Messages in this thread | | | Date | Mon, 22 Aug 2022 09:19:45 -0400 | Subject | Re: [PATCH v2 1/2] s390/vfio-ap: fix hang during removal of mdev after duplicate assignment | From | Anthony Krowiak <> |
| |
On 8/18/22 10:12 AM, Halil Pasic wrote: > On Thu, 18 Aug 2022 09:26:05 -0400 > Tony Krowiak <akrowiak@linux.ibm.com> wrote: > > Subject: s390/vfio-ap: fix hang during removal of mdev after duplicate > assignment > > It would have made sense to do it this way in the first place, even > if the link code were to take care of the duplicates. It did not really > make sense to do the whole filtering biz and everything else. Maybe we > should spin the short description and the rest of the commit message so > it reflects the code more.
Okay, I think I'm picking up what you're laying down here. I believe you are suggesting I change the subject to indicate that the unnecessary processing of AP resources should be bypassed and the rest of the description should expound on that.
> > >> When the same adapter or domain is assigned more than one time prior to >> removing the matrix mdev to which it is assigned, the remove operation >> will hang. The reason is because the same vfio_ap_queue objects with an >> APQN containing the APID of the adapter or APQI of the domain being >> assigned will get added to the hashtable that holds them multiple times. >> This results in the pprev and next pointers of the hlist_node (mdev_qnode >> field in the vfio_ap_queue object) pointing to the queue object itself. >> This causes an interminable loop when the mdev is removed and the queue >> table is iterated to reset the queues. >> >> To fix this problem, the assignment operation is bypassed when assigning >> an adapter or domain if it is already assigned to the matrix mdev. >> >> Since it is not necessary to assign a resource already assigned or to >> unassign a resource that has not been assigned, this patch will bypass >> all assignment/unassignment operations for an adapter, domain or >> control domain under these circumstances. >> >> Cc: stable@vger.kernel.org >> Fixes: 771e387d5e79 ("s390/vfio-ap: manage link between queue struct and matrix mdev") > Not 11cb2419fafe ("s390/vfio-ap: manage link between queue struct and > matrix mdev") > > Is my repo borked? > > >> Reported-by: Matthew Rosato <mjrosato@linux.ibm.com> >> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com> >> --- >> drivers/s390/crypto/vfio_ap_ops.c | 30 ++++++++++++++++++++++++++++++ >> 1 file changed, 30 insertions(+) >> >> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c >> index 6c8c41fac4e1..ee82207b4e60 100644 >> --- a/drivers/s390/crypto/vfio_ap_ops.c >> +++ b/drivers/s390/crypto/vfio_ap_ops.c >> @@ -984,6 +984,11 @@ static ssize_t assign_adapter_store(struct device *dev, >> goto done; >> } >> >> + if (test_bit_inv(apid, matrix_mdev->matrix.apm)) { >> + ret = count; >> + goto done; >> + } >> + >> set_bit_inv(apid, matrix_mdev->matrix.apm); >> >> ret = vfio_ap_mdev_validate_masks(matrix_mdev); >> @@ -1109,6 +1114,11 @@ static ssize_t unassign_adapter_store(struct device *dev, >> goto done; >> } >> >> + if (!test_bit_inv(apid, matrix_mdev->matrix.apm)) { >> + ret = count; >> + goto done; >> + } >> + >> clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm); >> vfio_ap_mdev_hot_unplug_adapter(matrix_mdev, apid); >> ret = count; >> @@ -1183,6 +1193,11 @@ static ssize_t assign_domain_store(struct device *dev, >> goto done; >> } >> >> + if (test_bit_inv(apqi, matrix_mdev->matrix.aqm)) { >> + ret = count; >> + goto done; >> + } >> + >> set_bit_inv(apqi, matrix_mdev->matrix.aqm); >> >> ret = vfio_ap_mdev_validate_masks(matrix_mdev); >> @@ -1286,6 +1301,11 @@ static ssize_t unassign_domain_store(struct device *dev, >> goto done; >> } >> >> + if (!test_bit_inv(apqi, matrix_mdev->matrix.aqm)) { >> + ret = count; >> + goto done; >> + } >> + >> clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm); >> vfio_ap_mdev_hot_unplug_domain(matrix_mdev, apqi); >> ret = count; >> @@ -1329,6 +1349,11 @@ static ssize_t assign_control_domain_store(struct device *dev, >> goto done; >> } >> >> + if (test_bit_inv(id, matrix_mdev->matrix.adm)) { >> + ret = count; >> + goto done; >> + } >> + >> /* Set the bit in the ADM (bitmask) corresponding to the AP control >> * domain number (id). The bits in the mask, from most significant to >> * least significant, correspond to IDs 0 up to the one less than the >> @@ -1378,6 +1403,11 @@ static ssize_t unassign_control_domain_store(struct device *dev, >> goto done; >> } >> >> + if (!test_bit_inv(domid, matrix_mdev->matrix.adm)) { >> + ret = count; >> + goto done; >> + } >> + >> clear_bit_inv(domid, matrix_mdev->matrix.adm); >> >> if (test_bit_inv(domid, matrix_mdev->shadow_apcb.adm)) {
| |