RE: [PATCH v10 10/13] iommu/arm-smmu-v3: Check for SVA features

Krishna Reddy
2020-12-09T19:50:54Z

Hi Jean,
> > Why is BTM mandated for SVA? I couldn't find this requirement in
> > SMMU spec (Sorry if I missed it or this got discussed earlier). But
> > if performance is the
> only concern here,
> > is it better just to allow it with a warning rather than limiting
> > SMMUs without
> BTM?
>
> It's a performance concern and requires to support multiple
> configurations, but the spec allows it. Are there SMMUs without BTM
> that need it?

The Tegra Next Generation SOC uses arm-smmu-v3, but it doesn't have support for BTM.
Do you have plan to get your earlier patch to handle invalidate notifications into upstream sometime soon?
Can the dependency on BTM be relaxed with the patch?

PATCH v9 13/13] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops
https://www.spinics.net/lists/arm-kernel/msg825099.html

-KR