[PATCH v11 11/14] s390/vfio-ap: Callback to get the size of data to be migrated during guest migration

[Anthony Krowiak <akrowiak@linux.ibm.com>]

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>
Reviewed-by: Jason J. Herne <jjherne@linux.ibm.com>
---
 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 c5534c6ee3ce..7c282d396f50 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -1308,7 +1308,15 @@ 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