KVM: x86: Mask off reserved bits in CPUID.80000001H

KVM_GET_SUPPORTED_CPUID should only enumerate features that KVM
actually supports. CPUID.80000001:EBX[27:16] are reserved bits and
should be masked off.

Fixes: 07716717 ("KVM: Enhance guest cpuid management")
Signed-off-by: Jim Mattson <jmattson@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/cpuid.c

@@ -1133,6 +1133,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 			entry->eax = max(entry->eax, 0x80000021);
 		break;
 	case 0x80000001:
+		entry->ebx &= ~GENMASK(27, 16);
 		cpuid_entry_override(entry, CPUID_8000_0001_EDX);
 		cpuid_entry_override(entry, CPUID_8000_0001_ECX);
 		break;