[PATCH v3] iommu/tegra241-cmdqv: Reject a VCMDQ base above the 48-bit hardware limit

[Nicolin Chen]

On Thu, Aug 06, 2026 at 11:09:51AM -0300, Jason Gunthorpe wrote:
> On Thu, Aug 06, 2026 at 02:17:31PM +0100, Robin Murphy wrote:
> 
> > But if we really do want to bother sanity-checking emulations, then why
> > allow them to still get away with being broken in the case that we do happen
> > to allocate queue memory at a sufficiently low PA anyway? Why not actually
> > validate smmu->oas itself (plus anything else relevant) in
> > __tegra241_cmdqv_probe()?
> 
> Yeah, if the VMM has setup the SMMU so it cannot access all of DRAM
> then it is going to be really broken across the entire driver. This
> just doesn't work at all. No reason to add any special cases to look
> for it only in vcmdq.

It sounds that a rejection in __tegra241_cmdqv_probe() wouldn't be
necessary either.

Let's drop the patch then.

Thanks
Nicolin