[PATCH v4 00/15] s390/vfio-ap: Add live guest migration support

[PATCH v4 00/15] s390/vfio-ap: Add live guest migration support

[Anthony Krowiak]

This patch series implements live guest migration support for KVM guests
with s390 AP (Adjunct Processor) devices passed through via the VFIO
mediated device framework.

Background
~~~~~~~~~~

The vfio-ap device driver differs from typical VFIO device drivers in that
it does not virtualize a physical device. Instead, it manages AP
configuration metadata identifying the AP adapters, domains, and control
domains to which a guest will be granted access. These AP resources are
configured by assigning them to a vfio-ap mediated device via its sysfs
assignment interfaces. When the fd for the VFIO device is opened by
userspace, the vfio_ap device driver sets the guest's AP configuration
from the metadata stored with the mediated device. As such, the AP devices
are not accessed directly through the vfio_ap driver, so the driver has no
internal AP device state to migrate. What it does migrate is the AP
configuration metadata of the source guest.

Implementation Approach
~~~~~~~~~~~~~~~~~~~~~~~

This series implements the VFIO migration protocol using the STOP_COPY
migration flow. The key aspects are:

1. On transition of the migration state from STOP to STOP_COPY
   - The vfio_ap device driver creates a filestream for userspace to use to
     read the guest's AP configuration from the mdev

2. During the STOP_COPY phase
   - Userspace uses the filestream created in #1 to read the source guest's
     AP configuration
   - The vfio_ap device driver copies the source guest's AP configuration
     information to userspace

3. On transition of the migration state from STOP to RESUMING
   - The vfio_ap device driver creates a filestream for userspace to use to
     write the source guest's AP configuration information so it can be
     restored to the mdev on the destination host.

4. During the RESUMING phase
   - Userspace uses the filestream created in #3 to send the source guest's
     AP configuration information to the vfio_ap device driver on the
     destination host.
   - The vfio_ap device driver first verifies the source guest's AP
     configuration is compatible with the destination host's.
   - The driver restores AP configuration to the mdev on the destination
     host which automatically hot plugs the AP resources identified
     therein.

5. Documentation
   - Add live guest migration chapter to vfio-ap.rst

Compatibility Validation
~~~~~~~~~~~~~~~~~~~~~~~~

The series includes comprehensive validation to ensure source and
destination AP configurations are compatible. For each queue, the following
characteristics must match:

- AP type (target must be same or newer than source)
- Installed facilities (APSC, APQKM, AP4KC, SLCF)
- Operating mode (CCA, Accelerator, XCP)
- APXA facility setting
- Classification (native vs stateless functions)
- Queue usability (binding/associated state)

When incompatibilities are detected, migration fails with detailed error
messages identifying the specific queue and characteristic that caused
the failure.

Configuration Management
~~~~~~~~~~~~~~~~~~~~~~~~

This implementation does not prevent configuration changes during
migration. Configuration stability is an orchestration-layer
responsibility, consistent with other VFIO device types. The driver's
role is to validate configurations and provide clear diagnostics when
incompatibilities are detected, enabling orchestration tools to implement
appropriate policies.

QEMU patches exploiting this series:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
https://lore.kernel.org/qemu-devel/20260409141352.997844-1-akrowiak@linux.ibm.com/

Change log v3 => v4:
~~~~~~~~~~~~~~~~~~~
Patch 2:
* Fixed kernel-doc fields that didn't match structures
* Removed config_sz field from vfio_ap_config structure; it was a dup of
  the config_sz in the vfio_ap_migration_data structure.
* Added a vfio_ap_mig_file structure to use to store AP configuration data
  between calls to the read/write callbacks invoked from userspace during
  the STOP_COPY (read) and RESUMING (write) phases of migration.
* Added adm field for control domains to the vfio_ap_config structure

Patch 3:
* Free storage for mig_data->resuming_mig_state.ap_config in the
  vfio_ap_release_migration_data function to fix potential memory leak.
* Release matrix_dev->mdevs_lock in error path before vfio_put_device in
  the vfio_ap_mdev_probe function to avoid deadlock when the VFIO device is
  released.

Patch 5:
* Replaced dev_err with dev_err_once for the migration not allowed for SE
  guests since SE guest status is fixed at boot time and there is no value
  in printing the message more than once. That circumvents a potential a
  kernel log flood if the ioctl is called in a tight loop.
* Check for VFIO_DEVICE_STATE_ERROR for while loop in the vfio_ap_set_state
  function
* Restored vfio_ap_release_mig_files function removed via this patch and
  again calling it from the vfio_ap_reset_migration_state function.

Patch 6:
* Refactored vfio_ap_release_mig_file function to take the
  matrix_dev->mdevs_lock for the duration of the function

Patch 7:
* Refactored the vfio_ap_stop_copy_read callback to use the new
  vfio_ap_mig_file structure (see Patch 2 above) to store the source
  guest's AP configuration between calls.
* Now migrating control domains

Patch 9:
* Removed filtering_allowed parameter and make it encumbent upon the caller
  to validate the queues are available and bound to the vfio_ap device
  driver and the control domains are in the host's AP config

Patch 10:
* Move setting the mig_data->resuming_mig_state.ap_config and
  mig_data->resuming_mig_state.config_sz values outside of check for
  completion of the write callback.
* Added cur_cfg_sz parameter to reallocat_ap_config function due to removal
  of config_sz field in the vfio_ap_migration_data structure (see Patch 2
  changes above)
* Refactored the vfio_ap_resuming_write callback to use the new
  vfio_ap_mig_file structure (see Patch 2 above) to store the source
  guest's AP configuration between calls.
* Now migrating control domains
* Added check for source and destination BS bits set to 0 if the hardware
  info for both matches
* Added initialization for guest_matrix before call to
  setup_ap_matrix_from_ap_config

Patch 15:
* Added debug log messages for unavailable control domains on destination
  host
* Fixed a few misspellings and format errors.

Anthony Krowiak (15):
  s390/vfio-ap: Provide function to get the number of queues assigned to
    mdev
  s390/vfio-ap: Data structures for facilitating vfio device migration
  s390/vfio-ap: Functions to initialize/release vfio device migration
    data
  s390/vfio-ap: Reset migration state in VFIO_DEVICE_RESET ioctl handler
  s390-vfio-ap: Callback to get/set vfio device mig state during guest
    migration
  s390/vfio-ap: Transition guest migration state from STOP to STOP_COPY
  s390/vfio-ap: File ops called to save the vfio device migration state
  s390/vfio-ap: Transition device migration state from STOP to RESUMING
  s390/vfio-ap: Add method to set a new guest AP configuration
  s390/vfio-ap: File ops called to resume the vfio device migration
  s390/vfio-ap: Transition device migration state to STOP
  s390/vfio-ap: Transition device migration state from STOP to RUNNING
    and vice versa
  s390/vfio-ap: Callback to get the size of data to be migrated during
    guest migration
  s390/vfio-ap: Add 'migratable' feature to sysfs 'features' attribute
  s390/vfio-ap: Add live guest migration chapter to vfio-ap.rst

 Documentation/arch/s390/vfio-ap.rst     |  514 +++++++--
 drivers/s390/crypto/Makefile            |    2 +-
 drivers/s390/crypto/vfio_ap_drv.c       |    4 +-
 drivers/s390/crypto/vfio_ap_migration.c | 1373 +++++++++++++++++++++++
 drivers/s390/crypto/vfio_ap_ops.c       |  462 ++++++--
 drivers/s390/crypto/vfio_ap_private.h   |   72 ++
 6 files changed, 2225 insertions(+), 202 deletions(-)
 create mode 100644 drivers/s390/crypto/vfio_ap_migration.c

--
2.53.0

[PATCH v4 01/15] s390/vfio-ap: Provide function to get the number of queues assigned to mdev

[Anthony Krowiak]

Provides a function that returns the number of queues that are or will be
passed through to a guest when the mdev is attached to a guest.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c     | 14 ++++++++++++++
 drivers/s390/crypto/vfio_ap_private.h |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 44b3a1dcc1b3..71d3e2c2e07c 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -2098,6 +2098,20 @@ static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)
 	release_update_locks_for_mdev(matrix_mdev);
 }
 
+int vfio_ap_mdev_get_num_queues(struct ap_matrix *ap_matrix)
+{
+	unsigned long apid, apqi;
+	int num_queues = 0;
+
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	for_each_set_bit_inv(apid, ap_matrix->apm, AP_DEVICES)
+		for_each_set_bit_inv(apqi, ap_matrix->aqm, AP_DOMAINS)
+			num_queues++;
+
+	return num_queues;
+}
+
 static int vfio_ap_mdev_get_device_info(unsigned long arg)
 {
 	unsigned long minsz;
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 9bff666b0b35..9677e49554d7 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -152,6 +152,8 @@ struct vfio_ap_queue {
 	struct work_struct reset_work;
 };
 
+int vfio_ap_mdev_get_num_queues(struct ap_matrix *ap_matrix);
+
 int vfio_ap_mdev_register(void);
 void vfio_ap_mdev_unregister(void);
 
-- 
2.53.0

[PATCH v4 02/15] s390/vfio-ap: Data structures for facilitating vfio device migration

[Anthony Krowiak]

Creates the data structures used to facilitate state transitions during
vfio device migration.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/Makefile            |  2 +-
 drivers/s390/crypto/vfio_ap_migration.c | 56 +++++++++++++++++++++++++
 drivers/s390/crypto/vfio_ap_private.h   |  5 +++
 3 files changed, 62 insertions(+), 1 deletion(-)
 create mode 100644 drivers/s390/crypto/vfio_ap_migration.c

diff --git a/drivers/s390/crypto/Makefile b/drivers/s390/crypto/Makefile
index e83c6603c858..20f29184825a 100644
--- a/drivers/s390/crypto/Makefile
+++ b/drivers/s390/crypto/Makefile
@@ -34,5 +34,5 @@ pkey-uv-objs := pkey_uv.o
 obj-$(CONFIG_PKEY_UV) += pkey-uv.o
 
 # adjunct processor matrix
-vfio_ap-objs := vfio_ap_drv.o vfio_ap_ops.o
+vfio_ap-objs := vfio_ap_drv.o vfio_ap_ops.o vfio_ap_migration.o
 obj-$(CONFIG_VFIO_AP) += vfio_ap.o
diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
new file mode 100644
index 000000000000..239168c4b7ff
--- /dev/null
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Drives vfio_ap mdev migration.
+ *
+ * Copyright IBM Corp. 2025
+ */
+#include "vfio_ap_private.h"
+
+/**
+ * vfio_ap_migration_data - the data needed to migrate a guest with pass-through
+ *			    access to AP devices
+ *
+ * @mig_state:		the current migration state
+ * @resuming_migf:	the object used to resume the target guest
+ * @saving_migf:	the object used to save the state of the source guest
+ */
+struct vfio_ap_migration_data {
+	enum vfio_device_mig_state	mig_state;
+
+	struct {
+		struct file *filp;
+		struct vfio_ap_config	*ap_config;
+		size_t			config_sz;
+	} resuming_mig_state;
+
+	struct file			*stop_copy_mig_file;
+};
+
+/**
+ * vfio_ap_queue_info - the information for an AP queue
+ *
+ * @data: contains the queue information returned in GR2 from the PQAP(TAPQ)
+ *	  command
+ * @apqn: the APQN of the queue
+ * @reserved: padding to ensure consistent structure size across platforms
+ */
+struct vfio_ap_queue_info {
+	u64 data;
+	u16 apqn;
+	u8  reserved[6];
+};
+
+/**
+ * vfio_ap_config - the guest's AP configuration
+ *
+ * @num_queues:	the number of queues passed through to the guest
+ * @reserved: padding to ensure proper alignment of qinfo array
+ * @qinfo:	an array of vfio_ap_queue_info objects, each specifying the
+ *		queue information for a queue passed through to the guest
+ */
+struct vfio_ap_config {
+	u32				num_queues;
+	u8				reserved[4];
+	size_t				config_sz;
+	struct vfio_ap_queue_info	qinfo[] __counted_by(num_queues);
+};
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 9677e49554d7..2b542648964b 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -91,6 +91,9 @@ struct ap_queue_table {
 	DECLARE_HASHTABLE(queues, 8);
 };
 
+/* Forward declaration for migration data structure */
+struct vfio_ap_migration_data;
+
 /**
  * struct ap_matrix_mdev - Contains the data associated with a matrix mediated
  *			   device.
@@ -110,6 +113,7 @@ struct ap_queue_table {
  * @aqm_add:	bitmap of APQIs added to the host's AP configuration
  * @adm_add:	bitmap of control domain numbers added to the host's AP
  *		configuration
+ * @mig_data:  vfio device migration data
  */
 struct ap_matrix_mdev {
 	struct vfio_device vdev;
@@ -125,6 +129,7 @@ struct ap_matrix_mdev {
 	DECLARE_BITMAP(apm_add, AP_DEVICES);
 	DECLARE_BITMAP(aqm_add, AP_DOMAINS);
 	DECLARE_BITMAP(adm_add, AP_DOMAINS);
+	struct vfio_ap_migration_data *mig_data;
 };
 
 /**
-- 
2.53.0

[PATCH v4 03/15] s390/vfio-ap: Functions to initialize/release vfio device migration data

[Anthony Krowiak]

Provides the functions that initialize and release the data structures
used during live guest migration:

* vfio_ap_init_migration_capabilities

  Sets the migration flags and vfio_migration_ops structure into the
  vfio_device object when the mdev is probed.

* vfio_ap_init_migration_data

  Allocates and initializes the object used to maintain the state of the
  VFIO migration. It is called when the VFIO device is opened.

* vfio_ap_release_migration_data

  Frees the memory of the object used to maintain the VFIO migration state.
  It is called when the VFIO device release callback is invoked and when
  the VFIO device is closed.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 75 +++++++++++++++++++++++++
 drivers/s390/crypto/vfio_ap_ops.c       | 60 +++++++++++++++++---
 drivers/s390/crypto/vfio_ap_private.h   |  4 ++
 3 files changed, 131 insertions(+), 8 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 239168c4b7ff..5b6d48ccf332 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -4,6 +4,7 @@
  *
  * Copyright IBM Corp. 2025
  */
+#include <linux/file.h>
 #include "vfio_ap_private.h"
 
 /**
@@ -54,3 +55,77 @@ struct vfio_ap_config {
 	size_t				config_sz;
 	struct vfio_ap_queue_info	qinfo[] __counted_by(num_queues);
 };
+
+static struct file *vfio_ap_set_state(struct vfio_device *vdev,
+				      enum vfio_device_mig_state  new_state)
+{
+	return NULL;
+}
+
+static int vfio_ap_get_state(struct vfio_device *vdev,
+			     enum vfio_device_mig_state  *current_state)
+{
+	return -EOPNOTSUPP;
+}
+
+static int vfio_ap_get_data_size(struct vfio_device *vdev,
+				 unsigned long *stop_copy_length)
+{
+	return -EOPNOTSUPP;
+}
+
+static const struct vfio_migration_ops vfio_ap_migration_ops = {
+	.migration_set_state = vfio_ap_set_state,
+	.migration_get_state = vfio_ap_get_state,
+	.migration_get_data_size = vfio_ap_get_data_size,
+};
+
+/**
+ * vfio_ap_init_migrations_capabilities - initialize migration capabilities
+ *
+ * @matrix_mdev: pointer to object containing the mdev state
+ */
+void vfio_ap_init_migration_capabilities(struct ap_matrix_mdev *matrix_mdev)
+{
+	matrix_mdev->vdev.migration_flags = VFIO_MIGRATION_STOP_COPY;
+	matrix_mdev->vdev.mig_ops = &vfio_ap_migration_ops;
+}
+
+/**
+ * vfio_ap_init_migration_data - initialize migration data and functions
+ *
+ * @matrix_mdev: pointer to object containing the mdev state
+ *
+ * Return: zero if initialization is successful; otherwise, returns a error.
