Re: [RFC PATCH v1 2/8] iommu/arm-smmu-v3: Perform invalidations over installed_smmus

Jason Gunthorpe
2023-08-18T13:52:19Z

On Fri, Aug 18, 2023 at 11:44:55AM +0800, Michael Shavit wrote:
> On Fri, Aug 18, 2023 at 3:41 AM Robin Murphy <robin.murphy@arm.com> wrote:
> >
> > On 2023-08-17 20:20, Jason Gunthorpe wrote:
> > > It is certainly wrong to skip invalidations generated for any other
> > > reason.
> > >
> > > From what I can tell SVA domains should have their CD table entry
> > > programmed with "ASET=0" and normal paging domains should be
> > > programmed with "ASET=1". This causes only the SVA domains to listen
> > > to the BTM invalidations.
> >
> > Correct.
> >
> > Thanks,
> > Robin.
>
> Would it be fair to rename arm_smmu_tlb_inv_asid (or move into
> arm-smmu-v3-sva) to make it explicit that it shouldn't be used outside
> of SVA then? Or add a parameter such as skip_btm_capable_devices.

???

arm_smmu_tlb_inv_asid() is generally used in many places and has
nothing to do with BTM..

Did you mean arm_smmu_tlb_inv_range_asid ?

Broadly, invalidation is not SVA specific..

Notice that arm_smmu_tlb_inv_range_asid() already duplicates
arm_smmu_tlb_inv_range_domain().

IMHO I would split the ATC step out of arm_smmu_mm_invalidate_range(),
get rid of arm_smmu_tlb_inv_range_domain(), and have the mmu notifier
just do as it already does:

if (!(smmu_domain->smmu->features & ARM_SMMU_FEAT_BTM))
arm_smmu_tlb_inv_range_domain_no_atc(start, size, smmu_mn->cd->asid,
PAGE_SIZE, false, smmu_domain);
arm_smmu_atc_inv_domain(smmu_domain, start, size);

And make arm_smmu_tlb_inv_range_domain() just call
arm_smmu_tlb_inv_range_domain_no_atc();
arm_smmu_atc_inv_domain();

Jason