Re: [RFC PATCH 12/21] KVM: IOMMUFD: MEMFD: Map private pages

Dan Williams
2024-09-03T20:34:38Z

Jason Gunthorpe wrote:
> On Fri, Aug 30, 2024 at 01:20:12PM +0800, Xu Yilun wrote:
>
> > > If that is true for the confidential compute, I don't know.
> >
> > For Intel TDX TEE-IO, there may be a different story.
> >
> > Architechturely the secure IOMMU page table has to share with KVM secure
> > stage 2 (SEPT). The SEPT is managed by firmware (TDX Module), TDX Module
> > ensures the SEPT operations good for secure IOMMU, so there is no much
> > trick to play for SEPT.
>
> Yes, I think ARM will do the same as well.
>
> From a uAPI perspective we need some way to create a secure vPCI
> function linked to a KVM and some IOMMUs will implicitly get a
> translation from the secure world and some IOMMUs will need to manage
> it in untrusted hypervisor memory.

Yes. This matches the line of though I had for the PCI TSM core
interface. It allows establishing the connection to the device's
security manager and facilitates linking that to a KVM context. So part
of the uAPI is charged with managing device-security independent of a
VM, and binding a vPCI device involves a rendezvous of the
secure-world IOMMU setup with secure-world PCI via IOMMU and PCI-TSM
coordination.