RE: [PATCH 3/7] iommu/arm-smmu: Add tlb_sync implementation hook

From: Krishna Reddy
Date: Fri Aug 30 2019 - 14:05:32 EST

>> + for (i = 0; i < to_nsmmu(smmu)->num_inst; i++)

>It might make more sense to make this the innermost loop, i.e.:
for (i = 0; i < nsmmu->num_inst; i++)
reg &= readl_relaxed(nsmmu_page(smmu, i, page)...
>since polling the instances in parallel rather than in series seems like it might be a bit more efficient.

Sync register is programmed at the same time for both instances. The status check is serialized.
I can update it to check status of both at the same time.

>> + if (smmu->impl->tlb_sync) {
>> + smmu->impl->tlb_sync(smmu, page, sync, status);

>What I'd hoped is that rather than needing a hook for this, you could just override smmu_domain->tlb_ops from .init_context to wire up the alternate .sync method directly. That would save this extra level of indirection.

With arm_smmu_domain now available in arm-smmu.h, arm-smmu-nvidia.c can directly update the tlb_ops->tlb_sync and avoid indirection.
Will update in next version.