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

From: Jason Gunthorpe <jgg@nvidia.com>
To: Michael Shavit <mshavit@google.com>
Cc: Robin Murphy <robin.murphy@arm.com>,
	iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, will@kernel.org,
	nicolinc@nvidia.com, tina.zhang@intel.com,
	jean-philippe@linaro.org
Subject: Re: [RFC PATCH v1 2/8] iommu/arm-smmu-v3: Perform invalidations over installed_smmus
Date: Tue, 22 Aug 2023 11:15:45 -0300	[thread overview]
Message-ID: <ZOTDEUm1gYLmcNK3@nvidia.com> (raw)
In-Reply-To: <CAKHBV26knnw7WjUP-6kw1v0T9=196d3cJa5zO1tQa4kjteO-fg@mail.gmail.com>

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@nvidia.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