KVM: VMX: do not check bit 12 of EPT violation exit qualification when undefined

Bit 12 is undefined in any of the following cases:
- If the "NMI exiting" VM-execution control is 1 and the "virtual NMIs"
  VM-execution control is 0.
- If the VM exit sets the valid bit in the IDT-vectoring information field
Signed-off-by: Gleb Natapov <gleb@redhat.com>
[Add parentheses around & within && - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -5345,7 +5345,9 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
 	 * There are errata that may cause this bit to not be set:
 	 * AAK134, BY25.
 	 */
-	if (exit_qualification & INTR_INFO_UNBLOCK_NMI)
+	if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
+			cpu_has_virtual_nmis() &&
+			(exit_qualification & INTR_INFO_UNBLOCK_NMI))
 		vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, GUEST_INTR_STATE_NMI);
 
 	gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);