RE: KVM Forum BoF on I/O + secure virtualization

[Dan Williams <dan.j.williams@intel.com>]

[ add Lukas ]

Giani, Dhaval wrote:
> [AMD Official Use Only - General]
> 
> Hi all,
> 
> We have proposed a trusted I/O BoF session at KVM forum this year. I wanted
> to kick off the discussion to maximize the 25 mins we have.
> 
> By trusted I/O, I mean using TDISP to have “trusted” communications with a
> device using something like AMD SEV-TIO [1] or Intel’s TDX connect [2].
>
> Some topics we would like to discuss are
> o What is the device model like?
> o Do we enlighten the PCI subsystem?
> o Do we enlighten device drivers?

One observation in relation to these first questions is something that
has been brewing since SPDM and IDE were discussed at Plumbers 2022.

https://lpc.events/event/16/contributions/1304/

Namely, that there is value in the base specs on the way to the full
vendor TSM implementations. I.e. that if the Linux kernel can aspire to
the role of a TSM it becomes easier to incrementally add proxying to a
platform TSM later. In the meantime, platforms and endpoints that
support CMA / SPDM and PCIe/CXL IDE but not full "trusted I/O" still
gain incremental benefit.

The first proof point for that idea is teaching the PCI core to perform
CMA / SPDM session establishment and provide that result to drivers.

That is what Lukas has been working on after picking up Jonathan's
initial SPDM RFC. I expect the discussion on those forthcoming patches
starts to answer device-model questions around attestation.

> o What does the guest need to know from the device?
> o How does the attestation workflow work?
> o Generic vs vendor specific TSMs
> 
> Some of these topics may be better suited for LPC, 

Maybe, but there's so much to discuss that the more opportunities to
collaborate on the details the better. 

> however we want to get the discussion going from the KVM perspective
> and continue wider discussions at LPC.

While I worry that my points above are more suited to something like a
PCI Micro-conference than a KVM BoF, I think the nature of "trusted I/O"
requires those tribes to talk more to each other.