Re: [PATCH v2 17/19] iommu/arm-smmu-v3: Add arm_smmu_viommu_cache_invalidate

Nicolin Chen
2024-09-05T18:03:39Z

On Thu, Sep 05, 2024 at 01:20:39PM -0300, Jason Gunthorpe wrote:
> On Tue, Aug 27, 2024 at 09:59:54AM -0700, Nicolin Chen wrote:
>
> > +static int arm_smmu_viommu_cache_invalidate(struct iommufd_viommu *viommu,
> > + struct iommu_user_data_array *array)
> > +{
> > + struct iommu_domain *domain = iommufd_viommu_to_parent_domain(viommu);
> > +
> > + return __arm_smmu_cache_invalidate_user(
> > + to_smmu_domain(domain), viommu, array);
>
> I'd like to have the viommu struct directly hold the VMID. The nested
> parent should be sharable between multiple viommus, it doesn't make
> any sense that it would hold the vmid.
>
> This is struggling because it is trying too hard to not have the
> driver allocate the viommu, and I think we should just go ahead and do
> that. Store the vmid, today copied from the nesting parent in the vmid
> private struct. No need for iommufd_viommu_to_parent_domain(), just
> rework the APIs to pass the vmid down not a domain.

OK. When I designed all this stuff, we still haven't made mind
about sharing the s2 domain, i.e. moving the VMID, which might
need a couple of more patches to achieve.

I will try making some change for that.

Thanks
Nicolin