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Date:   Tue, 14 Jul 2020 18:23:47 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Joerg Roedel <joro@8bytes.org>
Cc:     x86@kernel.org, Joerg Roedel <jroedel@suse.de>, hpa@zytor.com,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Jiri Slaby <jslaby@suse.cz>,
        Dan Williams <dan.j.williams@intel.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Juergen Gross <jgross@suse.com>,
        David Rientjes <rientjes@google.com>,
        Cfir Cohen <cfir@google.com>,
        Erdem Aktas <erdemaktas@google.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Mike Stunes <mstunes@vmware.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Martin Radev <martin.b.radev@gmail.com>,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v4 15/75] x86/boot/compressed/64: Always switch to own
 page-table
Message-ID: <202007141823.326D9DC102@keescook>
References: <20200714120917.11253-1-joro@8bytes.org>
 <20200714120917.11253-16-joro@8bytes.org>
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On Tue, Jul 14, 2020 at 02:08:17PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
> 
> When booted through startup_64 the kernel keeps running on the EFI
> page-table until the KASLR code sets up its own page-table. Without
> KASLR the pre-decompression boot code never switches off the EFI
> page-table. Change that by unconditionally switching to a kernel
> controlled page-table after relocation.
> 
> This makes sure we can make changes to the mapping when necessary, for
> example map pages unencrypted in SEV and SEV-ES guests.
> 
> Also remove the debug_putstr() calls in initialize_identity_maps()
> because the function now runs before console_init() is called.
> 
> Signed-off-by: Joerg Roedel <jroedel@suse.de>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook