Messages in this thread | | | Date | Wed, 27 Oct 2021 13:17:11 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v6 08/42] x86/sev-es: initialize sev_status/features within #VC handler |
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On Mon, Oct 25, 2021 at 11:35:18AM -0500, Michael Roth wrote: > As counter-intuitive as it sounds, it actually doesn't buy us if the CPUID > table is part of the PSP attestation report, since:
Thanks for taking the time to explain in detail - I think I know now what's going on, and David explained some additional stuff to me yesterday.
So, to cut to the chase:
- yeah, ok, I guess guest owner attestation is what should happen.
- as to the boot detection, I think you should do in sme_enable(), in pseudo:
bool snp_guest_detected;
if (CPUID page address) { read SEV_STATUS;
snp_guest_detected = SEV_STATUS & MSR_AMD64_SEV_SNP_ENABLED; }
/* old SME/SEV detection path */ read 0x8000_001F_EAX and look at bits SME and SEV, yadda yadda.
if (snp_guest_detected && (!SME || !SEV)) /* * HV is lying to me, do something there, dunno what. I guess we can * continue booting unencrypted so that the guest owner knows that * detection has failed and maybe the HV didn't want us to force SNP. * This way, attestation will fail and the user will know why. * Or something like that. */
/* normal feature detection continues. */
How does that sound?
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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