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Date:   Tue, 20 Oct 2020 11:41:10 +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: <20201020094110.GG9328@suse.de>
References: <20201019151121.826-1-joro@8bytes.org>
 <20201019151121.826-4-joro@8bytes.org>
 <20201019170008.GA2701355@rani.riverdale.lan>
 <20201019203345.GF3635@8bytes.org>
 <20201019212247.GA2815942@rani.riverdale.lan>
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On Mon, Oct 19, 2020 at 05:22:47PM -0400, Arvind Sankar wrote:
> The boot cpu also enables CR4.PGE -- that code is shared between boot
> and secondary cpus. The boot cpu jumps to the first "1" label below,
> just before the call to sev_verify_cbit you're adding.

You are right, in the real kernel image PGE gets enabled early. I added
code to save and restore CR4 in sev_verify_cbit() and disable PGE during
the test.

Thanks,

	Joerg