+ */
+int vfio_ap_init_migration_data(struct ap_matrix_mdev *matrix_mdev)
+{
+	struct vfio_ap_migration_data *mig_data;
+
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	mig_data = kzalloc_obj(struct vfio_ap_migration_data, GFP_KERNEL);
+	if (!mig_data)
+		return -ENOMEM;
+
+	mig_data->mig_state = VFIO_DEVICE_STATE_RUNNING;
+	matrix_mdev->mig_data = mig_data;
+
+	return 0;
+}
+
+/**
+ * vfio_ap_release_migration_data: reclaim private migration data
+ *
+ * @vdev: pointer to the mdev
+ */
+void vfio_ap_release_migration_data(struct ap_matrix_mdev *matrix_mdev)
+{
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	if (!matrix_mdev->mig_data)
+		return;
+
+	kfree(matrix_mdev->mig_data);
+	matrix_mdev->mig_data = NULL;
+}
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 71d3e2c2e07c..813290214866 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -775,18 +775,30 @@ static bool vfio_ap_mdev_filter_matrix(struct ap_matrix_mdev *matrix_mdev,
 
 static int vfio_ap_mdev_init_dev(struct vfio_device *vdev)
 {
-	struct ap_matrix_mdev *matrix_mdev =
-		container_of(vdev, struct ap_matrix_mdev, vdev);
+	struct ap_matrix_mdev *matrix_mdev;
 
+	mutex_lock(&matrix_dev->mdevs_lock);
+	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
 	matrix_mdev->mdev = to_mdev_device(vdev->dev);
 	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
 	matrix_mdev->pqap_hook = handle_pqap;
 	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
 	hash_init(matrix_mdev->qtable.queues);
+	mutex_unlock(&matrix_dev->mdevs_lock);
 
 	return 0;
 }
 
+static void vfio_ap_mdev_release_dev(struct vfio_device *vdev)
+{
+	struct ap_matrix_mdev *matrix_mdev;
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
+	vfio_ap_release_migration_data(matrix_mdev);
+	mutex_unlock(&matrix_dev->mdevs_lock);
+}
+
 static int vfio_ap_mdev_probe(struct mdev_device *mdev)
 {
 	struct ap_matrix_mdev *matrix_mdev;
@@ -797,19 +809,30 @@ static int vfio_ap_mdev_probe(struct mdev_device *mdev)
 	if (IS_ERR(matrix_mdev))
 		return PTR_ERR(matrix_mdev);
 
+	mutex_lock(&matrix_dev->mdevs_lock);
+
+	/*
+	 * Migration capabilities must be initialized before calling
+	 * vfio_register_emulated_iommu_dev; otherwise, the VFIO core
+	 * will see mig_ops as NULL during the registration. This could
+	 * prevent the VFIO core from properly setting up migration
+	 * infrastructure like debugfs entries.
+	 */
+	vfio_ap_init_migration_capabilities(matrix_mdev);
+
 	ret = vfio_register_emulated_iommu_dev(&matrix_mdev->vdev);
 	if (ret)
 		goto err_put_vdev;
 	matrix_mdev->req_trigger = NULL;
 	matrix_mdev->cfg_chg_trigger = NULL;
 	dev_set_drvdata(&mdev->dev, matrix_mdev);
-	mutex_lock(&matrix_dev->mdevs_lock);
 	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
 	mutex_unlock(&matrix_dev->mdevs_lock);
 	return 0;
 
 err_put_vdev:
 	vfio_put_device(&matrix_mdev->vdev);
+	mutex_unlock(&matrix_dev->mdevs_lock);
 	return ret;
 }
 
@@ -2052,19 +2075,39 @@ static int vfio_ap_mdev_reset_qlist(struct list_head *qlist)
 
 static int vfio_ap_mdev_open_device(struct vfio_device *vdev)
 {
-	struct ap_matrix_mdev *matrix_mdev =
-		container_of(vdev, struct ap_matrix_mdev, vdev);
+	struct ap_matrix_mdev *matrix_mdev;
+	int ret;
 
 	if (!vdev->kvm)
 		return -EINVAL;
 
-	return vfio_ap_mdev_set_kvm(matrix_mdev, vdev->kvm);
+	mutex_lock(&matrix_dev->mdevs_lock);
+	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
+	ret = vfio_ap_init_migration_data(matrix_mdev);
+	mutex_unlock(&matrix_dev->mdevs_lock);
+
+	if (ret)
+		return ret;
+
+	ret = vfio_ap_mdev_set_kvm(matrix_mdev, vdev->kvm);
+	if (ret) {
+		/* Clean up migration data on failure */
+		mutex_lock(&matrix_dev->mdevs_lock);
+		vfio_ap_release_migration_data(matrix_mdev);
+		mutex_unlock(&matrix_dev->mdevs_lock);
+	}
+
+	return ret;
 }
 
 static void vfio_ap_mdev_close_device(struct vfio_device *vdev)
 {
-	struct ap_matrix_mdev *matrix_mdev =
-		container_of(vdev, struct ap_matrix_mdev, vdev);
+	struct ap_matrix_mdev *matrix_mdev;
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
+	vfio_ap_release_migration_data(matrix_mdev);
+	mutex_unlock(&matrix_dev->mdevs_lock);
 
 	vfio_ap_mdev_unset_kvm(matrix_mdev);
 }
@@ -2374,6 +2417,7 @@ static const struct attribute_group vfio_queue_attr_group = {
 
 static const struct vfio_device_ops vfio_ap_matrix_dev_ops = {
 	.init = vfio_ap_mdev_init_dev,
+	.release = vfio_ap_mdev_release_dev,
 	.open_device = vfio_ap_mdev_open_device,
 	.close_device = vfio_ap_mdev_close_device,
 	.ioctl = vfio_ap_mdev_ioctl,
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 2b542648964b..a2a713f93674 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -172,4 +172,8 @@ void vfio_ap_on_cfg_changed(struct ap_config_info *new_config_info,
 void vfio_ap_on_scan_complete(struct ap_config_info *new_config_info,
 			      struct ap_config_info *old_config_info);
 
+void vfio_ap_init_migration_capabilities(struct ap_matrix_mdev *matrix_mdev);
+int vfio_ap_init_migration_data(struct ap_matrix_mdev *matrix_mdev);
+void vfio_ap_release_migration_data(struct ap_matrix_mdev *matrix_mdev);
+
 #endif /* _VFIO_AP_PRIVATE_H_ */
-- 
2.53.0

[PATCH v4 04/15] s390/vfio-ap: Reset migration state in VFIO_DEVICE_RESET ioctl handler

[Anthony Krowiak]

According to the VFIO migration specifications, userspace must issue a
VFIO_DEVICE_RESET ioctl if a vfio device enters an error state or fails a
state transition to recover the device and return its migration state to
RUNNING. This patch adds a function that is called when a VFIO_DEVICE_RESET
is issued that releases the migration files and frees the storage allocated
for maintaining the migration state.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 20 ++++++++++++++++++++
 drivers/s390/crypto/vfio_ap_ops.c       |  4 ++++
 drivers/s390/crypto/vfio_ap_private.h   |  1 +
 3 files changed, 25 insertions(+)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 5b6d48ccf332..c7c71980bdbb 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -129,3 +129,23 @@ void vfio_ap_release_migration_data(struct ap_matrix_mdev *matrix_mdev)
 	kfree(matrix_mdev->mig_data);
 	matrix_mdev->mig_data = NULL;
 }
+
+/**
+ * vfio_ap_reset_migration_state - Reset the vfio-ap migration state
+ *
+ * @matrix_mdev: pointer to the object maintaining the vfio-ap device state
+ *
+ * Called during VFIO_DEVICE_RESET to clean up any active migration
+ * stte and reset the device to RUNNING state as required by the VFIO
+ * migration specification.
+ */
+void vfio_ap_reset_migration_state(struct ap_matrix_mdev *matrix_mdev)
+{
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	if (!matrix_mdev->mig_data)
+		return;
+
+	vfio_ap_release_mig_files(matrix_mdev);
+	matrix_mdev->mig_data->mig_state = VFIO_DEVICE_STATE_RUNNING;
+}
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 813290214866..8a9e83921f74 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -2332,6 +2332,10 @@ static ssize_t vfio_ap_mdev_ioctl(struct vfio_device *vdev,
 		break;
 	case VFIO_DEVICE_RESET:
 		ret = vfio_ap_mdev_reset_queues(matrix_mdev);
+		if (ret == 0) {
+			/* Reset migration state per VFIO migration spec */
+			vfio_ap_reset_migration_state(matrix_mdev);
+		}
 		break;
 	case VFIO_DEVICE_GET_IRQ_INFO:
 		ret = vfio_ap_get_irq_info(arg);
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index a2a713f93674..1fbdfcce5a11 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -175,5 +175,6 @@ void vfio_ap_on_scan_complete(struct ap_config_info *new_config_info,
 void vfio_ap_init_migration_capabilities(struct ap_matrix_mdev *matrix_mdev);
 int vfio_ap_init_migration_data(struct ap_matrix_mdev *matrix_mdev);
 void vfio_ap_release_migration_data(struct ap_matrix_mdev *matrix_mdev);
+void vfio_ap_reset_migration_state(struct ap_matrix_mdev *matrix_mdev);
 
 #endif /* _VFIO_AP_PRIVATE_H_ */
-- 
2.53.0

[PATCH v4 05/15] s390-vfio-ap: Callback to get/set vfio device mig state during guest migration

[Anthony Krowiak]

Implements two callbacks related to the current state of a vfio-ap device:
* The callback that sets a new migration state of a vfio-ap device during
  live migration of guests with pass-through access to AP devices. This
  callback is mandatory for VFIO_DEVICE_FEATURE_MIGRATION support.

  The function pointer for this callback is specified via the
  'migration_set_state' field of the 'vfio_migration_ops' structure
  which is stored with the VFIO device when the 'vfio_device'
  structure representing the mediated device is initialized.

* The callback that returns the current vfio device migration state during
  live migration of guests with pass-through access to AP devices.

  The function pointer for this callback is specified via the
  'migration_get_state' field of the 'vfio_migration_ops' structure
  which is stored with the VFIO device when the 'vfio_device'
  structure representing the mediated device is initialized.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 130 +++++++++++++++++++++++-
 1 file changed, 127 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index c7c71980bdbb..8274e7b65eea 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -5,6 +5,7 @@
  * Copyright IBM Corp. 2025
  */
 #include <linux/file.h>
+#include "ap_bus.h"
 #include "vfio_ap_private.h"
 
 /**
@@ -56,16 +57,140 @@ struct vfio_ap_config {
 	struct vfio_ap_queue_info	qinfo[] __counted_by(num_queues);
 };
 
+static struct file *
+vfio_ap_transition_to_state(struct ap_matrix_mdev *matrix_mdev,
+			    enum vfio_device_mig_state new_state)
+{
+	struct vfio_ap_migration_data *mig_data;
+	enum vfio_device_mig_state cur_state;
+
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+	mig_data = matrix_mdev->mig_data;
+	cur_state = mig_data->mig_state;
+	dev_dbg(matrix_mdev->vdev.dev, "%s: %d -> %d\n", __func__, cur_state,
+		new_state);
+
+	if (cur_state == VFIO_DEVICE_STATE_STOP &&
+	    new_state == VFIO_DEVICE_STATE_STOP_COPY) {
+		/* TODO */
+		return ERR_PTR(-EOPNOTSUPP);
+	}
+
+	if (cur_state == VFIO_DEVICE_STATE_STOP &&
+	    new_state == VFIO_DEVICE_STATE_RESUMING) {
+		/* TODO */
+		return ERR_PTR(-EOPNOTSUPP);
+	}
+
+	if ((cur_state == VFIO_DEVICE_STATE_RESUMING &&
+	     new_state == VFIO_DEVICE_STATE_STOP) ||
+	    (cur_state == VFIO_DEVICE_STATE_STOP_COPY &&
+	     new_state == VFIO_DEVICE_STATE_STOP)) {
+		/* TODO */
+		return ERR_PTR(-EOPNOTSUPP);
+	}
+
+	if ((cur_state == VFIO_DEVICE_STATE_STOP &&
+	     new_state == VFIO_DEVICE_STATE_RUNNING) ||
+	    (cur_state == VFIO_DEVICE_STATE_RUNNING &&
+	     new_state == VFIO_DEVICE_STATE_STOP)) {
+		/* TODO */
+		return ERR_PTR(-EOPNOTSUPP);
+	}
+
+	/* vfio_mig_get_next_state() does not use arcs other than the above */
+	WARN_ON(true);
+
+	return ERR_PTR(-EINVAL);
+}
+
 static struct file *vfio_ap_set_state(struct vfio_device *vdev,
 				      enum vfio_device_mig_state  new_state)
 {
-	return NULL;
+	int ret;
+	struct file *filp = NULL;
+	struct ap_matrix_mdev *matrix_mdev;
+	enum vfio_device_mig_state next_state;
+	struct vfio_ap_migration_data *mig_data;
+
+	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+	if (ap_is_se_guest()) {
+		dev_err(matrix_mdev->vdev.dev,
+			"Migration not allowed from or to a Secure Execution guest\n");
+		mutex_unlock(&matrix_dev->mdevs_lock);
+		return ERR_PTR(-EPERM);
+	}
+
+	mig_data = matrix_mdev->mig_data;
+
+	/*
+	 * The mig_data pointer is set in the vfio_ap_init_migration_data
+	 * function which is called when the vfio-ap device fd is opened.
+	 * Since the implicit pre-open state is RUNNING, a request to set
+	 * RUNNING is a no-op. Any other state transition is invalid before
+	 * open_device.
+	 */
+	if (!mig_data) {
+		mutex_unlock(&matrix_dev->mdevs_lock);
+		if (new_state == VFIO_DEVICE_STATE_RUNNING)
+			return NULL;
+		return ERR_PTR(-ENODEV);
+	}
+
+	dev_dbg(vdev->dev, "%s -> %d\n", __func__, new_state);
+
+	while (mig_data->mig_state != new_state) {
+		ret = vfio_mig_get_next_state(vdev, mig_data->mig_state,
+					      new_state, &next_state);
+		if (ret) {
+			filp = ERR_PTR(ret);
+			break;
+		}
+
+		filp = vfio_ap_transition_to_state(matrix_mdev, next_state);
+		if (IS_ERR(filp))
+			break;
+
+		mig_data->mig_state = next_state;
+
+		if (WARN_ON(filp && new_state != next_state)) {
+			fput(filp);
+			filp = ERR_PTR(-EINVAL);
+			break;
+		}
+	}
+
+	mutex_unlock(&matrix_dev->mdevs_lock);
+
+	return filp;
 }
 
 static int vfio_ap_get_state(struct vfio_device *vdev,
 			     enum vfio_device_mig_state  *current_state)
 {
-	return -EOPNOTSUPP;
+	struct ap_matrix_mdev *matrix_mdev;
+	struct vfio_ap_migration_data *mig_data;
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+
+	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
+	mig_data =  matrix_mdev->mig_data;
+
+	/*
+	 * The mig_data pointer is set in the vfio_ap_init_migration_data
+	 * function which is called when the vfio-ap device fd is opened.
+	 * If mig_data is NULL, report RUNNING as the implicit pre-open state
+	 * so userspace doesn't need to perform any state transition before the
+	 * device becomes active.
+	 */
+	*current_state = (mig_data) ? mig_data->mig_state :
+				      VFIO_DEVICE_STATE_RUNNING;
+
+	mutex_unlock(&matrix_dev->mdevs_lock);
+
+	return 0;
 }
 
 static int vfio_ap_get_data_size(struct vfio_device *vdev,
@@ -146,6 +271,5 @@ void vfio_ap_reset_migration_state(struct ap_matrix_mdev *matrix_mdev)
 	if (!matrix_mdev->mig_data)
 		return;
 
-	vfio_ap_release_mig_files(matrix_mdev);
 	matrix_mdev->mig_data->mig_state = VFIO_DEVICE_STATE_RUNNING;
 }
-- 
2.53.0

[PATCH v4 06/15] s390/vfio-ap: Transition guest migration state from STOP to STOP_COPY

[Anthony Krowiak]

The transition of the guest migration state from VFIO_DEVICE_STATE_STOP to
VFIO_DEVICE_STATE_STOP_COPY begins the process of saving the
vfio device state. The vfio device state is comprised of the guest's
AP configuration which specifies the adapters, domains and control
domains to which the guest will be given access.

To begin the process of saving the vfio device state, the VFIO AP device
driver opens a file stream that will be used to read the source guest's
AP configuration.

Note:
This commit introduces the file operations structure for migration state
files with a stub implementation of the read operation. The complete
implementation is provided in the subsequent commit.

