Re: [PATCH v3 11/11] hw/arm/smmuv3: Advertise SMMUv3.2 range invalidation

[Peter Maydell]

On Wed, 8 Jul 2020 at 15:20, Eric Auger <eric.auger@redhat.com> wrote:
>
> Expose the RIL bit so that the guest driver uses range
> invalidation. Range invalidation being an SMMU3.2 feature,
> let AIDR advertise SMMUv3.2 support.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>

I think that to advertise SMMUv3.2 we would also need to
set the IDR3.BBML field to something non-zero. That means
we need to analyze our implementation of the caching of page
table structures to see if we need to do anything different
(per the behaviours and guarantees described in section 3.21.1
of the spec).

Alternatively, we could take advantage of the language
in section 2.5 that says that a v3.x implementation is
allowed to implement features from v3.(x+1), and just
set the RIL bit while leaving AIDR advertising us as v3.1.

thanks
-- PMM