[PATCH v8 12/15] s390/vfio-ap: Transition device migration state to from/to STOP

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

VFIO_DEVICE_STATE_RESUMING to VFIO_DEVICE_STATE_STOP
VFIO_DEVICE_STATE_STOP_COPY to VFIO_DEVICE_STATE_STOP
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Terminates the data transfer session of the vfio-ap device state
between the source and target hosts. Release the migration file
state (ap_config buffers and file pointers) so that a subsequent
migration captures a fresh AP configuration rather than serving
stale data. 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, so return NULL since no file stream
is needed in the STOP state.

VFIO_DEVICE_STATE_STOP to VFIO_DEVICE_STATE_RUNNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Migration has been cancelled. Release the migration file state so
that a subsequent migration captures a fresh AP configuration
rather than serving stale data.

VFIO_DEVICE_STATE_RUNNING to VFIO_DEVICE_STATE_STOP
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Migration has not yet been initiated. No migration file state
exists to release, so just return NULL.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_migration.c | 33 +++++++++++++++++++------
 1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_migration.c b/drivers/s390/crypto/vfio_ap_migration.c
index caae95b47a9a..ed30e6ff0127 100644
--- a/drivers/s390/crypto/vfio_ap_migration.c
+++ b/drivers/s390/crypto/vfio_ap_migration.c
@@ -186,6 +186,8 @@ static void vfio_ap_release_resuming_file(struct vfio_ap_migration_data *mig_dat
 	mig_data->resuming_mig_file.filp = NULL;
 }
 
+static void vfio_ap_release_mig_files(struct ap_matrix_mdev *matrix_mdev);
+
 static int vfio_ap_release_mig_file(struct inode *file_inode, struct file *filp)
 {
 	struct ap_matrix_mdev *matrix_mdev = filp->private_data;
@@ -1226,20 +1228,35 @@ 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);
+		vfio_ap_release_mig_files(matrix_mdev);
+		return NULL;
 	}
 
-	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);
+	/*
+	 * 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) {
+		vfio_ap_release_mig_files(matrix_mdev);
+		return NULL;
+	}
+
+	if (cur_state == VFIO_DEVICE_STATE_RUNNING &&
+	    new_state == VFIO_DEVICE_STATE_STOP) {
+		return NULL;
 	}
 
 	/* vfio_mig_get_next_state() does not use arcs other than the above */
-- 
2.53.0