Messages in this thread | | | Subject | Re: [PATCH v2 1/7] s390: vfio-ap: wait for queue empty on queue reset | From | Pierre Morel <> | Date | Tue, 7 May 2019 10:10:41 +0200 |
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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 .
> >> >>> 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.
> >> >>> >> >> >
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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