linux-kernel - Re: [PATCH v8 00/23] efi/x86: Avoid bare metal decompressor during EFI boot

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Message-ID: <20230805144030.GDZM5fXvaqXBLxwXfj@fat_crate.local>
Date:   Sat, 5 Aug 2023 16:40:30 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Evgeniy Baskov <baskov@...ras.ru>,
        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>,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH v8 00/23] efi/x86: Avoid bare metal decompressor during
 EFI boot

On Wed, Aug 02, 2023 at 05:48:08PM +0200, Ard Biesheuvel wrote:
> Update the x86 boot path to avoid the bare metal decompressor when
> booting via the EFI stub. The bare metal decompressor inherits the
> loader's 1:1 mapping of DRAM when entering in 64-bit mode, and assumes
> that all of it is mapped read/write/execute, which will no longer be the
> case on systems built to comply with recently tightened logo
> requirements (*).
> 
> Changes since v7 [10]:

My Zen1 box fails booting with those. It is related to memory encryption
because if I supply "mem_encrypt=off", it boots.

The failure is (typing it off from the video from the BMC):

/dev/root: Can't open blockdev
VFS: Cannot open root device "UUID=..."
Please append a correct "root=" boot option;
...

I'll bisect now but it is pretty clear which one is the culprit.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette