[GIT PULL 07/22] s390/vfio-ap: no need to check the 'E' and 'I' bits in APQSW after TAPQ

Janosch Frank
2023-08-24T12:47:30Z

From: Tony Krowiak <akrowiak@linux.ibm.com>

After a ZAPQ is executed to reset a queue, if the queue is not empty or
interrupts are still enabled, the vfio_ap driver will wait for the reset
operation to complete by repeatedly executing the TAPQ instruction and
checking the 'E' and 'I' bits in the APQSW to verify that the queue is
empty and interrupts are disabled. This is unnecessary because it is
sufficient to check only the response code in the APQSW. If the reset is
still in progress, the response code will be 02; however, if the reset has
completed successfully, the response code will be 00.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Tested-by: Viktor Mihajlovski <mihajlov@linux.ibm.com>
Link: https://lore.kernel.org/r/20230815184333.6554-2-akrowiak@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
drivers/s390/crypto/vfio_ap_ops.c | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index b441745b0418..3fd80533194b 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1608,19 +1608,10 @@ 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;
+ case AP_RESPONSE_RESET_IN_PROGRESS:
+ return -EBUSY;
default:
WARN(true,
"failed to verify reset of queue %02x.%04x: TAPQ rc=%u\n",
--
2.41.0