Re: [PATCH v4] iommu/amd: Make PerfOpt compulsory

[Vasant Hegde]

On 10/1/2026 11:54 PM, Mario Limonciello (AMD) wrote:
> PerfOpt is only a feature usable by integrated GPUs and only in identity
> mode.  Instead of leaving a policy knob in amdgpu, just turn it on when
> an integrated GPU is in identity.
> 
> PerfOpt locks the GPU into identity mode where the DTE is ignored, so mark
> it require_direct (blocks VFIO/iommufd claims) and disable PASID (no GCR3
> table in the fast path).
> 
> This drops quite a bit of compatibility glue.  There was a refcounting
> system, exported symbols, and device attach/detach logic.  By just setting
> it immediately it's a lot more straightforward.
> 
> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxx>
> Signed-off-by: Mario Limonciello (AMD) <superm1@xxxxxxxxxx>
> ---
> v4:
>  * Disable PASID for PerfOpt devices
>  * Don't allow attaching a blocked domain

This will block attaching device to guest via vfio-pci. Is that fine?

-Vasant