Re: [PATCH 4/4] iommu: Introduce guest PASID bind function

[Jean-Philippe Brucker]

On Wed, Sep 18, 2019 at 04:26:34PM -0700, Jacob Pan wrote:
> Guest shared virtual address (SVA) may require host to shadow guest
> PASID tables. Guest PASID can also be allocated from the host via
> enlightened interfaces. In this case, guest needs to bind the guest
> mm, i.e. cr3 in guest physical address to the actual PASID table in
> the host IOMMU. Nesting will be turned on such that guest virtual
> address can go through a two level translation:
> - 1st level translates GVA to GPA
> - 2nd level translates GPA to HPA
> This patch introduces APIs to bind guest PASID data to the assigned
> device entry in the physical IOMMU. See the diagram below for usage
> explaination.

explanation

Otherwise Looks fine to me. I was wondering if we would be able to reuse
the API for Arm SMMUv2, which allows nesting translation, but without
PASID - there is a single address space per device, with two stages of
translation. I think it would work, although it would look better with
something like "PGD" instead of "PASID" in the API names (e.g.
iommu_sva_bind_gpgd) since that case wouldn't use PASID at all. But I
don't want to quibble over names, so

Reviewed-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>