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Message-ID: <20230515140735.lw7vjxiv4wsj7pk3@box.shutemov.name>
Date: Mon, 15 May 2023 17:07:35 +0300
From: "Kirill A. Shutemov" <kirill@...temov.name>
To: Ard Biesheuvel <ardb@...nel.org>
Cc: linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
Evgeniy Baskov <baskov@...ras.ru>,
Borislav Petkov <bp@...en8.de>,
Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Alexey Khoroshilov <khoroshilov@...ras.ru>,
Peter Jones <pjones@...hat.com>,
Gerd Hoffmann <kraxel@...hat.com>,
Dave Young <dyoung@...hat.com>,
Mario Limonciello <mario.limonciello@....com>,
Kees Cook <keescook@...omium.org>,
Tom Lendacky <thomas.lendacky@....com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2 07/20] x86: decompressor: Only call the trampoline
when changing paging levels
On Mon, May 08, 2023 at 09:03:17AM +0200, Ard Biesheuvel wrote:
> Since we know the current and desired number of paging levels when
> preparing the trampoline, let's not call the trampoline at all when we
> know that calling it is not going to result in a change to the number of
> paging levels. Given that we are already running in long mode, the PAE
> and LA57 settings are necessarily consistent with the currently active
> page tables - the only difference is that we will always preserve
> CR4.MCE in this case, but this will be cleared by the real kernel
> startup code if CONFIG_X86_MCE is not enabled.
>
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
--
Kiryl Shutsemau / Kirill A. Shutemov
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