virtio-ccw: disable ioevent bit when ioeventfds are not enabled

This remove the corresponding error messages in TCG mode, and allow to
simplify the s390_assign_subch_ioeventfd() function.
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/s390x/virtio-ccw.c

@@ -1401,6 +1401,10 @@ static void virtio_ccw_device_plugged(DeviceState *d, Error **errp)
         return;
     }
 
+    if (!kvm_eventfds_enabled()) {
+        dev->flags &= ~VIRTIO_CCW_FLAG_USE_IOEVENTFD;
+    }
+
     sch->id.cu_model = virtio_bus_get_vdev_id(&dev->bus);
 
     css_generate_sch_crws(sch->cssid, sch->ssid, sch->schid,

target-s390x/cpu.h

@@ -1215,11 +1215,7 @@ static inline int s390_assign_subch_ioeventfd(EventNotifier *notifier,
                                               uint32_t sch_id, int vq,
                                               bool assign)
 {
-    if (kvm_enabled()) {
-        return kvm_s390_assign_subch_ioeventfd(notifier, sch_id, vq, assign);
-    } else {
-        return -ENOSYS;
-    }
+    return kvm_s390_assign_subch_ioeventfd(notifier, sch_id, vq, assign);
 }
 
 #ifdef CONFIG_KVM