Re: [ANNOUNCEMENT] COCONUT Secure VM Service Module for SEV-SNP

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Jörg Rödel (jroedel@suse.de) wrote:
> On Tue, Mar 21, 2023 at 04:56:20PM +0000, Dr. David Alan Gilbert wrote:
> > OK, I'm just trying to avoid having guests that have a zillion different
> > TPM setups for different SVSM and clouds.
> 
> My guess it that it will either be the SVSM TPM protocol or an emulation
> of an existing TPM interface.

OK; the other thing that needs to get nailed down for the vTPM's is the
relationship between the vTPM attestation and the SEV attestation.
i.e. how to prove that the vTPM you're dealing with is from an SNP host.
(Azure have a hack of putting an SNP attestation report into the vTPM
NVRAM; see
https://github.com/Azure/confidential-computing-cvm-guest-attestation/blob/main/cvm-guest-attestation.md
)

> > Timing is a little tricky here; in many ways the thing that sounds
> > nicest to me about Coconut is the mostly-unmodified guest (b) - but if
> > that's a while out then hmm.
> 
> Yeah, would be nice. But we are still in the early stages of SVSM
> development, so the priority now is to get services up and running.
> 
> But the project is open source and anyone can start looking into the
> unmodified guest handling and send PRs. Making this happen is certainly
> a multi-step process, as it requires several things to be implemented.
> Just out of my head an incomplete list what is required:
> 
> 	1) ReflectVC handling with instruction decoder and guest TLB
> 	   flush awareness
> 	2) vTOM handling
> 	3) Interrupt proxying using alternate injection (that can make
> 	   sense even earlier and without the other features imho)

So all the easy stuff then :-)

> So its quite some work, but if someone wants to look into that now I am
> all for it.

Dave
> 
> Regards,
> 
> -- 
> Jörg Rödel
> jroedel@suse.de
> 
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-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK