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Date:   Mon, 15 May 2023 17:07:35 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
        Evgeniy Baskov <baskov@ispras.ru>,
        Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Alexey Khoroshilov <khoroshilov@ispras.ru>,
        Peter Jones <pjones@redhat.com>,
        Gerd Hoffmann <kraxel@redhat.com>,
        Dave Young <dyoung@redhat.com>,
        Mario Limonciello <mario.limonciello@amd.com>,
        Kees Cook <keescook@chromium.org>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v2 07/20] x86: decompressor: Only call the trampoline
 when changing paging levels
Message-ID: <20230515140735.lw7vjxiv4wsj7pk3@box.shutemov.name>
References: <20230508070330.582131-1-ardb@kernel.org>
 <20230508070330.582131-8-ardb@kernel.org>
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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@kernel.org>

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov