RE: [PATCH v5] iommu/amd: Enable PerfOpt automatically for integrated GPUs

[Deucher, Alexander]

Public

> -----Original Message-----
> From: Hegde, Vasant <Vasant.Hegde@xxxxxxx>
> Sent: Thursday, November 5, 2026 5:25 AM
> To: Mario Limonciello (AMD) <superm1@xxxxxxxxxx>; Deucher, Alexander
> <Alexander.Deucher@xxxxxxx>
> Cc: Jason Gunthorpe <jgg@xxxxxxxx>; Deucher, Alexander
> <Alexander.Deucher@xxxxxxx>; Joerg Roedel <joro@xxxxxxxxxx>;
> Suthikulpanit, Suravee <Suravee.Suthikulpanit@xxxxxxx>; amd-
> gfx@xxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; iommu@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v5] iommu/amd: Enable PerfOpt automatically for
> integrated GPUs
>
> Alex,
>
>
> On 11/2/2026 8:26 PM, Vasant Hegde wrote:
> >
> >
> > On 10/23/2026 2:16 AM, Mario Limonciello (AMD) wrote:
> >> PerfOpt is usable by integrated GPUs in identity mode. Enable it from
> >> the IOMMU driver's domain attachment paths instead of requiring an
> >> amdgpu policy knob and exported enable/disable interfaces.
> >>
> >> Mark supported integrated GPUs as PerfOpt-eligible when selecting
> >> their default identity domain. Skip GCR3 setup and ATS/PRI/PASID
> >> enablement for these identity attachments, then enable PerfOpt after
> installing the DTE.
> >> Clear PerfOpt before attaching an eligible GPU to a translated or
> >> blocked domain, including unmanaged domains used by VFIO. Propagate
> >> failures to clear bypass, but keep a completed identity attachment
> >> successful if the optional PerfOpt enable fails.
> >>
> >> Clear inherited PerfOpt state during initialization, including when a
> >> crash kernel reuses device tables. Read feature support directly from
> >> hardware because cached features may not be available yet, and stop
> >> initialization if the initial clear fails.
> >>
> >> Each IOMMU has at most one PerfOpt-eligible GPU, so track activation
> >> with a boolean under the IOMMU lock. Preserve this state while
> >> clearing hardware at suspend and shutdown, and restore the bit on
> >> resume only where it was active. Do not enable PerfOpt
> >> unconditionally during early IOMMU initialization.
> >>
> >> Remove the amdgpu parameter, driver callbacks, and exported interfaces.
> >> Translated attachments retain their normal device capability setup.
> >>
> >> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxx>
> >> Signed-off-by: Mario Limonciello (AMD) <superm1@xxxxxxxxxx>
> >
> > Looks good. Queued for rc.
>
> Can you ack this patch so that we can pick it through IOMMU tree?

Acked-by: Alex Deucher <alexander.deucher@xxxxxxx>

>
> -Vasant