linux-kernel - Re: [PATCH v4 04/24] x86/sev: Run RMPADJUST on SVSM calling area page to test VMPL

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Message-ID: <4b50e347-fedc-d94a-9670-a5003220db57@amd.com>
Date: Wed, 9 Jul 2025 11:13:55 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Ard Biesheuvel <ardb+git@...gle.com>, linux-kernel@...r.kernel.org
Cc: linux-efi@...r.kernel.org, x86@...nel.org,
 Ard Biesheuvel <ardb@...nel.org>, Borislav Petkov <bp@...en8.de>,
 Ingo Molnar <mingo@...nel.org>, Dionna Amalie Glaze
 <dionnaglaze@...gle.com>, Kevin Loughlin <kevinloughlin@...gle.com>,
 Josh Poimboeuf <jpoimboe@...nel.org>, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v4 04/24] x86/sev: Run RMPADJUST on SVSM calling area page
 to test VMPL

On 7/9/25 03:08, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@...nel.org>
> 
> Determining the VMPL at which the kernel runs involves performing a
> RMPADJUST operation on an arbitrary page of memory, and observing whether
> it succeeds.
> 
> The use of boot_ghcb_page in the core kernel in this case is completely
> arbitrary, but results in the need to provide a PIC alias for it. So use
> boot_svsm_ca_page instead, which already needs this alias for other
> reasons.
> 
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org>

Reviewed-by: Tom Lendacky <thomas.lendacky@....com>

> ---
>  arch/x86/boot/compressed/sev.c      | 2 +-
>  arch/x86/boot/startup/sev-shared.c  | 5 +++--
>  arch/x86/boot/startup/sev-startup.c | 2 +-
>  3 files changed, 5 insertions(+), 4 deletions(-)
>