RE: [PATCH v10 11/13] iommu/arm-smmu-v3: Add SVA device feature

Krishna Reddy
2021-01-06T17:25:15Z

> I agree that we should let a device driver enable SVA if it supports some form of IOPF.

Right, The PCIe device has capability to handle IO page faults on its own when ATS translation request response indicates that no valid mapping exist.
SMMU doesn't involve/handle page faults for ATS translation failures here.
Neither the PCIe device nor the SMMU have PRI capability.

> Perhaps we could extract the IOPF capability from IOMMU_DEV_FEAT_SVA, into a new IOMMU_DEV_FEAT_IOPF feature.
> Device drivers that rely on PRI or stall can first check FEAT_IOPF, then FEAT_SVA, and enable both separately.
> Enabling FEAT_SVA would require FEAT_IOPF enabled if supported. Let me try to write this up.

Looks good to me. Allowing device driver to enable FEAT_IOPF and subsequently SVA should work. Thanks!

-KR