Re: [PATCH v3 05/13] iommu/arm-smmu-v3: Allocate IOPF queue without FEAT_SVA

arm_smmu_init_queues() currently allocates smmu->evtq.iopf only when both
FEAT_SVA and FEAT_STALLS are advertised by the SMMU. The FEAT_SVA gate is
unnecessary: iopf_queue_alloc() is a plain workqueue allocator with no SVA
dependency, and FEAT_STALLS alone can produce events that need IOPF.

On HW with FEAT_STALLS but no FEAT_SVA, a master with the "dma-can-stall"
device-tree property has master->stall_enabled set at probe. Then also with
CONFIG_ARM_SMMU_V3_SVA=y, arm_smmu_enable_iopf() sees stall_enabled, calls
iopf_queue_add_device(NULL, ...) at fault-handling domain attach, which now
oopses on mutex_lock(&queue->lock).

When you say 'now' you mean after other patches in this series?
If so then I'd make that more explicit.  If not, drop the 'now'.

Drop the FEAT_SVA term so the IOPF workqueue is allocated whenever the SMMU
can produce IOPF events, and select IOMMU_IOPF from ARM_SMMU_V3 as well, so
iopf_queue_alloc() has a real implementation instead of the NULL-returning
stub when CONFIG_ARM_SMMU_V3_SVA is unset.

IOPF is orthogonal to SVA anyway. So, drop the CONFIG_ARM_SMMU_V3_SVA gates
in arm_smmu_enable_iopf() and arm_smmu_disable_iopf().

Fixes: 395ad89d11fd9 ("iommu/arm-smmu-v3: Add stall support for platform devices")
Cc: stable@vger.kernel.org # v5.14
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Nicolin Chen <redacted>

You had me at the IOPF and SVA being orthogonal part.

Reviewed-by: Jonathan Cameron <redacted>

-- 
Jonathan Cameron [off-list ref]