Implements 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 | 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 750299fb1a84..305fd3221be1 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -1014,7 +1014,18 @@ static struct file *vfio_ap_set_state(struct vfio_device *vdev,
 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;
+	*current_state = mig_data->mig_state;
+
+	mutex_unlock(&matrix_dev->mdevs_lock);
+
+	return 0;
 }
 
 static int vfio_ap_get_data_size(struct vfio_device *vdev,
-- 
2.52.0