Re: [PATCH 9/9] iommu/amd: Set default domain to IDENTITY_DOMAIN when running in SEV guest

[Jason Gunthorpe]

On Tue, Apr 30, 2024 at 03:24:30PM +0000, Suravee Suthikulpanit wrote:
> Since SEV guest depends on the unencrypted swiotlb bounce buffer
> to support DMA, the guest AMD IOMMU driver must be force to setup to
> pass-through mode.

You should block the creation of paging domains as well if the HW
can't support them.

But, is there actually a functional problem here? Doesn't swiotlb work
OK with iommu even with the encrypted memory cases? What is missing if
not?

Jason