[PATCH v7 13/15] s390/vfio-ap: Callback to get the size of data to be migrated during guest migration

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 <[email protected]>
---
 drivers/s390/crypto/vfio_ap_migration.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index 24955f70e13e..01933a62dab9 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -1636,7 +1636,15 @@ 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;
+	int num_queues;
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
+	*stop_copy_length = vfio_ap_config_size(matrix_mdev, &num_queues);
+	mutex_unlock(&matrix_dev->mdevs_lock);
+
+	return 0;
 }
 
 static const struct vfio_migration_ops vfio_ap_migration_ops = {
-- 
2.53.0