On Mon, Oct 21, 2019 at 04:56:42PM -0700, Sean Christopherson wrote:
> WARN if the IA32_FEATURE_CONTROL MSR is somehow left unlocked now that
> CPU initialization unconditionally locks the MSR.
>
> Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Cc: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> Cc: Jim Mattson <jmattson@xxxxxxxxxx>
> Cc: kvm@xxxxxxxxxxxxxxx
> 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 88cd9598fa57..1008f14b803b 100644
> --- a/arch/x86/kernel/cpu/mce/intel.c
> +++ b/arch/x86/kernel/cpu/mce/intel.c
> @@ -117,11 +117,10 @@ static bool lmce_supported(void)
> * generate a #GP fault.
> */
> rdmsrl(MSR_IA32_FEATURE_CONTROL, tmp);
> - if ((tmp & (FEATURE_CONTROL_LOCKED | FEATURE_CONTROL_LMCE)) ==
> - (FEATURE_CONTROL_LOCKED | FEATURE_CONTROL_LMCE))
> - return true;
> + if (WARN_ON_ONCE(!(tmp & FEATURE_CONTROL_LOCKED)))
> + return false;
>
> - return false;
> + return tmp & FEATURE_CONTROL_LMCE;
> }
>
> bool mce_intel_cmci_poll(void)
> --
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
