diff options
Diffstat (limited to 'Documentation/s390')
| -rw-r--r-- | Documentation/s390/vfio-ap.rst | 492 |
1 files changed, 346 insertions, 146 deletions
diff --git a/Documentation/s390/vfio-ap.rst b/Documentation/s390/vfio-ap.rst index f57ae621f33e..f4b8748ab9a8 100644 --- a/Documentation/s390/vfio-ap.rst +++ b/Documentation/s390/vfio-ap.rst @@ -123,27 +123,24 @@ 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 three fields -to identify the adapters, usage domains and control domains assigned to the KVM -guest: +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 (i.e. from most - significant to least significant bit in big endian order), corresponds to + 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 (i.e. from - most significant to least significant bit in big endian order), 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. + 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 (i.e. from most significant to - least significant bit in big endian order), corresponds to a domain from + 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. @@ -151,10 +148,10 @@ 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 cross 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. +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 @@ -192,7 +189,7 @@ The design introduces three new objects: 1. AP matrix device 2. VFIO AP device driver (vfio_ap.ko) -3. VFIO AP mediated matrix pass-through device +3. VFIO AP mediated pass-through device The VFIO AP device driver ------------------------- @@ -200,12 +197,13 @@ 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 mediated matrix +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 CRYCB referenced by a KVM guest's - SIE state description to grant the guest access to a matrix of AP devices +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 --------------------------------------------- @@ -235,10 +233,10 @@ reserved:: | | 8 probe | | +--------^---------+ +--^--^------------+ 6 edit | | | - apmask | +-----------------------------+ | 9 mdev create + apmask | +-----------------------------+ | 11 mdev create aqmask | | 1 modprobe | +--------+-----+---+ +----------------+-+ +----------------+ - | | | |8 create | mediated | + | | | |10 create| mediated | | admin | | VFIO device core |---------> matrix | | + | | | device | +------+-+---------+ +--------^---------+ +--------^-------+ @@ -246,14 +244,14 @@ reserved:: | | 9 create vfio_ap-passthrough | | | +------------------------------+ | +-------------------------------------------------------------+ - 10 assign adapter/domain/control domain + 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 mediated matrix devices used to configure an AP matrix for a guest. + 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 @@ -269,24 +267,24 @@ The process for reserving an AP queue for use by a KVM guest is: 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 mediated matrix device to be +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 interface of the VFIO mediated +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 mediated matrix device to and +* 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 mediated matrix device -* Add a mediated matrix device to and remove it from the AP mediated bus driver -* Add a mediated matrix device to and remove it from an IOMMU 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 matrix device driver:: +of the VFIO AP mediated device driver:: +-------------+ | | @@ -343,7 +341,7 @@ matrix device. * device_api: the mediated device type's API * available_instances: - the number of mediated matrix passthrough devices + the number of vfio_ap mediated passthrough devices that can be created * device_api: specifies the VFIO API @@ -351,29 +349,37 @@ matrix device. 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 mediated matrix device's directory. The - sysfs attributes for a mediated matrix device are: + 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 - mediated matrix device. To assign/unassign an adapter, the APID of the - adapter is echoed to the respective attribute file. + 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 mediated matrix device. To assign/unassign a domain, the domain - number of the usage domain is echoed to the respective attribute + 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 cross product - of the adapter and domain numbers assigned to the mediated matrix device. + 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 mediated matrix device. To assign/unassign a control domain, - the ID of the domain to be assigned/unassigned is echoed to the respective - attribute file. + 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 - mediated matrix device. + vfio_ap mediated device. * functions: @@ -383,45 +389,75 @@ matrix device. * 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 mediated matrix device's ap_matrix_mdev structure. This will - be allowed only if a running guest is not using the mdev. + 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: + open_device: The vfio_ap driver uses this callback to register a - VFIO_GROUP_NOTIFY_SET_KVM notifier callback function for the mdev matrix - device. The open is invoked when QEMU connects the VFIO iommu group - for the mdev matrix 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 - mediated matrix device's sysfs attribute files. - release: + 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 - mdev matrix device and deconfigures the guest's AP matrix. + matrix mdev device and deconfigures the guest's AP matrix. -Configure the APM, AQM and ADM in the CRYCB -------------------------------------------- -Configuring the AP matrix for a KVM guest will be performed when the + 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 QEMU connects to KVM. The guest's AP matrix is -configured via it's CRYCB by: +function is called when userspace connects to KVM. The guest's AP resources are +configured via it's APCB by: * Setting the bits in the APM corresponding to the APIDs assigned to the - mediated matrix device via its 'assign_adapter' interface. + vfio_ap mediated device via its 'assign_adapter' interface. * Setting the bits in the AQM corresponding to the domains assigned to the - mediated matrix device via its 'assign_domain' interface. + vfio_ap mediated device via its 'assign_domain' interface. * Setting the bits in the ADM corresponding to the domain dIDs assigned to the - mediated matrix device via its 'assign_control_domains' interface. + 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 two -facilities: The AP Facilities Test (APFT) facility; and the AP Query -Configuration Information (QCI) facility. These features/facilities are made -available to a KVM guest via the following CPU model features: +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 @@ -435,24 +471,28 @@ available to a KVM guest via the following CPU model features: 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 + /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 + /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 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 the probe of device -drivers will fail since only type 10 and newer devices can be configured for -guest use. +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 ======= @@ -471,7 +511,7 @@ CARD.DOMAIN TYPE MODE 05.00ab CEX5C CCA-Coproc 06 CEX5A Accelerator 06.0004 CEX5A Accelerator -06.00ab CEX5C CCA-Coproc +06.00ab CEX5A Accelerator =========== ===== ============ Guest2 @@ -479,9 +519,9 @@ Guest2 =========== ===== ============ CARD.DOMAIN TYPE MODE =========== ===== ============ -05 CEX5A Accelerator -05.0047 CEX5A Accelerator -05.00ff CEX5A Accelerator +05 CEX5C CCA-Coproc +05.0047 CEX5C CCA-Coproc +05.00ff CEX5C CCA-Coproc =========== ===== ============ Guest3 @@ -529,40 +569,56 @@ These are the steps: 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 by the default AP - queue device drivers' or 'not usable by the default device drivers' and thus - available for use by the vfio_ap device driver'. The location of the sysfs - files containing the masks are:: + 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 (i.e., from most significant - to least significant bit in big endian order), corresponds to an APID from - 0-255. If a bit is set, the APID is marked as usable only by the default AP - queue device drivers; otherwise, the APID is usable by the vfio_ap - device driver. + (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 (i.e., from most significant - to least significant bit in big endian order), corresponds to an APQI from - 0-255. If a bit is set, the APQI is marked as usable only by the default AP - queue device drivers; otherwise, the APQI is usable by the vfio_ap device - driver. + (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 - Take, for example, the following mask:: + aqmask: + 0x8000000000000000000000000000000000000000000000000000000000000000 - 0x7dffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + The masks indicate: - It indicates: + * Adapters 1, 2, 3, 4, 5, and 7 are available for use by the host default + device drivers. - 1, 2, 3, 4, 5, and 7-255 belong to the default drivers' pool, and 0 and 6 - belong to the vfio_ap device driver's pool. + * 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 cross product of APIDs - and APQIs marked as usable only by the default AP queue device drivers. If a + 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. @@ -579,8 +635,7 @@ These are the steps: 0x4100000000000000000000000000000000000000000000000000000000000000 - Keep in mind that the mask reads from left to right (i.e., most - significant to least significant bit in big endian order), so the mask + 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 @@ -626,11 +681,22 @@ These are the steps: 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 either be removed from the default masks:: + APQNs can be removed from the default masks using either of the following + commands:: echo -5,-6 > /sys/bus/ap/apmask @@ -683,7 +749,7 @@ Securing the APQNs for our example /sys/devices/vfio_ap/matrix/ --- [mdev_supported_types] - ------ [vfio_ap-passthrough] (passthrough mediated matrix device type) + ------ [vfio_ap-passthrough] (passthrough vfio_ap mediated device type) --------- create --------- [devices] @@ -734,6 +800,9 @@ Securing the APQNs for our example ----------------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). @@ -755,6 +824,10 @@ Securing the APQNs for our example 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 @@ -774,17 +847,24 @@ Securing the APQNs for our example higher than the maximum is specified, the operation will terminate with an error (ENODEV). - * All APQNs that can be derived from the adapter ID and the IDs of - the previously assigned domains must be bound to the vfio_ap device - driver. If no domains have yet been assigned, then there must be at least - one APQN with the specified APID bound to the vfio_ap driver. If no such - APQNs are bound to the driver, the operation will terminate with an - error (EADDRNOTAVAIL). + 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: - No APQN that can be derived from the adapter ID and the IDs of the - previously assigned domains can be assigned to another mediated matrix - device. If an APQN is assigned to another mediated matrix device, the - operation will terminate with an error (EADDRINUSE). + - 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: @@ -793,41 +873,50 @@ Securing the APQNs for our example higher than the maximum is specified, the operation will terminate with an error (ENODEV). - * All APQNs that can be derived from the domain ID and the IDs of - the previously assigned adapters must be bound to the vfio_ap device - driver. If no domains have yet been assigned, then there must be at least - one APQN with the specified APQI bound to the vfio_ap driver. If no such - APQNs are bound to the driver, the operation will terminate with an - error (EADDRNOTAVAIL). + 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: - No APQN that can be derived from the domain ID and the IDs of the - previously assigned adapters can be assigned to another mediated matrix - device. If an APQN is assigned to another mediated matrix device, the - operation will terminate with an error (EADDRINUSE). + - 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). - 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). + - 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 \ + /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 \ + /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on,apqi=on \ -device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid2 ... 7. Start Guest3:: - /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on \ + /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on,apqi=on \ -device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid3 ... -When the guest is shut down, the mediated matrix devices may be removed. +When the guest is shut down, the vfio_ap mediated devices may be removed. -Using our example again, to remove the mediated matrix device $uuid1:: +Using our example again, to remove the vfio_ap mediated device $uuid1:: /sys/devices/vfio_ap/matrix/ --- [mdev_supported_types] @@ -840,26 +929,137 @@ Using our example again, to remove the mediated matrix device $uuid1:: echo 1 > remove -This will remove all of the mdev matrix device's sysfs structures including -the mdev device itself. To recreate and reconfigure the mdev matrix device, +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 mdev is still running. +that the remove will fail if a guest using the vfio_ap mdev is still running. -It is not necessary to remove an mdev matrix device, but one may want to +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 mdev matrix device is removed, one may want to also reconfigure +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 =========== -* The KVM/kernel interfaces do not provide a way to prevent restoring an APQN - to the default drivers pool of a queue that is still assigned to a mediated - device in use by a guest. It is incumbent upon the administrator to - ensure there is no mediated device in use by a guest to which the APQN is - assigned lest the host be given access to the private data of the AP queue - device such as a private key configured specifically for the guest. +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: + + <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': + + 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: + + <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>" -* Dynamically modifying the AP matrix for a running guest (which would amount to - hot(un)plug of AP devices for the guest) is currently not supported + For example, to plug the vfio_ap mediated device + 62177883-f1bb-47f0-914d-32a22e3a8804 into the guest with the device-id + hostdev0: -* Live guest migration is not supported for guests using AP devices. + (QEMU) device-add "vfio-ap,\ + sysfsdev=/sys/devices/vfio_ap/matrix/62177883-f1bb-47f0-914d-32a22e3a8804,\ + id=hostdev0" |