Re: [PATCH 09/22] iommu/amd: Introduce domain for IOMMU Private Address (IPA) region

[Suthikulpanit, Suravee]

On 3/30/2026 7:20 PM, Jason Gunthorpe wrote:
> On Mon, Mar 30, 2026 at 08:41:53AM +0000, Suravee Suthikulpanit wrote:
> > AMD vIOMMU introduces the IOMMU Private Address (IPA) region, which is
> > used to manage data structures necessary for IOMMU virtualization within
> > the guest.
> >
> > Introduce a new domain specifically for IPA region for each IOMMU, which
> > is stored in struct amd_iommu.viommu_pdom. This domain uses AMD IOMMU v1
> > page table.
>
> Why can't you use a normal v1 domain with all the normal existing code?
>
> Afaict it is not special at all other than it has a specific dte index?
>
> Jason

Actually, this is quite different from the normal GPA->SPA, but rather 
IPA->SPA (for case GstBufferTRPMode=1). It is used specifically for vIOMMU.

The current mapping is:

IOMMU General Backing Storatge: IPA = 0x0 - 0x80_0000 (8MB)
Domain ID Mapping Table: IPA = 0x10_0000_0000 - 0x1F_FFFF_FFFF (64GB)
Device ID Mapping Table: IPA = 0x20_0000_0000 - 0x27_FFFF_FFFF (32GB)

The v1 table containing this mapping is programmed onto the Device Table 
Entry index of the IOMMU device ID.

Thanks,
Suravee