Messages in this thread | | | Subject | Re: [PATCH v2 1/7] s390: vfio-ap: wait for queue empty on queue reset | From | Tony Krowiak <> | Date | Tue, 7 May 2019 11:12:22 -0400 |
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On 5/7/19 4:10 AM, Pierre Morel wrote: > On 06/05/2019 21:37, Tony Krowiak wrote: >> 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 <akrowiak@linux.ibm.com> >>>> --- >>>> 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? > > > Yes, I fear that if we reissue the zapq while RESET is in progress we > could fall in a loop depending on the reset hardware time and the > software retry .
I already did this in the forthcoming v4 series.
> >> >>> >>>> 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. > > Sorry, I should have add: NIT. > >> >>> >>> >>> >>>> /* >>>> * 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. > > Yes, this was the point, but I consider this as a enhancement, trying a > reset on bad queues AFAIK do no arm.
I included the enhancement in the forthcoming v4 series.
> >> >>> >>>> >>> >>> >> > >
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