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Date:   Tue, 20 Oct 2020 17:44:08 +0200
From:   Joerg Roedel <jroedel@suse.de>
To:     Arvind Sankar <nivedita@alum.mit.edu>
Cc:     Joerg Roedel <joro@8bytes.org>, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Kees Cook <keescook@chromium.org>,
        Martin Radev <martin.b.radev@gmail.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/5] x86/boot/compressed/64: Check SEV encryption in
 64-bit boot-path
Message-ID: <20201020154408.GA22179@suse.de>
References: <20201019151121.826-1-joro@8bytes.org>
 <20201019151121.826-4-joro@8bytes.org>
 <20201019170008.GA2701355@rani.riverdale.lan>
 <20201019175447.GA2720155@rani.riverdale.lan>
 <20201019203935.GG3635@8bytes.org>
 <20201019213106.GB2815942@rani.riverdale.lan>
 <20201020085957.GF9328@suse.de>
 <20201020143312.GE2996696@rani.riverdale.lan>
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On Tue, Oct 20, 2020 at 10:33:12AM -0400, Arvind Sankar wrote:
> That doesn't feel like a big loss: if a malicious hypervisor wanted to
> induce completely random code execution, it can do that anyway by just
> messing with the guest-to-host translation, no?

Yes, but relying on defined behavior is still better. Undefined behavior
could also mean it jumps to some other code which then leaks data.

Regards,

	Joerg