s390/vfio_ap: check TAPQ response code when waiting for queue reset

The vfio_ap_mdev_reset_queue() function does not check the status
response code returned form the PQAP(TAPQ) function when verifying the
queue's status; consequently, there is no way of knowing whether
verification failed because the wait time was exceeded, or because the
PQAP(TAPQ) failed.

This patch adds a function to check the status response code from the
PQAP(TAPQ) instruction and logs an appropriate message if it fails.

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/20230118203111.529766-3-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 785d07991da93a6ee0898ebbc02ff30c7b598ea3..7031e360411bcf6faca0f43ff02f2c02696ec817 100644 (file)
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1598,23 +1598,49 @@ static struct vfio_ap_queue *vfio_ap_find_queue(int apqn)
        return q;
 }
 
+static int apq_status_check(int apqn, struct ap_queue_status *status)
+{
+       switch (status->response_code) {
+       case AP_RESPONSE_NORMAL:
+       case AP_RESPONSE_RESET_IN_PROGRESS:
+               if (status->queue_empty && !status->irq_enabled)
+                       return 0;
+               return -EBUSY;
+       case AP_RESPONSE_DECONFIGURED:
+               /*
+                * If the AP queue is deconfigured, any subsequent AP command
+                * targeting the queue will fail with the same response code. On the
+                * other hand, when an AP adapter is deconfigured, the associated
+                * queues are reset, so let's return a value indicating the reset
+                * for which we're waiting completed successfully.
+                */
+               return 0;
+       default:
+               WARN(true,
+                    "failed to verify reset of queue %02x.%04x: TAPQ rc=%u\n",
+                    AP_QID_CARD(apqn), AP_QID_QUEUE(apqn),
+                    status->response_code);
+               return -EIO;
+       }
+}
+
 static int apq_reset_check(struct vfio_ap_queue *q)
 {
-       int iters = 2;
+       int iters = 2, ret;
        struct ap_queue_status status;
 
        while (iters--) {
                msleep(20);
                status = ap_tapq(q->apqn, NULL);
-               if (status.queue_empty && !status.irq_enabled)
-                       return 0;
+               ret = apq_status_check(q->apqn, &status);
+               if (ret != -EBUSY)
+                       return ret;
        }
        WARN_ONCE(iters <= 0,
                  "timeout verifying reset of queue %02x.%04x (%u, %u, %u)",
                  AP_QID_CARD(q->apqn), AP_QID_QUEUE(q->apqn),
                  status.queue_empty, status.irq_enabled, status.response_code);
-
-       return -EBUSY;
+       return ret;
 }
 
 static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q,