kvm/eventfd: move wildcard calculation outside loop

There is no need to calculate wildcard in each iteration
since wildcard is not changed.

Signed-off-by: Yi Li <yili@winhong.com>
Message-Id: <20200911055652.3041762-1-yili@winhong.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

virt/kvm/eventfd.c

@@ -853,15 +853,17 @@ kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx,
 	struct eventfd_ctx       *eventfd;
 	struct kvm_io_bus	 *bus;
 	int                       ret = -ENOENT;
+	bool                      wildcard;
 
 	eventfd = eventfd_ctx_fdget(args->fd);
 	if (IS_ERR(eventfd))
 		return PTR_ERR(eventfd);
 
+	wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
+
 	mutex_lock(&kvm->slots_lock);
 
 	list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
-		bool wildcard = !(args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH);
 
 		if (p->bus_idx != bus_idx ||
 		    p->eventfd != eventfd  ||