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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Wed, 26 Apr 2023 22:24:16 +0100
Message-ID: <CAMj1kXHM2kpk4CvrkJVW3EHDR9NEth_TzvX7+O+9x=Of8cdA6g@mail.gmail.com>
Subject: Re: [PATCH 0/6] efi/x86: Avoid legacy decompressor during EFI boot
To:     Borislav Petkov <bp@alien8.de>
Cc:     linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
        Evgeniy Baskov <baskov@ispras.ru>,
        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>
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On Wed, 26 Apr 2023 at 11:18, Borislav Petkov <bp@alien8.de> wrote:
>
> On Mon, Apr 24, 2023 at 06:57:20PM +0200, Ard Biesheuvel wrote:
> >  arch/x86/boot/compressed/efi_mixed.S           |  55 ---
> >  arch/x86/boot/compressed/head_32.S             |  24 --
> >  arch/x86/boot/compressed/head_64.S             |  39 +--
> >  arch/x86/boot/compressed/misc.c                |  44 ++-
> >  arch/x86/include/asm/efi.h                     |   2 +
> >  drivers/firmware/efi/libstub/efi-stub-helper.c |   4 +
> >  drivers/firmware/efi/libstub/x86-stub.c        | 360 +++++++++++++-------
> >  7 files changed, 279 insertions(+), 249 deletions(-)
>
> Upon a quick scan, I can't argue with that diffstat and would prefer
> a lot more if we did this instead of Evgeny's pile which touches a lot
> of nasty and hard to debug code which gets executed on *everything*.
>
> So if people agree with that approach, I'd gladly give it a more
> detailed look.
>

I think the general approach is better, but to be honest, I may have
missed a thing or two, so it would be good if people more familiar
with the history could chime in.