Re: [PATCH v1 08/12] iommufd/viommu: Replace ops->viommu_alloc with ops->viommu_init

[Nicolin Chen <nicolinc@nvidia.com>]

On Tue, Jun 10, 2025 at 01:55:05PM +0800, Baolu Lu wrote:
> On 6/10/25 01:13, Nicolin Chen wrote:
> > To ease the for-driver iommufd APIs, get_viommu_size and viommu_init ops
> > are introduced. Now, those existing vIOMMU supported drivers implemented
> > these two ops too.
> > 
> > Relace the ops->viommu_alloc call with the two new ones.
> > 
> > Note that this will fail a !viommu->ops case from now on, since a vIOMMU
> > is expected to support alloc_domain_nested at least.
> 
> Does this mean that the viommu implementation in the iommu driver is
> required to implement alloc_domain_nested? I suppose viommu should soon
> be extended to support TEE/IO.

It's a good point that CCA might not need a nested domain. So,
it's inaccurate to say that, although I suspect that CCA would
need some other viommu op then the check here would be sane.

With that being said, it's probably not worth adding that until
we are 100% sure that no case will work with a !viommu->ops, so
let's drop this new rejection, since we haven't had it so far.

Thanks
Nicolin