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Date:   Thu, 8 Apr 2021 10:17:40 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Brijesh Singh <brijesh.singh@amd.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org,
        ak@linux.intel.com, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Joerg Roedel <jroedel@suse.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Tony Luck <tony.luck@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        David Rientjes <rientjes@google.com>,
        Sean Christopherson <seanjc@google.com>
Subject: Re: [RFC Part1 PATCH 07/13] x86/compressed: register GHCB memory
 when SNP is active
Message-ID: <20210408081740.GA10192@zn.tnic>
References: <20210324164424.28124-1-brijesh.singh@amd.com>
 <20210324164424.28124-8-brijesh.singh@amd.com>
 <20210407115959.GC25319@zn.tnic>
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On Wed, Apr 07, 2021 at 12:34:59PM -0500, Brijesh Singh wrote:
> The feature is part of the GHCB version 2 and is enforced by the
> hypervisor. I guess it can be extended for the ES. Since this feature
> was not available in GHCB version 1 (base ES) so it should be presented
> as an optional for the ES ?

Yeah, it probably is not worth the effort. If an attacker controls the
guest kernel, then it can re-register a new GHCB so it doesn't really
matter.

-- 
Regards/Gruss,
    Boris.

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