On Fri, Jan 10, 2025 at 07:12:46AM +0000, Tian, Kevin wrote:

quoted

+	if (!viommu)
+		return -ENODEV;
+	if (WARN_ON_ONCE(!viommu->ops || !viommu->ops-

quoted

supports_veventq ||

+			 !viommu->ops->supports_veventq(type)))
+		return -EOPNOTSUPP;

Hmm the driver knows which type is supported by itself before
calling this helper. Why bother having the helper calling into
the driver again to verify?

Indeed, it might make sense to protect this with

        if (IS_ENABLED(CONFIG_IOMMUFD_TEST))

As a compiled out assertion

Or drop it

We shouldn't have unnecessary argument validation on fast paths,
!viommu should go too.

Jason