From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v2 1/7] s390: vfio-ap: wait for queue empty on queue reset References: <1556918073-13171-1-git-send-email-akrowiak@linux.ibm.com> <1556918073-13171-2-git-send-email-akrowiak@linux.ibm.com> <0bdb1655-4c4e-1982-a842-9dfc7c02a576@linux.ibm.com> From: Tony Krowiak Date: Mon, 6 May 2019 15:37:37 -0400 MIME-Version: 1.0 In-Reply-To: <0bdb1655-4c4e-1982-a842-9dfc7c02a576@linux.ibm.com> Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Language: en-US Content-Transfer-Encoding: 8bit Message-Id: Sender: kvm-owner@vger.kernel.org List-Archive: List-Post: To: pmorel@linux.ibm.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: freude@linux.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, frankja@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, pasic@linux.ibm.com, alex.williamson@redhat.com, kwankhede@nvidia.com List-ID: On 5/6/19 2:41 AM, Pierre Morel wrote: > On 03/05/2019 23:14, 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 >> --- >>   drivers/s390/crypto/vfio_ap_ops.c | 35 >> ++++++++++++++++++++++++++++++++--- >>   1 file changed, 32 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/s390/crypto/vfio_ap_ops.c >> b/drivers/s390/crypto/vfio_ap_ops.c >> index 900b9cf20ca5..b88a2a2ba075 100644 >> --- a/drivers/s390/crypto/vfio_ap_ops.c >> +++ b/drivers/s390/crypto/vfio_ap_ops.c >> @@ -271,6 +271,32 @@ static int vfio_ap_mdev_verify_no_sharing(struct >> ap_matrix_mdev *matrix_mdev) >>       return 0; >>   } >> +static void vfio_ap_mdev_wait_for_qempty(unsigned long apid, unsigned >> long apqi) >> +{ >> +    struct ap_queue_status status; >> +    ap_qid_t qid = AP_MKQID(apid, apqi); >> +    int retry = 5; >> + >> +    do { >> +        status = ap_tapq(qid, NULL); >> +        switch (status.response_code) { >> +        case AP_RESPONSE_NORMAL: >> +            if (status.queue_empty) >> +                return; >> +            msleep(20); > > NIT:     Fall through ? Yes > >> +            break; >> +        case AP_RESPONSE_RESET_IN_PROGRESS: >> +        case AP_RESPONSE_BUSY: >> +            msleep(20); >> +            break; >> +        default: >> +            pr_warn("%s: tapq err %02x: %04lx.%02lx may not be empty\n", >> +                __func__, status.response_code, apid, apqi); > > I do not thing the warning sentence is appropriate: > The only possible errors here are if the AP is not available due to AP > checkstop, deconfigured AP or invalid APQN. Right you are! I'll work on a new message. > > >> +            return; >> +        } >> +    } while (--retry); >> +} >> + >>   /** >>    * assign_adapter_store >>    * >> @@ -790,15 +816,18 @@ static int vfio_ap_mdev_group_notifier(struct >> notifier_block *nb, >>       return NOTIFY_OK; >>   } >> -static int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int >> apqi, >> -                    unsigned int retry) >> +int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi) >>   { >>       struct ap_queue_status status; >> +    int retry = 5; >>       do { >>           status = ap_zapq(AP_MKQID(apid, apqi)); >>           switch (status.response_code) { >>           case AP_RESPONSE_NORMAL: >> +            vfio_ap_mdev_wait_for_qempty(apid, apqi); >> +            return 0; >> +        case AP_RESPONSE_DECONFIGURED: > > Since you modify the switch, you can return for all the following cases: > AP_RESPONSE_DECONFIGURE > ..._CHECKSTOP > ..._INVALID_APQN > > > And you should wait for qempty on AP_RESET_IN_PROGRESS along with > AP_RESPONSE_NORMAL If a queue reset is in progress, we retry the zapq. Are you saying we should wait for qempty then reissue the zapq? > >>               return 0; >>           case AP_RESPONSE_RESET_IN_PROGRESS: >>           case AP_RESPONSE_BUSY: > > While at modifying this function, the AP_RESPONSE_BUSY is not a valid > code for ZAPQ, you can remove this. Okay > >> @@ -824,7 +853,7 @@ 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); >> +            ret = vfio_ap_mdev_reset_queue(apid, apqi); > > IMHO, since you are at changing this call, passing the apqn as parameter > would be a good simplification. Okay. > > > >>               /* >>                * Regardless whether a queue turns out to be busy, or >>                * is not operational, we need to continue resetting > > Depends on why the reset failed, but this is out of scope. I'm not sure what you mean by out of scope here, but you do make a valid point. If the response code for the zapq is AP_RESPONSE_DECONFIGURED, there is probably no sense in continuing to reset queues for that particular adapter. I'll consider a change here. > >> > >