Re: Hitting AUTOIBRS WARN_ON_ONCE() in init_amd() booting 32-bit kernel under KVM

[Sean Christopherson]

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@xxxxxxxxxx>
> > 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@xxxxxxxxxx>
> > Closes: https://lore.kernel.org/all/20241205220604.GA2054199@thelio-3990X
> > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> 
> 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").