Re: [PATCH v4 2/7] s390: vfio-ap: wait for queue empty on queue reset

Harald Freudenberger
2019-06-17T08:47:46Z

On 13.06.19 21:39, Tony Krowiak wrote:
> Refactors the AP queue reset function to wait until the queue is empty
> after the PQAP(ZAPQ) instruction is executed to zero out the queue as
> required by the AP architecture.
>
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 49 +++++++++++++++++++++++++++------------
> 1 file changed, 34 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index bf2ab02b9a0b..60efd3d7896d 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -1128,23 +1128,46 @@ static void vfio_ap_irq_disable_apqn(int apqn)
> }
> }
>
> -int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
> - unsigned int retry)
> +static void vfio_ap_mdev_wait_for_qempty(ap_qid_t qid)
> +{
> + struct ap_queue_status status;
> + int retry = 5;
> +
> + do {
> + status = ap_tapq(qid, NULL);
> + switch (status.response_code) {
> + case AP_RESPONSE_NORMAL:
> + if (status.queue_empty)
> + return;
> + case AP_RESPONSE_RESET_IN_PROGRESS:
> + case AP_RESPONSE_BUSY:
> + msleep(20);
> + break;
> + default:
> + pr_warn("%s: tapq response %02x waiting for queue %04x.%02x empty\n",
> + __func__, status.response_code,
> + AP_QID_CARD(qid), AP_QID_QUEUE(qid));
The ap and zcrypt code uses %02x.%04x for displaying an APQN.
I would also recommend to handle 0x01 (AP_RESPONSE_Q_NOT_AVAIL) and
0x03 (AP_RESPONSE_DECONFIGURED) as this code may run when a APQN
is removed from the configuration of the LPAR. However, it's up to you if you
want to handle these with the default statement and issue an sysfs warning.
> + return;
> + }
> + } while (--retry);
> +
> + WARN_ON_ONCE(retry <= 0);
> +}
> +
> +int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi)
> {
> struct ap_queue_status status;
> - int retry2 = 2;
> int apqn = AP_MKQID(apid, apqi);
> + int retry = 5;
>
> do {
> status = ap_zapq(apqn);
> switch (status.response_code) {
> case AP_RESPONSE_NORMAL:
> - while (!status.queue_empty && retry2--) {
> - msleep(20);
> - status = ap_tapq(apqn, NULL);
> - }
> - WARN_ON_ONCE(retry <= 0);
> + vfio_ap_mdev_wait_for_qempty(AP_MKQID(apid, apqi));
> return 0;
> + case AP_RESPONSE_DECONFIGURED:
> + return -ENODEV;
> case AP_RESPONSE_RESET_IN_PROGRESS:
> case AP_RESPONSE_BUSY:
> msleep(20);
> @@ -1169,14 +1192,10 @@ static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev)
> matrix_mdev->matrix.apm_max + 1) {
> for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
> matrix_mdev->matrix.aqm_max + 1) {
> - ret = vfio_ap_mdev_reset_queue(apid, apqi, 1);
> - /*
> - * Regardless whether a queue turns out to be busy, or
> - * is not operational, we need to continue resetting
> - * the remaining queues.
> - */
> + ret = vfio_ap_mdev_reset_queue(apid, apqi);
> if (ret)
> rc = ret;
> +
> vfio_ap_irq_disable_apqn(AP_MKQID(apid, apqi));
> }
> }
> @@ -1326,7 +1345,7 @@ void vfio_ap_mdev_remove_queue(struct ap_queue *queue)
> dev_set_drvdata(&queue->ap_dev.device, NULL);
> apid = AP_QID_CARD(q->apqn);
> apqi = AP_QID_QUEUE(q->apqn);
> - vfio_ap_mdev_reset_queue(apid, apqi, 1);
> + vfio_ap_mdev_reset_queue(apid, apqi);
> vfio_ap_irq_disable(q);
> kfree(q);
> }