Re: [PATCH] pci-ids.rst: Add Red Hat pci-id for AMD IOMMU device

[Suthikulpanit, Suravee]

On 3/5/2025 1:52 PM, Michael S. Tsirkin wrote:
> On Tue, Mar 04, 2025 at 06:37:47PM +0000, Suravee Suthikulpanit wrote:
> > The QEMU-emulated AMD IOMMU PCI device is implemented based on the AMD I/O
> > Virtualization Technology (IOMMU) Specification [1]. The PCI id for this
> > device is platform-specific.
> >
> > Currently, the QEMU-emulated AMD IOMMU device is using AMD vendor id and
> > undefined device id.
> undefined?
>
> > Therefore, change the vendor id to Red Hat and request a new QEMU-specific
> > device id.
> Won't the drivers fail to load then?
>
>
> > [1]https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/ 
> > specifications/48882_IOMMU.pdf
> what is this link teaching us? It's a 300 page document. Where to look
> in there?

What I am trying to say is that all AMD IOMMU implementations must 
adhere to this specification including the QEMU-emulated AMD IOMMU. 
Unlike cpu emulation, we don't need to exactly mimic a particular 
hardware implementation.

QEMU-emulated AMD IOMMU device can have its own set of features that it 
supports. Going forward, we might even have QEMU-specific feature / 
behavior. So, we should not be using an existing PCI ID.

Thanks,
Suravee