Messages in this thread | | | Date | Thu, 28 Mar 2024 15:24:29 +0100 | Subject | Re: [PATCH 5/5] x86/CPU/AMD: Track SNP host status with cc_platform_*() | From | Jeremi Piotrowski <> |
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On 28/03/2024 14:41, Borislav Petkov wrote: > On Thu, Mar 28, 2024 at 12:51:17PM +0100, Jeremi Piotrowski wrote: >> Shouldn't this line be inside the cpu_has(c, X86_FEATURE_SEV_SNP) check? > > The cc_vendor is not dependent on X86_FEATURE_SEV_SNP. >
It's not but if you set it before the check it will be set for all AMD systems, even if they are neither CC hosts nor CC guests.
cc_vendor being unset is handled correctly in cc_platform_has() checks.
>> How about turning this into a more specific check: >> >> if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP) && > > Why? >
To leave open the possibility of an SNP hypervisor running nested.
> The check is "am I running as a hypervisor on baremetal". >
I thought you wanted to filter out SEV-SNP guests, which also have X86_FEATURE_SEV_SNP CPUID bit set.
My understanding is that these are the cases:
CPUID(SEV_SNP) | MSR(SEV_SNP) | what am I --------------------------------------------- set | set | SNP-guest set | unset | SNP-host unset | ?? | not SNP
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