Re: [PATCH 3/7] s390/vfio_ap: use TAPQ to verify reset in progress completes

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

On 12/15/22 5:51 AM, Harald Freudenberger wrote:
> On 2022-12-13 16:44, Tony Krowiak wrote:
>> 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>
>> ---
>>  drivers/s390/crypto/vfio_ap_ops.c | 24 +++++++++++++-----------
>>  1 file changed, 13 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index a5530a46cf31..5bf2d93ae8af 100644
>> --- 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
>> @@ -1632,8 +1632,7 @@ 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;
>> @@ -1648,12 +1647,15 @@ static int vfio_ap_mdev_reset_queue(struct
>> vfio_ap_queue *q,
>>          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:
>> @@ -1688,7 +1690,7 @@ 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
>> @@ -1931,7 +1933,7 @@ 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);
>
> Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>


Thanks for the review.