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From:   "Liu, Yi L" <yi.l.liu@intel.com>
To:     Jason Gunthorpe <jgg@nvidia.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>
CC:     Jean-Philippe Brucker <jean-philippe@linaro.org>,
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        Jean-Philippe Brucker <jean-philippe@linaro.com>,
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        "Raj, Ashok" <ashok.raj@intel.com>,
        "Tian, Kevin" <kevin.tian@intel.com>, "Wu, Hao" <hao.wu@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>
Subject: RE: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation
 APIs
Thread-Topic: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and
 allocation APIs
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Date:   Wed, 31 Mar 2021 08:38:28 +0000
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> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Tuesday, March 30, 2021 9:43 PM
[..]
> No, the mdev device driver must enforce this directly. It is the one
> that programms the physical shared HW, it is the one that needs a list
> of PASID's it is allowed to program *for each mdev*
>=20
> ioasid_set doesn't seem to help at all, certainly not as a concept
> tied to /dev/ioasid.
>=20

As replied in another thread. We introduced ioasid_set based on the
motivation to have per-VM ioasid track, which is required when user
space tries to bind an ioasid with a device. Should ensure the ioasid
it is using was allocated to it. otherwise, we may suffer inter-VM ioasid
problem. It may not necessaty to be ioasid_set but a per-VM ioasid track
is necessary.

Regards,
Yi Liu