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From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Jean-Philippe Brucker <jean-philippe@linaro.org>
CC:     Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Christoph Hellwig <hch@infradead.org>,
        "Raj, Ashok" <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
        "Robin Murphy" <robin.murphy@arm.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        Vinod Koul <vkoul@kernel.org>,
        Eric Auger <eric.auger@redhat.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>,
        "Pan, Jacob jun" <jacob.jun.pan@intel.com>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v9 10/11] iommu: Per-domain I/O page fault handling
Thread-Topic: [PATCH v9 10/11] iommu: Per-domain I/O page fault handling
Thread-Index: AQHYhX4HMU+DWWITC0iALdyeXsFzmK1kiO3AgAATUgCAAAQ3gA==
Date:   Tue, 28 Jun 2022 10:02:00 +0000
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References: <20220621144353.17547-1-baolu.lu@linux.intel.com>
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> From: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Sent: Tuesday, June 28, 2022 5:44 PM
>=20
> On Tue, Jun 28, 2022 at 08:39:36AM +0000, Tian, Kevin wrote:
> > > From: Lu Baolu <baolu.lu@linux.intel.com>
> > > Sent: Tuesday, June 21, 2022 10:44 PM
> > >
> > > Tweak the I/O page fault handling framework to route the page faults =
to
> > > the domain and call the page fault handler retrieved from the domain.
> > > This makes the I/O page fault handling framework possible to serve mo=
re
> > > usage scenarios as long as they have an IOMMU domain and install a
> page
> > > fault handler in it. Some unused functions are also removed to avoid
> > > dead code.
> > >
> > > The iommu_get_domain_for_dev_pasid() which retrieves attached
> domain
> > > for a {device, PASID} pair is used. It will be used by the page fault
> > > handling framework which knows {device, PASID} reported from the
> iommu
> > > driver. We have a guarantee that the SVA domain doesn't go away durin=
g
> > > IOPF handling, because unbind() waits for pending faults with
> > > iopf_queue_flush_dev() before freeing the domain. Hence, there's no
> need
> > > to synchronize life cycle of the iommu domains between the unbind() a=
nd
> > > the interrupt threads.
> >
> > I found iopf_queue_flush_dev() is only called in intel-iommu driver. Di=
d
> > I overlook anything?
>=20
> The SMMU driver will need it as well when we upstream PRI support.
> Currently it only supports stall, and that requires the device driver to
> flush all DMA including stalled transactions *before* calling unbind(), s=
o
> ne need for iopf_queue_flush_dev() in this case.
>

then it makes sense. Probably Baolu can add this information in the
commit msg so others with similar question can quickly get the
point here.