Re: [edk2-devel] [PATCH v2 22/23] Ovmfpkg/CcExitLib: Provide SVSM discovery support

["Gerd Hoffmann" <kraxel@redhat.com>]

On Thu, Feb 22, 2024 at 11:30:01AM -0600, Tom Lendacky wrote:
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654
> 
> The SVSM specification documents an alternative method of discovery for
> the SVSM using a reserved CPUID bit and a reserved MSR.
> 
> For the CPUID support, the #VC handler of an SEV-SNP guest should modify
> the returned value in the EAX register for the 0x8000001f CPUID function
> by setting bit 28 when an SVSM is present.
> 
> For the MSR support, new reserved MSR 0xc001f000 has been defined. A #VC
> should be generated when accessing this MSR. The #VC handler is expected
> to ignore writes to this MSR and return the physical calling area address
> (CAA) on reads of this MSR.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>

Acked-by: Gerd Hoffmann <kraxel@redhat.com>



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