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Date:   Thu, 21 Oct 2021 16:51:06 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Michael Roth <michael.roth@amd.com>
Cc:     Brijesh Singh <brijesh.singh@amd.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org,
        linux-coco@lists.linux.dev, linux-mm@kvack.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Joerg Roedel <jroedel@suse.de>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ard Biesheuvel <ardb@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Jim Mattson <jmattson@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Sergio Lopez <slp@redhat.com>, Peter Gonda <pgonda@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Dov Murik <dovmurik@linux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@ibm.com>,
        Vlastimil Babka <vbabka@suse.cz>,
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        Andi Kleen <ak@linux.intel.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        tony.luck@intel.com, marcorr@google.com,
        sathyanarayanan.kuppuswamy@linux.intel.com
Subject: Re: [PATCH v6 08/42] x86/sev-es: initialize sev_status/features
 within #VC handler
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References: <20211008180453.462291-1-brijesh.singh@amd.com>
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 <20211018184003.3ob2uxcpd2rpee3s@amd.com>
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 <20211020161023.hzbj53ehmzjrt4xd@amd.com>
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On Wed, Oct 20, 2021 at 11:10:23AM -0500, Michael Roth wrote:
> The CPUID calls in snp_cpuid_init() weren't added specifically to induce
> the #VC-based SEV MSR read, they were added only because I thought the
> gist of your earlier suggestions were to do more validation against the
> CPUID table advertised by EFI

Well, if EFI is providing us with the CPUID table, who verified it? The
attestation process? Is it signed with the AMD platform key?

Because if we can verify the firmware is ok, then we can trust the CPUID
page, right?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette