[PATCH v6 20/25] iommu/arm-smmu-v3-iommufd: Add hw_info to impl_ops

[Jason Gunthorpe]

On Thu, Jun 19, 2025 at 11:47:24AM +0000, Pranjal Shrivastava wrote:
> I'm not sure if I get this right.. if the user (while porting a VMM or
> something) mistakenly passes *type == IOMMU_HW_INFO_TYPE_INTEL_VTD here,
> they'll get impl-specific info?

It should call the impl hw_info which should fail?

+static void *tegra241_cmdqv_hw_info(struct arm_smmu_device *smmu, u32 *length,
+				    u32 *type)
+{
+	if (*type != IOMMU_HW_INFO_TYPE_TEGRA241_CMDQV)
+		return ERR_PTR(-EOPNOTSUPP);

If impl ops is null/etc then it fails:

+             if (!impl_ops || !impl_ops->hw_info)
+                     return ERR_PTR(-EOPNOTSUPP);

Where does IOMMU_HW_INFO_TYPE_INTEL_VTD return something?

> I agree in that case the impl-specific
> driver needs to check the type, but shouldn't we simply return from here
> itself if the type isn't arm-smmu-v3?

Then how do you return IOMMU_HW_INFO_TYPE_TEGRA241_CMDQV?

Jason