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From: "Tian, Kevin" <kevin.tian@intel.com>
To: Jason Gunthorpe <jgg@nvidia.com>, Nicolin Chen <nicolinc@nvidia.com>
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Subject: RE: [PATCH RFCv1 07/14] iommufd: Add viommu set/unset_dev_id ops
Thread-Topic: [PATCH RFCv1 07/14] iommufd: Add viommu set/unset_dev_id ops
Thread-Index: AQHajVVq/X0HjqCDvU+a/LkdwhCQ/LGT28sAgADojoCAAk6vgIAAqT2AgAqBYwCAAlS+oA==
Date: Thu, 23 May 2024 06:19:59 +0000
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> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Wednesday, May 22, 2024 2:25 AM
>=20
> On Tue, May 14, 2024 at 06:59:07PM -0700, Nicolin Chen wrote:
> > So, you want a proxy S1 domain for a device to attach, in case
> > of a stage-2 only setup, because an S2 domain will no longer has
> > a VMID, since it's shared among viommus. In the SMMU driver case,
> > an arm_smmu_domain won't have an smmu pointer, so a device can't
> > attach to an S2 domain but always an nested S1 domain, right?
>=20
> That seems like a simple solution to the VMID lifetime, but it means
> the kernel has to decode more types of vSTE.
>=20

why does ATC invalidation need to know about VMID?

Or is above talking about beyond the discussion between DEV_INVALIDATE
vs. VIOMMU_INVALIDATE?