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From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Jacob Pan <jacob.jun.pan@linux.intel.com>
CC:     LKML <linux-kernel@vger.kernel.org>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
        "vkoul@kernel.org" <vkoul@kernel.org>,
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        Will Deacon <will@kernel.org>,
        David Woodhouse <dwmw2@infradead.org>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>,
        "Yu, Fenghua" <fenghua.yu@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        "Luck, Tony" <tony.luck@intel.com>,
        "Zanussi, Tom" <tom.zanussi@intel.com>
Subject: RE: [PATCH v2 6/8] iommu/vt-d: Implement set_dev_pasid domain op
Thread-Topic: [PATCH v2 6/8] iommu/vt-d: Implement set_dev_pasid domain op
Thread-Index: AQHZYQJZG2KyXXm2pk6VVsU4SfiGqq8P0HAwgACEuYCAAL77oA==
Date:   Wed, 29 Mar 2023 03:04:03 +0000
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> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Sent: Tuesday, March 28, 2023 11:40 PM
>=20
> Hi Kevin,
>=20
> On Tue, 28 Mar 2023 07:47:45 +0000, "Tian, Kevin" <kevin.tian@intel.com>
> wrote:
>=20
> > > From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > > Sent: Tuesday, March 28, 2023 7:22 AM
> > >
> > > Devices that use ENQCMDS to submit work on buffers mapped by DMA
> API
> > > must attach a PASID to the default domain of the device. In preparati=
on
> > > for this use case, this patch implements set_dev_pasid() for the
> > > default_domain_ops. Besides PASID attachment, device will also be
> > > attached to the domain as the result of this call if the device has n=
ot
> > > been attached before.
> > >
> >
> > I didn't get the last point. PASID attach should only have the scope
> > for the pasid. RID of the device might be attached to another domain
> > which shouldn't be changed by this call.
> I meant if the RID context has not been set up before attaching this PASI=
D,
> this call will also set up the context, PASID dir etc. In the end, we
> eliminated ordering requirement of attaching device, RID_PASID first, the=
n
> other PASIDs.
> How about:
> "If the device context has not been set up prior to this call, this will
> set up the device context in addition to PASID attachment."
>=20

this is clearer.