Messages in this thread | | | Date | Thu, 15 Sep 2022 16:53:51 +0200 | Subject | Re: [PATCH v3 1/2] s390/vfio-ap: bypass unnecessary processing of AP resources | From | Christian Borntraeger <> |
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Am 15.09.22 um 05:00 schrieb Halil Pasic: > On Tue, 23 Aug 2022 11:06:42 -0400 > Tony Krowiak <akrowiak@linux.ibm.com> wrote: > >> It is not necessary to go through the process of validation, linking of >> queues to mdev and vice versa and filtering the APQNs assigned to the >> matrix mdev to build an AP configuration for a guest if an adapter or >> domain being assigned is already assigned to the matrix mdev. Likewise, it >> is not necessary to proceed through the process the unassignment of an >> adapter, domain or control domain if it is not assigned to the matrix mdev. >> >> Since it is not necessary to process assignment of a resource resource >> already assigned or process unassignment of a resource that is been assigned, >> this patch will bypass all assignment/unassignment operations for an adapter, >> domain or control domain under these circumstances. >> >> Not only is assignment of a duplicate adapter or domain unnecessary, it >> will also cause a hang situation when removing the matrix mdev to which it is >> assigned. 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 multiple times to the hashtable that holds them. >> 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 >> resulting in an interminable loop when the mdev is removed and the queue >> table is iterated to reset the queues. >> >> Cc: stable@vger.kernel.org >> Fixes: 11cb2419fafe ("s390/vfio-ap: manage link between queue struct and matrix mdev") >> Reported-by: Matthew Rosato <mjrosato@linux.ibm.com> >> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com> > > Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Shall the patch go via the s390 tree (still into 6.0 I guess)?
> >> --- >> 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)) { >
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