[PATCH] KVM: x86: Advertise that the SMM_CTL MSR is not supported

From: Jim Mattson <jmattson@google.com>
To: kvm@vger.kernel.org, pbonzini@redhat.com, seanjc@google.com
Cc: Jim Mattson <jmattson@google.com>
Subject: [PATCH] KVM: x86: Advertise that the SMM_CTL MSR is not supported
Date: Fri,  7 Oct 2022 15:16:44 -0700	[thread overview]
Message-ID: <20221007221644.138355-1-jmattson@google.com> (raw)

CPUID.80000021H:EAX[bit 9] indicates that the SMM_CTL MSR (0xc0010116)
is not supported. This defeature can be advertised by
KVM_GET_SUPPORTED_CPUID regardless of whether or not the host
enumerates it.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/cpuid.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2796dde06302..b748fac2ae37 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1199,8 +1199,12 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 		 * Other defined bits are for MSRs that KVM does not expose:
 		 *   EAX      3      SPCL, SMM page configuration lock
 		 *   EAX      13     PCMSR, Prefetch control MSR
+		 *
+		 * KVM doesn't support SMM_CTL.
+		 *   EAX       9     SMM_CTL MSR is not supported
 		 */
 		entry->eax &= BIT(0) | BIT(2) | BIT(6);
+		entry->eax |= BIT(9);
 		if (static_cpu_has(X86_FEATURE_LFENCE_RDTSC))
 			entry->eax |= BIT(2);
 		if (!static_cpu_has_bug(X86_BUG_NULL_SEG))
-- 
2.38.0.rc1.362.ged0d419d3c-goog

