Messages in this thread | | | Date | Mon, 21 Aug 2023 08:57:58 -0300 | From | Jason Gunthorpe <> | Subject | Re: [RFC PATCH v1 2/8] iommu/arm-smmu-v3: Perform invalidations over installed_smmus |
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On Mon, Aug 21, 2023 at 04:33:36PM +0800, Michael Shavit wrote: > > 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(); > > That's a nice clean-up but doesn't really solve the problem faced by this patch. > > This patch series eliminates the smmu_domain->smmu handle, replacing > it for a list of SMMUs. So SVA can no longer optimize the > arm_smmu_tlb_inv_range_asid call away by checking whether the SMMU BTM > feature is enabled since there's now a list of SMMUs with possibly > heterogeneous support for the feature.
You could also go in the direction of making a SVA BTM and SV non-BTM domain type and then you know what to do immediately in the notifier.
> Since there's now a loop over a series of SMMUs inside > arm_smmu_tlb_inv_range_asid, it makes sense to move the check into > that loop. This technically works because only SVA is calling > arm_smmu_tlb_inv_range_asid but can (IMO) risk introducing bugs in > the future since it's not obvious from the function name.
Well, I would remove the duplication and add an argument if you intend to share the function that loops
Jason
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