Re: [PATCH 0/5] Convert virtio-iommu to domain_alloc_paging()

Jason Gunthorpe
2025-02-24T19:39:13Z

On Fri, Feb 21, 2025 at 11:42:06AM +0000, Jean-Philippe Brucker wrote:
> > There is no requirement that an iommu driver implement identity, this
> > is all an optimization. If it doesn't work in alot of cases can we
> > just remove it? It would simplfy a lot..
>
> No objection. Identity domains are useful if the use-case of virtio-iommu
> is assigning devices to guest userspace, in which case you'd want to
> bypass the IOMMU for the devices that are still owned by the kernel. But
> VMMs have at least two alternatives to identity-mapping (BYPASS feature
> and tailored topology).

Since Robin pointed out a few other drivers that would like to use the
domain_op lets leave it as is.

Thanks,
Jason