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From:   Michael Shavit <mshavit@google.com>
Date:   Fri, 14 Jul 2023 17:12:35 +0800
Message-ID: <CAKHBV240_0bUE-25sND3oSG57jT0yJiZzAt+fPTXehjm=zmRBw@mail.gmail.com>
Subject: Re: [PATCH v4 02/13] iommu/arm-smmu-v3: Add smmu_s1_cfg to smmu_master
To:     Nicolin Chen <nicolinc@nvidia.com>
Cc:     Jason Gunthorpe <jgg@nvidia.com>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Joerg Roedel <joro@8bytes.org>, jean-philippe@linaro.org,
        baolu.lu@linux.intel.com, linux-arm-kernel@lists.infradead.org,
        iommu@lists.linux.dev, linux-kernel@vger.kernel.org
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On Fri, Jul 14, 2023 at 9:14=E2=80=AFAM Nicolin Chen <nicolinc@nvidia.com> =
wrote:
> @Michael,
> Would it be possible for you to update a v5, following Jason's
> suggestion overall? And I think we can have a smaller refactor
> series first without set_dev_pasid, to have a common codeline
> sooner for us to add new features, such as set_dev_pasid, the
> use case of IDENTITY default substream, and the nesting series.
> I will help testing with some pasid/non-pasid use cases too.

Want to make sure I fully understand these last few messages first. At
a high level, we want:
1. arm_smmu_master is allowed to own a CD table, but not an
STE-precursor (s1_cfg/s2_cfg). The s1_cfg is practically already that,
and we can probably get there with minimal changes.
2. arm_smmu_master shouldn't point to the currently active CD table
(which may or may not be the one it owns) or STE-precursor as a
shortcut. All code should figure it out by looking at the master's
currently attached domain (functionality could be provided by helper).
3. arm_smmu_domain shouldn't pre-generate any STE-precursors. The
STE/CD for a domain should either be computed right when it is
written, or computed ahead of time and stored as a copy in the
smmu-domain.
Is that right?