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

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Message-ID: <20241209204414.psmh3yyllnwbrc4y@jpoimboe>
Date: Mon, 9 Dec 2024 12:44:14 -0800
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Sean Christopherson <seanjc@...gle.com>
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 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.

-- 
Josh