Re: [PATCH] iommu/arm-smmu-v3-sva: Relax ASID requirements

[Mostafa Saleh <smostafa@google.com>]

On Mon, Sep 07, 2026 at 03:45:13PM -0300, Jason Gunthorpe wrote:
> On Mon, Sep 07, 2026 at 03:49:28PM +0000, Mostafa Saleh wrote:
> > arm_smmu_sva_supported() have some residual checks for ASID from the
> > original commit d744f9e6c222 ("iommu/arm-smmu-v3: Check for SVA features")
> > 
> > As DVM was used for TLB invalidation and the ASID of the domain was shared
> > with the CPU process.
> > 
> > However, the commit
> > d38c28dbefee ("iommu/arm-smmu-v3: Put the SVA mmu notifier in the smmu_domain")
> > removed that support.
> > 
> > So matching the SMMU ASID space to the CPU is unnecessary and can be
> > relaxed.
> > 
> > Remove the CPU ASID related code, and update the print for the SMMUv3.
> 
> It is OK, but maybe this could also be but under an if
> ARM_SMMU_FEAT_BTM?  That is never enabled and is a placeholder to for
> eventual BTM support.

Yes, otherwise SMMUs with BTM would regress in the future.
But I’d assume non-BTM SMMUs will still be supported; falling back
to SW invalidation?

Thanks,
Mostafa

> 
> Once we get the last part of the invs code the BTM support can come
> back in.
> 
> Jasson