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

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Message-ID: <ZOTDEUm1gYLmcNK3@nvidia.com>
Date:   Tue, 22 Aug 2023 11:15:45 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Michael Shavit <mshavit@...gle.com>
Cc:     Robin Murphy <robin.murphy@....com>, iommu@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        will@...nel.org, nicolinc@...dia.com, tina.zhang@...el.com,
        jean-philippe@...aro.org
Subject: Re: [RFC PATCH v1 2/8] iommu/arm-smmu-v3: Perform invalidations over
 installed_smmus

On Tue, Aug 22, 2023 at 04:17:31PM +0800, Michael Shavit wrote:
> On Mon, Aug 21, 2023 at 7:58 PM Jason Gunthorpe <jgg@...dia.com> wrote:
> >
> > > 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
> 
> What do you think about this as a final stage:
> Once the set_dev_pasid and sva refactor lands, SVA could call a common
> arm_smmu_inv_range_domain implementation which would:
> 1. Skip the TLB invalidation on a per-smmu basis if it detects that
> the domain type is SVA, or based on a passed-in parameter that is only
> set True by SVA.
> 2. Issue ATC invalidations with SSIDs found in the arm_smmu_domain.
> This common function would be used for all use-cases: invalidations of
> domains attached on RIDs, on PASIDs (SVA and non SVA).

That seems like a good place to aim for

Jason