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SubjectRe: [PATCH 2/7] s390/vfio_ap: check TAPQ response code when waiting for queue reset
On 2022-12-13 16:44, Tony Krowiak wrote:
> 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>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 36 ++++++++++++++++++++++++++-----
> 1 file changed, 31 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
> b/drivers/s390/crypto/vfio_ap_ops.c
> index 83ff94a38102..a5530a46cf31 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -1587,23 +1587,49 @@ 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,

Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>

Just one word here: this function is only called once and it is very
very special
to just check the status after RAPQ/ZAPQ. I would merge this function
into the
calling code or rename the function to reflect the special condition
under which
it is called. However - this is not my code and I don't need to maintain
it, so
maybe simple ignore my words.

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