[PATCH v1 12/24] s390-vfio-ap: Callback to set vfio device mig state during guest migration

Anthony Krowiak
2026-03-25T21:02:11Z

Implements the callback that sets a new migration state of a vfio 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.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
drivers/s390/crypto/vfio_ap_migration.c | 87 ++++++++++++++++++++++++-
1 file changed, 86 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 76cbbe1adb7a..a8b109bc5cf9 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -96,10 +96,95 @@ static void vfio_ap_release_mig_files(struct ap_matrix_mdev *matrix_mdev)
}
}

+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) {
+ /* TODO */
+ return ERR_PTR(-EOPNOTSUPP);
+ }
+
+ if (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;
+
+ mutex_lock(&matrix_dev->mdevs_lock);
+ matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
+ mig_data = matrix_mdev->mig_data;
+ 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,
--
2.52.0