Re: [PATCH v6 03/22] x86/sev: Use MSR protocol only for early SVSM PVALIDATE call

[Tom Lendacky <thomas.lendacky@amd.com>]

On 7/22/25 02:27, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
> 
> The early page state change API performs an SVSM call to PVALIDATE each
> page when running under a SVSM, and this involves either a GHCB page
> based call or a call based on the MSR protocol.
> 
> The GHCB page based variant involves VA to PA translation of the GHCB
> address, and this is best avoided in the startup code, where virtual
> addresses are ambiguous (1:1 or kernel virtual).
> 
> As this is the last remaining occurrence of svsm_perform_call_protocol()
> in the startup code, switch to the MSR protocol exclusively in this
> particular case, so that the GHCB based plumbing can be moved out of the
> startup code entirely in a subsequent patch.
> 
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

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

> ---
>  arch/x86/boot/compressed/sev.c     | 20 --------------------
>  arch/x86/boot/startup/sev-shared.c |  9 ++++++---
>  2 files changed, 6 insertions(+), 23 deletions(-)
>