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From: Kevin Loughlin <kevinloughlin@google.com>
Date: Thu, 1 Feb 2024 08:23:41 -0800
Message-ID: <CAGdbjmJi_b0jt4-noJEdVFvQ80BOBULmHic8D-uGsNn4m9rTyg@mail.gmail.com>
Subject: Re: [PATCH v3 01/19] efi/libstub: Add generic support for parsing mem_encrypt=
To: Borislav Petkov <bp@alien8.de>
Cc: Ard Biesheuvel <ardb+git@google.com>, linux-kernel@vger.kernel.org, 
	Ard Biesheuvel <ardb@kernel.org>, Tom Lendacky <thomas.lendacky@amd.com>, 
	Dionna Glaze <dionnaglaze@google.com>, Thomas Gleixner <tglx@linutronix.de>, 
	Ingo Molnar <mingo@redhat.com>, Dave Hansen <dave.hansen@linux.intel.com>, 
	Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>, Nathan Chancellor <nathan@kernel.org>, 
	Nick Desaulniers <ndesaulniers@google.com>, Justin Stitt <justinstitt@google.com>, 
	Kees Cook <keescook@chromium.org>, Brian Gerst <brgerst@gmail.com>, linux-arch@vger.kernel.org, 
	llvm@lists.linux.dev, Conrad Grobler <grobler@google.com>, 
	Andri Saar <andrisaar@google.com>, Sidharth Telang <sidtelang@google.com>
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On Tue, Jan 30, 2024 at 11:32=E2=80=AFPM Borislav Petkov <bp@alien8.de> wro=
te:
>
> On Mon, Jan 29, 2024 at 07:05:04PM +0100, Ard Biesheuvel wrote:
> > From: Ard Biesheuvel <ardb@kernel.org>
> >
> > Parse the mem_encrypt=3D command line parameter from the EFI stub if
> > CONFIG_ARCH_HAS_MEM_ENCRYPT=3Dy, so that it can be passed to the early
> > boot code by the arch code in the stub.
>
> I guess all systems which do memory encryption are EFI systems anyway so
> we should not worry about the old ones...

There is at least one non-EFI firmware supporting memory encryption:
Oak stage0 firmware [0]. However, I think Ard's patch seems simple
enough to adopt in non-EFI firmware(s) if needed. I merely wanted to
point out the existence of non-EFI memory encryption systems for
potential future cases (ex: reviewing more complex patches at the
firmware interface).

[0] https://github.com/project-oak/oak/tree/main/stage0_bin