0620". + + To troubleshoot: do these things. + + A. Is the driver loaded? Use the lsmod command (no operands) + to find out. Probably it isn't. Try loading it manually, with + the command "insmod tub3270". Does that command give error + messages? Ha! There's your problem. + + B. Is the /etc/inittab file modified as in installation step 3 + above? Use the grep command to find out; for instance, issue + "grep 3270 /etc/inittab". Nothing found? There's your + problem! + + C. Are the device special files created, as in installation + step 2 above? Use the ls -l command to find out; for instance, + issue "ls -l /dev/3270/tty620". The output should start with the + letter "c" meaning character device and should contain "227, 1" + just to the left of the device name. No such file? no "c"? + Wrong major number? Wrong minor number? There's your + problem! + + D. Do you get the message:: + + "HCPDIA047E my-vm-guest-name 0620 does not exist"? + + If so, you must issue the command "DEF GRAF 620" from your VM + 3215 console and then reboot the system. + + + +OPERATION. +========== + +The driver defines three areas on the 3270 screen: the log area, the +input area, and the status area. + +The log area takes up all but the bottom two lines of the screen. The +driver writes terminal output to it, starting at the top line and going +down. When it fills, the status area changes from "Linux Running" to +"Linux More...". After a scrolling timeout of (default) 5 sec, the +screen clears and more output is written, from the top down. + +The input area extends from the beginning of the second-to-last screen +line to the start of the status area. You type commands in this area +and hit ENTER to execute them. + +The status area initializes to "Linux Running" to give you a warm +fuzzy feeling. When the log area fills up and output awaits, it +changes to "Linux More...". At this time you can do several things or +nothing. If you do nothing, the screen will clear in (default) 5 sec +and more output will appear. You may hit ENTER with nothing typed in +the input area to toggle between "Linux More..." and "Linux Holding", +which indicates no scrolling will occur. (If you hit ENTER with "Linux +Running" and nothing typed, the application receives a newline.) + +You may change the scrolling timeout value. For example, the following +command line:: + + echo scrolltime=60 > /proc/tty/driver/tty3270 + +changes the scrolling timeout value to 60 sec. Set scrolltime to 0 if +you wish to prevent scrolling entirely. + +Other things you may do when the log area fills up are: hit PA2 to +clear the log area and write more output to it, or hit CLEAR to clear +the log area and the input area and write more output to the log area. + +Some of the Program Function (PF) and Program Attention (PA) keys are +preassigned special functions. The ones that are not yield an alarm +when pressed. + +PA1 causes a SIGINT to the currently running application. You may do +the same thing from the input area, by typing "^C" and hitting ENTER. + +PA2 causes the log area to be cleared. If output awaits, it is then +written to the log area. + +PF3 causes an EOF to be received as input by the application. You may +cause an EOF also by typing "^D" and hitting ENTER. + +No PF key is preassigned to cause a job suspension, but you may cause a +job suspension by typing "^Z" and hitting ENTER. You may wish to +assign this function to a PF key. To make PF7 cause job suspension, +execute the command:: + + echo pf7=^z > /proc/tty/driver/tty3270 + +If the input you type does not end with the two characters "^n", the +driver appends a newline character and sends it to the tty driver; +otherwise the driver strips the "^n" and does not append a newline. +The IBM 3215 driver behaves similarly. + +Pf10 causes the most recent command to be retrieved from the tube's +command stack (default depth 20) and displayed in the input area. You +may hit PF10 again for the next-most-recent command, and so on. A +command is entered into the stack only when the input area is not made +invisible (such as for password entry) and it is not identical to the +current top entry. PF10 rotates backward through the command stack; +PF11 rotates forward. You may assign the backward function to any PF +key (or PA key, for that matter), say, PA3, with the command:: + + echo -e pa3=\\033k > /proc/tty/driver/tty3270 + +This assigns the string ESC-k to PA3. Similarly, the string ESC-j +performs the forward function. (Rationale: In bash with vi-mode line +editing, ESC-k and ESC-j retrieve backward and forward history. +Suggestions welcome.) + +Is a stack size of twenty commands not to your liking? Change it on +the fly. To change to saving the last 100 commands, execute the +command:: + + echo recallsize=100 > /proc/tty/driver/tty3270 + +Have a command you issue frequently? Assign it to a PF or PA key! Use +the command:: + + echo pf24="mkdir foobar; cd foobar" > /proc/tty/driver/tty3270 + +to execute the commands mkdir foobar and cd foobar immediately when you +hit PF24. Want to see the command line first, before you execute it? +Use the -n option of the echo command:: + + echo -n pf24="mkdir foo; cd foo" > /proc/tty/driver/tty3270 + + + +Happy testing! I welcome any and all comments about this document, the +driver, etc etc. + +Dick Hitt <rbh00@utsglobal.com> diff --git a/Documentation/arch/s390/cds.rst b/Documentation/arch/s390/cds.rst new file mode 100644 index 0000000000..bcad2a1424 --- /dev/null +++ b/Documentation/arch/s390/cds.rst @@ -0,0 +1,530 @@ +=========================== +Linux for S/390 and zSeries +=========================== + +Common Device Support (CDS) +Device Driver I/O Support Routines + +Authors: + - Ingo Adlung + - Cornelia Huck + +Copyright, IBM Corp. 1999-2002 + +Introduction +============ + +This document describes the common device support routines for Linux/390. +Different than other hardware architectures, ESA/390 has defined a unified +I/O access method. This gives relief to the device drivers as they don't +have to deal with different bus types, polling versus interrupt +processing, shared versus non-shared interrupt processing, DMA versus port +I/O (PIO), and other hardware features more. However, this implies that +either every single device driver needs to implement the hardware I/O +attachment functionality itself, or the operating system provides for a +unified method to access the hardware, providing all the functionality that +every single device driver would have to provide itself. + +The document does not intend to explain the ESA/390 hardware architecture in +every detail.This information can be obtained from the ESA/390 Principles of +Operation manual (IBM Form. No. SA22-7201). + +In order to build common device support for ESA/390 I/O interfaces, a +functional layer was introduced that provides generic I/O access methods to +the hardware. + +The common device support layer comprises the I/O support routines defined +below. Some of them implement common Linux device driver interfaces, while +some of them are ESA/390 platform specific. + +Note: + In order to write a driver for S/390, you also need to look into the interface + described in Documentation/arch/s390/driver-model.rst. + +Note for porting drivers from 2.4: + +The major changes are: + +* The functions use a ccw_device instead of an irq (subchannel). +* All drivers must define a ccw_driver (see driver-model.txt) and the associated + functions. +* request_irq() and free_irq() are no longer done by the driver. +* The oper_handler is (kindof) replaced by the probe() and set_online() functions + of the ccw_driver. +* The not_oper_handler is (kindof) replaced by the remove() and set_offline() + functions of the ccw_driver. +* The channel device layer is gone. +* The interrupt handlers must be adapted to use a ccw_device as argument. + Moreover, they don't return a devstat, but an irb. +* Before initiating an io, the options must be set via ccw_device_set_options(). +* Instead of calling read_dev_chars()/read_conf_data(), the driver issues + the channel program and handles the interrupt itself. + +ccw_device_get_ciw() + get commands from extended sense data. + +ccw_device_start(), ccw_device_start_timeout(), ccw_device_start_key(), ccw_device_start_key_timeout() + initiate an I/O request. + +ccw_device_resume() + resume channel program execution. + +ccw_device_halt() + terminate the current I/O request processed on the device. + +do_IRQ() + generic interrupt routine. This function is called by the interrupt entry + routine whenever an I/O interrupt is presented to the system. The do_IRQ() + routine determines the interrupt status and calls the device specific + interrupt handler according to the rules (flags) defined during I/O request + initiation with do_IO(). + +The next chapters describe the functions other than do_IRQ() in more details. +The do_IRQ() interface is not described, as it is called from the Linux/390 +first level interrupt handler only and does not comprise a device driver +callable interface. Instead, the functional description of do_IO() also +describes the input to the device specific interrupt handler. + +Note: + All explanations apply also to the 64 bit architecture s390x. + + +Common Device Support (CDS) for Linux/390 Device Drivers +======================================================== + +General Information +------------------- + +The following chapters describe the I/O related interface routines the +Linux/390 common device support (CDS) provides to allow for device specific +driver implementations on the IBM ESA/390 hardware platform. Those interfaces +intend to provide the functionality required by every device driver +implementation to allow to drive a specific hardware device on the ESA/390 +platform. Some of the interface routines are specific to Linux/390 and some +of them can be found on other Linux platforms implementations too. +Miscellaneous function prototypes, data declarations, and macro definitions +can be found in the architecture specific C header file +linux/arch/s390/include/asm/irq.h. + +Overview of CDS interface concepts +---------------------------------- + +Different to other hardware platforms, the ESA/390 architecture doesn't define +interrupt lines managed by a specific interrupt controller and bus systems +that may or may not allow for shared interrupts, DMA processing, etc.. Instead, +the ESA/390 architecture has implemented a so called channel subsystem, that +provides a unified view of the devices physically attached to the systems. +Though the ESA/390 hardware platform knows about a huge variety of different +peripheral attachments like disk devices (aka. DASDs), tapes, communication +controllers, etc. they can all be accessed by a well defined access method and +they are presenting I/O completion a unified way : I/O interruptions. Every +single device is uniquely identified to the system by a so called subchannel, +where the ESA/390 architecture allows for 64k devices be attached. + +Linux, however, was first built on the Intel PC architecture, with its two +cascaded 8259 programmable interrupt controllers (PICs), that allow for a +maximum of 15 different interrupt lines. All devices attached to such a system +share those 15 interrupt levels. Devices attached to the ISA bus system must +not share interrupt levels (aka. IRQs), as the ISA bus bases on edge triggered +interrupts. MCA, EISA, PCI and other bus systems base on level triggered +interrupts, and therewith allow for shared IRQs. However, if multiple devices +present their hardware status by the same (shared) IRQ, the operating system +has to call every single device driver registered on this IRQ in order to +determine the device driver owning the device that raised the interrupt. + +Up to kernel 2.4, Linux/390 used to provide interfaces via the IRQ (subchannel). +For internal use of the common I/O layer, these are still there. However, +device drivers should use the new calling interface via the ccw_device only. + +During its startup the Linux/390 system checks for peripheral devices. Each +of those devices is uniquely defined by a so called subchannel by the ESA/390 +channel subsystem. While the subchannel numbers are system generated, each +subchannel also takes a user defined attribute, the so called device number. +Both subchannel number and device number cannot exceed 65535. During sysfs +initialisation, the information about control unit type and device types that +imply specific I/O commands (channel command words - CCWs) in order to operate +the device are gathered. Device drivers can retrieve this set of hardware +information during their initialization step to recognize the devices they +support using the information saved in the struct ccw_device given to them. +This methods implies that Linux/390 doesn't require to probe for free (not +armed) interrupt request lines (IRQs) to drive its devices with. Where +applicable, the device drivers can use issue the READ DEVICE CHARACTERISTICS +ccw to retrieve device characteristics in its online routine. + +In order to allow for easy I/O initiation the CDS layer provides a +ccw_device_start() interface that takes a device specific channel program (one +or more CCWs) as input sets up the required architecture specific control blocks +and initiates an I/O request on behalf of the device driver. The +ccw_device_start() routine allows to specify whether it expects the CDS layer +to notify the device driver for every interrupt it observes, or with final status +only. See ccw_device_start() for more details. A device driver must never issue +ESA/390 I/O commands itself, but must use the Linux/390 CDS interfaces instead. + +For long running I/O request to be canceled, the CDS layer provides the +ccw_device_halt() function. Some devices require to initially issue a HALT +SUBCHANNEL (HSCH) command without having pending I/O requests. This function is +also covered by ccw_device_halt(). + + +get_ciw() - get command information word + +This call enables a device driver to get information about supported commands +from the extended SenseID data. + +:: + + struct ciw * + ccw_device_get_ciw(struct ccw_device *cdev, __u32 cmd); + +==== ======================================================== +cdev The ccw_device for which the command is to be retrieved. +cmd The command type to be retrieved. +==== ======================================================== + +ccw_device_get_ciw() returns: + +===== ================================================================ + NULL No extended data available, invalid device or command not found. +!NULL The command requested. +===== ================================================================ + +:: + + ccw_device_start() - Initiate I/O Request + +The ccw_device_start() routines is the I/O request front-end processor. All +device driver I/O requests must be issued using this routine. A device driver +must not issue ESA/390 I/O commands itself. Instead the ccw_device_start() +routine provides all interfaces required to drive arbitrary devices. + +This description also covers the status information passed to the device +driver's interrupt handler as this is related to the rules (flags) defined +with the associated I/O request when calling ccw_device_start(). + +:: + + int ccw_device_start(struct ccw_device *cdev, + struct ccw1 *cpa, + unsigned long intparm, + __u8 lpm, + unsigned long flags); + int ccw_device_start_timeout(struct ccw_device *cdev, + struct ccw1 *cpa, + unsigned long intparm, + __u8 lpm, + unsigned long flags, + int expires); + int ccw_device_start_key(struct ccw_device *cdev, + struct ccw1 *cpa, + unsigned long intparm, + __u8 lpm, + __u8 key, + unsigned long flags); + int ccw_device_start_key_timeout(struct ccw_device *cdev, + struct ccw1 *cpa, + unsigned long intparm, + __u8 lpm, + __u8 key, + unsigned long flags, + int expires); + +============= ============================================================= +cdev ccw_device the I/O is destined for +cpa logical start address of channel program +user_intparm user specific interrupt information; will be presented + back to the device driver's interrupt handler. Allows a + device driver to associate the interrupt with a + particular I/O request. +lpm defines the channel path to be used for a specific I/O + request. A value of 0 will make cio use the opm. +key the storage key to use for the I/O (useful for operating on a + storage with a storage key != default key) +flag defines the action to be performed for I/O processing +expires timeout value in jiffies. The common I/O layer will terminate + the running program after this and call the interrupt handler + with ERR_PTR(-ETIMEDOUT) as irb. +============= ============================================================= + +Possible flag values are: + +========================= ============================================= +DOIO_ALLOW_SUSPEND channel program may become suspended +DOIO_DENY_PREFETCH don't allow for CCW prefetch; usually + this implies the channel program might + become modified +DOIO_SUPPRESS_INTER don't call the handler on intermediate status +========================= ============================================= + +The cpa parameter points to the first format 1 CCW of a channel program:: + + struct ccw1 { + __u8 cmd_code;/* command code */ + __u8 flags; /* flags, like IDA addressing, etc. */ + __u16 count; /* byte count */ + __u32 cda; /* data address */ + } __attribute__ ((packed,aligned(8))); + +with the following CCW flags values defined: + +=================== ========================= +CCW_FLAG_DC data chaining +CCW_FLAG_CC command chaining +CCW_FLAG_SLI suppress incorrect length +CCW_FLAG_SKIP skip +CCW_FLAG_PCI PCI +CCW_FLAG_IDA indirect addressing +CCW_FLAG_SUSPEND suspend +=================== ========================= + + +Via ccw_device_set_options(), the device driver may specify the following +options for the device: + +========================= ====================================== +DOIO_EARLY_NOTIFICATION allow for early interrupt notification +DOIO_REPORT_ALL report all interrupt conditions +========================= ====================================== + + +The ccw_device_start() function returns: + +======== ====================================================================== + 0 successful completion or request successfully initiated + -EBUSY The device is currently processing a previous I/O request, or there is + a status pending at the device. +-ENODEV cdev is invalid, the device is not operational or the ccw_device is + not online. +======== ====================================================================== + +When the I/O request completes, the CDS first level interrupt handler will +accumulate the status in a struct irb and then call the device interrupt handler. +The intparm field will contain the value the device driver has associated with a +particular I/O request. If a pending device status was recognized, +intparm will be set to 0 (zero). This may happen during I/O initiation or delayed +by an alert status notification. In any case this status is not related to the +current (last) I/O request. In case of a delayed status notification no special +interrupt will be presented to indicate I/O completion as the I/O request was +never started, even though ccw_device_start() returned with successful completion. + +The irb may contain an error value, and the device driver should check for this +first: + +========== ================================================================= +-ETIMEDOUT the common I/O layer terminated the request after the specified + timeout value +-EIO the common I/O layer terminated the request due to an error state +========== ================================================================= + +If the concurrent sense flag in the extended status word (esw) in the irb is +set, the field erw.scnt in the esw describes the number of device specific +sense bytes available in the extended control word irb->scsw.ecw[]. No device +sensing by the device driver itself is required. + +The device interrupt handler can use the following definitions to investigate +the primary unit check source coded in sense byte 0 : + +======================= ==== +SNS0_CMD_REJECT 0x80 +SNS0_INTERVENTION_REQ 0x40 +SNS0_BUS_OUT_CHECK 0x20 +SNS0_EQUIPMENT_CHECK 0x10 +SNS0_DATA_CHECK 0x08 +SNS0_OVERRUN 0x04 +SNS0_INCOMPL_DOMAIN 0x01 +======================= ==== + +Depending on the device status, multiple of those values may be set together. +Please refer to the device specific documentation for details. + +The irb->scsw.cstat field provides the (accumulated) subchannel status : + +========================= ============================ +SCHN_STAT_PCI program controlled interrupt +SCHN_STAT_INCORR_LEN incorrect length +SCHN_STAT_PROG_CHECK program check +SCHN_STAT_PROT_CHECK protection check +SCHN_STAT_CHN_DATA_CHK channel data check +SCHN_STAT_CHN_CTRL_CHK channel control check +SCHN_STAT_INTF_CTRL_CHK interface control check +SCHN_STAT_CHAIN_CHECK chaining check +========================= ============================ + +The irb->scsw.dstat field provides the (accumulated) device status : + +===================== ================= +DEV_STAT_ATTENTION attention +DEV_STAT_STAT_MOD status modifier +DEV_STAT_CU_END control unit end +DEV_STAT_BUSY busy +DEV_STAT_CHN_END channel end +DEV_STAT_DEV_END device end +DEV_STAT_UNIT_CHECK unit check +DEV_STAT_UNIT_EXCEP unit exception +===================== ================= + +Please see the ESA/390 Principles of Operation manual for details on the +individual flag meanings. + +Usage Notes: + +ccw_device_start() must be called disabled and with the ccw device lock held. + +The device driver is allowed to issue the next ccw_device_start() call from +within its interrupt handler already. It is not required to schedule a +bottom-half, unless a non deterministically long running error recovery procedure +or similar needs to be scheduled. During I/O processing the Linux/390 generic +I/O device driver support has already obtained the IRQ lock, i.e. the handler +must not try to obtain it again when calling ccw_device_start() or we end in a +deadlock situation! + +If a device driver relies on an I/O request to be completed prior to start the +next it can reduce I/O processing overhead by chaining a NoOp I/O command +CCW_CMD_NOOP to the end of the submitted CCW chain. This will force Channel-End +and Device-End status to be presented together, with a single interrupt. +However, this should be used with care as it implies the channel will remain +busy, not being able to process I/O requests for other devices on the same +channel. Therefore e.g. read commands should never use this technique, as the +result will be presented by a single interrupt anyway. + +In order to minimize I/O overhead, a device driver should use the +DOIO_REPORT_ALL only if the device can report intermediate interrupt +information prior to device-end the device driver urgently relies on. In this +case all I/O interruptions are presented to the device driver until final +status is recognized. + +If a device is able to recover from asynchronously presented I/O errors, it can +perform overlapping I/O using the DOIO_EARLY_NOTIFICATION flag. While some +devices always report channel-end and device-end together, with a single +interrupt, others present primary status (channel-end) when the channel is +ready for the next I/O request and secondary status (device-end) when the data +transmission has been completed at the device. + +Above flag allows to exploit this feature, e.g. for communication devices that +can handle lost data on the network to allow for enhanced I/O processing. + +Unless the channel subsystem at any time presents a secondary status interrupt, +exploiting this feature will cause only primary status interrupts to be +presented to the device driver while overlapping I/O is performed. When a +secondary status without error (alert status) is presented, this indicates +successful completion for all overlapping ccw_device_start() requests that have +been issued since the last secondary (final) status. + +Channel programs that intend to set the suspend flag on a channel command word +(CCW) must start the I/O operation with the DOIO_ALLOW_SUSPEND option or the +suspend flag will cause a channel program check. At the time the channel program +becomes suspended an intermediate interrupt will be generated by the channel +subsystem. + +ccw_device_resume() - Resume Channel Program Execution + +If a device driver chooses to suspend the current channel program execution by +setting the CCW suspend flag on a particular CCW, the channel program execution +is suspended. In order to resume channel program execution the CIO layer +provides the ccw_device_resume() routine. + +:: + + int ccw_device_resume(struct ccw_device *cdev); + +==== ================================================ +cdev ccw_device the resume operation is requested for +==== ================================================ + +The ccw_device_resume() function returns: + +========= ============================================== + 0 suspended channel program is resumed + -EBUSY status pending + -ENODEV cdev invalid or not-operational subchannel + -EINVAL resume function not applicable +-ENOTCONN there is no I/O request pending for completion +========= ============================================== + +Usage Notes: + +Please have a look at the ccw_device_start() usage notes for more details on +suspended channel programs. + +ccw_device_halt() - Halt I/O Request Processing + +Sometimes a device driver might need a possibility to stop the processing of +a long-running channel program or the device might require to initially issue +a halt subchannel (HSCH) I/O command. For those purposes the ccw_device_halt() +command is provided. + +ccw_device_halt() must be called disabled and with the ccw device lock held. + +:: + + int ccw_device_halt(struct ccw_device *cdev, + unsigned long intparm); + +======= ===================================================== +cdev ccw_device the halt operation is requested for +intparm interruption parameter; value is only used if no I/O + is outstanding, otherwise the intparm associated with + the I/O request is returned +======= ===================================================== + +The ccw_device_halt() function returns: + +======= ============================================================== + 0 request successfully initiated +-EBUSY the device is currently busy, or status pending. +-ENODEV cdev invalid. +-EINVAL The device is not operational or the ccw device is not online. +======= ============================================================== + +Usage Notes: + +A device driver may write a never-ending channel program by writing a channel +program that at its end loops back to its beginning by means of a transfer in +channel (TIC) command (CCW_CMD_TIC). Usually this is performed by network +device drivers by setting the PCI CCW flag (CCW_FLAG_PCI). Once this CCW is +executed a program controlled interrupt (PCI) is generated. The device driver +can then perform an appropriate action. Prior to interrupt of an outstanding +read to a network device (with or without PCI flag) a ccw_device_halt() +is required to end the pending operation. + +:: + + ccw_device_clear() - Terminage I/O Request Processing + +In order to terminate all I/O processing at the subchannel, the clear subchannel +(CSCH) command is used. It can be issued via ccw_device_clear(). + +ccw_device_clear() must be called disabled and with the ccw device lock held. + +:: + + int ccw_device_clear(struct ccw_device *cdev, unsigned long intparm); + +======= =============================================== +cdev ccw_device the clear operation is requested for +intparm interruption parameter (see ccw_device_halt()) +======= =============================================== + +The ccw_device_clear() function returns: + +======= ============================================================== + 0 request successfully initiated +-ENODEV cdev invalid +-EINVAL The device is not operational or the ccw device is not online. +======= ============================================================== + +Miscellaneous Support Routines +------------------------------ + +This chapter describes various routines to be used in a Linux/390 device +driver programming environment. + +get_ccwdev_lock() + +Get the address of the device specific lock. This is then used in +spin_lock() / spin_unlock() calls. + +:: + + __u8 ccw_device_get_path_mask(struct ccw_device *cdev); + +Get the mask of the path currently available for cdev. diff --git a/Documentation/arch/s390/common_io.rst b/Documentation/arch/s390/common_io.rst new file mode 100644 index 0000000000..6dcb40cb71 --- /dev/null +++ b/Documentation/arch/s390/common_io.rst @@ -0,0 +1,140 @@ +====================== +S/390 common I/O-Layer +====================== + +command line parameters, procfs and debugfs entries +=================================================== + +Command line parameters +----------------------- + +* ccw_timeout_log + + Enable logging of debug information in case of ccw device timeouts. + +* cio_ignore = device[,device[,..]] + + device := {all | [!]ipldev | [!]condev | [!]<devno> | [!]<devno>-<devno>} + + The given devices will be ignored by the common I/O-layer; no detection + and device sensing will be done on any of those devices. The subchannel to + which the device in question is attached will be treated as if no device was + attached. + + An ignored device can be un-ignored later; see the "/proc entries"-section for + details. + + The devices must be given either as bus ids (0.x.abcd) or as hexadecimal + device numbers (0xabcd or abcd, for 2.4 backward compatibility). If you + give a device number 0xabcd, it will be interpreted as 0.0.abcd. + + You can use the 'all' keyword to ignore all devices. The 'ipldev' and 'condev' + keywords can be used to refer to the CCW based boot device and CCW console + device respectively (these are probably useful only when combined with the '!' + operator). The '!' operator will cause the I/O-layer to _not_ ignore a device. + The command line + is parsed from left to right. + + For example:: + + cio_ignore=0.0.0023-0.0.0042,0.0.4711 + + will ignore all devices ranging from 0.0.0023 to 0.0.0042 and the device + 0.0.4711, if detected. + + As another example:: + + cio_ignore=all,!0.0.4711,!0.0.fd00-0.0.fd02 + + will ignore all devices but 0.0.4711, 0.0.fd00, 0.0.fd01, 0.0.fd02. + + By default, no devices are ignored. + + +/proc entries +------------- + +* /proc/cio_ignore + + Lists the ranges of devices (by bus id) which are ignored by common I/O. + + You can un-ignore certain or all devices by piping to /proc/cio_ignore. + "free all" will un-ignore all ignored devices, + "free <device range>, <device range>, ..." will un-ignore the specified + devices. + + For example, if devices 0.0.0023 to 0.0.0042 and 0.0.4711 are ignored, + + - echo free 0.0.0030-0.0.0032 > /proc/cio_ignore + will un-ignore devices 0.0.0030 to 0.0.0032 and will leave devices 0.0.0023 + to 0.0.002f, 0.0.0033 to 0.0.0042 and 0.0.4711 ignored; + - echo free 0.0.0041 > /proc/cio_ignore will furthermore un-ignore device + 0.0.0041; + - echo free all > /proc/cio_ignore will un-ignore all remaining ignored + devices. + + When a device is un-ignored, device recognition and sensing is performed and + the device driver will be notified if possible, so the device will become + available to the system. Note that un-ignoring is performed asynchronously. + + You can also add ranges of devices to be ignored by piping to + /proc/cio_ignore; "add <device range>, <device range>, ..." will ignore the + specified devices. + + Note: While already known devices can be added to the list of devices to be + ignored, there will be no effect on then. However, if such a device + disappears and then reappears, it will then be ignored. To make + known devices go away, you need the "purge" command (see below). + + For example:: + + "echo add 0.0.a000-0.0.accc, 0.0.af00-0.0.afff > /proc/cio_ignore" + + will add 0.0.a000-0.0.accc and 0.0.af00-0.0.afff to the list of ignored + devices. + + You can remove already known but now ignored devices via:: + + "echo purge > /proc/cio_ignore" + + All devices ignored but still registered and not online (= not in use) + will be deregistered and thus removed from the system. + + The devices can be specified either by bus id (0.x.abcd) or, for 2.4 backward + compatibility, by the device number in hexadecimal (0xabcd or abcd). Device + numbers given as 0xabcd will be interpreted as 0.0.abcd. + +* /proc/cio_settle + + A write request to this file is blocked until all queued cio actions are + handled. This will allow userspace to wait for pending work affecting + device availability after changing cio_ignore or the hardware configuration. + +* For some of the information present in the /proc filesystem in 2.4 (namely, + /proc/subchannels and /proc/chpids), see driver-model.txt. + Information formerly in /proc/irq_count is now in /proc/interrupts. + + +debugfs entries +--------------- + +* /sys/kernel/debug/s390dbf/cio_*/ (S/390 debug feature) + + Some views generated by the debug feature to hold various debug outputs. + + - /sys/kernel/debug/s390dbf/cio_crw/sprintf + Messages from the processing of pending channel report words (machine check + handling). + + - /sys/kernel/debug/s390dbf/cio_msg/sprintf + Various debug messages from the common I/O-layer. + + - /sys/kernel/debug/s390dbf/cio_trace/hex_ascii + Logs the calling of functions in the common I/O-layer and, if applicable, + which subchannel they were called for, as well as dumps of some data + structures (like irb in an error case). + + The level of logging can be changed to be more or less verbose by piping to + /sys/kernel/debug/s390dbf/cio_*/level a number between 0 and 6; see the + documentation on the S/390 debug feature (Documentation/arch/s390/s390dbf.rst) + for details. diff --git a/Documentation/arch/s390/config3270.sh b/Documentation/arch/s390/config3270.sh new file mode 100644 index 0000000000..515e2f4314 --- /dev/null +++ b/Documentation/arch/s390/config3270.sh @@ -0,0 +1,76 @@ +#!/bin/sh +# +# config3270 -- Autoconfigure /dev/3270/* and /etc/inittab +# +# Usage: +# config3270 +# +# Output: +# /tmp/mkdev3270 +# +# Operation: +# 1. Run this script +# 2. Run the script it produces: /tmp/mkdev3270 +# 3. Issue "telinit q" or reboot, as appropriate. +# +P=/proc/tty/driver/tty3270 +ROOT= +D=$ROOT/dev +SUBD=3270 +TTY=$SUBD/tty +TUB=$SUBD/tub +SCR=$ROOT/tmp/mkdev3270 +SCRTMP=$SCR.a +GETTYLINE=:2345:respawn:/sbin/mingetty +INITTAB=$ROOT/etc/inittab +NINITTAB=$ROOT/etc/NEWinittab +OINITTAB=$ROOT/etc/OLDinittab +ADDNOTE=\\"# Additional mingettys for the 3270/tty* driver, tub3270 ---\\" + +if ! ls $P > /dev/null 2>&1; then + modprobe tub3270 > /dev/null 2>&1 +fi +ls $P > /dev/null 2>&1 || exit 1 + +# Initialize two files, one for /dev/3270 commands and one +# to replace the /etc/inittab file (old one saved in OLDinittab) +echo "#!/bin/sh" > $SCR || exit 1 +echo " " >> $SCR +echo "# Script built by /sbin/config3270" >> $SCR +if [ ! -d /dev/dasd ]; then + echo rm -rf "$D/$SUBD/*" >> $SCR +fi +echo "grep -v $TTY $INITTAB > $NINITTAB" > $SCRTMP || exit 1 +echo "echo $ADDNOTE >> $NINITTAB" >> $SCRTMP +if [ ! -d /dev/dasd ]; then + echo mkdir -p $D/$SUBD >> $SCR +fi + +# Now query the tub3270 driver for 3270 device information +# and add appropriate mknod and mingetty lines to our files +echo what=config > $P +while read devno maj min;do + if [ $min = 0 ]; then + fsmaj=$maj + if [ ! -d /dev/dasd ]; then + echo mknod $D/$TUB c $fsmaj 0 >> $SCR + echo chmod 666 $D/$TUB >> $SCR + fi + elif [ $maj = CONSOLE ]; then + if [ ! -d /dev/dasd ]; then + echo mknod $D/$TUB$devno c $fsmaj $min >> $SCR + fi + else + if [ ! -d /dev/dasd ]; then + echo mknod $D/$TTY$devno c $maj $min >>$SCR + echo mknod $D/$TUB$devno c $fsmaj $min >> $SCR + fi + echo "echo t$min$GETTYLINE $TTY$devno >> $NINITTAB" >> $SCRTMP + fi +done < $P + +echo mv $INITTAB $OINITTAB >> $SCRTMP || exit 1 +echo mv $NINITTAB $INITTAB >> $SCRTMP +cat $SCRTMP >> $SCR +rm $SCRTMP +exit 0 diff --git a/Documentation/arch/s390/driver-model.rst b/Documentation/arch/s390/driver-model.rst new file mode 100644 index 0000000000..ad4bc2dbea --- /dev/null +++ b/Documentation/arch/s390/driver-model.rst @@ -0,0 +1,328 @@ +============================= +S/390 driver model interfaces +============================= + +1. CCW devices +-------------- + +All devices which can be addressed by means of ccws are called 'CCW devices' - +even if they aren't actually driven by ccws. + +All ccw devices are accessed via a subchannel, this is reflected in the +structures under devices/:: + + devices/ + - system/ + - css0/ + - 0.0.0000/0.0.0815/ + - 0.0.0001/0.0.4711/ + - 0.0.0002/ + - 0.1.0000/0.1.1234/ + ... + - defunct/ + +In this example, device 0815 is accessed via subchannel 0 in subchannel set 0, +device 4711 via subchannel 1 in subchannel set 0, and subchannel 2 is a non-I/O +subchannel. Device 1234 is accessed via subchannel 0 in subchannel set 1. + +The subchannel named 'defunct' does not represent any real subchannel on the +system; it is a pseudo subchannel where disconnected ccw devices are moved to +if they are displaced by another ccw device becoming operational on their +former subchannel. The ccw devices will be moved again to a proper subchannel +if they become operational again on that subchannel. + +You should address a ccw device via its bus id (e.g. 0.0.4711); the device can +be found under bus/ccw/devices/. + +All ccw devices export some data via sysfs. + +cutype: + The control unit type / model. + +devtype: + The device type / model, if applicable. + +availability: + Can be 'good' or 'boxed'; 'no path' or 'no device' for + disconnected devices. + +online: + An interface to set the device online and offline. + In the special case of the device being disconnected (see the + notify function under 1.2), piping 0 to online will forcibly delete + the device. + +The device drivers can add entries to export per-device data and interfaces. + +There is also some data exported on a per-subchannel basis (see under +bus/css/devices/): + +chpids: + Via which chpids the device is connected. + +pimpampom: + The path installed, path available and path operational masks. + +There also might be additional data, for example for block devices. + + +1.1 Bringing up a ccw device +---------------------------- + +This is done in several steps. + +a. Each driver can provide one or more parameter interfaces where parameters can + be specified. These interfaces are also in the driver's responsibility. +b. After a. has been performed, if necessary, the device is finally brought up + via the 'online' interface. + + +1.2 Writing a driver for ccw devices +------------------------------------ + +The basic struct ccw_device and struct ccw_driver data structures can be found +under include/asm/ccwdev.h:: + + struct ccw_device { + spinlock_t *ccwlock; + struct ccw_device_private *private; + struct ccw_device_id id; + + struct ccw_driver *drv; + struct device dev; + int online; + + void (*handler) (struct ccw_device *dev, unsigned long intparm, + struct irb *irb); + }; + + struct ccw_driver { + struct module *owner; + struct ccw_device_id *ids; + int (*probe) (struct ccw_device *); + int (*remove) (struct ccw_device *); + int (*set_online) (struct ccw_device *); + int (*set_offline) (struct ccw_device *); + int (*notify) (struct ccw_device *, int); + struct device_driver driver; + char *name; + }; + +The 'private' field contains data needed for internal i/o operation only, and +is not available to the device driver. + +Each driver should declare in a MODULE_DEVICE_TABLE into which CU types/models +and/or device types/models it is interested. This information can later be found +in the struct ccw_device_id fields:: + + struct ccw_device_id { + __u16 match_flags; + + __u16 cu_type; + __u16 dev_type; + __u8 cu_model; + __u8 dev_model; + + unsigned long driver_info; + }; + +The functions in ccw_driver should be used in the following way: + +probe: + This function is called by the device layer for each device the driver + is interested in. The driver should only allocate private structures + to put in dev->driver_data and create attributes (if needed). Also, + the interrupt handler (see below) should be set here. + +:: + + int (*probe) (struct ccw_device *cdev); + +Parameters: + cdev + - the device to be probed. + + +remove: + This function is called by the device layer upon removal of the driver, + the device or the module. The driver should perform cleanups here. + +:: + + int (*remove) (struct ccw_device *cdev); + +Parameters: + cdev + - the device to be removed. + + +set_online: + This function is called by the common I/O layer when the device is + activated via the 'online' attribute. The driver should finally + setup and activate the device here. + +:: + + int (*set_online) (struct ccw_device *); + +Parameters: + cdev + - the device to be activated. The common layer has + verified that the device is not already online. + + +set_offline: This function is called by the common I/O layer when the device is + de-activated via the 'online' attribute. The driver should shut + down the device, but not de-allocate its private data. + +:: + + int (*set_offline) (struct ccw_device *); + +Parameters: + cdev + - the device to be deactivated. The common layer has + verified that the device is online. + + +notify: + This function is called by the common I/O layer for some state changes + of the device. + + Signalled to the driver are: + + * In online state, device detached (CIO_GONE) or last path gone + (CIO_NO_PATH). The driver must return !0 to keep the device; for + return code 0, the device will be deleted as usual (also when no + notify function is registered). If the driver wants to keep the + device, it is moved into disconnected state. + * In disconnected state, device operational again (CIO_OPER). The + common I/O layer performs some sanity checks on device number and + Device / CU to be reasonably sure if it is still the same device. + If not, the old device is removed and a new one registered. By the + return code of the notify function the device driver signals if it + wants the device back: !0 for keeping, 0 to make the device being + removed and re-registered. + +:: + + int (*notify) (struct ccw_device *, int); + +Parameters: + cdev + - the device whose state changed. + + event + - the event that happened. This can be one of CIO_GONE, + CIO_NO_PATH or CIO_OPER. + +The handler field of the struct ccw_device is meant to be set to the interrupt +handler for the device. In order to accommodate drivers which use several +distinct handlers (e.g. multi subchannel devices), this is a member of ccw_device +instead of ccw_driver. +The handler is registered with the common layer during set_online() processing +before the driver is called, and is deregistered during set_offline() after the +driver has been called. Also, after registering / before deregistering, path +grouping resp. disbanding of the path group (if applicable) are performed. + +:: + + void (*handler) (struct ccw_device *dev, unsigned long intparm, struct irb *irb); + +Parameters: dev - the device the handler is called for + intparm - the intparm which allows the device driver to identify + the i/o the interrupt is associated with, or to recognize + the interrupt as unsolicited. + irb - interruption response block which contains the accumulated + status. + +The device driver is called from the common ccw_device layer and can retrieve +information about the interrupt from the irb parameter. + + +1.3 ccwgroup devices +-------------------- + +The ccwgroup mechanism is designed to handle devices consisting of multiple ccw +devices, like lcs or ctc. + +The ccw driver provides a 'group' attribute. Piping bus ids of ccw devices to +this attributes creates a ccwgroup device consisting of these ccw devices (if +possible). This ccwgroup device can be set online or offline just like a normal +ccw device. + +Each ccwgroup device also provides an 'ungroup' attribute to destroy the device +again (only when offline). This is a generic ccwgroup mechanism (the driver does +not need to implement anything beyond normal removal routines). + +A ccw device which is a member of a ccwgroup device carries a pointer to the +ccwgroup device in the driver_data of its device struct. This field must not be +touched by the driver - it should use the ccwgroup device's driver_data for its +private data. + +To implement a ccwgroup driver, please refer to include/asm/ccwgroup.h. Keep in +mind that most drivers will need to implement both a ccwgroup and a ccw +driver. + + +2. Channel paths +----------------- + +Channel paths show up, like subchannels, under the channel subsystem root (css0) +and are called 'chp0.<chpid>'. They have no driver and do not belong to any bus. +Please note, that unlike /proc/chpids in 2.4, the channel path objects reflect +only the logical state and not the physical state, since we cannot track the +latter consistently due to lacking machine support (we don't need to be aware +of it anyway). + +status + - Can be 'online' or 'offline'. + Piping 'on' or 'off' sets the chpid logically online/offline. + Piping 'on' to an online chpid triggers path reprobing for all devices + the chpid connects to. This can be used to force the kernel to re-use + a channel path the user knows to be online, but the machine hasn't + created a machine check for. + +type + - The physical type of the channel path. + +shared + - Whether the channel path is shared. + +cmg + - The channel measurement group. + +3. System devices +----------------- + +3.1 xpram +--------- + +xpram shows up under devices/system/ as 'xpram'. + +3.2 cpus +-------- + +For each cpu, a directory is created under devices/system/cpu/. Each cpu has an +attribute 'online' which can be 0 or 1. + + +4. Other devices +---------------- + +4.1 Netiucv +----------- + +The netiucv driver creates an attribute 'connection' under +bus/iucv/drivers/netiucv. Piping to this attribute creates a new netiucv +connection to the specified host. + +Netiucv connections show up under devices/iucv/ as "netiucv<ifnum>". The interface +number is assigned sequentially to the connections defined via the 'connection' +attribute. + +user + - shows the connection partner. + +buffer + - maximum buffer size. Pipe to it to change buffer size. diff --git a/Documentation/arch/s390/features.rst b/Documentation/arch/s390/features.rst new file mode 100644 index 0000000000..2883dc9506 --- /dev/null +++ b/Documentation/arch/s390/features.rst @@ -0,0 +1,3 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. kernel-feat:: features s390 diff --git a/Documentation/arch/s390/index.rst b/Documentation/arch/s390/index.rst new file mode 100644 index 0000000000..73c79bf586 --- /dev/null +++ b/Documentation/arch/s390/index.rst @@ -0,0 +1,30 @@ +================= +s390 Architecture +================= + +.. toctree:: + :maxdepth: 1 + + cds + 3270 + driver-model + monreader + qeth + s390dbf + vfio-ap + vfio-ap-locking + vfio-ccw + zfcpdump + common_io + pci + + text_files + + features + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/arch/s390/monreader.rst b/Documentation/arch/s390/monreader.rst new file mode 100644 index 0000000000..21cdfb699b --- /dev/null +++ b/Documentation/arch/s390/monreader.rst @@ -0,0 +1,212 @@ +================================================= +Linux API for read access to z/VM Monitor Records +================================================= + +Date : 2004-Nov-26 + +Author: Gerald Schaefer (geraldsc@de.ibm.com) + + + + +Description +=========== +This item delivers a new Linux API in the form of a misc char device that is +usable from user space and allows read access to the z/VM Monitor Records +collected by the `*MONITOR` System Service of z/VM. + + +User Requirements +================= +The z/VM guest on which you want to access this API needs to be configured in +order to allow IUCV connections to the `*MONITOR` service, i.e. it needs the +IUCV `*MONITOR` statement in its user entry. If the monitor DCSS to be used is +restricted (likely), you also need the NAMESAVE <DCSS NAME> statement. +This item will use the IUCV device driver to access the z/VM services, so you +need a kernel with IUCV support. You also need z/VM version 4.4 or 5.1. + +There are two options for being able to load the monitor DCSS (examples assume +that the monitor DCSS begins at 144 MB and ends at 152 MB). You can query the +location of the monitor DCSS with the Class E privileged CP command Q NSS MAP +(the values BEGPAG and ENDPAG are given in units of 4K pages). + +See also "CP Command and Utility Reference" (SC24-6081-00) for more information +on the DEF STOR and Q NSS MAP commands, as well as "Saved Segments Planning +and Administration" (SC24-6116-00) for more information on DCSSes. + +1st option: +----------- +You can use the CP command DEF STOR CONFIG to define a "memory hole" in your +guest virtual storage around the address range of the DCSS. + +Example: DEF STOR CONFIG 0.140M 200M.200M + +This defines two blocks of storage, the first is 140MB in size an begins at +address 0MB, the second is 200MB in size and begins at address 200MB, +resulting in a total storage of 340MB. Note that the first block should +always start at 0 and be at least 64MB in size. + +2nd option: +----------- +Your guest virtual storage has to end below the starting address of the DCSS +and you have to specify the "mem=" kernel parameter in your parmfile with a +value greater than the ending address of the DCSS. + +Example:: + + DEF STOR 140M + +This defines 140MB storage size for your guest, the parameter "mem=160M" is +added to the parmfile. + + +User Interface +============== +The char device is implemented as a kernel module named "monreader", +which can be loaded via the modprobe command, or it can be compiled into the +kernel instead. There is one optional module (or kernel) parameter, "mondcss", +to specify the name of the monitor DCSS. If the module is compiled into the +kernel, the kernel parameter "monreader.mondcss=<DCSS NAME>" can be specified +in the parmfile. + +The default name for the DCSS is "MONDCSS" if none is specified. In case that +there are other users already connected to the `*MONITOR` service (e.g. +Performance Toolkit), the monitor DCSS is already defined and you have to use +the same DCSS. The CP command Q MONITOR (Class E privileged) shows the name +of the monitor DCSS, if already defined, and the users connected to the +`*MONITOR` service. +Refer to the "z/VM Performance" book (SC24-6109-00) on how to create a monitor +DCSS if your z/VM doesn't have one already, you need Class E privileges to +define and save a DCSS. + +Example: +-------- + +:: + + modprobe monreader mondcss=MYDCSS + +This loads the module and sets the DCSS name to "MYDCSS". + +NOTE: +----- +This API provides no interface to control the `*MONITOR` service, e.g. specify +which data should be collected. This can be done by the CP command MONITOR +(Class E privileged), see "CP Command and Utility Reference". + +Device nodes with udev: +----------------------- +After loading the module, a char device will be created along with the device +node /<udev directory>/monreader. + +Device nodes without udev: +-------------------------- +If your distribution does not support udev, a device node will not be created +automatically and you have to create it manually after loading the module. +Therefore you need to know the major and minor numbers of the device. These +numbers can be found in /sys/class/misc/monreader/dev. + +Typing cat /sys/class/misc/monreader/dev will give an output of the form +<major>:<minor>. The device node can be created via the mknod command, enter +mknod <name> c <major> <minor>, where <name> is the name of the device node +to be created. + +Example: +-------- + +:: + + # modprobe monreader + # cat /sys/class/misc/monreader/dev + 10:63 + # mknod /dev/monreader c 10 63 + +This loads the module with the default monitor DCSS (MONDCSS) and creates a +device node. + +File operations: +---------------- +The following file operations are supported: open, release, read, poll. +There are two alternative methods for reading: either non-blocking read in +conjunction with polling, or blocking read without polling. IOCTLs are not +supported. + +Read: +----- +Reading from the device provides a 12 Byte monitor control element (MCE), +followed by a set of one or more contiguous monitor records (similar to the +output of the CMS utility MONWRITE without the 4K control blocks). The MCE +contains information on the type of the following record set (sample/event +data), the monitor domains contained within it and the start and end address +of the record set in the monitor DCSS. The start and end address can be used +to determine the size of the record set, the end address is the address of the +last byte of data. The start address is needed to handle "end-of-frame" records +correctly (domain 1, record 13), i.e. it can be used to determine the record +start offset relative to a 4K page (frame) boundary. + +See "Appendix A: `*MONITOR`" in the "z/VM Performance" document for a description +of the monitor control element layout. The layout of the monitor records can +be found here (z/VM 5.1): https://www.vm.ibm.com/pubs/mon510/index.html + +The layout of the data stream provided by the monreader device is as follows:: + + ... + <0 byte read> + <first MCE> \ + <first set of records> | + ... |- data set + <last MCE> | + <last set of records> / + <0 byte read> + ... + +There may be more than one combination of MCE and corresponding record set +within one data set and the end of each data set is indicated by a successful +read with a return value of 0 (0 byte read). +Any received data must be considered invalid until a complete set was +read successfully, including the closing 0 byte read. Therefore you should +always read the complete set into a buffer before processing the data. + +The maximum size of a data set can be as large as the size of the +monitor DCSS, so design the buffer adequately or use dynamic memory allocation. +The size of the monitor DCSS will be printed into syslog after loading the +module. You can also use the (Class E privileged) CP command Q NSS MAP to +list all available segments and information about them. + +As with most char devices, error conditions are indicated by returning a +negative value for the number of bytes read. In this case, the errno variable +indicates the error condition: + +EIO: + reply failed, read data is invalid and the application + should discard the data read since the last successful read with 0 size. +EFAULT: + copy_to_user failed, read data is invalid and the application should + discard the data read since the last successful read with 0 size. +EAGAIN: + occurs on a non-blocking read if there is no data available at the + moment. There is no data missing or corrupted, just try again or rather + use polling for non-blocking reads. +EOVERFLOW: + message limit reached, the data read since the last successful + read with 0 size is valid but subsequent records may be missing. + +In the last case (EOVERFLOW) there may be missing data, in the first two cases +(EIO, EFAULT) there will be missing data. It's up to the application if it will +continue reading subsequent data or rather exit. + +Open: +----- +Only one user is allowed to open the char device. If it is already in use, the +open function will fail (return a negative value) and set errno to EBUSY. +The open function may also fail if an IUCV connection to the `*MONITOR` service +cannot be established. In this case errno will be set to EIO and an error +message with an IPUSER SEVER code will be printed into syslog. The IPUSER SEVER +codes are described in the "z/VM Performance" book, Appendix A. + +NOTE: +----- +As soon as the device is opened, incoming messages will be accepted and they +will account for the message limit, i.e. opening the device without reading +from it will provoke the "message limit reached" error (EOVERFLOW error code) +eventually. diff --git a/Documentation/arch/s390/pci.rst b/Documentation/arch/s390/pci.rst new file mode 100644 index 0000000000..d5755484d8 --- /dev/null +++ b/Documentation/arch/s390/pci.rst @@ -0,0 +1,133 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========= +S/390 PCI +========= + +Authors: + - Pierre Morel + +Copyright, IBM Corp. 2020 + + +Command line parameters and debugfs entries +=========================================== + +Command line parameters +----------------------- + +* nomio + + Do not use PCI Mapped I/O (MIO) instructions. + +* norid + + Ignore the RID field and force use of one PCI domain per PCI function. + +debugfs entries +--------------- + +The S/390 debug feature (s390dbf) generates views to hold various debug results in sysfs directories of the form: + + * /sys/kernel/debug/s390dbf/pci_*/ + +For example: + + - /sys/kernel/debug/s390dbf/pci_msg/sprintf + Holds messages from the processing of PCI events, like machine check handling + and setting of global functionality, like UID checking. + + Change the level of logging to be more or less verbose by piping + a number between 0 and 6 to /sys/kernel/debug/s390dbf/pci_*/level. For + details, see the documentation on the S/390 debug feature at + Documentation/arch/s390/s390dbf.rst. + +Sysfs entries +============= + +Entries specific to zPCI functions and entries that hold zPCI information. + +* /sys/bus/pci/slots/XXXXXXXX + + The slot entries are set up using the function identifier (FID) of the + PCI function. The format depicted as XXXXXXXX above is 8 hexadecimal digits + with 0 padding and lower case hexadecimal digits. + + - /sys/bus/pci/slots/XXXXXXXX/power + + A physical function that currently supports a virtual function cannot be + powered off until all virtual functions are removed with: + echo 0 > /sys/bus/pci/devices/XXXX:XX:XX.X/sriov_numvf + +* /sys/bus/pci/devices/XXXX:XX:XX.X/ + + - function_id + A zPCI function identifier that uniquely identifies the function in the Z server. + + - function_handle + Low-level identifier used for a configured PCI function. + It might be useful for debugging. + + - pchid + Model-dependent location of the I/O adapter. + + - pfgid + PCI function group ID, functions that share identical functionality + use a common identifier. + A PCI group defines interrupts, IOMMU, IOTLB, and DMA specifics. + + - vfn + The virtual function number, from 1 to N for virtual functions, + 0 for physical functions. + + - pft + The PCI function type + + - port + The port corresponds to the physical port the function is attached to. + It also gives an indication of the physical function a virtual function + is attached to. + + - uid + The user identifier (UID) may be defined as part of the machine + configuration or the z/VM or KVM guest configuration. If the accompanying + uid_is_unique attribute is 1 the platform guarantees that the UID is unique + within that instance and no devices with the same UID can be attached + during the lifetime of the system. + + - uid_is_unique + Indicates whether the user identifier (UID) is guaranteed to be and remain + unique within this Linux instance. + + - pfip/segmentX + The segments determine the isolation of a function. + They correspond to the physical path to the function. + The more the segments are different, the more the functions are isolated. + +Enumeration and hotplug +======================= + +The PCI address consists of four parts: domain, bus, device and function, +and is of this form: DDDD:BB:dd.f + +* When not using multi-functions (norid is set, or the firmware does not + support multi-functions): + + - There is only one function per domain. + + - The domain is set from the zPCI function's UID as defined during the + LPAR creation. + +* When using multi-functions (norid parameter is not set), + zPCI functions are addressed differently: + + - There is still only one bus per domain. + + - There can be up to 256 functions per bus. + + - The domain part of the address of all functions for + a multi-Function device is set from the zPCI function's UID as defined + in the LPAR creation for the function zero. + + - New functions will only be ready for use after the function zero + (the function with devfn 0) has been enumerated. diff --git a/Documentation/arch/s390/qeth.rst b/Documentation/arch/s390/qeth.rst new file mode 100644 index 0000000000..f02fdaa68d --- /dev/null +++ b/Documentation/arch/s390/qeth.rst @@ -0,0 +1,64 @@ +============================= +IBM s390 QDIO Ethernet Driver +============================= + +OSA and HiperSockets Bridge Port Support +======================================== + +Uevents +------- + +To generate the events the device must be assigned a role of either +a primary or a secondary Bridge Port. For more information, see +"z/VM Connectivity, SC24-6174". + +When run on an OSA or HiperSockets Bridge Capable Port hardware, and the state +of some configured Bridge Port device on the channel changes, a udev +event with ACTION=CHANGE is emitted on behalf of the corresponding +ccwgroup device. The event has the following attributes: + +BRIDGEPORT=statechange + indicates that the Bridge Port device changed + its state. + +ROLE={primary|secondary|none} + the role assigned to the port. + +STATE={active|standby|inactive} + the newly assumed state of the port. + +When run on HiperSockets Bridge Capable Port hardware with host address +notifications enabled, a udev event with ACTION=CHANGE is emitted. +It is emitted on behalf of the corresponding ccwgroup device when a host +or a VLAN is registered or unregistered on the network served by the device. +The event has the following attributes: + +BRIDGEDHOST={reset|register|deregister|abort} + host address + notifications are started afresh, a new host or VLAN is registered or + deregistered on the Bridge Port HiperSockets channel, or address + notifications are aborted. + +VLAN=numeric-vlan-id + VLAN ID on which the event occurred. Not included + if no VLAN is involved in the event. + +MAC=xx:xx:xx:xx:xx:xx + MAC address of the host that is being registered + or deregistered from the HiperSockets channel. Not reported if the + event reports the creation or destruction of a VLAN. + +NTOK_BUSID=x.y.zzzz + device bus ID (CSSID, SSID and device number). + +NTOK_IID=xx + device IID. + +NTOK_CHPID=xx + device CHPID. + +NTOK_CHID=xxxx + device channel ID. + +Note that the `NTOK_*` attributes refer to devices other than the one +connected to the system on which the OS is running. diff --git a/Documentation/arch/s390/s390dbf.rst b/Documentation/arch/s390/s390dbf.rst new file mode 100644 index 0000000000..af8bdc3629 --- /dev/null +++ b/Documentation/arch/s390/s390dbf.rst @@ -0,0 +1,478 @@ +================== +S390 Debug Feature +================== + +files: + - arch/s390/kernel/debug.c + - arch/s390/include/asm/debug.h + +Description: +------------ +The goal of this feature is to provide a kernel debug logging API +where log records can be stored efficiently in memory, where each component +(e.g. device drivers) can have one separate debug log. +One purpose of this is to inspect the debug logs after a production system crash +in order to analyze the reason for the crash. + +If the system still runs but only a subcomponent which uses dbf fails, +it is possible to look at the debug logs on a live system via the Linux +debugfs filesystem. + +The debug feature may also very useful for kernel and driver development. + +Design: +------- +Kernel components (e.g. device drivers) can register themselves at the debug +feature with the function call :c:func:`debug_register()`. +This function initializes a +debug log for the caller. For each debug log exists a number of debug areas +where exactly one is active at one time. Each debug area consists of contiguous +pages in memory. In the debug areas there are stored debug entries (log records) +which are written by event- and exception-calls. + +An event-call writes the specified debug entry to the active debug +area and updates the log pointer for the active area. If the end +of the active debug area is reached, a wrap around is done (ring buffer) +and the next debug entry will be written at the beginning of the active +debug area. + +An exception-call writes the specified debug entry to the log and +switches to the next debug area. This is done in order to be sure +that the records which describe the origin of the exception are not +overwritten when a wrap around for the current area occurs. + +The debug areas themselves are also ordered in form of a ring buffer. +When an exception is thrown in the last debug area, the following debug +entries are then written again in the very first area. + +There are four versions for the event- and exception-calls: One for +logging raw data, one for text, one for numbers (unsigned int and long), +and one for sprintf-like formatted strings. + +Each debug entry contains the following data: + +- Timestamp +- Cpu-Number of calling task +- Level of debug entry (0...6) +- Return Address to caller +- Flag, if entry is an exception or not + +The debug logs can be inspected in a live system through entries in +the debugfs-filesystem. Under the toplevel directory "``s390dbf``" there is +a directory for each registered component, which is named like the +corresponding component. The debugfs normally should be mounted to +``/sys/kernel/debug`` therefore the debug feature can be accessed under +``/sys/kernel/debug/s390dbf``. + +The content of the directories are files which represent different views +to the debug log. Each component can decide which views should be +used through registering them with the function :c:func:`debug_register_view()`. +Predefined views for hex/ascii and sprintf data are provided. +It is also possible to define other views. The content of +a view can be inspected simply by reading the corresponding debugfs file. + +All debug logs have an actual debug level (range from 0 to 6). +The default level is 3. Event and Exception functions have a :c:data:`level` +parameter. Only debug entries with a level that is lower or equal +than the actual level are written to the log. This means, when +writing events, high priority log entries should have a low level +value whereas low priority entries should have a high one. +The actual debug level can be changed with the help of the debugfs-filesystem +through writing a number string "x" to the ``level`` debugfs file which is +provided for every debug log. Debugging can be switched off completely +by using "-" on the ``level`` debugfs file. + +Example:: + + > echo "-" > /sys/kernel/debug/s390dbf/dasd/level + +It is also possible to deactivate the debug feature globally for every +debug log. You can change the behavior using 2 sysctl parameters in +``/proc/sys/s390dbf``: + +There are currently 2 possible triggers, which stop the debug feature +globally. The first possibility is to use the ``debug_active`` sysctl. If +set to 1 the debug feature is running. If ``debug_active`` is set to 0 the +debug feature is turned off. + +The second trigger which stops the debug feature is a kernel oops. +That prevents the debug feature from overwriting debug information that +happened before the oops. After an oops you can reactivate the debug feature +by piping 1 to ``/proc/sys/s390dbf/debug_active``. Nevertheless, it's not +suggested to use an oopsed kernel in a production environment. + +If you want to disallow the deactivation of the debug feature, you can use +the ``debug_stoppable`` sysctl. If you set ``debug_stoppable`` to 0 the debug +feature cannot be stopped. If the debug feature is already stopped, it +will stay deactivated. + +Kernel Interfaces: +------------------ + +.. kernel-doc:: arch/s390/kernel/debug.c +.. kernel-doc:: arch/s390/include/asm/debug.h + +Predefined views: +----------------- + +.. code-block:: c + + extern struct debug_view debug_hex_ascii_view; + + extern struct debug_view debug_sprintf_view; + +Examples +-------- + +.. code-block:: c + + /* + * hex_ascii-view Example + */ + + #include <linux/init.h> + #include <asm/debug.h> + + static debug_info_t *debug_info; + + static int init(void) + { + /* register 4 debug areas with one page each and 4 byte data field */ + + debug_info = debug_register("test", 1, 4, 4 ); + debug_register_view(debug_info, &debug_hex_ascii_view); + + debug_text_event(debug_info, 4 , "one "); + debug_int_exception(debug_info, 4, 4711); + debug_event(debug_info, 3, &debug_info, 4); + + return 0; + } + + static void cleanup(void) + { + debug_unregister(debug_info); + } + + module_init(init); + module_exit(cleanup); + +.. code-block:: c + + /* + * sprintf-view Example + */ + + #include <linux/init.h> + #include <asm/debug.h> + + static debug_info_t *debug_info; + + static int init(void) + { + /* register 4 debug areas with one page each and data field for */ + /* format string pointer + 2 varargs (= 3 * sizeof(long)) */ + + debug_info = debug_register("test", 1, 4, sizeof(long) * 3); + debug_register_view(debug_info, &debug_sprintf_view); + + debug_sprintf_event(debug_info, 2 , "first event in %s:%i\n",__FILE__,__LINE__); + debug_sprintf_exception(debug_info, 1, "pointer to debug info: %p\n",&debug_info); + + return 0; + } + + static void cleanup(void) + { + debug_unregister(debug_info); + } + + module_init(init); + module_exit(cleanup); + +Debugfs Interface +----------------- +Views to the debug logs can be investigated through reading the corresponding +debugfs-files: + +Example:: + + > ls /sys/kernel/debug/s390dbf/dasd + flush hex_ascii level pages + > cat /sys/kernel/debug/s390dbf/dasd/hex_ascii | sort -k2,2 -s + 00 00974733272:680099 2 - 02 0006ad7e 07 ea 4a 90 | .... + 00 00974733272:682210 2 - 02 0006ade6 46 52 45 45 | FREE + 00 00974733272:682213 2 - 02 0006adf6 07 ea 4a 90 | .... + 00 00974733272:682281 1 * 02 0006ab08 41 4c 4c 43 | EXCP + 01 00974733272:682284 2 - 02 0006ab16 45 43 4b 44 | ECKD + 01 00974733272:682287 2 - 02 0006ab28 00 00 00 04 | .... + 01 00974733272:682289 2 - 02 0006ab3e 00 00 00 20 | ... + 01 00974733272:682297 2 - 02 0006ad7e 07 ea 4a 90 | .... + 01 00974733272:684384 2 - 00 0006ade6 46 52 45 45 | FREE + 01 00974733272:684388 2 - 00 0006adf6 07 ea 4a 90 | .... + +See section about predefined views for explanation of the above output! + +Changing the debug level +------------------------ + +Example:: + + + > cat /sys/kernel/debug/s390dbf/dasd/level + 3 + > echo "5" > /sys/kernel/debug/s390dbf/dasd/level + > cat /sys/kernel/debug/s390dbf/dasd/level + 5 + +Flushing debug areas +-------------------- +Debug areas can be flushed with piping the number of the desired +area (0...n) to the debugfs file "flush". When using "-" all debug areas +are flushed. + +Examples: + +1. Flush debug area 0:: + + > echo "0" > /sys/kernel/debug/s390dbf/dasd/flush + +2. Flush all debug areas:: + + > echo "-" > /sys/kernel/debug/s390dbf/dasd/flush + +Changing the size of debug areas +------------------------------------ +It is possible the change the size of debug areas through piping +the number of pages to the debugfs file "pages". The resize request will +also flush the debug areas. + +Example: + +Define 4 pages for the debug areas of debug feature "dasd":: + + > echo "4" > /sys/kernel/debug/s390dbf/dasd/pages + +Stopping the debug feature +-------------------------- +Example: + +1. Check if stopping is allowed:: + + > cat /proc/sys/s390dbf/debug_stoppable + +2. Stop debug feature:: + + > echo 0 > /proc/sys/s390dbf/debug_active + +crash Interface +---------------- +The ``crash`` tool since v5.1.0 has a built-in command +``s390dbf`` to display all the debug logs or export them to the file system. +With this tool it is possible +to investigate the debug logs on a live system and with a memory dump after +a system crash. + +Investigating raw memory +------------------------ +One last possibility to investigate the debug logs at a live +system and after a system crash is to look at the raw memory +under VM or at the Service Element. +It is possible to find the anchor of the debug-logs through +the ``debug_area_first`` symbol in the System map. Then one has +to follow the correct pointers of the data-structures defined +in debug.h and find the debug-areas in memory. +Normally modules which use the debug feature will also have +a global variable with the pointer to the debug-logs. Following +this pointer it will also be possible to find the debug logs in +memory. + +For this method it is recommended to use '16 * x + 4' byte (x = 0..n) +for the length of the data field in :c:func:`debug_register()` in +order to see the debug entries well formatted. + + +Predefined Views +---------------- + +There are two predefined views: hex_ascii and sprintf. +The hex_ascii view shows the data field in hex and ascii representation +(e.g. ``45 43 4b 44 | ECKD``). + +The sprintf view formats the debug entries in the same way as the sprintf +function would do. The sprintf event/exception functions write to the +debug entry a pointer to the format string (size = sizeof(long)) +and for each vararg a long value. So e.g. for a debug entry with a format +string plus two varargs one would need to allocate a (3 * sizeof(long)) +byte data area in the debug_register() function. + +IMPORTANT: + Using "%s" in sprintf event functions is dangerous. You can only + use "%s" in the sprintf event functions, if the memory for the passed string + is available as long as the debug feature exists. The reason behind this is + that due to performance considerations only a pointer to the string is stored + in the debug feature. If you log a string that is freed afterwards, you will + get an OOPS when inspecting the debug feature, because then the debug feature + will access the already freed memory. + +NOTE: + If using the sprintf view do NOT use other event/exception functions + than the sprintf-event and -exception functions. + +The format of the hex_ascii and sprintf view is as follows: + +- Number of area +- Timestamp (formatted as seconds and microseconds since 00:00:00 Coordinated + Universal Time (UTC), January 1, 1970) +- level of debug entry +- Exception flag (* = Exception) +- Cpu-Number of calling task +- Return Address to caller +- data field + +A typical line of the hex_ascii view will look like the following (first line +is only for explanation and will not be displayed when 'cating' the view):: + + area time level exception cpu caller data (hex + ascii) + -------------------------------------------------------------------------- + 00 00964419409:440690 1 - 00 88023fe + + +Defining views +-------------- + +Views are specified with the 'debug_view' structure. There are defined +callback functions which are used for reading and writing the debugfs files: + +.. code-block:: c + + struct debug_view { + char name[DEBUG_MAX_PROCF_LEN]; + debug_prolog_proc_t* prolog_proc; + debug_header_proc_t* header_proc; + debug_format_proc_t* format_proc; + debug_input_proc_t* input_proc; + void* private_data; + }; + +where: + +.. code-block:: c + + typedef int (debug_header_proc_t) (debug_info_t* id, + struct debug_view* view, + int area, + debug_entry_t* entry, + char* out_buf); + + typedef int (debug_format_proc_t) (debug_info_t* id, + struct debug_view* view, char* out_buf, + const char* in_buf); + typedef int (debug_prolog_proc_t) (debug_info_t* id, + struct debug_view* view, + char* out_buf); + typedef int (debug_input_proc_t) (debug_info_t* id, + struct debug_view* view, + struct file* file, const char* user_buf, + size_t in_buf_size, loff_t* offset); + + +The "private_data" member can be used as pointer to view specific data. +It is not used by the debug feature itself. + +The output when reading a debugfs file is structured like this:: + + "prolog_proc output" + + "header_proc output 1" "format_proc output 1" + "header_proc output 2" "format_proc output 2" + "header_proc output 3" "format_proc output 3" + ... + +When a view is read from the debugfs, the Debug Feature calls the +'prolog_proc' once for writing the prolog. +Then 'header_proc' and 'format_proc' are called for each +existing debug entry. + +The input_proc can be used to implement functionality when it is written to +the view (e.g. like with ``echo "0" > /sys/kernel/debug/s390dbf/dasd/level``). + +For header_proc there can be used the default function +:c:func:`debug_dflt_header_fn()` which is defined in debug.h. +and which produces the same header output as the predefined views. +E.g:: + + 00 00964419409:440761 2 - 00 88023ec + +In order to see how to use the callback functions check the implementation +of the default views! + +Example: + +.. code-block:: c + + #include <asm/debug.h> + + #define UNKNOWNSTR "data: %08x" + + const char* messages[] = + {"This error...........\n", + "That error...........\n", + "Problem..............\n", + "Something went wrong.\n", + "Everything ok........\n", + NULL + }; + + static int debug_test_format_fn( + debug_info_t *id, struct debug_view *view, + char *out_buf, const char *in_buf + ) + { + int i, rc = 0; + + if (id->buf_size >= 4) { + int msg_nr = *((int*)in_buf); + if (msg_nr < sizeof(messages) / sizeof(char*) - 1) + rc += sprintf(out_buf, "%s", messages[msg_nr]); + else + rc += sprintf(out_buf, UNKNOWNSTR, msg_nr); + } + return rc; + } + + struct debug_view debug_test_view = { + "myview", /* name of view */ + NULL, /* no prolog */ + &debug_dflt_header_fn, /* default header for each entry */ + &debug_test_format_fn, /* our own format function */ + NULL, /* no input function */ + NULL /* no private data */ + }; + +test: +===== + +.. code-block:: c + + debug_info_t *debug_info; + int i; + ... + debug_info = debug_register("test", 0, 4, 4); + debug_register_view(debug_info, &debug_test_view); + for (i = 0; i < 10; i ++) + debug_int_event(debug_info, 1, i); + +:: + + > cat /sys/kernel/debug/s390dbf/test/myview + 00 00964419734:611402 1 - 00 88042ca This error........... + 00 00964419734:611405 1 - 00 88042ca That error........... + 00 00964419734:611408 1 - 00 88042ca Problem.............. + 00 00964419734:611411 1 - 00 88042ca Something went wrong. + 00 00964419734:611414 1 - 00 88042ca Everything ok........ + 00 00964419734:611417 1 - 00 88042ca data: 00000005 + 00 00964419734:611419 1 - 00 88042ca data: 00000006 + 00 00964419734:611422 1 - 00 88042ca data: 00000007 + 00 00964419734:611425 1 - 00 88042ca data: 00000008 + 00 00964419734:611428 1 - 00 88042ca data: 00000009 diff --git a/Documentation/arch/s390/text_files.rst b/Documentation/arch/s390/text_files.rst new file mode 100644 index 0000000000..c94d05d4fa --- /dev/null +++ b/Documentation/arch/s390/text_files.rst @@ -0,0 +1,11 @@ +ibm 3270 changelog +------------------ + +.. include:: 3270.ChangeLog + :literal: + +ibm 3270 config3270.sh +---------------------- + +.. literalinclude:: config3270.sh + :language: shell diff --git a/Documentation/arch/s390/vfio-ap-locking.rst b/Documentation/arch/s390/vfio-ap-locking.rst new file mode 100644 index 0000000000..0dfcdb562e --- /dev/null +++ b/Documentation/arch/s390/vfio-ap-locking.rst @@ -0,0 +1,115 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====================== +VFIO AP Locks Overview +====================== +This document describes the locks that are pertinent to the secure operation +of the vfio_ap device driver. Throughout this document, the following variables +will be used to denote instances of the structures herein described: + +.. code-block:: c + + struct ap_matrix_dev *matrix_dev; + struct ap_matrix_mdev *matrix_mdev; + struct kvm *kvm; + +The Matrix Devices Lock (drivers/s390/crypto/vfio_ap_private.h) +--------------------------------------------------------------- + +.. code-block:: c + + struct ap_matrix_dev { + ... + struct list_head mdev_list; + struct mutex mdevs_lock; + ... + } + +The Matrix Devices Lock (matrix_dev->mdevs_lock) is implemented as a global +mutex contained within the single object of struct ap_matrix_dev. This lock +controls access to all fields contained within each matrix_mdev +(matrix_dev->mdev_list). This lock must be held while reading from, writing to +or using the data from a field contained within a matrix_mdev instance +representing one of the vfio_ap device driver's mediated devices. + +The KVM Lock (include/linux/kvm_host.h) +--------------------------------------- + +.. code-block:: c + + struct kvm { + ... + struct mutex lock; + ... + } + +The KVM Lock (kvm->lock) controls access to the state data for a KVM guest. This +lock must be held by the vfio_ap device driver while one or more AP adapters, +domains or control domains are being plugged into or unplugged from the guest. + +The KVM pointer is stored in the in the matrix_mdev instance +(matrix_mdev->kvm = kvm) containing the state of the mediated device that has +been attached to the KVM guest. + +The Guests Lock (drivers/s390/crypto/vfio_ap_private.h) +----------------------------------------------------------- + +.. code-block:: c + + struct ap_matrix_dev { + ... + struct list_head mdev_list; + struct mutex guests_lock; + ... + } + +The Guests Lock (matrix_dev->guests_lock) controls access to the +matrix_mdev instances (matrix_dev->mdev_list) that represent mediated devices +that hold the state for the mediated devices that have been attached to a +KVM guest. This lock must be held: + +1. To control access to the KVM pointer (matrix_mdev->kvm) while the vfio_ap + device driver is using it to plug/unplug AP devices passed through to the KVM + guest. + +2. To add matrix_mdev instances to or remove them from matrix_dev->mdev_list. + This is necessary to ensure the proper locking order when the list is perused + to find an ap_matrix_mdev instance for the purpose of plugging/unplugging + AP devices passed through to a KVM guest. + + For example, when a queue device is removed from the vfio_ap device driver, + if the adapter is passed through to a KVM guest, it will have to be + unplugged. In order to figure out whether the adapter is passed through, + the matrix_mdev object to which the queue is assigned will have to be + found. The KVM pointer (matrix_mdev->kvm) can then be used to determine if + the mediated device is passed through (matrix_mdev->kvm != NULL) and if so, + to unplug the adapter. + +It is not necessary to take the Guests Lock to access the KVM pointer if the +pointer is not used to plug/unplug devices passed through to the KVM guest; +however, in this case, the Matrix Devices Lock (matrix_dev->mdevs_lock) must be +held in order to access the KVM pointer since it is set and cleared under the +protection of the Matrix Devices Lock. A case in point is the function that +handles interception of the PQAP(AQIC) instruction sub-function. This handler +needs to access the KVM pointer only for the purposes of setting or clearing IRQ +resources, so only the matrix_dev->mdevs_lock needs to be held. + +The PQAP Hook Lock (arch/s390/include/asm/kvm_host.h) +----------------------------------------------------- + +.. code-block:: c + + typedef int (*crypto_hook)(struct kvm_vcpu *vcpu); + + struct kvm_s390_crypto { + ... + struct rw_semaphore pqap_hook_rwsem; + crypto_hook *pqap_hook; + ... + }; + +The PQAP Hook Lock is a r/w semaphore that controls access to the function +pointer of the handler ``(*kvm->arch.crypto.pqap_hook)`` to invoke when the +PQAP(AQIC) instruction sub-function is intercepted by the host. The lock must be +held in write mode when pqap_hook value is set, and in read mode when the +pqap_hook function is called. diff --git a/Documentation/arch/s390/vfio-ap.rst b/Documentation/arch/s390/vfio-ap.rst new file mode 100644 index 0000000000..929ee1c1c9 --- /dev/null +++ b/Documentation/arch/s390/vfio-ap.rst @@ -0,0 +1,1069 @@ +=============================== +Adjunct Processor (AP) facility +=============================== + + +Introduction +============ +The Adjunct Processor (AP) facility is an IBM Z cryptographic facility comprised +of three AP instructions and from 1 up to 256 PCIe cryptographic adapter cards. +The AP devices provide cryptographic functions to all CPUs assigned to a +linux system running in an IBM Z system LPAR. + +The AP adapter cards are exposed via the AP bus. The motivation for vfio-ap +is to make AP cards available to KVM guests using the VFIO mediated device +framework. This implementation relies considerably on the s390 virtualization +facilities which do most of the hard work of providing direct access to AP +devices. + +AP Architectural Overview +========================= +To facilitate the comprehension of the design, let's start with some +definitions: + +* AP adapter + + An AP adapter is an IBM Z adapter card that can perform cryptographic + functions. There can be from 0 to 256 adapters assigned to an LPAR. Adapters + assigned to the LPAR in which a linux host is running will be available to + the linux host. Each adapter is identified by a number from 0 to 255; however, + the maximum adapter number is determined by machine model and/or adapter type. + When installed, an AP adapter is accessed by AP instructions executed by any + CPU. + + The AP adapter cards are assigned to a given LPAR via the system's Activation + Profile which can be edited via the HMC. When the linux host system is IPL'd + in the LPAR, the AP bus detects the AP adapter cards assigned to the LPAR and + creates a sysfs device for each assigned adapter. For example, if AP adapters + 4 and 10 (0x0a) are assigned to the LPAR, the AP bus will create the following + sysfs device entries:: + + /sys/devices/ap/card04 + /sys/devices/ap/card0a + + Symbolic links to these devices will also be created in the AP bus devices + sub-directory:: + + /sys/bus/ap/devices/[card04] + /sys/bus/ap/devices/[card04] + +* AP domain + + An adapter is partitioned into domains. An adapter can hold up to 256 domains + depending upon the adapter type and hardware configuration. A domain is + identified by a number from 0 to 255; however, the maximum domain number is + determined by machine model and/or adapter type.. A domain can be thought of + as a set of hardware registers and memory used for processing AP commands. A + domain can be configured with a secure private key used for clear key + encryption. A domain is classified in one of two ways depending upon how it + may be accessed: + + * Usage domains are domains that are targeted by an AP instruction to + process an AP command. + + * Control domains are domains that are changed by an AP command sent to a + usage domain; for example, to set the secure private key for the control + domain. + + The AP usage and control domains are assigned to a given LPAR via the system's + Activation Profile which can be edited via the HMC. When a linux host system + is IPL'd in the LPAR, the AP bus module detects the AP usage and control + domains assigned to the LPAR. The domain number of each usage domain and + adapter number of each AP adapter are combined to create AP queue devices + (see AP Queue section below). The domain number of each control domain will be + represented in a bitmask and stored in a sysfs file + /sys/bus/ap/ap_control_domain_mask. The bits in the mask, from most to least + significant bit, correspond to domains 0-255. + +* AP Queue + + An AP queue is the means by which an AP command is sent to a usage domain + inside a specific adapter. An AP queue is identified by a tuple + comprised of an AP adapter ID (APID) and an AP queue index (APQI). The + APQI corresponds to a given usage domain number within the adapter. This tuple + forms an AP Queue Number (APQN) uniquely identifying an AP queue. AP + instructions include a field containing the APQN to identify the AP queue to + which the AP command is to be sent for processing. + + The AP bus will create a sysfs device for each APQN that can be derived from + the cross product of the AP adapter and usage domain numbers detected when the + AP bus module is loaded. For example, if adapters 4 and 10 (0x0a) and usage + domains 6 and 71 (0x47) are assigned to the LPAR, the AP bus will create the + following sysfs entries:: + + /sys/devices/ap/card04/04.0006 + /sys/devices/ap/card04/04.0047 + /sys/devices/ap/card0a/0a.0006 + /sys/devices/ap/card0a/0a.0047 + + The following symbolic links to these devices will be created in the AP bus + devices subdirectory:: + + /sys/bus/ap/devices/[04.0006] + /sys/bus/ap/devices/[04.0047] + /sys/bus/ap/devices/[0a.0006] + /sys/bus/ap/devices/[0a.0047] + +* AP Instructions: + + There are three AP instructions: + + * NQAP: to enqueue an AP command-request message to a queue + * DQAP: to dequeue an AP command-reply message from a queue + * PQAP: to administer the queues + + AP instructions identify the domain that is targeted to process the AP + command; this must be one of the usage domains. An AP command may modify a + domain that is not one of the usage domains, but the modified domain + must be one of the control domains. + +AP and SIE +========== +Let's now take a look at how AP instructions executed on a guest are interpreted +by the hardware. + +A satellite control block called the Crypto Control Block (CRYCB) is attached to +our main hardware virtualization control block. The CRYCB contains an AP Control +Block (APCB) that has three fields to identify the adapters, usage domains and +control domains assigned to the KVM guest: + +* The AP Mask (APM) field is a bit mask that identifies the AP adapters assigned + to the KVM guest. Each bit in the mask, from left to right, corresponds to + an APID from 0-255. If a bit is set, the corresponding adapter is valid for + use by the KVM guest. + +* The AP Queue Mask (AQM) field is a bit mask identifying the AP usage domains + assigned to the KVM guest. Each bit in the mask, from left to right, + corresponds to an AP queue index (APQI) from 0-255. If a bit is set, the + corresponding queue is valid for use by the KVM guest. + +* The AP Domain Mask field is a bit mask that identifies the AP control domains + assigned to the KVM guest. The ADM bit mask controls which domains can be + changed by an AP command-request message sent to a usage domain from the + guest. Each bit in the mask, from left to right, corresponds to a domain from + 0-255. If a bit is set, the corresponding domain can be modified by an AP + command-request message sent to a usage domain. + +If you recall from the description of an AP Queue, AP instructions include +an APQN to identify the AP queue to which an AP command-request message is to be +sent (NQAP and PQAP instructions), or from which a command-reply message is to +be received (DQAP instruction). The validity of an APQN is defined by the matrix +calculated from the APM and AQM; it is the Cartesian product of all assigned +adapter numbers (APM) with all assigned queue indexes (AQM). For example, if +adapters 1 and 2 and usage domains 5 and 6 are assigned to a guest, the APQNs +(1,5), (1,6), (2,5) and (2,6) will be valid for the guest. + +The APQNs can provide secure key functionality - i.e., a private key is stored +on the adapter card for each of its domains - so each APQN must be assigned to +at most one guest or to the linux host:: + + Example 1: Valid configuration: + ------------------------------ + Guest1: adapters 1,2 domains 5,6 + Guest2: adapter 1,2 domain 7 + + This is valid because both guests have a unique set of APQNs: + Guest1 has APQNs (1,5), (1,6), (2,5), (2,6); + Guest2 has APQNs (1,7), (2,7) + + Example 2: Valid configuration: + ------------------------------ + Guest1: adapters 1,2 domains 5,6 + Guest2: adapters 3,4 domains 5,6 + + This is also valid because both guests have a unique set of APQNs: + Guest1 has APQNs (1,5), (1,6), (2,5), (2,6); + Guest2 has APQNs (3,5), (3,6), (4,5), (4,6) + + Example 3: Invalid configuration: + -------------------------------- + Guest1: adapters 1,2 domains 5,6 + Guest2: adapter 1 domains 6,7 + + This is an invalid configuration because both guests have access to + APQN (1,6). + +The Design +========== +The design introduces three new objects: + +1. AP matrix device +2. VFIO AP device driver (vfio_ap.ko) +3. VFIO AP mediated pass-through device + +The VFIO AP device driver +------------------------- +The VFIO AP (vfio_ap) device driver serves the following purposes: + +1. Provides the interfaces to secure APQNs for exclusive use of KVM guests. + +2. Sets up the VFIO mediated device interfaces to manage a vfio_ap mediated + device and creates the sysfs interfaces for assigning adapters, usage + domains, and control domains comprising the matrix for a KVM guest. + +3. Configures the APM, AQM and ADM in the APCB contained in the CRYCB referenced + by a KVM guest's SIE state description to grant the guest access to a matrix + of AP devices + +Reserve APQNs for exclusive use of KVM guests +--------------------------------------------- +The following block diagram illustrates the mechanism by which APQNs are +reserved:: + + +------------------+ + 7 remove | | + +--------------------> cex4queue driver | + | | | + | +------------------+ + | + | + | +------------------+ +----------------+ + | 5 register driver | | 3 create | | + | +----------------> Device core +----------> matrix device | + | | | | | | + | | +--------^---------+ +----------------+ + | | | + | | +-------------------+ + | | +-----------------------------------+ | + | | | 4 register AP driver | | 2 register device + | | | | | + +--------+---+-v---+ +--------+-------+-+ + | | | | + | ap_bus +--------------------- > vfio_ap driver | + | | 8 probe | | + +--------^---------+ +--^--^------------+ + 6 edit | | | + apmask | +-----------------------------+ | 11 mdev create + aqmask | | 1 modprobe | + +--------+-----+---+ +----------------+-+ +----------------+ + | | | |10 create| mediated | + | admin | | VFIO device core |---------> matrix | + | + | | | device | + +------+-+---------+ +--------^---------+ +--------^-------+ + | | | | + | | 9 create vfio_ap-passthrough | | + | +------------------------------+ | + +-------------------------------------------------------------+ + 12 assign adapter/domain/control domain + +The process for reserving an AP queue for use by a KVM guest is: + +1. The administrator loads the vfio_ap device driver +2. The vfio-ap driver during its initialization will register a single 'matrix' + device with the device core. This will serve as the parent device for + all vfio_ap mediated devices used to configure an AP matrix for a guest. +3. The /sys/devices/vfio_ap/matrix device is created by the device core +4. The vfio_ap device driver will register with the AP bus for AP queue devices + of type 10 and higher (CEX4 and newer). The driver will provide the vfio_ap + driver's probe and remove callback interfaces. Devices older than CEX4 queues + are not supported to simplify the implementation by not needlessly + complicating the design by supporting older devices that will go out of + service in the relatively near future, and for which there are few older + systems around on which to test. +5. The AP bus registers the vfio_ap device driver with the device core +6. The administrator edits the AP adapter and queue masks to reserve AP queues + for use by the vfio_ap device driver. +7. The AP bus removes the AP queues reserved for the vfio_ap driver from the + default zcrypt cex4queue driver. +8. The AP bus probes the vfio_ap device driver to bind the queues reserved for + it. +9. The administrator creates a passthrough type vfio_ap mediated device to be + used by a guest +10. The administrator assigns the adapters, usage domains and control domains + to be exclusively used by a guest. + +Set up the VFIO mediated device interfaces +------------------------------------------ +The VFIO AP device driver utilizes the common interfaces of the VFIO mediated +device core driver to: + +* Register an AP mediated bus driver to add a vfio_ap mediated device to and + remove it from a VFIO group. +* Create and destroy a vfio_ap mediated device +* Add a vfio_ap mediated device to and remove it from the AP mediated bus driver +* Add a vfio_ap mediated device to and remove it from an IOMMU group + +The following high-level block diagram shows the main components and interfaces +of the VFIO AP mediated device driver:: + + +-------------+ + | | + | +---------+ | mdev_register_driver() +--------------+ + | | Mdev | +<-----------------------+ | + | | bus | | | vfio_mdev.ko | + | | driver | +----------------------->+ |<-> VFIO user + | +---------+ | probe()/remove() +--------------+ APIs + | | + | MDEV CORE | + | MODULE | + | mdev.ko | + | +---------+ | mdev_register_parent() +--------------+ + | |Physical | +<-----------------------+ | + | | device | | | vfio_ap.ko |<-> matrix + | |interface| +----------------------->+ | device + | +---------+ | callback +--------------+ + +-------------+ + +During initialization of the vfio_ap module, the matrix device is registered +with an 'mdev_parent_ops' structure that provides the sysfs attribute +structures, mdev functions and callback interfaces for managing the mediated +matrix device. + +* sysfs attribute structures: + + supported_type_groups + The VFIO mediated device framework supports creation of user-defined + mediated device types. These mediated device types are specified + via the 'supported_type_groups' structure when a device is registered + with the mediated device framework. The registration process creates the + sysfs structures for each mediated device type specified in the + 'mdev_supported_types' sub-directory of the device being registered. Along + with the device type, the sysfs attributes of the mediated device type are + provided. + + The VFIO AP device driver will register one mediated device type for + passthrough devices: + + /sys/devices/vfio_ap/matrix/mdev_supported_types/vfio_ap-passthrough + + Only the read-only attributes required by the VFIO mdev framework will + be provided:: + + ... name + ... device_api + ... available_instances + ... device_api + + Where: + + * name: + specifies the name of the mediated device type + * device_api: + the mediated device type's API + * available_instances: + the number of vfio_ap mediated passthrough devices + that can be created + * device_api: + specifies the VFIO API + mdev_attr_groups + This attribute group identifies the user-defined sysfs attributes of the + mediated device. When a device is registered with the VFIO mediated device + framework, the sysfs attribute files identified in the 'mdev_attr_groups' + structure will be created in the vfio_ap mediated device's directory. The + sysfs attributes for a vfio_ap mediated device are: + + assign_adapter / unassign_adapter: + Write-only attributes for assigning/unassigning an AP adapter to/from the + vfio_ap mediated device. To assign/unassign an adapter, the APID of the + adapter is echoed into the respective attribute file. + assign_domain / unassign_domain: + Write-only attributes for assigning/unassigning an AP usage domain to/from + the vfio_ap mediated device. To assign/unassign a domain, the domain + number of the usage domain is echoed into the respective attribute + file. + matrix: + A read-only file for displaying the APQNs derived from the Cartesian + product of the adapter and domain numbers assigned to the vfio_ap mediated + device. + guest_matrix: + A read-only file for displaying the APQNs derived from the Cartesian + product of the adapter and domain numbers assigned to the APM and AQM + fields respectively of the KVM guest's CRYCB. This may differ from the + the APQNs assigned to the vfio_ap mediated device if any APQN does not + reference a queue device bound to the vfio_ap device driver (i.e., the + queue is not in the host's AP configuration). + assign_control_domain / unassign_control_domain: + Write-only attributes for assigning/unassigning an AP control domain + to/from the vfio_ap mediated device. To assign/unassign a control domain, + the ID of the domain to be assigned/unassigned is echoed into the + respective attribute file. + control_domains: + A read-only file for displaying the control domain numbers assigned to the + vfio_ap mediated device. + +* functions: + + create: + allocates the ap_matrix_mdev structure used by the vfio_ap driver to: + + * Store the reference to the KVM structure for the guest using the mdev + * Store the AP matrix configuration for the adapters, domains, and control + domains assigned via the corresponding sysfs attributes files + * Store the AP matrix configuration for the adapters, domains and control + domains available to a guest. A guest may not be provided access to APQNs + referencing queue devices that do not exist, or are not bound to the + vfio_ap device driver. + + remove: + deallocates the vfio_ap mediated device's ap_matrix_mdev structure. + This will be allowed only if a running guest is not using the mdev. + +* callback interfaces + + open_device: + The vfio_ap driver uses this callback to register a + VFIO_GROUP_NOTIFY_SET_KVM notifier callback function for the matrix mdev + devices. The open_device callback is invoked by userspace to connect the + VFIO iommu group for the matrix mdev device to the MDEV bus. Access to the + KVM structure used to configure the KVM guest is provided via this callback. + The KVM structure, is used to configure the guest's access to the AP matrix + defined via the vfio_ap mediated device's sysfs attribute files. + + close_device: + unregisters the VFIO_GROUP_NOTIFY_SET_KVM notifier callback function for the + matrix mdev device and deconfigures the guest's AP matrix. + + ioctl: + this callback handles the VFIO_DEVICE_GET_INFO and VFIO_DEVICE_RESET ioctls + defined by the vfio framework. + +Configure the guest's AP resources +---------------------------------- +Configuring the AP resources for a KVM guest will be performed when the +VFIO_GROUP_NOTIFY_SET_KVM notifier callback is invoked. The notifier +function is called when userspace connects to KVM. The guest's AP resources are +configured via its APCB by: + +* Setting the bits in the APM corresponding to the APIDs assigned to the + vfio_ap mediated device via its 'assign_adapter' interface. +* Setting the bits in the AQM corresponding to the domains assigned to the + vfio_ap mediated device via its 'assign_domain' interface. +* Setting the bits in the ADM corresponding to the domain dIDs assigned to the + vfio_ap mediated device via its 'assign_control_domains' interface. + +The linux device model precludes passing a device through to a KVM guest that +is not bound to the device driver facilitating its pass-through. Consequently, +an APQN that does not reference a queue device bound to the vfio_ap device +driver will not be assigned to a KVM guest's matrix. The AP architecture, +however, does not provide a means to filter individual APQNs from the guest's +matrix, so the adapters, domains and control domains assigned to vfio_ap +mediated device via its sysfs 'assign_adapter', 'assign_domain' and +'assign_control_domain' interfaces will be filtered before providing the AP +configuration to a guest: + +* The APIDs of the adapters, the APQIs of the domains and the domain numbers of + the control domains assigned to the matrix mdev that are not also assigned to + the host's AP configuration will be filtered. + +* Each APQN derived from the Cartesian product of the APIDs and APQIs assigned + to the vfio_ap mdev is examined and if any one of them does not reference a + queue device bound to the vfio_ap device driver, the adapter will not be + plugged into the guest (i.e., the bit corresponding to its APID will not be + set in the APM of the guest's APCB). + +The CPU model features for AP +----------------------------- +The AP stack relies on the presence of the AP instructions as well as three +facilities: The AP Facilities Test (APFT) facility; the AP Query +Configuration Information (QCI) facility; and the AP Queue Interruption Control +facility. These features/facilities are made available to a KVM guest via the +following CPU model features: + +1. ap: Indicates whether the AP instructions are installed on the guest. This + feature will be enabled by KVM only if the AP instructions are installed + on the host. + +2. apft: Indicates the APFT facility is available on the guest. This facility + can be made available to the guest only if it is available on the host (i.e., + facility bit 15 is set). + +3. apqci: Indicates the AP QCI facility is available on the guest. This facility + can be made available to the guest only if it is available on the host (i.e., + facility bit 12 is set). + +4. apqi: Indicates AP Queue Interruption Control faclity is available on the + guest. This facility can be made available to the guest only if it is + available on the host (i.e., facility bit 65 is set). + +Note: If the user chooses to specify a CPU model different than the 'host' +model to QEMU, the CPU model features and facilities need to be turned on +explicitly; for example:: + + /usr/bin/qemu-system-s390x ... -cpu z13,ap=on,apqci=on,apft=on,apqi=on + +A guest can be precluded from using AP features/facilities by turning them off +explicitly; for example:: + + /usr/bin/qemu-system-s390x ... -cpu host,ap=off,apqci=off,apft=off,apqi=off + +Note: If the APFT facility is turned off (apft=off) for the guest, the guest +will not see any AP devices. The zcrypt device drivers on the guest that +register for type 10 and newer AP devices - i.e., the cex4card and cex4queue +device drivers - need the APFT facility to ascertain the facilities installed on +a given AP device. If the APFT facility is not installed on the guest, then no +adapter or domain devices will get created by the AP bus running on the +guest because only type 10 and newer devices can be configured for guest use. + +Example +======= +Let's now provide an example to illustrate how KVM guests may be given +access to AP facilities. For this example, we will show how to configure +three guests such that executing the lszcrypt command on the guests would +look like this: + +Guest1 +------ +=========== ===== ============ +CARD.DOMAIN TYPE MODE +=========== ===== ============ +05 CEX5C CCA-Coproc +05.0004 CEX5C CCA-Coproc +05.00ab CEX5C CCA-Coproc +06 CEX5A Accelerator +06.0004 CEX5A Accelerator +06.00ab CEX5A Accelerator +=========== ===== ============ + +Guest2 +------ +=========== ===== ============ +CARD.DOMAIN TYPE MODE +=========== ===== ============ +05 CEX5C CCA-Coproc +05.0047 CEX5C CCA-Coproc +05.00ff CEX5C CCA-Coproc +=========== ===== ============ + +Guest3 +------ +=========== ===== ============ +CARD.DOMAIN TYPE MODE +=========== ===== ============ +06 CEX5A Accelerator +06.0047 CEX5A Accelerator +06.00ff CEX5A Accelerator +=========== ===== ============ + +These are the steps: + +1. Install the vfio_ap module on the linux host. The dependency chain for the + vfio_ap module is: + * iommu + * s390 + * zcrypt + * vfio + * vfio_mdev + * vfio_mdev_device + * KVM + + To build the vfio_ap module, the kernel build must be configured with the + following Kconfig elements selected: + * IOMMU_SUPPORT + * S390 + * ZCRYPT + * VFIO + * KVM + + If using make menuconfig select the following to build the vfio_ap module:: + + -> Device Drivers + -> IOMMU Hardware Support + select S390 AP IOMMU Support + -> VFIO Non-Privileged userspace driver framework + -> Mediated device driver frramework + -> VFIO driver for Mediated devices + -> I/O subsystem + -> VFIO support for AP devices + +2. Secure the AP queues to be used by the three guests so that the host can not + access them. To secure them, there are two sysfs files that specify + bitmasks marking a subset of the APQN range as usable only by the default AP + queue device drivers. All remaining APQNs are available for use by + any other device driver. The vfio_ap device driver is currently the only + non-default device driver. The location of the sysfs files containing the + masks are:: + + /sys/bus/ap/apmask + /sys/bus/ap/aqmask + + The 'apmask' is a 256-bit mask that identifies a set of AP adapter IDs + (APID). Each bit in the mask, from left to right, corresponds to an APID from + 0-255. If a bit is set, the APID belongs to the subset of APQNs marked as + available only to the default AP queue device drivers. + + The 'aqmask' is a 256-bit mask that identifies a set of AP queue indexes + (APQI). Each bit in the mask, from left to right, corresponds to an APQI from + 0-255. If a bit is set, the APQI belongs to the subset of APQNs marked as + available only to the default AP queue device drivers. + + The Cartesian product of the APIDs corresponding to the bits set in the + apmask and the APQIs corresponding to the bits set in the aqmask comprise + the subset of APQNs that can be used only by the host default device drivers. + All other APQNs are available to the non-default device drivers such as the + vfio_ap driver. + + Take, for example, the following masks:: + + apmask: + 0x7d00000000000000000000000000000000000000000000000000000000000000 + + aqmask: + 0x8000000000000000000000000000000000000000000000000000000000000000 + + The masks indicate: + + * Adapters 1, 2, 3, 4, 5, and 7 are available for use by the host default + device drivers. + + * Domain 0 is available for use by the host default device drivers + + * The subset of APQNs available for use only by the default host device + drivers are: + + (1,0), (2,0), (3,0), (4.0), (5,0) and (7,0) + + * All other APQNs are available for use by the non-default device drivers. + + The APQN of each AP queue device assigned to the linux host is checked by the + AP bus against the set of APQNs derived from the Cartesian product of APIDs + and APQIs marked as available to the default AP queue device drivers. If a + match is detected, only the default AP queue device drivers will be probed; + otherwise, the vfio_ap device driver will be probed. + + By default, the two masks are set to reserve all APQNs for use by the default + AP queue device drivers. There are two ways the default masks can be changed: + + 1. The sysfs mask files can be edited by echoing a string into the + respective sysfs mask file in one of two formats: + + * An absolute hex string starting with 0x - like "0x12345678" - sets + the mask. If the given string is shorter than the mask, it is padded + with 0s on the right; for example, specifying a mask value of 0x41 is + the same as specifying:: + + 0x4100000000000000000000000000000000000000000000000000000000000000 + + Keep in mind that the mask reads from left to right, so the mask + above identifies device numbers 1 and 7 (01000001). + + If the string is longer than the mask, the operation is terminated with + an error (EINVAL). + + * Individual bits in the mask can be switched on and off by specifying + each bit number to be switched in a comma separated list. Each bit + number string must be prepended with a ('+') or minus ('-') to indicate + the corresponding bit is to be switched on ('+') or off ('-'). Some + valid values are: + + - "+0" switches bit 0 on + - "-13" switches bit 13 off + - "+0x41" switches bit 65 on + - "-0xff" switches bit 255 off + + The following example: + + +0,-6,+0x47,-0xf0 + + Switches bits 0 and 71 (0x47) on + + Switches bits 6 and 240 (0xf0) off + + Note that the bits not specified in the list remain as they were before + the operation. + + 2. The masks can also be changed at boot time via parameters on the kernel + command line like this: + + ap.apmask=0xffff ap.aqmask=0x40 + + This would create the following masks:: + + apmask: + 0xffff000000000000000000000000000000000000000000000000000000000000 + + aqmask: + 0x4000000000000000000000000000000000000000000000000000000000000000 + + Resulting in these two pools:: + + default drivers pool: adapter 0-15, domain 1 + alternate drivers pool: adapter 16-255, domains 0, 2-255 + + **Note:** + Changing a mask such that one or more APQNs will be taken from a vfio_ap + mediated device (see below) will fail with an error (EBUSY). A message + is logged to the kernel ring buffer which can be viewed with the 'dmesg' + command. The output identifies each APQN flagged as 'in use' and identifies + the vfio_ap mediated device to which it is assigned; for example: + + Userspace may not re-assign queue 05.0054 already assigned to 62177883-f1bb-47f0-914d-32a22e3a8804 + Userspace may not re-assign queue 04.0054 already assigned to cef03c3c-903d-4ecc-9a83-40694cb8aee4 + +Securing the APQNs for our example +---------------------------------- + To secure the AP queues 05.0004, 05.0047, 05.00ab, 05.00ff, 06.0004, 06.0047, + 06.00ab, and 06.00ff for use by the vfio_ap device driver, the corresponding + APQNs can be removed from the default masks using either of the following + commands:: + + echo -5,-6 > /sys/bus/ap/apmask + + echo -4,-0x47,-0xab,-0xff > /sys/bus/ap/aqmask + + Or the masks can be set as follows:: + + echo 0xf9ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff \ + > apmask + + echo 0xf7fffffffffffffffeffffffffffffffffffffffffeffffffffffffffffffffe \ + > aqmask + + This will result in AP queues 05.0004, 05.0047, 05.00ab, 05.00ff, 06.0004, + 06.0047, 06.00ab, and 06.00ff getting bound to the vfio_ap device driver. The + sysfs directory for the vfio_ap device driver will now contain symbolic links + to the AP queue devices bound to it:: + + /sys/bus/ap + ... [drivers] + ...... [vfio_ap] + ......... [05.0004] + ......... [05.0047] + ......... [05.00ab] + ......... [05.00ff] + ......... [06.0004] + ......... [06.0047] + ......... [06.00ab] + ......... [06.00ff] + + Keep in mind that only type 10 and newer adapters (i.e., CEX4 and later) + can be bound to the vfio_ap device driver. The reason for this is to + simplify the implementation by not needlessly complicating the design by + supporting older devices that will go out of service in the relatively near + future and for which there are few older systems on which to test. + + The administrator, therefore, must take care to secure only AP queues that + can be bound to the vfio_ap device driver. The device type for a given AP + queue device can be read from the parent card's sysfs directory. For example, + to see the hardware type of the queue 05.0004: + + cat /sys/bus/ap/devices/card05/hwtype + + The hwtype must be 10 or higher (CEX4 or newer) in order to be bound to the + vfio_ap device driver. + +3. Create the mediated devices needed to configure the AP matrixes for the + three guests and to provide an interface to the vfio_ap driver for + use by the guests:: + + /sys/devices/vfio_ap/matrix/ + --- [mdev_supported_types] + ------ [vfio_ap-passthrough] (passthrough vfio_ap mediated device type) + --------- create + --------- [devices] + + To create the mediated devices for the three guests:: + + uuidgen > create + uuidgen > create + uuidgen > create + + or + + echo $uuid1 > create + echo $uuid2 > create + echo $uuid3 > create + + This will create three mediated devices in the [devices] subdirectory named + after the UUID written to the create attribute file. We call them $uuid1, + $uuid2 and $uuid3 and this is the sysfs directory structure after creation:: + + /sys/devices/vfio_ap/matrix/ + --- [mdev_supported_types] + ------ [vfio_ap-passthrough] + --------- [devices] + ------------ [$uuid1] + --------------- assign_adapter + --------------- assign_control_domain + --------------- assign_domain + --------------- matrix + --------------- unassign_adapter + --------------- unassign_control_domain + --------------- unassign_domain + + ------------ [$uuid2] + --------------- assign_adapter + --------------- assign_control_domain + --------------- assign_domain + --------------- matrix + --------------- unassign_adapter + ----------------unassign_control_domain + ----------------unassign_domain + + ------------ [$uuid3] + --------------- assign_adapter + --------------- assign_control_domain + --------------- assign_domain + --------------- matrix + --------------- unassign_adapter + ----------------unassign_control_domain + ----------------unassign_domain + + Note *****: The vfio_ap mdevs do not persist across reboots unless the + mdevctl tool is used to create and persist them. + +4. The administrator now needs to configure the matrixes for the mediated + devices $uuid1 (for Guest1), $uuid2 (for Guest2) and $uuid3 (for Guest3). + + This is how the matrix is configured for Guest1:: + + echo 5 > assign_adapter + echo 6 > assign_adapter + echo 4 > assign_domain + echo 0xab > assign_domain + + Control domains can similarly be assigned using the assign_control_domain + sysfs file. + + If a mistake is made configuring an adapter, domain or control domain, + you can use the unassign_xxx files to unassign the adapter, domain or + control domain. + + To display the matrix configuration for Guest1:: + + cat matrix + + To display the matrix that is or will be assigned to Guest1:: + + cat guest_matrix + + This is how the matrix is configured for Guest2:: + + echo 5 > assign_adapter + echo 0x47 > assign_domain + echo 0xff > assign_domain + + This is how the matrix is configured for Guest3:: + + echo 6 > assign_adapter + echo 0x47 > assign_domain + echo 0xff > assign_domain + + In order to successfully assign an adapter: + + * The adapter number specified must represent a value from 0 up to the + maximum adapter number configured for the system. If an adapter number + higher than the maximum is specified, the operation will terminate with + an error (ENODEV). + + Note: The maximum adapter number can be obtained via the sysfs + /sys/bus/ap/ap_max_adapter_id attribute file. + + * Each APQN derived from the Cartesian product of the APID of the adapter + being assigned and the APQIs of the domains previously assigned: + + - Must only be available to the vfio_ap device driver as specified in the + sysfs /sys/bus/ap/apmask and /sys/bus/ap/aqmask attribute files. If even + one APQN is reserved for use by the host device driver, the operation + will terminate with an error (EADDRNOTAVAIL). + + - Must NOT be assigned to another vfio_ap mediated device. If even one APQN + is assigned to another vfio_ap mediated device, the operation will + terminate with an error (EBUSY). + + - Must NOT be assigned while the sysfs /sys/bus/ap/apmask and + sys/bus/ap/aqmask attribute files are being edited or the operation may + terminate with an error (EBUSY). + + In order to successfully assign a domain: + + * The domain number specified must represent a value from 0 up to the + maximum domain number configured for the system. If a domain number + higher than the maximum is specified, the operation will terminate with + an error (ENODEV). + + Note: The maximum domain number can be obtained via the sysfs + /sys/bus/ap/ap_max_domain_id attribute file. + + * Each APQN derived from the Cartesian product of the APQI of the domain + being assigned and the APIDs of the adapters previously assigned: + + - Must only be available to the vfio_ap device driver as specified in the + sysfs /sys/bus/ap/apmask and /sys/bus/ap/aqmask attribute files. If even + one APQN is reserved for use by the host device driver, the operation + will terminate with an error (EADDRNOTAVAIL). + + - Must NOT be assigned to another vfio_ap mediated device. If even one APQN + is assigned to another vfio_ap mediated device, the operation will + terminate with an error (EBUSY). + + - Must NOT be assigned while the sysfs /sys/bus/ap/apmask and + sys/bus/ap/aqmask attribute files are being edited or the operation may + terminate with an error (EBUSY). + + In order to successfully assign a control domain: + + * The domain number specified must represent a value from 0 up to the maximum + domain number configured for the system. If a control domain number higher + than the maximum is specified, the operation will terminate with an + error (ENODEV). + +5. Start Guest1:: + + /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on,apqi=on \ + -device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid1 ... + +7. Start Guest2:: + + /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on,apqi=on \ + -device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid2 ... + +7. Start Guest3:: + + /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on,apqi=on \ + -device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid3 ... + +When the guest is shut down, the vfio_ap mediated devices may be removed. + +Using our example again, to remove the vfio_ap mediated device $uuid1:: + + /sys/devices/vfio_ap/matrix/ + --- [mdev_supported_types] + ------ [vfio_ap-passthrough] + --------- [devices] + ------------ [$uuid1] + --------------- remove + +:: + + echo 1 > remove + +This will remove all of the matrix mdev device's sysfs structures including +the mdev device itself. To recreate and reconfigure the matrix mdev device, +all of the steps starting with step 3 will have to be performed again. Note +that the remove will fail if a guest using the vfio_ap mdev is still running. + +It is not necessary to remove a vfio_ap mdev, but one may want to +remove it if no guest will use it during the remaining lifetime of the linux +host. If the vfio_ap mdev is removed, one may want to also reconfigure +the pool of adapters and queues reserved for use by the default drivers. + +Hot plug/unplug support: +======================== +An adapter, domain or control domain may be hot plugged into a running KVM +guest by assigning it to the vfio_ap mediated device being used by the guest if +the following conditions are met: + +* The adapter, domain or control domain must also be assigned to the host's + AP configuration. + +* Each APQN derived from the Cartesian product comprised of the APID of the + adapter being assigned and the APQIs of the domains assigned must reference a + queue device bound to the vfio_ap device driver. + +* To hot plug a domain, each APQN derived from the Cartesian product + comprised of the APQI of the domain being assigned and the APIDs of the + adapters assigned must reference a queue device bound to the vfio_ap device + driver. + +An adapter, domain or control domain may be hot unplugged from a running KVM +guest by unassigning it from the vfio_ap mediated device being used by the +guest. + +Over-provisioning of AP queues for a KVM guest: +=============================================== +Over-provisioning is defined herein as the assignment of adapters or domains to +a vfio_ap mediated device that do not reference AP devices in the host's AP +configuration. The idea here is that when the adapter or domain becomes +available, it will be automatically hot-plugged into the KVM guest using +the vfio_ap mediated device to which it is assigned as long as each new APQN +resulting from plugging it in references a queue device bound to the vfio_ap +device driver. + +Limitations +=========== +Live guest migration is not supported for guests using AP devices without +intervention by a system administrator. Before a KVM guest can be migrated, +the vfio_ap mediated device must be removed. Unfortunately, it can not be +removed manually (i.e., echo 1 > /sys/devices/vfio_ap/matrix/$UUID/remove) while +the mdev is in use by a KVM guest. If the guest is being emulated by QEMU, +its mdev can be hot unplugged from the guest in one of two ways: + +1. If the KVM guest was started with libvirt, you can hot unplug the mdev via + the following commands: + + virsh detach-device <guestname> <path-to-device-xml> + + For example, to hot unplug mdev 62177883-f1bb-47f0-914d-32a22e3a8804 from + the guest named 'my-guest': + + virsh detach-device my-guest ~/config/my-guest-hostdev.xml + + The contents of my-guest-hostdev.xml: + +.. code-block:: xml + + <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-ap'> + <source> + <address uuid='62177883-f1bb-47f0-914d-32a22e3a8804'/> + </source> + </hostdev> + + + virsh qemu-monitor-command <guest-name> --hmp "device-del <device-id>" + + For example, to hot unplug the vfio_ap mediated device identified on the + qemu command line with 'id=hostdev0' from the guest named 'my-guest': + +.. code-block:: sh + + virsh qemu-monitor-command my-guest --hmp "device_del hostdev0" + +2. A vfio_ap mediated device can be hot unplugged by attaching the qemu monitor + to the guest and using the following qemu monitor command: + + (QEMU) device-del id=<device-id> + + For example, to hot unplug the vfio_ap mediated device that was specified + on the qemu command line with 'id=hostdev0' when the guest was started: + + (QEMU) device-del id=hostdev0 + +After live migration of the KVM guest completes, an AP configuration can be +restored to the KVM guest by hot plugging a vfio_ap mediated device on the target +system into the guest in one of two ways: + +1. If the KVM guest was started with libvirt, you can hot plug a matrix mediated + device into the guest via the following virsh commands: + + virsh attach-device <guestname> <path-to-device-xml> + + For example, to hot plug mdev 62177883-f1bb-47f0-914d-32a22e3a8804 into + the guest named 'my-guest': + + virsh attach-device my-guest ~/config/my-guest-hostdev.xml + + The contents of my-guest-hostdev.xml: + +.. code-block:: xml + + <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-ap'> + <source> + <address uuid='62177883-f1bb-47f0-914d-32a22e3a8804'/> + </source> + </hostdev> + + + virsh qemu-monitor-command <guest-name> --hmp \ + "device_add vfio-ap,sysfsdev=<path-to-mdev>,id=<device-id>" + + For example, to hot plug the vfio_ap mediated device + 62177883-f1bb-47f0-914d-32a22e3a8804 into the guest named 'my-guest' with + device-id hostdev0: + + virsh qemu-monitor-command my-guest --hmp \ + "device_add vfio-ap,\ + sysfsdev=/sys/devices/vfio_ap/matrix/62177883-f1bb-47f0-914d-32a22e3a8804,\ + id=hostdev0" + +2. A vfio_ap mediated device can be hot plugged by attaching the qemu monitor + to the guest and using the following qemu monitor command: + + (qemu) device_add "vfio-ap,sysfsdev=<path-to-mdev>,id=<device-id>" + + For example, to plug the vfio_ap mediated device + 62177883-f1bb-47f0-914d-32a22e3a8804 into the guest with the device-id + hostdev0: + + (QEMU) device-add "vfio-ap,\ + sysfsdev=/sys/devices/vfio_ap/matrix/62177883-f1bb-47f0-914d-32a22e3a8804,\ + id=hostdev0" diff --git a/Documentation/arch/s390/vfio-ccw.rst b/Documentation/arch/s390/vfio-ccw.rst new file mode 100644 index 0000000000..42960b7b0d --- /dev/null +++ b/Documentation/arch/s390/vfio-ccw.rst @@ -0,0 +1,445 @@ +================================== +vfio-ccw: the basic infrastructure +================================== + +Introduction +------------ + +Here we describe the vfio support for I/O subchannel devices for +Linux/s390. Motivation for vfio-ccw is to passthrough subchannels to a +virtual machine, while vfio is the means. + +Different than other hardware architectures, s390 has defined a unified +I/O access method, which is so called Channel I/O. It has its own access +patterns: + +- Channel programs run asynchronously on a separate (co)processor. +- The channel subsystem will access any memory designated by the caller + in the channel program directly, i.e. there is no iommu involved. + +Thus when we introduce vfio support for these devices, we realize it +with a mediated device (mdev) implementation. The vfio mdev will be +added to an iommu group, so as to make itself able to be managed by the +vfio framework. And we add read/write callbacks