WARN if the IA32_FEAT_CTL MSR is somehow left unlocked now that CPU initialization unconditionally locks the MSR. Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> --- arch/x86/kernel/cpu/mce/intel.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c index c238518b84a2..5627b1091b85 100644 --- a/arch/x86/kernel/cpu/mce/intel.c +++ b/arch/x86/kernel/cpu/mce/intel.c @@ -116,14 +116,15 @@ static bool lmce_supported(void) /* * BIOS should indicate support for LMCE by setting bit 20 in * IA32_FEAT_CTL without which touching MCG_EXT_CTL will generate a #GP - * fault. + * fault. The MSR must also be locked for LMCE_ENABLED to take effect. + * WARN if the MSR isn't locked as init_ia32_feat_ctl() unconditionally + * locks the MSR in the event that it wasn't already locked by BIOS. */ rdmsrl(MSR_IA32_FEAT_CTL, tmp); - if ((tmp & (FEAT_CTL_LOCKED | FEAT_CTL_LMCE_ENABLED)) == - (FEAT_CTL_LOCKED | FEAT_CTL_LMCE_ENABLED)) - return true; + 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
