KVM: x86: allow KVM_STATE_NESTED_MTF_PENDING in kvm_state flags

The migration functionality was left incomplete in commit 5ef8acbd
("KVM: nVMX: Emulate MTF when performing instruction emulation", 2020-02-23),
fix it.

Fixes: 5ef8acbd ("KVM: nVMX: Emulate MTF when performing instruction emulation")
Cc: stable@vger.kernel.org
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

@@ -4626,7 +4626,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 
 		if (kvm_state.flags &
 		    ~(KVM_STATE_NESTED_RUN_PENDING | KVM_STATE_NESTED_GUEST_MODE
-		      | KVM_STATE_NESTED_EVMCS))
+		      | KVM_STATE_NESTED_EVMCS | KVM_STATE_NESTED_MTF_PENDING))
 			break;
 
 		/* nested_run_pending implies guest_mode.  */