diff --git a/MAINTAINERS b/MAINTAINERS
index 2730757b4482..fb81b3a8eb06 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -96,6 +96,7 @@ F: include/hw/watchdog/wdt_diag288.h
 F: pc-bios/s390-ccw/
 F: pc-bios/s390-ccw.img
 F: target/s390x/
+F: docs/vfio-ap.txt
 K: ^Subject:.*(?i)s390x?
 T: git git://github.com/cohuck/qemu.git s390-next
 L: qemu-s390x@nongnu.org
@@ -1219,6 +1220,7 @@ F: hw/s390x/ap-bridge.c
 F: include/hw/s390x/ap-device.h
 F: include/hw/s390x/ap-bridge.h
 F: hw/vfio/ap.c
+F: docs/vfio-ap.txt
 L: qemu-s390x@nongnu.org
 
 vhost
diff --git a/docs/vfio-ap.txt b/docs/vfio-ap.txt
new file mode 100644
index 000000000000..12339684cd52
--- /dev/null
+++ b/docs/vfio-ap.txt
@@ -0,0 +1,825 @@
+Adjunct Processor (AP) Device
+=============================
+
+Contents:
+=========
+* Introduction
+* AP Architectural Overview
+* Start Interpretive Execution (SIE) Instruction
+* AP Matrix Configuration on Linux Host
+* Starting a Linux Guest Configured with an AP Matrix
+* Example: Configure AP Matrices for Three Linux Guests
+
+Introduction:
+============
+The IBM Adjunct Processor (AP) Cryptographic Facility is comprised
+of three AP instructions and from 1 to 256 PCIe cryptographic adapter cards.
+These AP devices provide cryptographic functions to all CPUs assigned to a
+linux system running in an IBM Z system LPAR.
+
+On s390x, AP adapter cards are exposed via the AP bus. This document
+describes how those cards may be made available to KVM guests using the
+VFIO mediated device framework.
+
+AP Architectural Overview:
+=========================
+In order understand the terminology used in the rest of this document, 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 depending
+  on the machine model. 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 allowed is
+  determined by machine model. When installed, an AP adapter is accessed by
+  AP instructions executed by any CPU.
+
+* AP domain
+
+  An adapter is partitioned into domains. Each domain can be thought of as
+  a set of hardware registers for processing AP instructions. An adapter can
+  hold up to 256 domains; however, the maximum domain number allowed is
+  determined by machine model. Each domain is identified by a number from 0 to
+  255. Domains can be further classified into two types:
+
+    * Usage domains are domains that can be accessed directly to process AP
+      commands
+
+    * Control domains are domains that are accessed indirectly by AP
+      commands sent to a usage domain to control or change the domain; for
+      example, to set a secure private key for the domain.
+
+* AP Queue
+
+  An AP queue is the means by which an AP command-request message is sent to an
+  AP usage domain inside a specific AP. 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-request message is to be sent for processing.
+
+* 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.
+
+Start Interpretive Execution (SIE) Instruction
+==============================================
+A KVM guest is started by executing the Start Interpretive Execution (SIE)
+instruction. The SIE state description is a control block that contains the
+state information for a KVM guest and is supplied as input to the SIE
+instruction. The SIE state description contains a satellite control block called
+the Crypto Control Block (CRYCB). The CRYCB contains 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 adapter and 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.
+
+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 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) and (2,6); Guest2 has APQNs (1,7) and (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).
+
+AP Matrix Configuration on Linux Host:
+=====================================
+A linux system is a guest of the LPAR in which it is running and has access to
+the AP resources configured for the LPAR. The LPAR's AP matrix is
+configured via its Activation Profile which can be edited on the HMC. When the
+linux system is started, the AP bus will detect the AP devices assigned to the
+LPAR and create the following in sysfs:
+
+/sys/bus/ap
+... [devices]
+...... xx.yyyy
+...... ...
+...... cardxx
+...... ...
