linux-kernel - Re: [GIT PULL] x86/cpu for v5.17

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Date:   Mon, 10 Jan 2022 10:18:06 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Borislav Petkov <bp@...e.de>
Cc:     x86-ml <x86@...nel.org>, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] x86/cpu for v5.17

On Mon, Jan 10, 2022 at 3:16 AM Borislav Petkov <bp@...e.de> wrote:
>
> - Avoid writing MSR_CSTAR on Intel due to TDX guests raising a #VE trap

This is all fine, but my reaction to this is that I would have
expected it to be either a wrmsrl_safe(), or using an actual CPU
feature check.

Checking for a particular vendor seems a bit hacky. We generally try
to avoid things like that, don't we?

Not a big deal, I just thought I'd mention it since I reacted to it.
And we don't seem to have those vendor checks in any of the other code
that uses MSR_CSTAR (just grepping for that and seeing it mentioned in
kvm code etc)

             Linus