s390/vfio_ap: use TAPQ to verify reset in progress completes

To eliminate the repeated calls to the PQAP(ZAPQ) function to verify that
a reset in progress completed successfully and ensure that error response
codes get appropriately logged, let's call the apq_reset_check() function
when the ZAPQ response code indicates that a reset that is already in
progress.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Jason J. Herne <jjherne@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Link: https://lore.kernel.org/r/20230118203111.529766-4-akrowiak@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 7031e360411bcf6faca0f43ff02f2c02696ec817..bc9a814e6508cee45f0a8bade304ea751911531e 100644 (file)
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -33,7 +33,7 @@
 static int vfio_ap_mdev_reset_queues(struct ap_queue_table *qtable);
 static struct vfio_ap_queue *vfio_ap_find_queue(int apqn);
 static const struct vfio_device_ops vfio_ap_matrix_dev_ops;
-static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q, unsigned int retry);
+static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q);
 
 /**
  * get_update_locks_for_kvm: Acquire the locks required to dynamically update a
@@ -1643,8 +1643,7 @@ static int apq_reset_check(struct vfio_ap_queue *q)
        return ret;
 }
 
-static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q,
-                                   unsigned int retry)
+static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q)
 {
        struct ap_queue_status status;
        int ret;
@@ -1659,12 +1658,15 @@ retry_zapq:
                ret = 0;
                break;
        case AP_RESPONSE_RESET_IN_PROGRESS:
-               if (retry--) {
-                       msleep(20);
-                       goto retry_zapq;
-               }
-               ret = -EBUSY;
-               break;
+               /*
+                * There is a reset issued by another process in progress. Let's wait
+                * for that to complete. Since we have no idea whether it was a RAPQ or
+                * ZAPQ, then if it completes successfully, let's issue the ZAPQ.
+                */
+               ret = apq_reset_check(q);
+               if (ret)
+                       break;
+               goto retry_zapq;
        case AP_RESPONSE_Q_NOT_AVAIL:
        case AP_RESPONSE_DECONFIGURED:
        case AP_RESPONSE_CHECKSTOPPED:
@@ -1699,7 +1701,7 @@ static int vfio_ap_mdev_reset_queues(struct ap_queue_table *qtable)
        struct vfio_ap_queue *q;
 
        hash_for_each(qtable->queues, loop_cursor, q, mdev_qnode) {
-               ret = vfio_ap_mdev_reset_queue(q, 1);
+               ret = vfio_ap_mdev_reset_queue(q);
                /*
                 * Regardless whether a queue turns out to be busy, or
                 * is not operational, we need to continue resetting
@@ -1950,7 +1952,7 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
                }
        }
 
-       vfio_ap_mdev_reset_queue(q, 1);
+       vfio_ap_mdev_reset_queue(q);
        dev_set_drvdata(&apdev->device, NULL);
        kfree(q);
        release_update_locks_for_mdev(matrix_mdev);