On Wed, Jul 06, 2022 at 11:42:17AM -0600, Alex Williamson wrote: > On Fri, 1 Jul 2022 14:44:50 -0700 > Nicolin Chen <nicolinc@xxxxxxxxxx> wrote: > > > This is a preparatory series for IOMMUFD v2 patches. It enforces error > > code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when > > an IOMMU domain and a device/group are incompatible. It also drops the > > useless domain->ops check since it won't fail in current environment. > > > > These allow VFIO iommu code to simplify its group attachment routine, by > > avoiding the extra IOMMU domain allocations and attach/detach sequences > > of the old code. > > > > Worths mentioning the exact match for enforce_cache_coherency is removed > > with this series, since there's very less value in doing that as KVM will > > not be able to take advantage of it -- this just wastes domain memory. > > Instead, we rely on Intel IOMMU driver taking care of that internally. > > > > This is on github: > > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach > > How do you foresee this going in, I'm imagining Joerg would merge the > first patch via the IOMMU tree and provide a topic branch that I'd > merge into the vfio tree along with the remaining patches. Sound > right? Thanks, We don't have any build dependency between the IOMMU change and VFIO changes, yet, without the IOMMU one, any iommu_attach_group() failure now would be a hard failure without a chance falling back to a new_domain, which is slightly different from the current flow. For a potential existing use case that relies on reusing existing domain, I think it'd be safer to have Joerg acking the first change so you merge them all? Thank!
