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Message-ID: <29a5eb8259fc9735aa3a7de5334d9919@linux.ibm.com>
Date: Thu, 15 Dec 2022 09:24:15 +0100
From: Harald Freudenberger <freude@...ux.ibm.com>
To: Tony Krowiak <akrowiak@...ux.ibm.com>
Cc: linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, jjherne@...ux.ibm.com, borntraeger@...ibm.com,
cohuck@...hat.com, mjrosato@...ux.ibm.com, pasic@...ux.ibm.com,
alex.williamson@...hat.com, kwankhede@...dia.com,
fiuczy@...ux.ibm.com
Subject: Re: [PATCH 1/7] s390/vfio-ap: verify reset complete in separate
function
On 2022-12-13 16:44, Tony Krowiak wrote:
> The vfio_ap_mdev_reset_queue() function contains a loop to verify that
> the
> reset successfully completes within 40ms. This patch moves that loop
> into
> a separate function.
>
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 30 +++++++++++++++++++++---------
> 1 file changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
> b/drivers/s390/crypto/vfio_ap_ops.c
> index 0b4cc8c597ae..83ff94a38102 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -1587,12 +1587,30 @@ static struct vfio_ap_queue
> *vfio_ap_find_queue(int apqn)
> return q;
> }
>
> +static int apq_reset_check(struct vfio_ap_queue *q)
> +{
> + int iters = 2;
> + struct ap_queue_status status;
> +
> + while (iters--) {
> + msleep(20);
> + status = ap_tapq(q->apqn, NULL);
> + if (status.queue_empty && !status.irq_enabled)
> + return 0;
> + }
> + 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;
> +}
> +
> static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q,
> unsigned int retry)
> {
> struct ap_queue_status status;
> int ret;
> - int retry2 = 2;
>
> if (!q)
> return 0;
> @@ -1629,14 +1647,8 @@ static int vfio_ap_mdev_reset_queue(struct
> vfio_ap_queue *q,
> }
>
> /* wait for the reset to take effect */
> - while (retry2--) {
> - if (status.queue_empty && !status.irq_enabled)
> - break;
> - msleep(20);
> - status = ap_tapq(q->apqn, NULL);
> - }
> - WARN_ONCE(retry2 <= 0, "unable to verify reset of queue %02x.%04x",
> - AP_QID_CARD(q->apqn), AP_QID_QUEUE(q->apqn));
> + if (!status.queue_empty && status.irq_enabled)
Hm, you check for
a) status.queue_empty and
b) !status.irq_enabled
which is (status.queue_empty && !status.irq_enabled)
and now let's negate this to:
!(status.queue_empty && !status.irq_enabled)
with de-morgan this gives:
(!status.queue_empty || status.irq_enabled)
> + ret = apq_reset_check(q);
>
> free_resources:
> vfio_ap_free_aqic_resources(q);
Reviewed-by: Harald Freudenberger <freude@...ux.ibm.com>
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