linux-kernel - Re: Hitting AUTOIBRS WARN_ON_ONCE() in init

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Message-ID: <Z1dZAD4_kgmm-B-_@google.com>
Date: Mon, 9 Dec 2024 12:54:24 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: Nathan Chancellor <nathan@...nel.org>, Borislav Petkov <bp@...en8.de>, x86@...nel.org, 
	Kim Phillips <kim.phillips@....com>, Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org, 
	kvm@...r.kernel.org
Subject: Re: Hitting AUTOIBRS WARN_ON_ONCE() in init_amd() booting 32-bit
 kernel under KVM

On Mon, Dec 09, 2024, Josh Poimboeuf wrote:
> On Fri, Dec 06, 2024 at 08:20:06AM -0800, Sean Christopherson wrote:
> > From: Sean Christopherson <seanjc@...gle.com>
> > Date: Fri, 6 Dec 2024 08:14:45 -0800
> > Subject: [PATCH] x86/CPU/AMD: WARN when setting EFER.AUTOIBRS if and only if
> >  the WRMSR fails
> > 
> > When ensuring EFER.AUTOIBRS is set, WARN only on a negative return code
> > from msr_set_bit(), as '1' is used to indicate the WRMSR was successful
> > ('0' indicates the MSR bit was already set).
> > 
> > Fixes: 8cc68c9c9e92 ("x86/CPU/AMD: Make sure EFER[AIBRSE] is set")
> > Reported-by: Nathan Chancellor <nathan@...nel.org>
> > Closes: https://lore.kernel.org/all/20241205220604.GA2054199@thelio-3990X
> > Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> 
> LGTM, but please post as a proper patch in its own thread so the -tip
> maintainers are more likely to see it.

In Boris I trust :-)

Already in Linus' tree, commit 492077668fb4 ("x86/CPU/AMD: WARN when setting
EFER.AUTOIBRS if and only if the WRMSR fails").