for special vfio I/O +regions to pass the channel programs from the mdev to its parent device +(the real I/O subchannel device) to do further address translation and +to perform I/O instructions. + +This document does not intend to explain the s390 I/O architecture in +every detail. More information/reference could be found here: + +- A good start to know Channel I/O in general: + https://en.wikipedia.org/wiki/Channel_I/O +- s390 architecture: + s390 Principles of Operation manual (IBM Form. No. SA22-7832) +- The existing QEMU code which implements a simple emulated channel + subsystem could also be a good reference. It makes it easier to follow + the flow. + qemu/hw/s390x/css.c + +For vfio mediated device framework: +- Documentation/driver-api/vfio-mediated-device.rst + +Motivation of vfio-ccw +---------------------- + +Typically, a guest virtualized via QEMU/KVM on s390 only sees +paravirtualized virtio devices via the "Virtio Over Channel I/O +(virtio-ccw)" transport. This makes virtio devices discoverable via +standard operating system algorithms for handling channel devices. + +However this is not enough. On s390 for the majority of devices, which +use the standard Channel I/O based mechanism, we also need to provide +the functionality of passing through them to a QEMU virtual machine. +This includes devices that don't have a virtio counterpart (e.g. tape +drives) or that have specific characteristics which guests want to +exploit. + +For passing a device to a guest, we want to use the same interface as +everybody else, namely vfio. We implement this vfio support for channel +devices via the vfio mediated device framework and the subchannel device +driver "vfio_ccw". + +Access patterns of CCW devices +------------------------------ + +s390 architecture has implemented a so called channel subsystem, that +provides a unified view of the devices physically attached to the +systems. Though the s390 hardware platform knows about a huge variety of +different peripheral attachments like disk devices (aka. DASDs), tapes, +communication controllers, etc. They can all be accessed by a well +defined access method and they are presenting I/O completion a unified +way: I/O interruptions. + +All I/O requires the use of channel command words (CCWs). A CCW is an +instruction to a specialized I/O channel processor. A channel program is +a sequence of CCWs which are executed by the I/O channel subsystem. To +issue a channel program to the channel subsystem, it is required to +build an operation request block (ORB), which can be used to point out +the format of the CCW and other control information to the system. The +operating system signals the I/O channel subsystem to begin executing +the channel program with a SSCH (start sub-channel) instruction. The +central processor is then free to proceed with non-I/O instructions +until interrupted. The I/O completion result is received by the +interrupt handler in the form of interrupt response block (IRB). + +Back to vfio-ccw, in short: + +- ORBs and channel programs are built in guest kernel (with guest + physical addresses). +- ORBs and channel programs are passed to the host kernel. +- Host kernel translates the guest physical addresses to real addresses + and starts the I/O with issuing a privileged Channel I/O instruction + (e.g SSCH). +- channel programs run asynchronously on a separate processor. +- I/O completion will be signaled to the host with I/O interruptions. + And it will be copied as IRB to user space to pass it back to the + guest. + +Physical vfio ccw device and its child mdev +------------------------------------------- + +As mentioned above, we realize vfio-ccw with a mdev implementation. + +Channel I/O does not have IOMMU hardware support, so the physical +vfio-ccw device does not have an IOMMU level translation or isolation. + +Subchannel I/O instructions are all privileged instructions. When +handling the I/O instruction interception, vfio-ccw has the software +policing and translation how the channel program is programmed before +it gets sent to hardware. + +Within this implementation, we have two drivers for two types of +devices: + +- The vfio_ccw driver for the physical subchannel device. + This is an I/O subchannel driver for the real subchannel device. It + realizes a group of callbacks and registers to the mdev framework as a + parent (physical) device. As a consequence, mdev provides vfio_ccw a + generic interface (sysfs) to create mdev devices. A vfio mdev could be + created by vfio_ccw then and added to the mediated bus. It is the vfio + device that added to an IOMMU group and a vfio group. + vfio_ccw also provides an I/O region to accept channel program + request from user space and store I/O interrupt result for user + space to retrieve. To notify user space an I/O completion, it offers + an interface to setup an eventfd fd for asynchronous signaling. + +- The vfio_mdev driver for the mediated vfio ccw device. + This is provided by the mdev framework. It is a vfio device driver for + the mdev that created by vfio_ccw. + It realizes a group of vfio device driver callbacks, adds itself to a + vfio group, and registers itself to the mdev framework as a mdev + driver. + It uses a vfio iommu backend that uses the existing map and unmap + ioctls, but rather than programming them into an IOMMU for a device, + it simply stores the translations for use by later requests. This + means that a device programmed in a VM with guest physical addresses + can have the vfio kernel convert that address to process virtual + address, pin the page and program the hardware with the host physical + address in one step. + For a mdev, the vfio iommu backend will not pin the pages during the + VFIO_IOMMU_MAP_DMA ioctl. Mdev framework will only maintain a database + of the iova<->vaddr mappings in this operation. And they export a + vfio_pin_pages and a vfio_unpin_pages interfaces from the vfio iommu + backend for the physical devices to pin and unpin pages by demand. + +Below is a high Level block diagram:: + + +-------------+ + | | + | +---------+ | mdev_register_driver() +--------------+ + | | Mdev | +<-----------------------+ | + | | bus | | | vfio_mdev.ko | + | | driver | +----------------------->+ |<-> VFIO user + | +---------+ | probe()/remove() +--------------+ APIs + | | + | MDEV CORE | + | MODULE | + | mdev.ko | + | +---------+ | mdev_register_parent() +--------------+ + | |Physical | +<-----------------------+ | + | | device | | | vfio_ccw.ko |<-> subchannel + | |interface| +----------------------->+ | device + | +---------+ | callback +--------------+ + +-------------+ + +The process of how these work together. + +1. vfio_ccw.ko drives the physical I/O subchannel, and registers the + physical device (with callbacks) to mdev framework. + When vfio_ccw probing the subchannel device, it registers device + pointer and callbacks to the mdev framework. Mdev related file nodes + under the device node in sysfs would be created for the subchannel + device, namely 'mdev_create', 'mdev_destroy' and + 'mdev_supported_types'. +2. Create a mediated vfio ccw device. + Use the 'mdev_create' sysfs file, we need to manually create one (and + only one for our case) mediated device. +3. vfio_mdev.ko drives the mediated ccw device. + vfio_mdev is also the vfio device driver. It will probe the mdev and + add it to an iommu_group and a vfio_group. Then we could pass through + the mdev to a guest. + + +VFIO-CCW Regions +---------------- + +The vfio-ccw driver exposes MMIO regions to accept requests from and return +results to userspace. + +vfio-ccw I/O region +------------------- + +An I/O region is used to accept channel program request from user +space and store I/O interrupt result for user space to retrieve. The +definition of the region is:: + + struct ccw_io_region { + #define ORB_AREA_SIZE 12 + __u8 orb_area[ORB_AREA_SIZE]; + #define SCSW_AREA_SIZE 12 + __u8 scsw_area[SCSW_AREA_SIZE]; + #define IRB_AREA_SIZE 96 + __u8 irb_area[IRB_AREA_SIZE]; + __u32 ret_code; + } __packed; + +This region is always available. + +While starting an I/O request, orb_area should be filled with the +guest ORB, and scsw_area should be filled with the SCSW of the Virtual +Subchannel. + +irb_area stores the I/O result. + +ret_code stores a return code for each access of the region. The following +values may occur: + +``0`` + The operation was successful. + +``-EOPNOTSUPP`` + The ORB specified transport mode or the + SCSW specified a function other than the start function. + +``-EIO`` + A request was issued while the device was not in a state ready to accept + requests, or an internal error occurred. + +``-EBUSY`` + The subchannel was status pending or busy, or a request is already active. + +``-EAGAIN`` + A request was being processed, and the caller should retry. + +``-EACCES`` + The channel path(s) used for the I/O were found to be not operational. + +``-ENODEV`` + The device was found to be not operational. + +``-EINVAL`` + The orb specified a chain longer than 255 ccws, or an internal error + occurred. + + +vfio-ccw cmd region +------------------- + +The vfio-ccw cmd region is used to accept asynchronous instructions +from userspace:: + + #define VFIO_CCW_ASYNC_CMD_HSCH (1 << 0) + #define VFIO_CCW_ASYNC_CMD_CSCH (1 << 1) + struct ccw_cmd_region { + __u32 command; + __u32 ret_code; + } __packed; + +This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD. + +Currently, CLEAR SUBCHANNEL and HALT SUBCHANNEL use this region. + +command specifies the command to be issued; ret_code stores a return code +for each access of the region. The following values may occur: + +``0`` + The operation was successful. + +``-ENODEV`` + The device was found to be not operational. + +``-EINVAL`` + A command other than halt or clear was specified. + +``-EIO`` + A request was issued while the device was not in a state ready to accept + requests. + +``-EAGAIN`` + A request was being processed, and the caller should retry. + +``-EBUSY`` + The subchannel was status pending or busy while processing a halt request. + +vfio-ccw schib region +--------------------- + +The vfio-ccw schib region is used to return Subchannel-Information +Block (SCHIB) data to userspace:: + + struct ccw_schib_region { + #define SCHIB_AREA_SIZE 52 + __u8 schib_area[SCHIB_AREA_SIZE]; + } __packed; + +This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_SCHIB. + +Reading this region triggers a STORE SUBCHANNEL to be issued to the +associated hardware. + +vfio-ccw crw region +--------------------- + +The vfio-ccw crw region is used to return Channel Report Word (CRW) +data to userspace:: + + struct ccw_crw_region { + __u32 crw; + __u32 pad; + } __packed; + +This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_CRW. + +Reading this region returns a CRW if one that is relevant for this +subchannel (e.g. one reporting changes in channel path state) is +pending, or all zeroes if not. If multiple CRWs are pending (including +possibly chained CRWs), reading this region again will return the next +one, until no more CRWs are pending and zeroes are returned. This is +similar to how STORE CHANNEL REPORT WORD works. + +vfio-ccw operation details +-------------------------- + +vfio-ccw follows what vfio-pci did on the s390 platform and uses +vfio-iommu-type1 as the vfio iommu backend. + +* CCW translation APIs + A group of APIs (start with `cp_`) to do CCW translation. The CCWs + passed in by a user space program are organized with their guest + physical memory addresses. These APIs will copy the CCWs into kernel + space, and assemble a runnable kernel channel program by updating the + guest physical addresses with their corresponding host physical addresses. + Note that we have to use IDALs even for direct-access CCWs, as the + referenced memory can be located anywhere, including above 2G. + +* vfio_ccw device driver + This driver utilizes the CCW translation APIs and introduces + vfio_ccw, which is the driver for the I/O subchannel devices you want + to pass through. + vfio_ccw implements the following vfio ioctls:: + + VFIO_DEVICE_GET_INFO + VFIO_DEVICE_GET_IRQ_INFO + VFIO_DEVICE_GET_REGION_INFO + VFIO_DEVICE_RESET + VFIO_DEVICE_SET_IRQS + + This provides an I/O region, so that the user space program can pass a + channel program to the kernel, to do further CCW translation before + issuing them to a real device. + This also provides the SET_IRQ ioctl to setup an event notifier to + notify the user space program the I/O completion in an asynchronous + way. + +The use of vfio-ccw is not limited to QEMU, while QEMU is definitely a +good example to get understand how these patches work. Here is a little +bit more detail how an I/O request triggered by the QEMU guest will be +handled (without error handling). + +Explanation: + +- Q1-Q7: QEMU side process. +- K1-K5: Kernel side process. + +Q1. + Get I/O region info during initialization. + +Q2. + Setup event notifier and handler to handle I/O completion. + +... ... + +Q3. + Intercept a ssch instruction. +Q4. + Write the guest channel program and ORB to the I/O region. + + K1. + Copy from guest to kernel. + K2. + Translate the guest channel program to a host kernel space + channel program, which becomes runnable for a real device. + K3. + With the necessary information contained in the orb passed in + by QEMU, issue the ccwchain to the device. + K4. + Return the ssch CC code. +Q5. + Return the CC code to the guest. + +... ... + + K5. + Interrupt handler gets the I/O result and write the result to + the I/O region. + K6. + Signal QEMU to retrieve the result. + +Q6. + Get the signal and event handler reads out the result from the I/O + region. +Q7. + Update the irb for the guest. + +Limitations +----------- + +The current vfio-ccw implementation focuses on supporting basic commands +needed to implement block device functionality (read/write) of DASD/ECKD +device only. Some commands may need special handling in the future, for +example, anything related to path grouping. + +DASD is a kind of storage device. While ECKD is a data recording format. +More information for DASD and ECKD could be found here: +https://en.wikipedia.org/wiki/Direct-access_storage_device +https://en.wikipedia.org/wiki/Count_key_data + +Together with the corresponding work in QEMU, we can bring the passed +through DASD/ECKD device online in a guest now and use it as a block +device. + +The current code allows the guest to start channel programs via +START SUBCHANNEL, and to issue HALT SUBCHANNEL, CLEAR SUBCHANNEL, +and STORE SUBCHANNEL. + +Currently all channel programs are prefetched, regardless of the +p-bit setting in the ORB. As a result, self modifying channel +programs are not supported. For this reason, IPL has to be handled as +a special case by a userspace/guest program; this has been implemented +in QEMU's s390-ccw bios as of QEMU 4.1. + +vfio-ccw supports classic (command mode) channel I/O only. Transport +mode (HPF) is not supported. + +QDIO subchannels are currently not supported. Classic devices other than +DASD/ECKD might work, but have not been tested. + +Reference +--------- +1. ESA/s390 Principles of Operation manual (IBM Form. No. SA22-7832) +2. ESA/390 Common I/O Device Commands manual (IBM Form. No. SA22-7204) +3. https://en.wikipedia.org/wiki/Channel_I/O +4. Documentation/arch/s390/cds.rst +5. Documentation/driver-api/vfio.rst +6. Documentation/driver-api/vfio-mediated-device.rst diff --git a/Documentation/arch/s390/zfcpdump.rst b/Documentation/arch/s390/zfcpdump.rst new file mode 100644 index 0000000000..a61de7aa87 --- /dev/null +++ b/Documentation/arch/s390/zfcpdump.rst @@ -0,0 +1,50 @@ +================================== +The s390 SCSI dump tool (zfcpdump) +================================== + +System z machines (z900 or higher) provide hardware support for creating system +dumps on SCSI disks. The dump process is initiated by booting a dump tool, which +has to create a dump of the current (probably crashed) Linux image. In order to +not overwrite memory of the crashed Linux with data of the dump tool, the +hardware saves some memory plus the register sets of the boot CPU before the +dump tool is loaded. There exists an SCLP hardware interface to obtain the saved +memory afterwards. Currently 32 MB are saved. + +This zfcpdump implementation consists of a Linux dump kernel together with +a user space dump tool, which are loaded together into the saved memory region +below 32 MB. zfcpdump is installed on a SCSI disk using zipl (as contained in +the s390-tools package) to make the device bootable. The operator of a Linux +system can then trigger a SCSI dump by booting the SCSI disk, where zfcpdump +resides on. + +The user space dump tool accesses the memory of the crashed system by means +of the /proc/vmcore interface. This interface exports the crashed system's +memory and registers in ELF core dump format. To access the memory which has +been saved by the hardware SCLP requests will be created at the time the data +is needed by /proc/vmcore. The tail part of the crashed systems memory which +has not been stashed by hardware can just be copied from real memory. + +To build a dump enabled kernel the kernel config option CONFIG_CRASH_DUMP +has to be set. + +To get a valid zfcpdump kernel configuration use "make zfcpdump_defconfig". + +The s390 zipl tool looks for the zfcpdump kernel and optional initrd/initramfs +under the following locations: + +* kernel: <zfcpdump directory>/zfcpdump.image +* ramdisk: <zfcpdump directory>/zfcpdump.rd + +The zfcpdump directory is defined in the s390-tools package. + +The user space application of zfcpdump can reside in an intitramfs or an +initrd. It can also be included in a built-in kernel initramfs. The application +reads from /proc/vmcore or zcore/mem and writes the system dump to a SCSI disk. + +The s390-tools package version 1.24.0 and above builds an external zfcpdump +initramfs with a user space application that writes the dump to a SCSI +partition. + +For more information on how to use zfcpdump refer to the s390 'Using the Dump +Tools' book, which is available from IBM Knowledge Center: +https://www.ibm.com/support/knowledgecenter/linuxonibm/liaaf/lnz_r_dt.html |