linux-kernel - Re: [PATCH v4 08/24] x86/sev: Share implementation of MSR-based page state change

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Message-ID: <CAMj1kXFPQyAwSfyXjhrpvThsVtMT31AYG5JdypsCEBJee=Dgsg@mail.gmail.com>
Date: Tue, 15 Jul 2025 15:09:15 +1000
From: Ard Biesheuvel <ardb@...nel.org>
To: Tom Lendacky <thomas.lendacky@....com>
Cc: Ard Biesheuvel <ardb+git@...gle.com>, linux-kernel@...r.kernel.org, 
	linux-efi@...r.kernel.org, x86@...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 08/24] x86/sev: Share implementation of MSR-based page
 state change

On Thu, 10 Jul 2025 at 04:24, Tom Lendacky <thomas.lendacky@....com> wrote:
>
> On 7/9/25 03:08, Ard Biesheuvel wrote:
> > From: Ard Biesheuvel <ardb@...nel.org>
> >
> > Both the decompressor and the SEV startup code implement the exact same
> > sequence for invoking the MSR based communication protocol to effectuate
> > a page state change.
> >
> > Before tweaking the internal APIs used in both versions, merge them and
> > share them so those tweaks are only needed in a single place.
>
> I think you can keep the save and restore of the MSR in the the combined
> code so that you don't need the previous patch and that will keep
> everything safe. We should be doing a minimal amount of MSR protocol
> page state changes, so it really shouldn't have much effect.
>

OK, so I'll drop the previous patch, and rework this one accordingly.