On Fri, Jan 10, 2025 at 07:12:46AM +0000, Tian, Kevin wrote: > > + if (!viommu) > > + return -ENODEV; > > + if (WARN_ON_ONCE(!viommu->ops || !viommu->ops- > > >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