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From: Kevin Loughlin <kevinloughlin@google.com>
Date: Fri, 2 Feb 2024 16:22:02 -0800
Message-ID: <CAGdbjmJgu4euOTEzns4-7pqUWo8n-gNJiAfARoZWxw8T252zJQ@mail.gmail.com>
Subject: Re: [PATCH v3 0/2] x86: enforce and cleanup RIP-relative accesses in
 early boot code
To: Borislav Petkov <bp@alien8.de>
Cc: Jacob Xu <jacobhxu@google.com>, Thomas Gleixner <tglx@linutronix.de>, 
	Ingo Molnar <mingo@redhat.com>, Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org, 
	Nick Desaulniers <ndesaulniers@google.com>, Justin Stitt <justinstitt@google.com>, 
	Tom Lendacky <thomas.lendacky@amd.com>, Pankaj Gupta <pankaj.gupta@amd.com>, 
	Hou Wenlong <houwenlong.hwl@antgroup.com>, Ard Biesheuvel <ardb@kernel.org>, 
	Dionna Glaze <dionnaglaze@google.com>, Brijesh Singh <brijesh.singh@amd.com>, 
	Michael Roth <michael.roth@amd.com>, 
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, linux-kernel@vger.kernel.org, 
	llvm@lists.linux.dev, linux-coco@lists.linux.dev, 
	Ashish Kalra <ashish.kalra@amd.com>, Andi Kleen <ak@linux.intel.com>, 
	Adam Dunlap <acdunlap@google.com>, Peter Gonda <pgonda@google.com>, 
	Sidharth Telang <sidtelang@google.com>
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On Wed, Jan 31, 2024 at 10:30=E2=80=AFAM Borislav Petkov <bp@alien8.de> wro=
te:
>
> On Wed, Jan 31, 2024 at 10:16:55AM -0800, Jacob Xu wrote:
> > We're interested in fixing SEV-SNP guest boots which are currently
> > broken when using a guest kernel compiled with clang. It seems like
> > every other user of SEV/SNP linux kernel code uses GCC to compile the
> > kernel so they've avoided this issue.
>
> Lemme give that a try here.
>
> > E.g. Google COS uses clang to compile the kernel and we've made do
> > with an internal fix for a while.
>
> Which means that, theoretically, you could forward-port this internal
> fix until the issue is fixed for real, I'd say.

True. I just think it would be better to have an upstream fix for
clang builds of SEV-SNP guests; I believe the first such SEV-SNP code
was merged in 5.19 if I'm not mistaken.