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From: Ard Biesheuvel <ardb@kernel.org>
Date: Thu, 1 Feb 2024 17:28:22 +0100
Message-ID: <CAMj1kXFZKM5wU8djcVBxDmnCJwV4Xpest6u1EbE=7wyLUUeUUQ@mail.gmail.com>
Subject: Re: [PATCH v3 01/19] efi/libstub: Add generic support for parsing mem_encrypt=
To: Kevin Loughlin <kevinloughlin@google.com>
Cc: Borislav Petkov <bp@alien8.de>, Ard Biesheuvel <ardb+git@google.com>, linux-kernel@vger.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 Thu, 1 Feb 2024 at 17:23, Kevin Loughlin <kevinloughlin@google.com> wrot=
e:
>
> On Tue, Jan 30, 2024 at 11:32=E2=80=AFPM Borislav Petkov <bp@alien8.de> w=
rote:
> >
> > 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 earl=
y
> > > boot code by the arch code in the stub.
> >
> > I guess all systems which do memory encryption are EFI systems anyway s=
o
> > 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
>

The second patch in this series actually implements the mem_encrypt=3D
parsing for both EFI and non-EFI boot. I just broke this out in a
separate patch because it affects architectures other than x86.