This incremental approach allows for easier review of the migration
infrastructure setup separate from the actual implementation logic.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 68 ++++++++++++++++++++++++-
 1 file changed, 66 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 8274e7b65eea..76e06abe5a9e 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -4,6 +4,7 @@
  *
  * Copyright IBM Corp. 2025
  */
+#include <linux/anon_inodes.h>
 #include <linux/file.h>
 #include "ap_bus.h"
 #include "vfio_ap_private.h"
@@ -57,6 +58,57 @@ struct vfio_ap_config {
 	struct vfio_ap_queue_info	qinfo[] __counted_by(num_queues);
 };
 
+static void
+vfio_ap_release_stop_copy_file(struct vfio_ap_migration_data *mig_data)
+{
+	if (mig_data->stop_copy_mig_file)
+		mig_data->stop_copy_mig_file = NULL;
+}
+
+static ssize_t
+vfio_ap_stop_copy_read(struct file *, char __user *, size_t, loff_t *)
+{
+	/* TODO */
+	return -EOPNOTSUPP;
+}
+
+static int vfio_ap_release_mig_file(struct inode *file_inode, struct file *filp)
+{
+	struct ap_matrix_mdev *matrix_mdev = filp->private_data;
+
+	if (!matrix_mdev || !matrix_mdev->mig_data)
+		return -ENODEV;
+
+	if (filp == matrix_mdev->mig_data->stop_copy_mig_file)
+		vfio_ap_release_stop_copy_file(matrix_mdev->mig_data);
+	else
+		return -ENOENT;
+
+	return 0;
+}
+
+static const struct file_operations vfio_ap_stop_copy_fops = {
+	.owner = THIS_MODULE,
+	.read = vfio_ap_stop_copy_read,
+	.compat_ioctl = compat_ptr_ioctl,
+	.release = vfio_ap_release_mig_file,
+};
+
+static struct file *vfio_ap_open_file_stream(struct ap_matrix_mdev *matrix_mdev,
+					     const struct file_operations *fops,
+					     int flags)
+{
+	struct file *filp;
+
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	filp = anon_inode_getfile("vfio_ap_mig_file", fops, matrix_mdev, flags);
+	if (!IS_ERR(filp))
+		stream_open(filp->f_inode, filp);
+
+	return filp;
+}
+
 static struct file *
 vfio_ap_transition_to_state(struct ap_matrix_mdev *matrix_mdev,
 			    enum vfio_device_mig_state new_state)
@@ -70,10 +122,22 @@ vfio_ap_transition_to_state(struct ap_matrix_mdev *matrix_mdev,
 	dev_dbg(matrix_mdev->vdev.dev, "%s: %d -> %d\n", __func__, cur_state,
 		new_state);
 
+	/*
+	 * Begins the process of saving the vfio device state by creating and
+	 * returning a streaming data_fd to be used to read out the internal
+	 * state of the vfio-ap device on the source host.
+	 */
 	if (cur_state == VFIO_DEVICE_STATE_STOP &&
 	    new_state == VFIO_DEVICE_STATE_STOP_COPY) {
-		/* TODO */
-		return ERR_PTR(-EOPNOTSUPP);
+		struct file *filp = vfio_ap_open_file_stream(matrix_mdev,
+							     &vfio_ap_stop_copy_fops,
+							     O_RDONLY);
+		if (IS_ERR(filp))
+			return ERR_CAST(filp);
+
+		mig_data->stop_copy_mig_file = filp;
+
+		return filp;
 	}
 
 	if (cur_state == VFIO_DEVICE_STATE_STOP &&
-- 
2.53.0

[PATCH v4 07/15] s390/vfio-ap: File ops called to save the vfio device migration state

[Anthony Krowiak]

Implements the read callback function that was added to the
file_operations structure for the file created to save the state of the
vfio-ap device when the migration state transitioned from STOP to
to the STOP_COPY state.

This function copies the guest's AP configuration information to
userspace. The information copied is comprised of the APQN of each queue
device passed through to the guest along with its hardware information.
This state data will be transferred to the vfio_ap device driver on the
destination host when the state is transitioned to RESUMING.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 216 +++++++++++++++++++++++-
 1 file changed, 209 insertions(+), 7 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 76e06abe5a9e..5ef7127b697a 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -65,13 +65,6 @@ vfio_ap_release_stop_copy_file(struct vfio_ap_migration_data *mig_data)
 		mig_data->stop_copy_mig_file = NULL;
 }
 
-static ssize_t
-vfio_ap_stop_copy_read(struct file *, char __user *, size_t, loff_t *)
-{
-	/* TODO */
-	return -EOPNOTSUPP;
-}
-
 static int vfio_ap_release_mig_file(struct inode *file_inode, struct file *filp)
 {
 	struct ap_matrix_mdev *matrix_mdev = filp->private_data;
@@ -87,6 +80,215 @@ static int vfio_ap_release_mig_file(struct inode *file_inode, struct file *filp)
 	return 0;
 }
 
+/**
+ * validate_stop_copy_read_parms: Validate the input parameters to the
+ *                                vfio_ap_stop_copy_read function
+ *
+ * @matrix_mdev: The object device containing the state to be read
+ * @filp: Pointer to the file stream used to read the vfio-ap device state
+ * @pos:  The file offset from which to start reading data
+ * @len:  The length of the data to be read
+ *
+ * Verify the following:
+ * - @filp private data is an ap_matrix_mdev instance
+ * - @filp is the instance opened when state transitioned from STOP to STOP_COPY
+ * - @pos + @len does not cause integer overflow
+ *
+ * Returns: 0 if the parameters pass validation; otherwise returns an error
+ */
+static int validate_stop_copy_read_parms(struct file *filp, loff_t *pos,
+					 size_t len)
+{
+	struct vfio_ap_migration_data *mig_data;
+	struct ap_matrix_mdev *matrix_mdev;
+	loff_t total_len;
+
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	if (check_add_overflow((loff_t)len, *pos, &total_len))
+		return -EIO;
+
+	matrix_mdev = filp->private_data;
+
+	if (!matrix_mdev || !matrix_mdev->mig_data)
+		return -ENODEV;
+
+	mig_data = matrix_mdev->mig_data;
+
+	if (mig_data->stop_copy_mig_file != filp)
+		return -EINVAL;
+
+	return 0;
+}
+
+static size_t vfio_ap_config_size(struct ap_matrix_mdev *matrix_mdev,
+				  int *num_queues)
+{
+	size_t qinfo_size;
+
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	*num_queues = vfio_ap_mdev_get_num_queues(&matrix_mdev->shadow_apcb);
+	qinfo_size = *num_queues * sizeof(struct vfio_ap_queue_info);
+
+	return qinfo_size + sizeof(struct vfio_ap_config);
+}
+
+static int get_hardware_info_for_queue(struct ap_matrix_mdev *matrix_mdev,
+				       struct ap_tapq_hwinfo *hwinfo,
+				       unsigned long apqn)
+{
+	struct ap_queue_status status;
+
+	status = ap_tapq(apqn, hwinfo);
+
+	switch (status.response_code) {
+	case AP_RESPONSE_NORMAL:
+	case AP_RESPONSE_RESET_IN_PROGRESS:
+	case AP_RESPONSE_DECONFIGURED:
+	case AP_RESPONSE_CHECKSTOPPED:
+	case AP_RESPONSE_BUSY:
+		/* For all these RCs the tapq info should be available */
+		return 0;
+	case AP_RESPONSE_Q_NOT_AVAIL:
+		dev_err(matrix_mdev->vdev.dev,
+			"migration failed: Failed to get hwinfo for queue %02lx.%04lx on target host: TAPQ rc=%d",
+			AP_QID_CARD(apqn), AP_QID_QUEUE(apqn), status.response_code);
+		return -ENODEV;
+	default:
+		/* On a pending async error the tapq info should be available */
+		if (!status.async)
+			return 0;
+
+		dev_err(matrix_mdev->vdev.dev,
+			"Failed to get hwinfo for queue %02lx.%04lx: TAPQ rc=%d",
+			AP_QID_CARD(apqn), AP_QID_QUEUE(apqn), status.response_code);
+		return -EIO;
+	}
+
+	return -EINVAL;
+}
+
+static int vfio_ap_store_queue_info(struct ap_matrix_mdev *matrix_mdev,
+				    struct vfio_ap_config *ap_config)
+{
+	unsigned long *apm, *aqm, num_queues, apid, apqi, apqn;
+	struct ap_tapq_hwinfo source_hwinfo;
+	int ret;
+
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	apm = matrix_mdev->shadow_apcb.apm;
+	aqm = matrix_mdev->shadow_apcb.aqm;
+	num_queues = 0;
+
+	for_each_set_bit_inv(apid, apm, AP_DEVICES) {
+		for_each_set_bit_inv(apqi, aqm, AP_DOMAINS) {
+			apqn = AP_MKQID(apid, apqi);
+
+			ret = get_hardware_info_for_queue(matrix_mdev,
+							  &source_hwinfo, apqn);
+			if (ret)
+				return ret;
+
+			ap_config->qinfo[num_queues].apqn = apqn;
+			ap_config->qinfo[num_queues].data = source_hwinfo.value;
+			num_queues += 1;
+		}
+	}
+
+	return (num_queues != ap_config->num_queues) ? -EINVAL : 0;
+}
+
+static int
+vfio_ap_get_config(struct ap_matrix_mdev *matrix_mdev,
+		   struct vfio_ap_config **ap_config, size_t *ap_config_size)
+{
+	struct vfio_ap_config *ap_configuration;
+	int num_queues, ret;
+
+	*ap_config_size = vfio_ap_config_size(matrix_mdev, &num_queues);
+
+	ap_configuration = kzalloc(*ap_config_size, GFP_KERNEL_ACCOUNT);
+	if (!ap_configuration)
+		return -ENOMEM;
+
+	ap_configuration->num_queues = num_queues;
+
+	ret = vfio_ap_store_queue_info(matrix_mdev, ap_configuration);
+	if (ret) {
+		kfree(ap_configuration);
+		return ret;
+	}
+
+	*ap_config = ap_configuration;
+
+	return 0;
+}
+
+static ssize_t vfio_ap_stop_copy_read(struct file *filp, char __user *buf,
+				      size_t len, loff_t *pos)
+{
+	struct ap_matrix_mdev *matrix_mdev;
+	size_t ret = 0, ap_config_size;
+	struct vfio_ap_config *ap_config;
+
+	/*
+	 * When userspace calls read() with an explicit offset (pread), pos is
+	 * non-NULL and the function rejects it with -ESPIPE (illegal seek). For
+	 * normal read() calls, pos is NULL, so we'll use the file's internal
+	 * position filp->f_pos
+	 */
+	if (pos)
+		return -ESPIPE;
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+
+	pos = &filp->f_pos;
+
+	ret = validate_stop_copy_read_parms(filp, pos, len);
+	if (ret) {
+		mutex_unlock(&matrix_dev->mdevs_lock);
+		return ret;
+	}
+
+	matrix_mdev = filp->private_data;
+
+	ret = vfio_ap_get_config(matrix_mdev, &ap_config, &ap_config_size);
+	if (ret) {
+		mutex_unlock(&matrix_dev->mdevs_lock);
+		return ret;
+	}
+
+	/*
+	 * If the position exceeds the size of the AP configuration data,
+	 * then indicate EOF; otherwise calculate the length of the data to
+	 * read such that a buffer overrun is prevented.
+	 */
+	if (*pos >= ap_config_size)
+		len = 0;
+	else
+		len = min_t(size_t, ap_config_size - *pos, len);
+
+	/* If we've reached an EOF condition, let the caller know */
+	if (len == 0) {
+		kfree(ap_config);
+		mutex_unlock(&matrix_dev->mdevs_lock);
+		return 0;
+	}
+
+	mutex_unlock(&matrix_dev->mdevs_lock);
+
+	if (copy_to_user(buf, (char *)ap_config + *pos, len)) {
+		kfree(ap_config);
+		return -EFAULT;
+	}
+
+	kfree(ap_config);
+	*pos += len;
+	return len;
+}
+
 static const struct file_operations vfio_ap_stop_copy_fops = {
 	.owner = THIS_MODULE,
 	.read = vfio_ap_stop_copy_read,
-- 
2.53.0

[PATCH v4 08/15] s390/vfio-ap: Transition device migration state from STOP to RESUMING

[Anthony Krowiak]

Transitioning from VFIO_DEVICE_STATE_STOP to VFIO_DEVICE_STATE_RESUMING
starts a process of restoring the device state of the vfio device on the
target system. To prepare for restoring the device state, open a file
stream to receive the guest's AP configuration saved when the device state
on the source system transitioned from VFIO_DEVICE_STATE_STOP to
VFIO_DEVICE_STATE_STOP_COPY.

Note:
This commit introduces the file operations structure for migration state
files with a stub implementation of the write operation. The complete
implementation is provided in the subsequent commit.

This incremental approach allows for easier review of the migration
infrastructure setup separate from the actual implementation logic.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 54 ++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 5ef7127b697a..e917cc995d35 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -65,6 +65,17 @@ vfio_ap_release_stop_copy_file(struct vfio_ap_migration_data *mig_data)
 		mig_data->stop_copy_mig_file = NULL;
 }
 
+static void
+vfio_ap_release_resuming_file(struct vfio_ap_migration_data *mig_data)
+{
+	if (mig_data->resuming_mig_state.filp)
+		mig_data->resuming_mig_state.filp = NULL;
+
+	kfree(mig_data->resuming_mig_state.ap_config);
+	mig_data->resuming_mig_state.ap_config = NULL;
+	mig_data->resuming_mig_state.config_sz = 0;
+}
+
 static int vfio_ap_release_mig_file(struct inode *file_inode, struct file *filp)
 {
 	struct ap_matrix_mdev *matrix_mdev = filp->private_data;
@@ -74,6 +85,8 @@ static int vfio_ap_release_mig_file(struct inode *file_inode, struct file *filp)
 
 	if (filp == matrix_mdev->mig_data->stop_copy_mig_file)
 		vfio_ap_release_stop_copy_file(matrix_mdev->mig_data);
+	else if (filp == matrix_mdev->mig_data->resuming_mig_state.filp)
+		vfio_ap_release_resuming_file(matrix_mdev->mig_data);
 	else
 		return -ENOENT;
 
@@ -311,6 +324,32 @@ static struct file *vfio_ap_open_file_stream(struct ap_matrix_mdev *matrix_mdev,
 	return filp;
 }
 
+static ssize_t vfio_ap_resuming_write(struct file *filp, const char __user *buf,
+				      size_t len, loff_t *pos)
+{
+	/* TODO */
+	return -EOPNOTSUPP;
+}
+
+static const struct file_operations vfio_ap_resume_fops = {
+	.owner = THIS_MODULE,
+	.write = vfio_ap_resuming_write,
+	.release = vfio_ap_release_mig_file,
+};
+
+static struct file *vfio_ap_resuming_init(struct ap_matrix_mdev *matrix_mdev)
+{
+	struct vfio_ap_migration_data *mig_data;
+	struct file *filp;
+
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	mig_data = matrix_mdev->mig_data;
+	filp = vfio_ap_open_file_stream(matrix_mdev, &vfio_ap_resume_fops, O_WRONLY);
+
+	return filp;
+}
+
 static struct file *
 vfio_ap_transition_to_state(struct ap_matrix_mdev *matrix_mdev,
 			    enum vfio_device_mig_state new_state)
@@ -342,10 +381,21 @@ vfio_ap_transition_to_state(struct ap_matrix_mdev *matrix_mdev,
 		return filp;
 	}
 
+	/*
+	 * Begins the process of restoring the vfio device state by creating and
+	 * returning a streaming data_fd to be used to read in the internal
+	 * state of the vfio-ap device on the destination host.
+	 */
 	if (cur_state == VFIO_DEVICE_STATE_STOP &&
 	    new_state == VFIO_DEVICE_STATE_RESUMING) {
-		/* TODO */
-		return ERR_PTR(-EOPNOTSUPP);
+		struct file *filp = vfio_ap_resuming_init(matrix_mdev);
+
+		if (IS_ERR(filp))
+			return ERR_CAST(filp);
+
+		mig_data->resuming_mig_state.filp = filp;
+
+		return filp;
 	}
 
 	if ((cur_state == VFIO_DEVICE_STATE_RESUMING &&
-- 
2.53.0

[PATCH v4 09/15] s390/vfio-ap: Add method to set a new guest AP configuration

[Anthony Krowiak]

Adds a new vfio_ap_set_new_config function to set a guest's AP
configuration. This is needed in order to set the state of the mdev when
it is migrated from a remote host system during the RESUMING phase.

Key changes:
* Refactored code from the ap_config_store function - handles changes to
  the sysfs ap_config attribute - into a new, non-static function which
  is callable from the ap_config_store function as well as the live guest
  migration code.

* A flag parameter indicating whether the update to the guest's AP
  configuration can proceed if APIDs must be filtered out because one or
  more of the queues are not bound to the vfio_ap device driver. This is
  primarily for calls from the migration code because we don't want code
  that is running in the guest to lose access. The ap_config_store function
  will continue to operate as it did before and allow filtering.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c     | 358 +++++++++++++++++++++-----
 drivers/s390/crypto/vfio_ap_private.h |   4 +
 2 files changed, 298 insertions(+), 64 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 8a9e83921f74..c5eb9e4aa85c 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -105,6 +105,27 @@ static inline void get_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
 	mutex_lock(&matrix_dev->mdevs_lock);
 }
 
+/**
+ * assert_has_update_locks_for_mdev:
+ *
+ * Assert the locks required to dynamically update a KVM guest's APCB are
+ * currently held.
+ *
+ * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP
+ *		 configuration data to use to update a KVM guest's APCB.
+ *
+ * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM
+ *		 lock will not be taken.
+ */
+static inline void
+assert_has_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
+{
+	lockdep_assert_held(&matrix_dev->guests_lock);
+	if (matrix_mdev && matrix_mdev->kvm)
+		lockdep_assert_held(&matrix_mdev->kvm->lock);
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+}
+
 /**
  * release_update_locks_for_mdev: Release the locks used to dynamically update a
  *				  KVM guest's APCB in the proper order.
@@ -875,7 +896,40 @@ static void vfio_ap_mdev_unlink_fr_queues(struct ap_matrix_mdev *matrix_mdev)
 			q = vfio_ap_mdev_get_queue(matrix_mdev,
 						   AP_MKQID(apid, apqi));
 			if (q)
-				q->matrix_mdev = NULL;
+				vfio_ap_mdev_link_queue(matrix_mdev, q);
+		}
+	}
+}
+
+static void vfio_ap_unlink_queues(struct ap_matrix_mdev *matrix_mdev)
+{
+	struct vfio_ap_queue *q;
+	unsigned long apid, apqi;
+
+	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
+		for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
+				     AP_DOMAINS) {
+			q = vfio_ap_mdev_get_queue(matrix_mdev,
+						   AP_MKQID(apid, apqi));
+			if (q) {
+				vfio_ap_unlink_queue_fr_mdev(q);
+				vfio_ap_unlink_mdev_fr_queue(q);
+			}
+		}
+	}
+}
+
+static void vfio_ap_link_queues(struct ap_matrix_mdev *matrix_mdev)
+{
+	struct vfio_ap_queue *q;
+	unsigned long apid, apqi;
+
+	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
+		for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
+				     AP_DOMAINS) {
+			q = vfio_ap_find_queue(AP_MKQID(apid, apqi));
+			if (q)
+				vfio_ap_mdev_link_queue(matrix_mdev, q);
 		}
 	}
 }
@@ -1014,19 +1068,36 @@ static void vfio_ap_mdev_link_adapter(struct ap_matrix_mdev *matrix_mdev,
 	unsigned long apqi;
 
 	for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS)
-		vfio_ap_mdev_link_apqn(matrix_mdev,
-				       AP_MKQID(apid, apqi));
+		vfio_ap_mdev_link_apqn(matrix_mdev, AP_MKQID(apid, apqi));
 }
 
-static void collect_queues_to_reset(struct ap_matrix_mdev *matrix_mdev,
-				    unsigned long apid,
-				    struct list_head *qlist)
+static void collect_queues_by_apid(struct ap_matrix_mdev *matrix_mdev,
+				   unsigned long apid,
+				   struct list_head *qlist)
 {
 	struct vfio_ap_queue *q;
 	unsigned long  apqi;
 
 	for_each_set_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm, AP_DOMAINS) {
-		q = vfio_ap_mdev_get_queue(matrix_mdev, AP_MKQID(apid, apqi));
+		q = matrix_mdev ?
+				vfio_ap_mdev_get_queue(matrix_mdev, AP_MKQID(apid, apqi)) :
+				vfio_ap_find_queue(AP_MKQID(apid, apqi));
+		if (q)
+			list_add_tail(&q->reset_qnode, qlist);
+	}
+}
+
+static void collect_queues_by_apqi(struct ap_matrix_mdev *matrix_mdev,
+				   unsigned long apqi,
+				   struct list_head *qlist)
+{
+	struct vfio_ap_queue *q;
+	unsigned long  apid;
+
+	for_each_set_bit_inv(apid, matrix_mdev->shadow_apcb.apm, AP_DEVICES) {
+		q = matrix_mdev ?
+			vfio_ap_mdev_get_queue(matrix_mdev, AP_MKQID(apid, apqi)) :
+			vfio_ap_find_queue(AP_MKQID(apid, apqi));
 		if (q)
 			list_add_tail(&q->reset_qnode, qlist);
 	}
@@ -1038,7 +1109,7 @@ static void reset_queues_for_apid(struct ap_matrix_mdev *matrix_mdev,
 	struct list_head qlist;
 
 	INIT_LIST_HEAD(&qlist);
-	collect_queues_to_reset(matrix_mdev, apid, &qlist);
+	collect_queues_by_apid(matrix_mdev, apid, &qlist);
 	vfio_ap_mdev_reset_qlist(&qlist);
 }
 
@@ -1054,7 +1125,7 @@ static int reset_queues_for_apids(struct ap_matrix_mdev *matrix_mdev,
 	INIT_LIST_HEAD(&qlist);
 
 	for_each_set_bit_inv(apid, apm_reset, AP_DEVICES)
-		collect_queues_to_reset(matrix_mdev, apid, &qlist);
+		collect_queues_by_apid(matrix_mdev, apid, &qlist);
 
 	return vfio_ap_mdev_reset_qlist(&qlist);
 }
@@ -1725,82 +1796,241 @@ static void ap_matrix_copy(struct ap_matrix *dst, struct ap_matrix *src)
 	bitmap_copy(dst->adm, src->adm, AP_DOMAINS);
 }
 
-static ssize_t ap_config_store(struct device *dev, struct device_attribute *attr,
-			       const char *buf, size_t count)
+static int validate_ap_matrix(struct ap_matrix_mdev *matrix_mdev)
 {
-	struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
-	struct ap_matrix m_new, m_old, m_added, m_removed;
-	DECLARE_BITMAP(apm_filtered, AP_DEVICES);
-	unsigned long newbit;
-	char *newbuf, *rest;
-	int rc = count;
-	bool do_update;
+	int rc;
 
-	newbuf = kstrndup(buf, AP_CONFIG_STRLEN, GFP_KERNEL);
-	if (!newbuf)
-		return -ENOMEM;
-	rest = newbuf;
+	lockdep_assert_held(&ap_attr_mutex);
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
 
-	mutex_lock(&ap_attr_mutex);
-	get_update_locks_for_mdev(matrix_mdev);
+	rc = vfio_ap_mdev_validate_masks(matrix_mdev);
+	if (rc)
+		return rc;
+	rc = ap_matrix_overflow_check(matrix_mdev);
+	if (rc)
+		return rc;
 
-	/* Save old state */
-	ap_matrix_copy(&m_old, &matrix_mdev->matrix);
-	if (parse_bitmap(&rest, m_new.apm, AP_DEVICES) ||
-	    parse_bitmap(&rest, m_new.aqm, AP_DOMAINS) ||
-	    parse_bitmap(&rest, m_new.adm, AP_DOMAINS)) {
-		rc = -EINVAL;
-		goto out;
+	return 0;
+}
+
+static void get_removed_matrixes(struct ap_matrix *m_removed,
+				 struct ap_matrix *m_old,
+				 struct ap_matrix *m_new)
+{
+	bitmap_andnot(m_removed->apm, m_old->apm, m_new->apm, AP_DEVICES);
+	bitmap_andnot(m_removed->aqm, m_old->aqm, m_new->aqm, AP_DOMAINS);
+	bitmap_andnot(m_removed->adm, m_old->adm, m_new->adm, AP_DOMAINS);
+}
+
+static void reset_removed_queues_by_apid(unsigned long *apm_removed,
+					 unsigned long *apm_filtered,
+					 struct list_head *qlist)
+{
+	DECLARE_BITMAP(apids_removed, AP_DEVICES);
+	unsigned long apid;
+
+	for_each_set_bit_inv(apid, apm_filtered, AP_DEVICES)
+		set_bit_inv(apid, apids_removed);
+
+	for_each_set_bit_inv(apid, apm_removed, AP_DEVICES) {
+		if (!test_bit_inv(apid, apids_removed))
+			set_bit_inv(apid, apids_removed);
 	}
 
-	bitmap_andnot(m_removed.apm, m_old.apm, m_new.apm, AP_DEVICES);
-	bitmap_andnot(m_removed.aqm, m_old.aqm, m_new.aqm, AP_DOMAINS);
-	bitmap_andnot(m_added.apm, m_new.apm, m_old.apm, AP_DEVICES);
-	bitmap_andnot(m_added.aqm, m_new.aqm, m_old.aqm, AP_DOMAINS);
+	if (!bitmap_empty(apids_removed, AP_DEVICES)) {
+		for_each_set_bit_inv(apid, apids_removed, AP_DEVICES)
+			collect_queues_by_apid(NULL, apid, qlist);
+	}
 
-	/* Need new bitmaps in matrix_mdev for validation */
-	ap_matrix_copy(&matrix_mdev->matrix, &m_new);
+	if (!list_empty(qlist))
+		vfio_ap_mdev_reset_qlist(qlist);
+}
 
-	/* Ensure new state is valid, else undo new state */
-	rc = vfio_ap_mdev_validate_masks(matrix_mdev);
-	if (rc) {
-		ap_matrix_copy(&matrix_mdev->matrix, &m_old);
-		goto out;
+/**
+ * remove_queues_already_reset:
+ *
+ * Remove the queues that have already beeen reset from a list of queues that
+ * have yet to be reset.
+ *
+ * @qlist_rst:	A list of queues that have already been reset
+ * @qlist_rem:	A list of queues from which already reset queues are to be
+ *		removed.
+ */
+static void remove_queues_already_reset(struct list_head *qlist_rst,
+					struct list_head *qlist_rem)
+{
+	struct vfio_ap_queue *rq, *qr, *trq, *tqr;
+
+	if (list_empty(qlist_rst))
+		return;
+
+	/*
+	 * Each queue in qlist_reset has already been reset, so remove the
+	 * matching queues from qlist_reset so they don't get reset again
+	 */
+	list_for_each_entry_safe(qr, tqr, qlist_rem, reset_qnode) {
+		list_for_each_entry_safe(rq, trq, qlist_rst, reset_qnode) {
+			if (qr->apqn == rq->apqn)
+				list_del(&qr->reset_qnode);
+		}
 	}
-	rc = ap_matrix_overflow_check(matrix_mdev);
-	if (rc) {
-		ap_matrix_copy(&matrix_mdev->matrix, &m_old);
-		goto out;
+}
+
+static void reset_removed_queues(struct ap_matrix *m_removed,
+				 unsigned long *apm_filtered)
+{
+	struct list_head qlist_by_apid, qlist_by_apqi;
+	DECLARE_BITMAP(apqis, AP_DOMAINS);
+	unsigned long apqi;
+
+	INIT_LIST_HEAD(&qlist_by_apid);
+	INIT_LIST_HEAD(&qlist_by_apqi);
+	bitmap_clear(apqis, 0, AP_DOMAINS);
+
+	reset_removed_queues_by_apid(m_removed->apm, apm_filtered, &qlist_by_apid);
+
+	for_each_set_bit_inv(apqi, m_removed->aqm, AP_DEVICES) {
+		set_bit_inv(apqi, apqis);
+		collect_queues_by_apqi(NULL, apqi, &qlist_by_apqi);
 	}
-	rc = count;
 
-	/* Need old bitmaps in matrix_mdev for unplug/unlink */
-	ap_matrix_copy(&matrix_mdev->matrix, &m_old);
+	if (list_empty(&qlist_by_apqi))
+		return;
 
-	/* Unlink removed adapters/domains */
-	vfio_ap_mdev_hot_unplug_adapters(matrix_mdev, m_removed.apm);
-	vfio_ap_mdev_hot_unplug_domains(matrix_mdev, m_removed.aqm);
+	remove_queues_already_reset(&qlist_by_apid, &qlist_by_apqi);
 
-	/* Need new bitmaps in matrix_mdev for linking new adapters/domains */
-	ap_matrix_copy(&matrix_mdev->matrix, &m_new);
+	if (!list_empty(&qlist_by_apqi))
+		vfio_ap_mdev_reset_qlist(&qlist_by_apid);
+}
 
-	/* Link newly added adapters */
-	for_each_set_bit_inv(newbit, m_added.apm, AP_DEVICES)
-		vfio_ap_mdev_link_adapter(matrix_mdev, newbit);
+/**
+ * restore_mdev_state:
+ *
+ * Restore the mdev to its previous state:
+ * - Unlink the queues from the updated mdev
+ * - Copy the previous matrix and shadow_apcb to the mdev
+ * - Re-link the original queues to the mdev
+ *
+ * @matrix_mdev:	The object that maintains the AP configuration for a guest
+ * @m_old:		The object containing the bitmaps specifying the guest AP
+ *			configuration profile as it was prior to the attempt to set
+ *			a new one
+ * @m_old_shadow:	The object containing the bitmaps specifying the guest AP
+ *			configuration as it was prior to the attempt to set a new
+ *			one
+ */
+static void restore_mdev_state(struct ap_matrix_mdev *matrix_mdev,
+			       struct ap_matrix *m_old,
+			       struct ap_matrix *m_old_shadow)
+{
+	vfio_ap_unlink_queues(matrix_mdev);
+	ap_matrix_copy(&matrix_mdev->matrix, m_old);
+	ap_matrix_copy(&matrix_mdev->shadow_apcb, m_old_shadow);
+	vfio_ap_link_queues(matrix_mdev);
+}
 
-	for_each_set_bit_inv(newbit, m_added.aqm, AP_DOMAINS)
-		vfio_ap_mdev_link_domain(matrix_mdev, newbit);
+/**
+ * vfio_ap_set_new_guest_config:
+ *
+ * Set a new AP configuration for a guest.
+ *
+ * @matrix_mdev: Object used to maintain the AP configuration for a guest
+ * @m_new:		 Object used to set the new AP configuration
+ * @filtering_allowable: A boolean value indicating whether any filtering of
+ *			 new AP configuration is acceptable. If the configuration
+ *			 needs to be filtered before it can be passed through to
+ *			 the guest and this flag is set to false, then
+ *			 the operation shall be terminated with an error.
+ *
+ * Returns: zero (0) if the new AP configuration is successfully set; otherwise,
+ *	    returns an error:
+ *
+ *	    ~ EADDRNOTAVAIL One or more APQNs are reserved for host use
+ *	    ~ EADDRINUSE    One or more APQNs are assigned to another mdev
+ *	    ~ ENODEV	    An adapter, domain or control domain in the new
+ *			    AP configuration exceeds the max architected value
+ *	    ~ ECANCELED	    @filtering_allowed was specified as false and the
+ *			    AP configuration needs to be filtered.
+ */
+int vfio_ap_set_new_guest_config(struct ap_matrix_mdev *matrix_mdev,
+				 struct ap_matrix *m_new,
+				 bool filtering_allowable)
+{
+	DECLARE_BITMAP(apm_filtered, AP_DEVICES);
+	struct ap_matrix m_old, m_old_shadow, m_removed;
+	bool do_update;
+	int rc;
 
-	/* filter resources not bound to vfio-ap */
+	lockdep_assert_held(&ap_attr_mutex);
+	assert_has_update_locks_for_mdev(matrix_mdev);
+
+	/* Save old state */
+	ap_matrix_copy(&m_old, &matrix_mdev->matrix);
+	ap_matrix_copy(&m_old_shadow, &matrix_mdev->shadow_apcb);
+
+	/* Reset mdev state */
+	vfio_ap_unlink_queues(matrix_mdev);
+	ap_matrix_copy(&matrix_mdev->matrix, m_new);
+	vfio_ap_link_queues(matrix_mdev);
+
+	rc = validate_ap_matrix(matrix_mdev);
+	if (rc) {
+		restore_mdev_state(matrix_mdev, &m_old, &m_old_shadow);
+		return rc;
+	}
+
+	/*
+	 * If APIDs need to be filtered from the guest AP config and filtering
+	 * is not allowable according to the caller, then terminate the operation.
+	 */
 	do_update = vfio_ap_mdev_filter_matrix(matrix_mdev, apm_filtered);
+	if (!bitmap_empty(apm_filtered, AP_DEVICES) && !filtering_allowable) {
+		restore_mdev_state(matrix_mdev, &m_old, &m_old_shadow);
+		return -ECANCELED;
+	}
+
 	do_update |= vfio_ap_mdev_filter_cdoms(matrix_mdev);
 
-	/* Apply changes to shadow apbc if things changed */
-	if (do_update) {
+	if (do_update)
 		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
-		reset_queues_for_apids(matrix_mdev, apm_filtered);
+
+	get_removed_matrixes(&m_removed, &m_old, m_new);
+	if (!bitmap_empty(m_removed.apm, AP_DEVICES) ||
+	    !bitmap_empty(apm_filtered, AP_DEVICES))
+		reset_removed_queues(&m_removed, apm_filtered);
+
+	return 0;
+}
+
+static ssize_t ap_config_store(struct device *dev, struct device_attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
+	struct ap_matrix m_new;
+	char *newbuf, *rest;
+	ssize_t rc;
+
+	newbuf = kstrndup(buf, AP_CONFIG_STRLEN, GFP_KERNEL);
+	if (!newbuf)
+		return -ENOMEM;
+	rest = newbuf;
+
+	mutex_lock(&ap_attr_mutex);
+	get_update_locks_for_mdev(matrix_mdev);
+
+	if (parse_bitmap(&rest, m_new.apm, AP_DEVICES) ||
+	    parse_bitmap(&rest, m_new.aqm, AP_DOMAINS) ||
+	    parse_bitmap(&rest, m_new.adm, AP_DOMAINS)) {
+		kfree(newbuf);
+		release_update_locks_for_mdev(matrix_mdev);
+		mutex_unlock(&ap_attr_mutex);
+		return -EINVAL;
 	}
-out:
+
+	rc = vfio_ap_set_new_guest_config(matrix_mdev, &m_new, true);
+	if (!rc)
+		rc = count;
+
 	release_update_locks_for_mdev(matrix_mdev);
 	mutex_unlock(&ap_attr_mutex);
 	kfree(newbuf);
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 1fbdfcce5a11..7ae48729cafa 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -177,4 +177,8 @@ int vfio_ap_init_migration_data(struct ap_matrix_mdev *matrix_mdev);
 void vfio_ap_release_migration_data(struct ap_matrix_mdev *matrix_mdev);
 void vfio_ap_reset_migration_state(struct ap_matrix_mdev *matrix_mdev);
 
+int vfio_ap_set_new_guest_config(struct ap_matrix_mdev *matrix_mdev,
+				 struct ap_matrix *m_new,
+				 bool filtering_allowable);
+
 #endif /* _VFIO_AP_PRIVATE_H_ */
-- 
2.53.0

[PATCH v4 10/15] s390/vfio-ap: File ops called to resume the vfio device migration

[Anthony Krowiak]

Implements the 'write' callback function that was added to the
'file_operations' structure for the file stream created to restore the
state of the vfio-ap device on the destination system when the migration
state transitioned from STOP to RESUMING

The write callback retrieves the vfio device migration state saved to the
file stream created when the vfio device state was transitioned from
STOP to STOP_COPY. The saved state contains the source guest's AP
configuration information. This data is copied from the userspace buffer
passed to the 'write' callback and stored in the vfio_ap_config structure
used to set the state of the vfio-ap device on the destination host. If the
source guest's AP configuration is compatible with the AP configuration on
the destination host, it will be hot plugged into the destination guest.

In order for the source guest's and destination host's AP configurations
to be considered compatible:

* Each APQN in the source guest's AP configuration must also be in the
  destination host's AP configuration

* Each matching APQN in the destination host's AP configuration must be
  bound to the vfio_ap device driver

* Each matching APQN in the destination host's AP configuration must
  reference a queue device with compatible hardware:

  - The source and destination queues must have the same facilities
    installed:
    ~ APSC facility
    ~ APQKM facility
    ~ AP4KC facility

  - The source and destination queues must have the same mode:
    ~ Coprocessor-mode
    ~ Accelerator-mode
    ~ XCP-mode

  - The source and destination queues must have the same APXA facility
    setting
    ~ If the APXA facility is installed on source queue, it must also
      be installed on the destination queue and vice versa

  - The source and destination queues must have a compatible
    classification setting. If the source queue has full native card
    function, then the destination queue must also have full native
    card function. If the source queue has stateless functions, then
    the destination queue can have stateless functions or full native card
    function because the latter includes the stateless functions.

  - The binding and associated state for both the source and destination
    queues must indicate that the queue is usable for all messages
    (i.e., BS bits equal to 00).

  - The AP type of the destination queue must be the same as or newer than
    the source queue (backward compatibility)

Note: The get_hardware_info_for_queue function that was created in
      a previous patch was modified to take a mediated device name rather
      than an ap_matrix_mdev object because that is what is needed for
      this patch so the function can be executed without holding the
      matrix_dev->mdevs_lock.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 785 +++++++++++++++++++++++-
 drivers/s390/crypto/vfio_ap_ops.c       |  68 --
 drivers/s390/crypto/vfio_ap_private.h   |  56 ++
 3 files changed, 829 insertions(+), 80 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index e917cc995d35..9cd1e7a3f743 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -9,6 +9,40 @@
 #include "ap_bus.h"
 #include "vfio_ap_private.h"
 
+/*
+ * Masks the fields of the queue information returned from the PQAP(TAPQ)
+ * command. In order to migrate a guest, it's AP configuration must be
+ * compatible with AP configuration assigned to the target guest's mdev.
+ * This mask is used to verify that the queue information for each source and
+ * target queue is compatible (i.e., the masked fields are equivalent).
+ *
+ * The relevant fields covered by this mask are:
+ * S bit 0: APSC  facility installed
+ * M bit 1: APQKM facility installed
+ * C bit 2: AP4KC facility installed
+ * Mode bits 3-5:
+ *     D bit 3: CCA-mode facility
+ *     A bit 4: accelerator-mode facility
+ *     X bit 5: XCP-mode facility
+ * N  bit 6: APXA facility installed
+ * SL bit 7: SLCF facility installed
+ * Classification (functional capabilities) bits 8-16
+ *     bit 8: Native card function
+ *     bit 9: Only stateless functions
+ * BS bits 16-17:
+ * AP Type bits 32-40:
+ */
+#define QINFO_DATA_MASK		0xffffc000ff000000
+
+/*
+ * Masks the bit that indicates whether full native card function is available
+ * from the 8 bits specifying the functional capabilities of a queue
+ */
+#define CLASSIFICATION_NATIVE_FCN_MASK		0x80
+
+/* The maximum number of queues that can be installed in an s390 system */
+#define MAX_AP_QUEUES				(AP_DEVICES * AP_DOMAINS)
+
 /**
  * vfio_ap_migration_data - the data needed to migrate a guest with pass-through
  *			    access to AP devices
@@ -147,7 +181,7 @@ static size_t vfio_ap_config_size(struct ap_matrix_mdev *matrix_mdev,
 	return qinfo_size + sizeof(struct vfio_ap_config);
 }
 
-static int get_hardware_info_for_queue(struct ap_matrix_mdev *matrix_mdev,
+static int get_hardware_info_for_queue(const char *mdev_name,
 				       struct ap_tapq_hwinfo *hwinfo,
 				       unsigned long apqn)
 {
@@ -164,22 +198,20 @@ static int get_hardware_info_for_queue(struct ap_matrix_mdev *matrix_mdev,
 		/* For all these RCs the tapq info should be available */
 		return 0;
 	case AP_RESPONSE_Q_NOT_AVAIL:
-		dev_err(matrix_mdev->vdev.dev,
-			"migration failed: Failed to get hwinfo for queue %02lx.%04lx on target host: TAPQ rc=%d",
-			AP_QID_CARD(apqn), AP_QID_QUEUE(apqn), status.response_code);
+		pr_err("vfio_ap_mdev %s: migration failed: Failed to get hwinfo for queue %02lx.%04lx on target host: TAPQ rc=%d",
+		       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn), status.response_code);
+
 		return -ENODEV;
 	default:
 		/* On a pending async error the tapq info should be available */
 		if (!status.async)
 			return 0;
 
-		dev_err(matrix_mdev->vdev.dev,
-			"Failed to get hwinfo for queue %02lx.%04lx: TAPQ rc=%d",
-			AP_QID_CARD(apqn), AP_QID_QUEUE(apqn), status.response_code);
+		pr_err("vfio_ap_mdev %s: Failed to get hwinfo for queue %02lx.%04lx: TAPQ rc=%d",
+		       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn), status.response_code);
+
 		return -EIO;
 	}
-
-	return -EINVAL;
 }
 
 static int vfio_ap_store_queue_info(struct ap_matrix_mdev *matrix_mdev,
@@ -187,10 +219,12 @@ static int vfio_ap_store_queue_info(struct ap_matrix_mdev *matrix_mdev,
 {
 	unsigned long *apm, *aqm, num_queues, apid, apqi, apqn;
 	struct ap_tapq_hwinfo source_hwinfo;
+	const char *mdev_name;
 	int ret;
 
 	lockdep_assert_held(&matrix_dev->mdevs_lock);
 
+	mdev_name = dev_name(matrix_mdev->vdev.dev);
 	apm = matrix_mdev->shadow_apcb.apm;
 	aqm = matrix_mdev->shadow_apcb.aqm;
 	num_queues = 0;
@@ -199,7 +233,7 @@ static int vfio_ap_store_queue_info(struct ap_matrix_mdev *matrix_mdev,
 		for_each_set_bit_inv(apqi, aqm, AP_DOMAINS) {
 			apqn = AP_MKQID(apid, apqi);
 
-			ret = get_hardware_info_for_queue(matrix_mdev,
+			ret = get_hardware_info_for_queue(mdev_name,
 							  &source_hwinfo, apqn);
 			if (ret)
 				return ret;
@@ -324,11 +358,738 @@ static struct file *vfio_ap_open_file_stream(struct ap_matrix_mdev *matrix_mdev,
 	return filp;
 }
 
+static int validate_resuming_write_parms(struct file *filp,
+					 size_t len, loff_t *pos)
+{
+	struct ap_matrix_mdev *matrix_mdev;
+	loff_t total_len;
+	int ret;
+
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+
+	matrix_mdev = filp->private_data;
+	if (!matrix_mdev || !matrix_mdev->mig_data) {
+		ret = -ENODEV;
+		goto done;
+	}
+
+	if (filp != matrix_mdev->mig_data->resuming_mig_state.filp) {
+		ret = -ENXIO;
+		goto done;
+	}
+
+	if (*pos < 0) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	if (check_add_overflow((loff_t)len, *pos, &total_len)) {
+		ret = -ERANGE;
+		goto done;
+	}
+
+	/*
+	 * If the ap_config has not yet been allocated and the file position
+	 * indicates this is not the first write, or the ap_config has been allocated
+	 * but the file position indicates this is the first write, then this is an
+	 * error condition.
+	 */
+	if ((!matrix_mdev->mig_data->resuming_mig_state.ap_config && *pos != 0) ||
+	    (matrix_mdev->mig_data->resuming_mig_state.ap_config && *pos == 0)) {
+		ret = -EFAULT;
+
+		goto done;
+	}
+
+	ret = 0;
+
+done:
+	return ret;
+}
+
+static ssize_t calculate_ap_config_size(unsigned int num_queues)
+{
+	size_t qinfo_size;
+
+	if (num_queues > MAX_AP_QUEUES)
+		return -EINVAL;
+
+	qinfo_size = num_queues * sizeof(struct vfio_ap_queue_info);
+	return qinfo_size + sizeof(struct vfio_ap_config);
+}
+
+/**
+ * allocate_ap_config:
+ *
+ * Allocate storage for the source guest's AP configuration data sent from
+ * userspace.
+ *
+ * @ap_config:	The location in which to store the pointer to the storage
+ *		allocated for the AP configuration data.
+ * @buf:	The userspace buffer containing some or all of the source
+ *		guest's AP configuration data
+ * @len:	The number of bytes of data to copy from @buf
+ *
+ * Returns:	The number of bytes of storage allocated for the config data or
+ *		an error:
+ *
+ *
+ *		-EIO: failed to copy data from @buf
+ *		-EINVAL: the number of queues specified exceeds the max allowed
+ *		-ENOMEM: the allocation of storage failed
+ */
+static ssize_t allocate_ap_config(struct vfio_ap_config **ap_config,
+				  const char __user *buf, size_t len)
+{
+	struct vfio_ap_config tmp_ap_config;
+	ssize_t config_size;
+	size_t copy_size;
+
+	/*
+	 * If the length of the data sent exceeds the size of the vfio_ap_config
+	 * structure, then we will copy enough data from userspace to get the
+	 * number of queues which we can use to allocate enough space all of
+	 * the queue information.
+	 */
+	copy_size = min(len, sizeof(tmp_ap_config));
+
+	if (copy_from_user(&tmp_ap_config, buf, copy_size))
+		return -EIO;
+
+	/*
+	 * If the length of data sent includes the number of queues
+	 * in the AP configuration, then calculate its size; otherwise
+	 * set config_size to the length of data sent.
+	 */
+	if (len >= sizeof(struct vfio_ap_config)) {
+		config_size = calculate_ap_config_size(tmp_ap_config.num_queues);
+
+		/* If the calculation returned an error */
+		if (config_size < 0)
+			return config_size;
+	} else {
+		config_size = len;
+	}
+
+	*ap_config = kzalloc(config_size, GFP_KERNEL_ACCOUNT);
+	if (!*ap_config)
+		return -ENOMEM;
+
+	return config_size;
+}
+
+/**
+ * reallocate_ap_config:
+ *
+ * Reallocate the storage buffer so it is large enough to store the source
+ * guest's AP configuration data sent from userspace.
+ *
+ * @mig_ap_config: The location in which to store the pointer to the storage
+ *		   reallocated for the AP configuration data.
+ * len:		   The length of the data to be stored
+ *
+ * Returns:	   The size of the memory allocated for the source guest's
+ *		   AP configuration data or an error:
+ *
+ *		   -ENOMEM: The call to krealloc failed
+ *		   -EINVAL: The guest's AP configuration size changed between
+ *		   calls to the vfio_ap_resuming_write function.
+ *
+ */
+static ssize_t reallocate_ap_config(struct vfio_ap_config **mig_ap_config,
+				    size_t len)
+{
+	struct vfio_ap_config *ap_config = *mig_ap_config;
+	struct vfio_ap_config *new_ap_config;
+	size_t new_cfg_sz, cur_cfg_sz;
+	unsigned int num_queues;
+
+	cur_cfg_sz = ap_config->config_sz;
+	num_queues = ap_config->num_queues;
+
+	/*
+	 * If the current configuration size is greater than the
+	 * size of a vfio_ap_config structure (i.e., contains the num_queues
+	 * field), then there should already be enough storage allocated
+	 * to store the source guest's AP configuration. Let's verify that the
+	 * amount of storage allocated is what we expect based on the number of
+	 * vfio_ap_queue_info objects that must be stored.
+	 */
+	if (cur_cfg_sz >= sizeof(struct vfio_ap_config)) {
+		new_cfg_sz = calculate_ap_config_size(num_queues);
+		if (cur_cfg_sz != new_cfg_sz)
+			return -EINVAL;
+	} else {
+		new_cfg_sz = cur_cfg_sz + len;
+	}
+
+	new_ap_config = krealloc(ap_config, new_cfg_sz, GFP_KERNEL_ACCOUNT);
+	if (!new_ap_config)
+		return -ENOMEM;
+
+	*mig_ap_config = new_ap_config;
+
+	return new_cfg_sz;
+}
+
+/**
+ * qdev_is_bound_to_vfio_ap:
+ *
+ * Query to determine whether a queue with the specified APQN is available on
+ * the host system and bound to the vfio_ap device driver.
+ *
+ * @apqn: The APQN of the queue device being queried
+ *
+ * Returns: True if there is a queue device with the specified @apqn installed
+ *	    in the system and is bound to the vfio_ap device driver; otherwise,
+ *	    returns false.
+ */
+static bool qdev_is_bound_to_vfio_ap(unsigned int apqn)
+{
+	struct ap_queue *queue;
+	bool is_bound = true;
+
+	queue = ap_get_qdev(apqn);
+	if (!queue)
+		return false;
+
+	if (queue->ap_dev.device.driver != &matrix_dev->vfio_ap_drv->driver)
+		is_bound = false;
+
+	put_device(&queue->ap_dev.device);
+
+	return is_bound;
+}
+
+/**
+ * queues_available_on_target_system:
+ *
+ * Query whether each queue from the source guest's AP configuration is
+ * available and bound to the vfio_ap device driver; if not, log an error
+ * message.
+ *
+ * @mdev_name:	   The mdev name to use in error messages
+ * @source_config: The object specifying the source guest's AP configuration
+ *
+ * Returns: true if each queue identified in @source_config is available and
+ *	    bound to the vfio_ap device driver; otherwise, returns false.
+ */
+static bool
+queues_available_on_target_system(const char *mdev_name,
+				  struct vfio_ap_config *source_config)
+{
+	unsigned long apqn;
+	bool ret = true;
+
+	for (int i = 0; i < source_config->num_queues; i++) {
+		apqn = source_config->qinfo[i].apqn;
+
+		/*
+		 * Find the queue device bound to the vfio_ap device driver. If it is
+		 * not found, log an error and continue so users see all problems
+		 * at once, not one-at-a-time through retries of the migration.
+		 */
+		if (!qdev_is_bound_to_vfio_ap(apqn)) {
+			pr_err("vfio_ap_mdev %s: Queue %02lx.%04lx not available to vfio_ap driver on target host\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+			ret = false;
+		}
+	}
+
+	return ret;
+}
+
+static void report_facilities_compatibility(const char *mdev_name,
+					    unsigned long apqn,
+					    struct ap_tapq_hwinfo *src_hwinfo,
+					    struct ap_tapq_hwinfo *target_hwinfo)
+{
+	if (src_hwinfo->apsc != target_hwinfo->apsc) {
+		if (src_hwinfo->apsc) {
+			pr_err("vfio_ap_mdev %s: APSC facility installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: APSC facility not installed in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		} else {
+			pr_err("vfio_ap_mdev %s: APSC facility not installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s APSC facility installed in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		}
+	}
+
+	if (src_hwinfo->mex4k != target_hwinfo->mex4k) {
+		if (src_hwinfo->mex4k) {
+			pr_err("vfio_ap_mdev %s: mex4k facility installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: mex4k facility not installed in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		} else {
+			pr_err("vfio_ap_mdev %s: mex4k facility not installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: mex4k facility installed in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		}
+	}
+
+	if (src_hwinfo->crt4k != target_hwinfo->crt4k) {
+		if (src_hwinfo->crt4k) {
+			pr_err("vfio_ap_mdev %s: crt4k facility installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: crt4k facility not installed in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		} else {
+			pr_err("vfio_ap_mdev %s: crt4k facility not installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: crt4k facility installed in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		}
+	}
+}
+
+static void report_mode_compatibility(const char *mdev_name,
+				      unsigned long apqn,
+				      struct ap_tapq_hwinfo *src_hwinfo,
+				      struct ap_tapq_hwinfo *target_hwinfo)
+{
+	if (src_hwinfo->cca != target_hwinfo->cca) {
+		if (src_hwinfo->cca) {
+			pr_err("vfio_ap_mdev %s: Coprocessor-mode facility installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: Coprocessor-mode  facility not installed target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		} else {
+			pr_err("vfio_ap_mdev %s: Coprocessor-mode facility not installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: Coprocessor-mode  facility installed target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		}
+	}
+
+	if (src_hwinfo->accel != target_hwinfo->accel) {
+		if (src_hwinfo->accel) {
+			pr_err("vfio_ap_mdev %s: Accelerator-mode facility installed source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: Accelerator-mode facility not installed target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		} else {
+			pr_err("vfio_ap_mdev %s: Accelerator-mode facility not installed source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: Accelerator-mode facility installed target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		}
+	}
+
+	if (src_hwinfo->ep11 != target_hwinfo->ep11) {
+		if (src_hwinfo->ep11) {
+			pr_err("vfio_ap_mdev %s: XCP-mode facility installed source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: XCP-mode facility not installed target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		} else {
+			pr_err("vfio_ap_mdev %s: XCP-mode facility not installed source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: XCP-mode facility installed target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		}
+	}
+}
+
+static void report_apxa_compatibility(const char *mdev_name,
+				      unsigned long apqn,
+				      struct ap_tapq_hwinfo *src_hwinfo,
+				      struct ap_tapq_hwinfo *target_hwinfo)
+{
+	if (src_hwinfo->apxa != target_hwinfo->apxa) {
+		if (src_hwinfo->apxa) {
+			pr_err("vfio_ap_mdev %s: AP-extended-addressing (APXA) facility installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: AP-extended-addressing (APXA) facility not installed in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		} else {
+			pr_err("vfio_ap_mdev %s: AP-extended-addressing (APXA) facility not installed in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: AP-extended-addressing (APXA) facility installed in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		}
+	}
+}
+
+static void report_slcf_compatibility(const char *mdev_name,
+				      unsigned long apqn,
+				      struct ap_tapq_hwinfo *src_hwinfo,
+				      struct ap_tapq_hwinfo *target_hwinfo)
+{
+	if (src_hwinfo->slcf != target_hwinfo->slcf) {
+		if (src_hwinfo->slcf) {
+			pr_err("vfio_ap_mdev %s: Stateless-command-filtering (SLCF) available in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: Stateless-command-filtering (SLCF) not available in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		} else {
+			pr_err("vfio_ap_mdev %s: Stateless-command-filtering (SLCF) not available in source queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+			pr_err("vfio_ap_mdev %s: Stateless-command-filtering (SLCF) available in target queue %02lx.%04lx\n",
+			       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+		}
+	}
+}
+
+static void report_bs_compatibility(const char *mdev_name,
+				    unsigned long apqn,
+				    struct ap_tapq_hwinfo *src_hwinfo,
+				    struct ap_tapq_hwinfo *target_hwinfo)
+{
+	/*
+	 * The BS field on both the source and destination must be 0, so if one of
+	 * them is not, then report an error.
+	 */
+	if (src_hwinfo->bs || target_hwinfo->bs) {
+		pr_err("vfio_ap_mdev %s: Bind/associate state for source (%01x) and target (%01x) queue %02lx.%04lx must be 0\n",
+		       mdev_name, src_hwinfo->bs, target_hwinfo->bs,
+		       AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+	}
+}
+
+static void report_aptype_compatibility(const char *mdev_name,
+					unsigned long apqn,
+					struct ap_tapq_hwinfo *src_hwinfo,
+					struct ap_tapq_hwinfo *target_hwinfo)
+{
+	if (src_hwinfo->at > target_hwinfo->at) {
+		pr_err("vfio_ap_mdev %s: AP type of source (%02x) not compatible with target (%02x)\n",
+		       mdev_name, src_hwinfo->at, target_hwinfo->at);
+	}
+}
+
+static bool classes_compatible(struct ap_tapq_hwinfo *src_hwinfo,
+			       struct ap_tapq_hwinfo *target_hwinfo)
+{
+	unsigned long src_native, target_native;
+
+	src_native = src_hwinfo->class & CLASSIFICATION_NATIVE_FCN_MASK;
+	target_native = target_hwinfo->class & CLASSIFICATION_NATIVE_FCN_MASK;
+
+	/*
+	 * If the source queue has full native card function and the
+	 * target queue has only stateless functions available, then
+	 * there may be instructions that will not execute on the
+	 * target queue. This shall be reported as an error.
+	 *
+	 * If the source queue has only stateless card functions and the
+	 * target queue has full native card function available, then
+	 * we are okay because the target queue can run all stateless card
+	 * functions.
+	 */
+	return (src_native != target_native) ? !src_native : true;
+}
+
+static void report_class_compatibility(const char *mdev_name,
+				       unsigned long apqn,
+				       struct ap_tapq_hwinfo *src_hwinfo,
+				       struct ap_tapq_hwinfo *target_hwinfo)
+{
+	if (!classes_compatible(src_hwinfo, target_hwinfo)) {
+		pr_err("vfio_ap_mdev %s: Full native card function available on source queue %02lx.%04lx\n",
+		       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+		pr_err("vfio_ap_mdev %s: Only stateless functions available on target queue %02lx.%04lx\n",
+		       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+	}
+}
+
+/*
+ * Log a device error reporting that migration failed due to queue
+ * incompatibilities followed by a device error for each incompatible feature.
+ */
+static void report_qinfo_incompatibilities(const char *mdev_name,
+					   unsigned long apqn,
+					   struct ap_tapq_hwinfo *src_hwinfo,
+					   struct ap_tapq_hwinfo *target_hwinfo)
+{
+	pr_err("vfio_ap_mdev %s: Migration failed: Source and target queue (%02lx.%04lx) not compatible\n",
+	       mdev_name, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+
+	report_facilities_compatibility(mdev_name, apqn, src_hwinfo, target_hwinfo);
+	report_mode_compatibility(mdev_name, apqn, src_hwinfo, target_hwinfo);
+	report_apxa_compatibility(mdev_name, apqn, src_hwinfo, target_hwinfo);
+	report_slcf_compatibility(mdev_name, apqn, src_hwinfo, target_hwinfo);
+	report_aptype_compatibility(mdev_name, apqn, src_hwinfo, target_hwinfo);
+	report_bs_compatibility(mdev_name, apqn, src_hwinfo, target_hwinfo);
+	report_class_compatibility(mdev_name, apqn, src_hwinfo, target_hwinfo);
+}
+
+/**
+ * queue_hardware_info_is_compatible:
+ *
+ * Verify whether the hardware information for a source queue is compatible with
+ * the hardware info for the corresponding queue on this system.
+ *
+ * In order to be compatible, the hardware information for each queue must
+ * meet the following requirements:
+ *
+ * 1. The hardware facilities bits much match
+ * 2. The AP type of the source queue must be the same as or older than that
+ *    of the target queue (target is backwards compatible)
+ * 3. The classification bits must indicate:
+ *    - Both queues have full native card function or both have stateless
+ *      functions available
+ *    - If the classification bits don't match, then the only acceptable
+ *      configuration is stateless functions for the source queue and
+ *      full native function for the target queue
+ * 4. The BS bits for both queues must be 0 (Queue usable for all messages
+ *    supported by the adapter)
+ *
+ * @mdev_name:	The mdev name to use in error messages
+ * @apqn:	The APQN for the queues
+ * @src_hwinfo: The hardware info for the source queue
+ * @target_hwinfo: The hardware info for the corresponding queue on this system
+ *
+ * Returns: true if the hardware info for the two queues is compatible;
+ *          otherwise, returns false.
+ */
+static bool queue_hardware_info_is_compatible(const char *mdev_name,
+					      unsigned long apqn,
+					      struct ap_tapq_hwinfo *src_hwinfo,
+					      struct ap_tapq_hwinfo *target_hwinfo)
+{
+	unsigned long src_bits, target_bits;
+
+	src_bits = src_hwinfo->value & QINFO_DATA_MASK;
+	target_bits = target_hwinfo->value & QINFO_DATA_MASK;
+
+	/* If all bits match the queues are compatible */
+	if (src_bits == target_bits)
+		return true;
+
+	if (src_hwinfo->fac == target_hwinfo->fac &&
+	    src_hwinfo->at <= target_hwinfo->at &&
+	    classes_compatible(src_hwinfo, target_hwinfo) &&
+	    (src_hwinfo->bs == 0 && target_hwinfo->bs == 0)) {
+		return true;
+	}
+
+	report_qinfo_incompatibilities(mdev_name, apqn, src_hwinfo, target_hwinfo);
+
+	return false;
+}
+
+/**
+ * verify_ap_configs_are_compatible:
+ *
+ * Verifies that the queues in the source guest's AP configuration are
+ * compatible with the corresponding queues on this system.
+ *
+ * @mdev_name:	   The mdev name to use in error messages
+ * @source_config: The object specifying the source guest's AP configuration
+ *
+ * Returns: an error indicating either a failure to retrieve a queue's
+ *			hardware information or one or more source queues are not
+ *			compatible with the corresponding queue on this system; otherwise,
+ *			returns zero to indicate compatibility.
+ */
+static int verify_ap_configs_are_compatible(const char *mdev_name,
+					    struct vfio_ap_config *source_config)
+{
+	struct ap_tapq_hwinfo src_hwinfo, dest_hwinfo;
+	unsigned long apqn;
+	int ret = 0, rc;
+
+	for (int i = 0; i < source_config->num_queues; i++) {
+		apqn = source_config->qinfo[i].apqn;
+
+		/*
+		 * If we can't get the hardware info for a particular queue, then let's
+		 * capture the function return code and continue so we can log all
+		 * errors to aid in debugging of migration.
+		 */
+		rc = get_hardware_info_for_queue(mdev_name, &dest_hwinfo, apqn);
+		if (rc) {
+			ret = rc;
+			continue;
+		}
+
+		src_hwinfo.value =  source_config->qinfo[i].data;
+
+		if (!queue_hardware_info_is_compatible(mdev_name, apqn,
+						       &src_hwinfo,
+						       &dest_hwinfo))
+			ret = -EFAULT;
+	}
+
+	return ret;
+}
+
+static int do_post_copy_validation(const char *mdev_name,
+				   struct vfio_ap_config *source_config)
+{
+	if (!queues_available_on_target_system(mdev_name, source_config))
+		return -ENODEV;
+
+	return verify_ap_configs_are_compatible(mdev_name, source_config);
+}
+
+/**
+ * setup_ap_matrix_from_ap_config:
+ *
+ * Set the bits corresponding to the adapters, domains and control domains
+ * in the source guest's AP configuration into an ap_matrix object to be
+ * used to update the target guest to run on this host. An error message will
+ * be logged for each adapter, domain or control domain that is not available
+ * on this host. Returning an error after the each error may result in needing
+ * to initiate multiple migrations in order to find and fix each of them.
+ *
+ * Returns: zero (0) if each adapter, domain and control domain from the
+ *          source guest's ap configuration is available on this host;
+ *          otherwise, returns -ENODEV.
+ */
+static void setup_ap_matrix_from_ap_config(const char *mdev_name,
+					   struct vfio_ap_config *ap_config,
+					   struct ap_matrix *guest_matrix)
+{
+	struct vfio_ap_queue_info qinfo;
+	unsigned long apid, apqi;
+
+	for (int i = 0; i < ap_config->num_queues; i++) {
+		qinfo = ap_config->qinfo[i];
+		apid = AP_QID_CARD(qinfo.apqn);
+		apqi = AP_QID_QUEUE(qinfo.apqn);
+
+		if (!test_bit_inv(apid, guest_matrix->apm))
+			set_bit_inv(apid, guest_matrix->apm);
+		if (!test_bit_inv(apqi, guest_matrix->aqm))
+			set_bit_inv(apqi, guest_matrix->aqm);
+	}
+}
+
 static ssize_t vfio_ap_resuming_write(struct file *filp, const char __user *buf,
 				      size_t len, loff_t *pos)
 {
-	/* TODO */
-	return -EOPNOTSUPP;
+	struct vfio_ap_migration_data *mig_data;
+	struct ap_matrix_mdev *matrix_mdev;
+	struct vfio_ap_config *ap_config;
+	struct ap_matrix guest_matrix;
+	ssize_t ret = 0, cfg_sz;
+	const char *mdev_name;
+
+	/*
+	 * When userspace calls write() with an explicit offset (pwrite), pos is
+	 * non-NULL and the function rejects it with -ESPIPE (illegal seek). For
+	 * normal write() calls, pos is NULL, so we'll use the file's internal
+	 * position filp->f_pos
+	 */
+	if (pos)
+		return -ESPIPE;
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+	pos = &filp->f_pos;
+
+	ret = validate_resuming_write_parms(filp, len, pos);
+	if (ret)
+		goto done;
+
+	matrix_mdev = filp->private_data;
+	mig_data = matrix_mdev->mig_data;
+	mdev_name = dev_name(matrix_mdev->vdev.dev);
+
+	/*
+	 * If this is the first write operation, then allocate storage for the
+	 * AP configuration information; otherwise, reallocate the
+	 * struct vfio_ap_config object used to store the AP configuration data
+	 * sent from userspace.
+	 */
+	if (*pos == 0) {
+		ret = allocate_ap_config(&ap_config, buf, len);
+
+		/* If the allocation failed, we'll return the error */
+		if (ret < 0)
+			goto done;
+
+		cfg_sz = ret;
+	} else {
+		ap_config = mig_data->resuming_mig_state.ap_config;
+
+		ret = reallocate_ap_config(&ap_config, len);
+		if (ret < 0)
+			goto cleanup;
+
+		cfg_sz = ret;
+	}
+
+	if (*pos + len > cfg_sz) {
+		ret = -EIO;
+		goto cleanup;
+	}
+
+	/*
+	 * We don't want to lock all mdevs while copying data from userspace so
+	 * we don't block all other mdevs in case the I/O takes a long time.
+	 * From here on out we don't need this lock because we are not
+	 * accessing the matrix_mdev until we need to get the update
+	 * locks to set the new destination guest's AP configuration in which
+	 * case this lock will be taken then.
+	 */
+	mutex_unlock(&matrix_dev->mdevs_lock);
+
+	if (copy_from_user((char *)ap_config + *pos, buf, len)) {
+		ret = -EIO;
+		goto cleanup;
+	}
+
+	/* Check if we've completed writing the entire configuration */
+	if (*pos + len == cfg_sz) {
+		ret = do_post_copy_validation(mdev_name, ap_config);
+		if (ret < 0)
+			goto cleanup;
+
+		setup_ap_matrix_from_ap_config(mdev_name, ap_config,
+					       &guest_matrix);
+
+		/* Acquire locks required to update the guest's AP config */
+		mutex_lock(&ap_attr_mutex);
+		get_update_locks_for_mdev(matrix_mdev);
+
+		ret = vfio_ap_set_new_guest_config(matrix_mdev, &guest_matrix,
+						   false);
+		if (!ret) {
+			mig_data->resuming_mig_state.ap_config = ap_config;
+			mig_data->resuming_mig_state.config_sz = cfg_sz;
+		}
+
+		release_update_locks_for_mdev(matrix_mdev);
+		mutex_unlock(&ap_attr_mutex);
+
+		if (ret)
+			goto cleanup;
+	}
+
+	ret = len;
+	*pos += len;
+	goto done;
+
+cleanup:
+	kfree(ap_config);
+done:
+	if (mutex_is_locked(&matrix_dev->mdevs_lock))
+		mutex_unlock(&matrix_dev->mdevs_lock);
+
+	return ret;
 }
 
 static const struct file_operations vfio_ap_resume_fops = {
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index c5eb9e4aa85c..2c4cca4920b3 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -81,74 +81,6 @@ static inline void release_update_locks_for_kvm(struct kvm *kvm)
 	mutex_unlock(&matrix_dev->guests_lock);
 }
 
-/**
- * get_update_locks_for_mdev: Acquire the locks required to dynamically update a
- *			      KVM guest's APCB in the proper order.
- *
- * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP
- *		 configuration data to use to update a KVM guest's APCB.
- *
- * The proper locking order is:
- * 1. matrix_dev->guests_lock: required to use the KVM pointer to update a KVM
- *			       guest's APCB.
- * 2. matrix_mdev->kvm->lock:  required to update a guest's APCB
- * 3. matrix_dev->mdevs_lock:  required to access data stored in a matrix_mdev
- *
- * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM
- *	 lock will not be taken.
- */
-static inline void get_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
-{
-	mutex_lock(&matrix_dev->guests_lock);
-	if (matrix_mdev && matrix_mdev->kvm)
-		mutex_lock(&matrix_mdev->kvm->lock);
-	mutex_lock(&matrix_dev->mdevs_lock);
-}
-
-/**
- * assert_has_update_locks_for_mdev:
- *
- * Assert the locks required to dynamically update a KVM guest's APCB are
- * currently held.
- *
- * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP
- *		 configuration data to use to update a KVM guest's APCB.
- *
- * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM
- *		 lock will not be taken.
- */
-static inline void
-assert_has_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
-{
-	lockdep_assert_held(&matrix_dev->guests_lock);
-	if (matrix_mdev && matrix_mdev->kvm)
-		lockdep_assert_held(&matrix_mdev->kvm->lock);
-	lockdep_assert_held(&matrix_dev->mdevs_lock);
-}
-
-/**
- * release_update_locks_for_mdev: Release the locks used to dynamically update a
- *				  KVM guest's APCB in the proper order.
- *
- * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP
- *		 configuration data to use to update a KVM guest's APCB.
- *
- * The proper unlocking order is:
- * 1. matrix_dev->mdevs_lock
- * 2. matrix_mdev->kvm->lock
- * 3. matrix_dev->guests_lock
- *
- * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM
- *	 lock will not be released.
- */
-static inline void release_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
-{
-	mutex_unlock(&matrix_dev->mdevs_lock);
-	if (matrix_mdev && matrix_mdev->kvm)
-		mutex_unlock(&matrix_mdev->kvm->lock);
-	mutex_unlock(&matrix_dev->guests_lock);
-}
-
 /**
  * get_update_locks_by_apqn: Find the mdev to which an APQN is assigned and
  *			     acquire the locks required to update the APCB of
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 7ae48729cafa..7f0c69f2fd9e 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -157,6 +157,62 @@ struct vfio_ap_queue {
 	struct work_struct reset_work;
 };
 
+/**
+ * get_update_locks_for_mdev: Acquire the locks required to dynamically update a
+ *			      KVM guest's APCB in the proper order.
+ *
+ * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP
+ *		 configuration data to use to update a KVM guest's APCB.
+ *
+ * The proper locking order is:
+ * 1. matrix_dev->guests_lock: required to use the KVM pointer to update a KVM
+ *			       guest's APCB.
+ * 2. matrix_mdev->kvm->lock:  required to update a guest's APCB
+ * 3. matrix_dev->mdevs_lock:  required to access data stored in a matrix_mdev
+ *
+ * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM
+ *	 lock will not be taken.
+ */
+static inline void get_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
+{
+	mutex_lock(&matrix_dev->guests_lock);
+	if (matrix_mdev && matrix_mdev->kvm)
+		mutex_lock(&matrix_mdev->kvm->lock);
+	mutex_lock(&matrix_dev->mdevs_lock);
+}
+
+/**
+ * release_update_locks_for_mdev: Release the locks used to dynamically update a
+ *				  KVM guest's APCB in the proper order.
+ *
+ * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP
+ *		 configuration data to use to update a KVM guest's APCB.
+ *
+ * The proper unlocking order is:
+ * 1. matrix_dev->mdevs_lock
+ * 2. matrix_mdev->kvm->lock
+ * 3. matrix_dev->guests_lock
+ *
+ * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM
+ *	 lock will not be released.
+ */
+static inline void release_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
+{
+	mutex_unlock(&matrix_dev->mdevs_lock);
+	if (matrix_mdev && matrix_mdev->kvm)
+		mutex_unlock(&matrix_mdev->kvm->lock);
+	mutex_unlock(&matrix_dev->guests_lock);
+}
+
+static inline void
+assert_has_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
+{
+	lockdep_assert_held(&matrix_dev->guests_lock);
+	if (matrix_mdev && matrix_mdev->kvm)
+		lockdep_assert_held(&matrix_mdev->kvm->lock);
+	lockdep_assert_held(&matrix_dev->mdevs_lock);
+}
+
 int vfio_ap_mdev_get_num_queues(struct ap_matrix *ap_matrix);
 
 int vfio_ap_mdev_register(void);
-- 
2.53.0

[PATCH v4 11/15] s390/vfio-ap: Transition device migration state to STOP

[Anthony Krowiak]

Typically at this point, interrupt processing for the device, DMA and other
changes to the device's external state must be prohibited. For VFIO AP,
there is no physical DMA device virtualized by the vfio-ap device . It
merely manages the guest's AP configuration that identifies the devices
passed through to the guest, but does not have access to any of them. Those
AP devices are passed through and controlled exclusively by the SIE program
used to start the guest. There  only thing to do at this point is return
NULL to the caller since the file streams and associated data will get
cleaned up as a result of the VFIO migration framework releasing the files.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 9cd1e7a3f743..1b526b743ad0 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -1159,12 +1159,17 @@ vfio_ap_transition_to_state(struct ap_matrix_mdev *matrix_mdev,
 		return filp;
 	}
 
+	/*
+	 * Terminates the data transfer session of the vfio-ap device state
+	 * between the source and target hosts. Since the vfio-ap device does
+	 * not virtualize a DMA device, there is no internal device state to
+	 * incorporate into the vfio-ap device on the target.
+	 */
 	if ((cur_state == VFIO_DEVICE_STATE_RESUMING &&
 	     new_state == VFIO_DEVICE_STATE_STOP) ||
 	    (cur_state == VFIO_DEVICE_STATE_STOP_COPY &&
 	     new_state == VFIO_DEVICE_STATE_STOP)) {
-		/* TODO */
-		return ERR_PTR(-EOPNOTSUPP);
+		return NULL;
 	}
 
 	if ((cur_state == VFIO_DEVICE_STATE_STOP &&
-- 
2.53.0

[PATCH v4 12/15] s390/vfio-ap: Transition device migration state from STOP to RUNNING and vice versa

[Anthony Krowiak]

The transition from STOP to RUNNING and vice versa indicates that
the vfio device is operating normally and migration is not
currently taking place. In this case, just set the new state.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 1b526b743ad0..572db04c4ac1 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -1172,12 +1172,17 @@ vfio_ap_transition_to_state(struct ap_matrix_mdev *matrix_mdev,
 		return NULL;
 	}
 
+	/*
+	 * These states indicate migration has either not been initiated or
+	 * has completed and the vfio-ap device is operating normally.Since the
+	 * vfio-ap device does not virtualize a DMA device, there is no internal
+	 * device state to incorporate into the vfio-ap device on the target.
+	 */
 	if ((cur_state == VFIO_DEVICE_STATE_STOP &&
 	     new_state == VFIO_DEVICE_STATE_RUNNING) ||
 	    (cur_state == VFIO_DEVICE_STATE_RUNNING &&
 	     new_state == VFIO_DEVICE_STATE_STOP)) {
-		/* TODO */
-		return ERR_PTR(-EOPNOTSUPP);
+		return NULL;
 	}
 
 	/* vfio_mig_get_next_state() does not use arcs other than the above */
-- 
2.53.0

[PATCH v4 13/15] s390/vfio-ap: Callback to get the size of data to be migrated during guest migration

[Anthony Krowiak]

Callback to get the estimated data length of the data that will be required
to complete reading of the vfio device's internal state. It's mandatory for
VFIO_DEVICE_FEATURE_MIGRATION migration support.

The function pointer for this callback is specified via the
'migration_get_data_size' field of the 'vfio_migration_ops' structure
which is stored with the VFIO device when the 'vfio_device'
structure representing the mediated device is initialized.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 572db04c4ac1..83e1ce2c40c0 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -1283,7 +1283,18 @@ static int vfio_ap_get_state(struct vfio_device *vdev,
 static int vfio_ap_get_data_size(struct vfio_device *vdev,
 				 unsigned long *stop_copy_length)
 {
-	return -EOPNOTSUPP;
+	struct ap_matrix_mdev *matrix_mdev;
+	size_t qinfo_sz;
+	int num_queues;
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
+	num_queues = vfio_ap_mdev_get_num_queues(&matrix_mdev->shadow_apcb);
+	qinfo_sz = num_queues * sizeof(struct vfio_ap_queue_info);
+	*stop_copy_length = qinfo_sz + sizeof(struct vfio_ap_config);
+	mutex_unlock(&matrix_dev->mdevs_lock);
+
+	return 0;
 }
 
 static const struct vfio_migration_ops vfio_ap_migration_ops = {
-- 
2.53.0

[PATCH v4 14/15] s390/vfio-ap: Add 'migratable' feature to sysfs 'features' attribute

[Anthony Krowiak]

Add the 'migratable' feature to the features provided by the sysfs
/sys/devices/vfio_ap/matrix/feature attribute to indicate that migration
of vfio devices is supported.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_drv.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index fd7394d81880..d2fc3598cd24 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -26,9 +26,11 @@ MODULE_LICENSE("GPL v2");
 struct ap_matrix_dev *matrix_dev;
 debug_info_t *vfio_ap_dbf_info;
 
+#define FEATURES "guest_matrix hotplug ap_config migratable"
+
 static ssize_t features_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	return sysfs_emit(buf, "guest_matrix hotplug ap_config\n");
+	return sysfs_emit(buf, "%s\n", FEATURES);
 }
 static DEVICE_ATTR_RO(features);
 
-- 
2.53.0

[PATCH v4 15/15] s390/vfio-ap: Add live guest migration chapter to vfio-ap.rst

[Anthony Krowiak]

Add a 'Live Guest Migration' chapter to the
Documentation/arch/s390/vfio-ap.rst document to describe the details for
initiating live guest migration for a guest to which AP adapters, domains
and control domains have been passed through.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 Documentation/arch/s390/vfio-ap.rst | 514 +++++++++++++++++++++++-----
 1 file changed, 433 insertions(+), 81 deletions(-)

diff --git a/Documentation/arch/s390/vfio-ap.rst b/Documentation/arch/s390/vfio-ap.rst
index ac0c07f76ddd..fc0707c0dffd 100644
--- a/Documentation/arch/s390/vfio-ap.rst
+++ b/Documentation/arch/s390/vfio-ap.rst
@@ -1012,7 +1012,7 @@ guest_matrix dyn ap_config
 
 the following features are advertised:
 
----------------+---------------------------------------------------------------+
++--------------+---------------------------------------------------------------+
 | Flag         | Description                                                   |
 +==============+===============================================================+
 | guest_matrix | guest_matrix attribute exists. It reports the matrix of       |
@@ -1021,105 +1021,457 @@ the following features are advertised:
 +--------------+---------------------------------------------------------------+
 | dyn          | Indicates hot plug/unplug of AP adapters, domains and control |
 |              | domains for a guest to which the mdev is attached.            |
-+------------+-----------------------------------------------------------------+
++--------------+---------------------------------------------------------------+
 | ap_config    | ap_config interface for one-shot modifications to mdev config |
 +--------------+---------------------------------------------------------------+
+| migratable   | Indicates that live guest migration is supported for guests   |
+|              | to which crypto devices are passed through                    |
++--------------+---------------------------------------------------------------+
 
-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:
+Live Guest Migration
+====================
+The VFIO AP mediated device is not used to provide userspace with direct
+access to a device as is the case with other devices that use the VFIO
+framework for device pass-through. Instead, it manages AP
+configuration metadata identifying the adapters, domains, and control
+domains to which a guest will be granted access. These AP resources are
+configured by assigning them to a vfio-ap mediated device via its sysfs
+assignment interfaces. When the guest is started, the vfio_ap device driver
+sets the guest's AP configuration from the metadata stored with the mediated
+device. The AP devices are not accessed directly through the vfio_ap driver,
+so the driver does not migrate the state of the AP devices themselves.
+Instead, it migrates the AP configuration metadata. The vfio_ap device
+driver on the destination host will then ensure that the AP configuration
+metadata migrated from the source host is compatible with the AP
+configuration available on the destination host and if
+so, will set the destination guest's AP configuration accordingly.
 
-      (QEMU) device-del id=<device-id>
+To be considered compatible, the AP configuration for the destination host must
+meet these requirements:
 
-      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:
+* Each AP adapter, domain and control domain number assigned to the source
+  guest's AP configuration must be in the destination host's AP
+  configuration. This can be verified as follows:
 
-         (QEMU) device-del id=hostdev0
+  * On the source host, display the AP configuration of the source guest:
 
-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:
+    .. code-block:: bash
 
-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:
+       cat /sys/devices/vfio_ap/matrix/$UUID/guest_matrix
+       cat /sys/devices/vfio_ap/matrix/$UUID/control_domains
 
-   virsh attach-device <guestname> <path-to-device-xml>
+    .. note::
+       Replace ``$UUID`` with the actual UUID of your mediated device.
 
-      For example, to hot plug mdev 62177883-f1bb-47f0-914d-32a22e3a8804 into
-      the guest named 'my-guest':
+  * Display the AP configuration of the destination host:
 
-         virsh attach-device my-guest ~/config/my-guest-hostdev.xml
+    .. code-block:: bash
 
-            The contents of my-guest-hostdev.xml:
+       lszcrypt -V
+       cat /sys/bus/ap/ap_control_domain_mask
 
-.. code-block:: xml
+    Note that each bit in the ap_control_domain_mask corresponds to
+    correspond to domain numbers 0-255. If a bit is set to one, then
+    the control domain is available on the destination host. For
+    example:
 
-            <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-ap'>
-              <source>
-                <address uuid='62177883-f1bb-47f0-914d-32a22e3a8804'/>
-              </source>
-            </hostdev>
+    .. code-block:: bash
 
+       0x0000000000001020000000000000000000000000000000000000000000000000
 
-   virsh qemu-monitor-command <guest-name> --hmp \
-   "device_add vfio-ap,sysfsdev=<path-to-mdev>,id=<device-id>"
+       This mask indicates that AP adapters 51 (0x33) and 58 (0x58) are
+       available on the host system.
 
-      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:
+  * Verify the configurations:
 
-      virsh qemu-monitor-command my-guest --hmp \
-      "device_add vfio-ap,\
-      sysfsdev=/sys/devices/vfio_ap/matrix/62177883-f1bb-47f0-914d-32a22e3a8804,\
-      id=hostdev0"
+    * Each APQN in the guest's sysfs ``guest_matrix`` file must match an
+      APQN returned from the lszcrypt command on the destination host. It
+      is important to note the driver to which the queue is bound which
+      is displayed in the ``driver`` column. Queues not bound to the vfio_ap
+      driver are not available to the destination guest. That, however, does
+      not guarantee they can be used by the guest being migrated; for example,
+      migration will fail if any of these APQNs are assigned to a mediated
+      device other than the one being migrated.
 
-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:
+    * Each domain number from the source guest's sysfs
+      ``control_domains`` attribute must correspond to a bit set to one in
+      the destination host's ``ap_control_domain_mask``.
 
-      (qemu) device_add "vfio-ap,sysfsdev=<path-to-mdev>,id=<device-id>"
+* Each APQN assigned to the source guest and destination guest must
+  reference a queue device with compatible hardware capabilities:
 
-      For example, to plug the vfio_ap mediated device
-      62177883-f1bb-47f0-914d-32a22e3a8804 into the guest with the device-id
-      hostdev0:
++--------------+---------------------------------------------------------------+
+| Hardware     | Description                                                   |
+| Capabilities |                                                               |
++==============+===============================================================+
+| [1]          | * AP special command facility (APSC)                          |
+| Facilities   | * AP 4096-bit ME PKU commands facility (AP4KM)                |
+|              | * AP 4096-bit CRT PKU commands (AP4KC)                        |
++--------------+---------------------------------------------------------------+
+| [1] Mode     | * CCA-mode                                                    |
+|              | * Accelerator-mode                                            |
+|              | * XCP-mode (EP11)                                             |
++--------------+---------------------------------------------------------------+
+| [1] AP       |   APXA installed                                              |
+| extended     |                                                               |
+| addressing   |                                                               |
++--------------+---------------------------------------------------------------+
+| [1] Command  |   Command filtering available                                 |
+| filtering    |                                                               |
++--------------+---------------------------------------------------------------+
+| [2]          | * Full native card function                                   |
+| Functional   | * Only stateless functions                                    |
+| capabilities |                                                               |
++--------------+---------------------------------------------------------------+
+| [3] AP type  | * 10 (0x0a): CEX4                                             |
+|              | * 11 (0x0b): CEX5                                             |
+|              | * 12 (0x0c)  CEX6                                             |
+|              | * 13 (0x0d)  CEX7                                             |
+|              | * 14 (0x0e)  CEX8                                             |
++--------------+---------------------------------------------------------------+
 
-         (QEMU) device-add "vfio-ap,\
-         sysfsdev=/sys/devices/vfio_ap/matrix/62177883-f1bb-47f0-914d-32a22e3a8804,\
-         id=hostdev0"
++-----------------------------------------------------------------------------+
+| Table Keys                                                                  |
++=============================================================================+
+|                                                                             |
+| [1]        The hardware capability must be the same for both the source     |
+|            and destination queue device.                                    |
+|                                                                             |
+| [2]        The source and destination queues must either both have          |
+|            full native card function or both have stateless functions.      |
+|            If the functional capabilities don't match, then the source      |
+|            queue can have stateless capabilities since full native card     |
+|            function can handle stateless functions; otherwise, migration    |
+|            will fail.                                                       |
+|                                                                             |
+| [3]        The AP type on the source and destination guests can             |
+|            differ if the queue passed through to the target guest is a      |
+|            newer model (backwards compatible)                               |
++--------------+--------------------------------------------------------------+
+
+* To verify the hardware capabilities are compatible:
+
+  * On both the source and destination hosts, display the hardware capabilities
+    for each AP adapter in the AP configuration for that host::
+
+       cat /sys/bus/ap/devices/card$APID/ap_functions
+
+    .. note::
+       The ``$APID`` is the two-character adapter number in hexidecimal format;
+       for example, card02 or card1f. The ``/sys/bus/ap/devices`` directory
+       also lists the APQNs of the queue devices installed in the respective
+       host system with the first two characters being the APID.
+
+  * Verify the hardware capabilities for each AP adapter device on the source
+    and destination host are compatible. The ``ap_functions`` attribute is a
+    bitmask. The bits in the mask read from left to right starting with bit 0.
+    Each bit that is set to one indicates the corresponding hardware capability
+    is installed:
+
+    * Bits 0-3 are the facilities bits. Each bit value must match for the AP
+      devices on the source and destination systems. The values indicate the
+      following:
+      * bit-0: APSC is installed
+      * bit-1: AP4KM is installed
+      * bit-2: AP4KC is installed
+
+    * Bits 3-5 specify the adapter Modes. Only one of these bits will be set to
+      one and must be the same for both the source and destination adapter
+      devices:
+      * bit-3: CCA-mode
+      * bit-4: Accelerator-mode
+      * bit-5: XCP-mode (EP11)
+
+    * Bit 6 specifies whether APXA is installed and must be the same for both
+      the source and destination adapter devices.
+
+    * Bit 7 specifies command whether command filtering is installed
+      and must be the same for both the source and destination adapter devices.
+
+    * Bits 8-15 are the classification bits. There are only two relevant
+      bits and only one of them will be set to one. For the source and destination
+      adapter devices to be considered compatible:
+
+      * Bit 8 may be set to 1 on both hosts (full native card function)
+      * Bit 9 may be set to 1 on both hosts (only stateless functions available)
+      * Bit 9 may be set to 1 on the source host and bit 8 may be set to 1 on
+        the destination host
+
+    * Bits 16-17 are the binding state bits which must be 00
+
+* To verify the AP types are compatible:
+
+  * On both the source and destination hosts, display the hardware type
+    for each AP adapter in the AP configuration for that host to ensure the
+    source and destination adapter types are the same, or the source type is
+    less than the destination type::
+
+       cat /sys/bus/ap/devices/card$APID/hwtype
+
+    .. note::
+       The ``$APID`` is the two-character adapter number in hexidecimal format;
+       for example, card02 or card1f.
+
+Setting up for live guest migration on the destination host
+-----------------------------------------------------------
+To set up a host as the destination for live guest migration, do the
+following:
+
+Create a mediated device
+~~~~~~~~~~~~~~~~~~~~~~~~
+Create a mediated device with the same name (UUID) as the mediated device
+used to supply the AP configuration to the source guest. For example, if
+the mediated device on the source guest is named
+62177883-f1bb-47f0-914d-32a22e3a8804:
+
+.. code-block:: bash
+
+   echo 62177883-f1bb-47f0-914d-32a22e3a8804 > \
+     /sys/devices/vfio_ap/matrix/mdev_supported_types/vfio_ap-passthrough/create
+
+Reserve adapters and domains for the vfio_ap device driver's use
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Reserve the same adapters and domains passed through to the source guest
+for the vfio_ap device driver on the destination host by clearing the
+adapter numbers from the ``/sys/bus/ap/ap_mask`` and/or the domain numbers
+from the ``/sys/bus/ap/aqmask`` files.
+
+For example, suppose adapters 0, 20 (0x14) and 22 (0x16) as well as
+domains 51 (0x33) and 58 (0x3a) are passed through to the source guest. To
+ensure they can be passed through to the destination guest, they must be
+made available to the vfio_ap device driver. To make them available, do one
+or both of the following on the destination host:
+
+.. code-block:: bash
+
+   echo -0,-0x14,-22 > /sys/bus/ap/apmask
+   echo -0,-0x33,-0x3a > /sys/bus/ap/aqmask
+
+.. note::
+
+    * It is not necessary to reserve both the adapters and domains.
+      Reserving an adapter implicitly allows the vfio_ap driver to assign
+      each of the domains available on the system along with the reserved
+      adapters to a guest's AP configuration and vice versa.
+
+    * Reserving adapters and/or domains will result in binding the queue
+      devices referenced by the APQNs derived from the Cartesian product of
+      the adapters and domains made available to the vfio_ap device driver
+      with one caveat; an APQN does not necessarily have to reference a
+      queue device installed in the system in order to reserve it for the
+      vfio_ap device driver; however, if the APQN does not reference a
+      queue device installed on the destination host, migration will fail.
+
+    * It is not necessary to configure the destination mediated device with
+      adapters, domains and control domains because the source guest's AP
+      configuration will overlay the destination guest's during migration.
+
+    * To verify that the queue devices are reserved for the vfio_ap
+      device driver, issue the ``lszcrypt -V`` command and you should
+      see ``vfio_ap`` in the ``driver`` column of the output.
+
+Live guest migration failures due to AP configuration errors
+------------------------------------------------------------
+This section describes the errors that may occur during live guest migration
+when the AP configuration of the source guest and destination host are not
+compatible and where to look for problem determination.
+
+The destination host is missing the mediated device
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This error occurs when a mediated device with the same name (UUID) as the
+mediated device being migrated has not been created on the destination host.
+
+**Source host**
+
++--------------+----------------------------------------------------------------+
+| Log          | Message                                                        |
++==============+================================================================+
+| Console log: | error: device not found: mediated device '$UUID' not           |
+|              | found                                                          |
++--------------+----------------------------------------------------------------+
+| QEMU log:    | initiating migration                                           |
+|              | qemu-system-s390x: Sibling indicated error 1                   |
++--------------+----------------------------------------------------------------+
+
+.. note::
+   $UUID is the UUID of the mediated device being migrated from the source host.
+
+
+One or more queues are not bound to the vfio_ap driver on the destination host
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The queue devices passed through to the source guest are not installed in the
+destination host or are not bound to its vfio_ap device driver.
+
+**Source host**
+
++--------------+----------------------------------------------------------------+
+| Log          | Message                                                        |
++==============+================================================================+
+| Console log: | error: operation failed: migration failed. Message from the    |
+|              | source host: operation failed: job 'migration out' failed:     |
+|              | Sibling indicated error 1. Message from the destination host:  |
+|              | operation failed: job 'migration in' failed: load of migration |
+|              | failed: No such device: Failed to load vmstate version_id: 1,  |
+|              | ret: -19                                                       |
++--------------+----------------------------------------------------------------+
+
+**Destinaton host**
+
++--------------+----------------------------------------------------------------+
+| Kernel log:  | vfio_ap_mdev $UUID: Queue $APID.$APQI not available to         |
+|              | vfio_ap driver on target host                                  |
++--------------+----------------------------------------------------------------+
+| QEMU log:    | shutting down, reason=failed                                   |
+|              | qemu-system-s390x: terminating on signal $SIGNAL_NUM from      |
+|              | pid $PID $DAEMON                                               |
++--------------+----------------------------------------------------------------+
+
+
+.. note::
+   * $UUID is the UUID of the mediated device being migrated from the source host.
+   * $APID.$APQI is adapter number and queue index (domain number) comprising the
+     $APQN (for example, 00.0033) of the queue device that is not available.
+   * $SIGNAL_NUM is the signal number that caused the QEMU process to terminate.
+   * $PID is the process ID of the QEMU process on the destination host.
+   * $DAEMON is the name of the QEMU daemon process.
+   * This message will be logged for each queue for which this error is detected.
+
+Failure to get hardware information for a queue device on destination host
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The vfio_ap device driver on the destination host will execute an AP instruction
+to get the hardware information for a queue device to perform queue compatibility
+checks. The instruction can fail for a number of reasons in which case the
+migration will be terminated.
+
+**Source host**
+
++--------------+----------------------------------------------------------------+
+| Log          | Message                                                        |
++==============+================================================================+
+| Console log: | error: operation failed: migration failed. Message from the    |
+|              | source host: operation failed: job 'migration out' failed:     |
+|              | Sibling indicated error 1. Message from the destination host:  |
+|              | operation failed: job 'migration in' failed: load of migration |
+|              | failed: failed to get hardware information for queue device    |
+|              | $APQN                                                          |
++--------------+----------------------------------------------------------------+
+
+**Destination host**
+
++--------------+----------------------------------------------------------------+
+| Log          | Message                                                        |
++==============+================================================================+
+| Console log: | vfio_ap_mdev $UUID: migration failed: Failed to get hwinfo for |
+|              | queue $APQN on target host: rc=$RESPONSE-CODE"                 |
++--------------+----------------------------------------------------------------+
+| QEMU log:    | shutting down, reason=failed                                   |
+|              | qemu-system-s390x: terminating on signal $SIGNAL-ID from pid   |
+|              | $PID $DAEMON                                                   |
++--------------+----------------------------------------------------------------+
+
+.. note::
+   * $UUID is the UUID of the mediated device being migrated from the source host.
+   * $APQN (for example, 00.0033) of the queue device that is not compatible.
+   * $RESPONSE_CODE is the response code from the AP instruction.
+   * $SIGNAL_NUM is the signal number of the signal that caused the QEMU process
+     to terminate.
+   * $PID is the process ID of the QEMU process on the destination host.
+   * $DAEMON is the name of the QEMU daemon process.
+   * This message will be logged for each queue for which this error is detected.
+
+The AP configurations of the source guest and destination host not incompatible
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The functional capabilities or facilities available on one or more of the queues
+passed through to the source guest are not compatible with the queue device with
+the same APQN on the destination system (see the Hardware Capabilities table above)
+
+**Source host**
+
++--------------+----------------------------------------------------------------+
+| Log          | Message                                                        |
++==============+================================================================+
+| Console log: | error: operation failed: migration failed. Message from the    |
+|              | source host: operation failed: job 'migration out' failed:     |
+|              | Sibling indicated error 1. Message from the destination host:  |
+|              | operation failed: job 'migration in' failed: load of migration |
+|              | failed: No such device: Failed to load vmstate version_id: 1,  |
+|              | ret: -19                                                       |
++--------------+----------------------------------------------------------------+
+| Kernel log:  | N/A                                                            |
++--------------+----------------------------------------------------------------+
+| QEMU log:    | *initiating migration*                                         |
+|              |                                                                |
+|              | *qemu-system-s390x: Sibling indicated error 1*                 |
++--------------+----------------------------------------------------------------+
+
+**Destination host**
+
++--------------+----------------------------------------------------------------+
+| Log          | Message                                                        |
++==============+================================================================+
+| Console log: | N/A                                                            |
++--------------+----------------------------------------------------------------+
+| Kernel log:  | *vfio_ap_mdev $UUID: Migration failed: Source and target       |
+|              | queue ($APQN) not compatible*                                  |
+|              |                                                                |
+|              | The message above will be followed by one or more messages     |
+|              | enumerating the incompatible features; for example:            |
+|              |                                                                |
+|              | ``vfio_ap_mdev $UUID: APSC facility installed in source queue  |
+|              | $APQN``                                                        |
+|              | ``vfio_ap_mdev $UUID: APSC facility not installed in target    |
+|              | queue $APQN``                                                  |
+|              |                                                                |
+|              | ``AP type of source ($APTYPE1) not compatible with target      |
+|              | ($APTYPE2)`` ...                                               |
++--------------+----------------------------------------------------------------+
+| QEMU log:    | *initiating migration*                                         |
+|              |                                                                |
+|              | *qemu-system-s390x: error while loading state section id ...*  |
+|              |                                                                |
+|              | *shutting down, reason=failed*                                 |
+|              |                                                                |
+|              | *terminating on signal $SIGNAL-ID from pid $PID $DAEMON*       |
++--------------+----------------------------------------------------------------+
+
+.. note::
+   * $UUID is the UUID of the mediated device being migrated from the source host.
+   * $APQN (for example, 00.0033) of the queue device that is incompatible.
+   * $APTYPE1 is the type of the source queue device.
+   * $APTYPE2 is the type of the target queue device.
+   * $SIGNAL-ID is the signal number of the signal that caused the QEMU process
+     to terminate.
+   * $PROCESS-ID is the process ID of the QEMU process on the source host.
+   * $PID is the process ID of the QEMU process on the destination host.
+   * $DAEMON is the name of the QEMU daemon process.
+   * Each follow-on message logging the incompatibility will be logged for each
+     error detected for the specified queue device.
+
+AP Configuration Management
+---------------------------
+The AP configurations of the source guest and destination host must be kept
+in synchronization or live guest migration will likely fail due to potential
+incompatibilities introduced by such changes. In particular, changing adapter
+or domain reservations via the sysfs ``apmask`` or ``aqmask`` attributes on
+either the source or destination host without coordinating such changes between
+the two hosts -especially while a migration is taking place - can result in
+migration failures.
+
+Configuration stability is an orchestration-layer or system administrator
+responsibility, which is consistent with other VFIO device types. The vfio_ap
+device driver will validate source and destination configurations and provide
+clear diagnostics when incompatibilities are detected, enabling orchestration
+tools to implement appropriate policies; for example, blocking migration when
+such changes are to be made.
+
+Master Key administration
+--------------------------
+It is imperative that s390 Common Cryptographic Architecture (CCA) master key
+administration be performed on both the source and destination AP
+devices to synchronize the key values prior to allowing live guest
+migration. If the master keys do not match, then crypto applications that
+rely on secure keys wrapped by a CCA master key will fail when the guest on
+which they are running is migrated to the destination host. Again, this is
+an orchestration-layer or system administrator responsibility and migration must
+be blocked while master key administration is being performed.
-- 
2.53.0