On Sat, May 23, 2020 at 07:14:55PM +0300, Maxim Levitsky wrote: > This msr is only available when the host supports WAITPKG feature. > > This breaks a nested guest, if the L1 hypervisor is set to ignore > unknown msrs, because the only other safety check that the > kernel does is that it attempts to read the msr and > rejects it if it gets an exception. > > Fixes: 6e3ba4abce KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL Same comments on the line wraps and Fixes tag. For the code: Reviewed-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx> > --- > arch/x86/kvm/x86.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index b226fb8abe41b..4752293312947 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -5316,6 +5316,10 @@ static void kvm_init_msr_list(void) > min(INTEL_PMC_MAX_GENERIC, x86_pmu.num_counters_gp)) > continue; > break; > + case MSR_IA32_UMWAIT_CONTROL: > + if (!kvm_cpu_cap_has(X86_FEATURE_WAITPKG)) > + continue; > + break; > default: > break; > } > -- > 2.26.2 >