+
+Where:
+    cardxx     is AP adapter number xx (in hex)
+....xx.yyyy    is an APQN with xx specifying the APID and yyyy specifying the
+               APQI
+
+For example, if AP adapters 5 and 6 and domains 4, 71 (0x47), 171 (0xab) and
+255 (0xff) are configured for the LPAR, the sysfs representation on the linux
+host system would look like this:
+
+/sys/bus/ap
+... [devices]
+...... 05.0004
+...... 05.0047
+...... 05.00ab
+...... 05.00ff
+...... 06.0004
+...... 06.0047
+...... 06.00ab
+...... 06.00ff
+...... card05
+...... card06
+
+A set of default device drivers are also created to control each type of AP
+device that can be assigned to the LPAR on which a linux host is running:
+
+/sys/bus/ap
+... [drivers]
+...... [cex2acard]        for Crypto Express 2/3 accelerator cards
+...... [cex2aqueue]       for AP queues served by Crypto Express 2/3
+                          accelerator cards
+...... [cex4card]         for Crypto Express 4/5/6 accelerator and coprocessor
+                          cards
+...... [cex4queue]        for AP queues served by Crypto Express 4/5/6
+                          accelerator and coprocessor cards
+...... [pcixcccard]       for Crypto Express 2/3 coprocessor cards
+...... [pcixccqueue]      for AP queues served by Crypto Express 2/3
+                          coprocessor cards
+
+Binding AP devices to device drivers
+------------------------------------
+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 alternate device
+driver(s). The sysfs locations of 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.
+
+   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.
+
+   Take, for example, the following mask:
+
+      0x7dffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
+
+    It indicates:
+
+      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.
+
+   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
+   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 (i.e., most
+        significant to least significant bit in big endian order), 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
+
+Configuring an AP matrix for a linux guest.
+------------------------------------------
+The sysfs interfaces for configuring an AP matrix for a guest are built on the
+VFIO mediated device framework. To configure an AP matrix for a guest, a
+mediated matrix device must first be created for the /sys/devices/vfio_ap/matrix
+device. When the vfio_ap device driver is loaded, it registers with the VFIO
+mediated device framework. When the driver registers, the sysfs interfaces for
+creating mediated matrix devices is created:
+
+/sys/devices
+... [vfio_ap]
+......[matrix]
+......... [mdev_supported_types]
+............ [vfio_ap-passthrough]
+............... create
+............... [devices]
+
+A mediated AP matrix device is created by writing a UUID to the attribute file
+named 'create', for example:
+
+   uuidgen > create
+
+   or
+
+   echo $uuid > create
+
+When a mediated AP matrix device is created, a sysfs directory named after
+the UUID is created in the 'devices' subdirectory:
+
+/sys/devices
+... [vfio_ap]
+......[matrix]
+......... [mdev_supported_types]
+............ [vfio_ap-passthrough]
+............... create
+............... [devices]
+.................. [$uuid]
+
+There will also be three sets of attribute files created in the mediated
+matrix device's sysfs directory to configure an AP matrix for the
+KVM guest:
+
+/sys/devices
+... [vfio_ap]
+......[matrix]
+......... [mdev_supported_types]
+............ [vfio_ap-passthrough]
+............... create
+............... [devices]
+.................. [$uuid]
+..................... assign_adapter
+..................... assign_control_domain
+..................... assign_domain
+..................... matrix
+..................... unassign_adapter
+..................... unassign_control_domain
+..................... unassign_domain
+
+assign_adapter
+   To assign an AP adapter to the mediated matrix device, its APID is written
+   to the 'assign_adapter' file. This may be done multiple times to assign more
+   than one adapter. The APID may be specified using conventional semantics
+   as a decimal, hexadecimal, or octal number. For example, to assign adapters
+   4, 5 and 16 to a mediated matrix device in decimal, hexadecimal and octal
+   respectively:
+
+       echo 4 > assign_adapter
+       echo 0x5 > assign_adapter
+       echo 020 > assign_adapter
+
+   In order to successfully assign an adapter:
+
+   * The adapter number specified must represent a value from 0 up to the
+     maximum adapter number allowed by the machine model. If an adapter number
+     higher than the maximum is specified, the operation will terminate with
+     an error (ENODEV).
+
+   * All APQNs that can be derived from the adapter ID being assigned 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).
+
+     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).
+
+unassign_adapter
+   To unassign an AP adapter, its APID is written to the 'unassign_adapter'
+   file. This may also be done multiple times to unassign more than one adapter.
+
+assign_domain
+   To assign a usage domain, the domain number is written into the
+   'assign_domain' file. This may be done multiple times to assign more than one
+   usage domain. The domain number is specified using conventional semantics as
+   a decimal, hexadecimal, or octal number. For example, to assign usage domains
+   4, 8, and 71 to a mediated matrix device in decimal, hexadecimal and octal
+   respectively:
+
+      echo 4 > assign_domain
+      echo 0x8 > assign_domain
+      echo 0107 > assign_domain
+
+   In order to successfully assign a domain:
+
+   * The domain number specified must represent a value from 0 up to the
+     maximum domain number allowed by the machine model. If a domain number
+     higher than the maximum is specified, the operation will terminate with
+     an error (ENODEV).
+
+   * All APQNs that can be derived from the domain ID being assigned 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).
+
+     No APQN that can be derived from the domain ID being assigned 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).
+
+unassign_domain
+   To unassign a usage domain, the domain number is written into the
+   'unassign_domain' file. This may be done multiple times to unassign more than
+   one usage domain.
+
+assign_control_domain
+   To assign a control domain, the domain number is written into the
+   'assign_control_domain' file. This may be done multiple times to
+   assign more than one control domain. The domain number may be specified using
+   conventional semantics as a decimal, hexadecimal, or octal number. For
+   example, to assign  control domains 4, 8, and 71 to  a mediated matrix device
+   in decimal, hexadecimal and octal respectively:
+
+      echo 4 > assign_domain
+      echo 0x8 > assign_domain
+      echo 0107 > assign_domain
+
+   In order to successfully assign a control domain, the domain number
+   specified must represent a value from 0 up to the maximum domain number
+   allowed by the machine model. If a control domain number higher than the
+   maximum is specified, the operation will terminate with an error (ENODEV).
+
+unassign_control_domain
+   To unassign a control domain, the domain number is written into the
+   'unassign_domain' file. This may be done multiple times to unassign more than
+   one control domain.
+
+Notes: Hot plug/unplug is not currently supported for mediated AP matrix
+devices, so no changes to the AP matrix will be allowed while a guest using
+the mediated matrix device is running. Attempts to assign an adapter,
+domain or control domain will be rejected and an error (EBUSY) returned.
+
+Starting a Linux Guest Configured with an AP Matrix:
+===================================================
+To provide a mediated matrix device for use by a guest, the following option
+must be specified on the QEMU command line:
+
+   -device vfio_ap,sysfsdev=$path-to-mdev
+
+The sysfsdev parameter specifies the path to the mediated matrix device.
+There are a number of ways to specify this path:
+
+/sys/devices/vfio_ap/matrix/$uuid
+/sys/bus/mdev/devices/$uuid
+/sys/bus/mdev/drivers/vfio_mdev/$uuid
+/sys/devices/vfio_ap/matrix/mdev_supported_types/vfio_ap-passthrough/devices/$uuid
+
+When the linux guest is started, the guest will open the mediated
+matrix device's file descriptor to get information about the mediated matrix
+device. The vfio_ap device driver will update the APM, AQM, and ADM fields in
+the guest's CRYCB with the adapter, usage domain and control domains assigned
+via the mediated matrix device's sysfs attribute files. Programs running on the
+linux guest will then:
+
+1. Have direct access to the APQNs derived from the cross product of the AP
+   adapter numbers (APID) and queue indexes (APQI) specified in the APM and AQM
+   fields of the guests's CRYCB respectively. These APQNs identify the AP queues
+   that are valid for use by the guest; meaning, AP commands can be sent by the
+   guest to any of these queues for processing.
+
+2. Have authorization to process AP commands to change a control domain
+   identified in the ADM field of the guest's CRYCB. The AP command must be sent
+   to a valid APQN (see 1 above).
+
+CPU model features:
+
+Three CPU model features are available for controlling guest access to AP
+facilities:
+
+1. AP facilities feature
+
+   The AP facilities feature indicates that AP facilities are installed on the
+   guest. This feature will be exposed for use only if the AP facilities
+   are installed on the host system. The feature is s390-specific and is
+   represented as a parameter of the -cpu option on the QEMU command line:
+
+      qemu-system-s390x -cpu $model,ap=on|off
+
+      Where:
+
+         $model is the CPU model defined for the guest (defaults to the model of
+                the host system if not specified).
+
+         ap=on|off indicates whether AP facilities are installed (on) or not
+                   (off). The default for CPU models zEC12 or newer
+                   is ap=on. AP facilities must be installed on the guest if a
+                   vfio-ap device (-device vfio-ap,sysfsdev=$path) is configured
+                   for the guest, or the guest will fail to start.
+
+2. Query Configuration Information (QCI) facility
+
+   The QCI facility is used by the AP bus running on the guest to query the
+   configuration of the AP facilities. This facility will be available
+   only if the QCI facility is installed on the host system. The feature is
+   s390-specific and is represented as a parameter of the -cpu option on the
+   QEMU command line:
+
+      qemu-system-s390x -cpu $model,apqci=on|off
+
+      Where:
+
+         $model is the CPU model defined for the guest
+
+         apqci=on|off indicates whether the QCI facility is installed (on) or
+                      not (off). The default for CPU models zEC12 or newer
+                      is apqci=on; for older models, QCI will not be installed.
+
+                      If QCI is installed (apqci=on) but AP facilities are not
+                      (ap=off), an error message will be logged, but the guest
+                      will be allowed to start. It makes no sense to have QCI
+                      installed if the AP facilities are not; this is considered
+                      an invalid configuration.
+
+                      If the QCI facility is not installed, APQNs with an APQI
+                      greater than 15 will not be detected by the AP bus
+                      running on the guest.
+
+3. Adjunct Process Facility Test (APFT) facility
+
+   The APFT facility is used by the AP bus running on the guest to test the
+   AP facilities available for a given AP queue. This facility will be available
+   only if the APFT facility is installed on the host system. The feature is
+   s390-specific and is represented as a parameter of the -cpu option on the
+   QEMU command line:
+
+      qemu-system-s390x -cpu $model,apft=on|off
+
+      Where:
+
+         $model is the CPU model defined for the guest (defaults to the model of
+                the host system if not specified).
+
+         apft=on|off indicates whether the APFT facility is installed (on) or
+                     not (off). The default for CPU models zEC12 and
+                     newer is apft=on for older models, APFT will not be
+                     installed.
+
+                     If APFT is installed (apft=on) but AP facilities are not
+                     (ap=off), an error message will be logged, but the guest
+                     will be allowed to start. It makes no sense to have APFT
+                     installed if the AP facilities are not; this is considered
+                     an invalid configuration.
+
+                     It also makes no sense to turn APFT off because the AP bus
+                     running on the guest will not detect CEX4 and newer devices
+                     without it. Since only CEX4 and newer devices are supported
+                     for guest usage, no AP devices can be made accessible to a
+                     guest started without APFT installed.
+
+Example: Configure AP Matrixes for Three Linux Guests:
+=====================================================
+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     CEX5C CCA-Coproc
+
+Guest2
+------
+CARD.DOMAIN TYPE  MODE
+------------------------------
+05          CEX5A Accelerator
+05.0047     CEX5A Accelerator
+05.00ff     CEX5A Accelerator (5,4), (5,171), (6,4), (6,171),
+
+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
+   * S390_AP_IOMMU
+   * VFIO
+   * VFIO_MDEV
+   * VFIO_MDEV_DEVICE
+   * 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 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 must be removed from the default queue drivers pool
+   as follows:
+
+      echo -5,-6 > /sys/bus/ap/apmask
+
+      echo -4,-0x47,-0xab,-0xff > /sys/bus/ap/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 mediated matrix 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 used to create the mediated device. We'll 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
+
+4. The administrator now needs to configure the matrixes for the mediated
+   devices $uuid1 (for Guest1), $uuid2 (for Guest2) and $uuid3 (for Guest3).
+
+   This is how the matrix is configured for Guest1:
+
+      echo 5 > assign_adapter
+      echo 6 > assign_adapter
+      echo 4 > assign_domain
+      echo 0xab > assign_domain
+
+      Control domains can similarly be assigned using the assign_control_domain
+      sysfs file.
+
+      If a mistake is made configuring an adapter, domain or control domain,
+      you can use the unassign_xxx interfaces to unassign the adapter, domain or
+      control domain.
+
+      To display the matrix configuration for Guest1:
+
+         cat matrix
+
+         The output will display the APQNs in the format xx.yyyy, where xx is
+         the adapter number and yyyy is the domain number. The output for Guest1
+         will look like this:
+
+         05.0004
+         05.00ab
+         06.0004
+         06.00ab
+
+   This is how the matrix is configured for Guest2:
+
+      echo 5 > assign_adapter
+      echo 0x47 > assign_domain
+      echo 0xff > assign_domain
+
+   This is how the matrix is configured for Guest3:
+
+      echo 6 > assign_adapter
+      echo 0x47 > assign_domain
+      echo 0xff > assign_domain
+
+5. Start Guest1:
+
+   /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on \
+      -device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid1 ...
+
+7. Start Guest2:
+
+   /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on \
+      -device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid2 ...
+
+7. Start Guest3:
+
+   /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on \
+      -device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid3 ...
+
+When the guest is shut down, the mediated matrix devices may be removed.
+
+Using our example again, to remove the mediated matrix 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 mdev matrix device's sysfs structures including
+   the mdev device itself. To recreate and reconfigure the mdev matrix 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.
+
+   It is not necessary to remove an mdev matrix device, 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
+   the pool of adapters and queues reserved for use by the default drivers.
+
+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.
+
+* 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
+
+* Live guest migration is not supported for guests using AP devices.
