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Date: Thu, 14 Oct 2021 09:47:24 +0200
From: "Gerd Hoffmann" <kraxel@redhat.com>
To: Brijesh Singh <brijesh.singh@amd.com>
Cc: devel@edk2.groups.io, James Bottomley <jejb@linux.ibm.com>,
	Min Xu <min.m.xu@intel.com>, Jiewen Yao <jiewen.yao@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Jordan Justen <jordan.l.justen@intel.com>,
	Ard Biesheuvel <ardb+tianocore@kernel.org>,
	Erdem Aktas <erdemaktas@google.com>,
	Michael Roth <Michael.Roth@amd.com>
Subject: Re: [PATCH v9 11/32] OvmfPkg/VmgExitLib: use SEV-SNP-validated CPUID values
Message-ID: <20211014074724.ndb37nhpwhcf23ru@sirius.home.kraxel.org>
References: <20211013165713.727815-1-brijesh.singh@amd.com>
 <20211013165713.727815-12-brijesh.singh@amd.com>
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On Wed, Oct 13, 2021 at 11:56:52AM -0500, Brijesh Singh wrote:
> From: Michael Roth <michael.roth@amd.com>
> 
> SEV-SNP firmware allows a special guest page to be populated with
> guest CPUID values so that they can be validated against supported
> host features before being loaded into encrypted guest memory to be
> used instead of hypervisor-provided values [1].
> 
> Add handling for this in the CPUID #VC handler and use it whenever
> SEV-SNP is enabled. To do so, existing CPUID handling via VmgExit is
> moved to a helper, GetCpuidHyp(), and a new helper that uses the CPUID
> page to do the lookup, GetCpuidFw(), is used instead when SNP is
> enabled. For cases where SNP CPUID lookups still rely on fetching
> specific CPUID fields from hypervisor, GetCpuidHyp() is used there as
> well.
> 
> [1]: SEV SNP Firmware ABI Specification, Rev. 0.8, 8.13.2.6

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