KVM: x86: Mask off reserved bits in CPUID.8000001FH

KVM_GET_SUPPORTED_CPUID should only enumerate features that KVM
actually supports. CPUID.8000001FH:EBX[31:16] are reserved bits and
should be masked off.

Fixes: 8765d753 ("KVM: X86: Extend CPUID range to include new leaf")
Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20220929225203.2234702-6-jmattson@google.com>
Cc: stable@vger.kernel.org
[Clear NumVMPL too. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/cpuid.c

@@ -1199,7 +1199,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
 		} else {
 			cpuid_entry_override(entry, CPUID_8000_001F_EAX);
-
+			/* Clear NumVMPL since KVM does not support VMPL.  */
+			entry->ebx &= ~GENMASK(31, 12);
 			/*
 			 * Enumerate '0' for "PA bits reduction", the adjusted
 			 * MAXPHYADDR is enumerated directly (see 0x80000008).