On Mon, Nov 18, 2019 at 07:12:26PM -0800, Sean Christopherson wrote: > WARN if the IA32_FEATURE_CONTROL MSR is somehow left unlocked now that > CPU initialization unconditionally locks the MSR. > > Reviewed-by: Borislav Petkov <bp@xxxxxxx> > Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > --- > arch/x86/kernel/cpu/mce/intel.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c > index 3e5b29acd301..5abc55a67fce 100644 > --- a/arch/x86/kernel/cpu/mce/intel.c > +++ b/arch/x86/kernel/cpu/mce/intel.c > @@ -119,11 +119,10 @@ static bool lmce_supported(void) > * generate a #GP fault. > */ > rdmsrl(MSR_IA32_FEATURE_CONTROL, tmp); > - if ((tmp & (FEAT_CTL_LOCKED | FEAT_CTL_LMCE_ENABLED)) == > - (FEAT_CTL_LOCKED | FEAT_CTL_LMCE_ENABLED)) > - return true; I'd add a prepending comment: /* * FEAT_CTL_LOCKED should have been always set either by * BIOS before handover to the kernel or init_feature_control_msr(). */ > + if (WARN_ON_ONCE(!(tmp & FEAT_CTL_LOCKED))) > + return false; > > - return false; > + return tmp & FEAT_CTL_LMCE_ENABLED; > } > > bool mce_intel_cmci_poll(void) > -- > 2.24.0 > /Jarkko
