[04/12] virtio: introduce virtio_device_ioeventfd_enabled

diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 3e450eb..86c1340 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -59,11 +59,11 @@  static void virtio_ccw_stop_ioeventfd(VirtioCcwDevice *dev)
     virtio_bus_stop_ioeventfd(&dev->bus);
 }
 
-static bool virtio_ccw_ioeventfd_disabled(DeviceState *d)
+static bool virtio_ccw_ioeventfd_enabled(DeviceState *d)
 {
     VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
 
-    return !(dev->flags & VIRTIO_CCW_FLAG_USE_IOEVENTFD);
+    return (dev->flags & VIRTIO_CCW_FLAG_USE_IOEVENTFD) != 0;
 }
 
 static int virtio_ccw_ioeventfd_assign(DeviceState *d, EventNotifier *notifier,
@@ -1569,7 +1569,7 @@  static void virtio_ccw_bus_class_init(ObjectClass *klass, void *data)
     k->device_plugged = virtio_ccw_device_plugged;
     k->post_plugged = virtio_ccw_post_plugged;
     k->device_unplugged = virtio_ccw_device_unplugged;
-    k->ioeventfd_disabled = virtio_ccw_ioeventfd_disabled;
+    k->ioeventfd_enabled = virtio_ccw_ioeventfd_enabled;
     k->ioeventfd_assign = virtio_ccw_ioeventfd_assign;
 }
 
diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index 94e202d..f60efd7 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -191,7 +191,7 @@  int virtio_bus_start_ioeventfd(VirtioBusState *bus)
     VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
     int r;
 
-    if (!k->ioeventfd_assign || k->ioeventfd_disabled(proxy)) {
+    if (!k->ioeventfd_assign || !k->ioeventfd_enabled(proxy)) {
         return -ENOSYS;
     }
     if (bus->ioeventfd_started || bus->ioeventfd_disabled) {
@@ -218,6 +218,14 @@  void virtio_bus_stop_ioeventfd(VirtioBusState *bus)
     bus->ioeventfd_started = false;
 }
 
+bool virtio_bus_ioeventfd_enabled(VirtIODevice *vdev)
+{
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
+    DeviceState *proxy = DEVICE(BUS(bus)->parent);
+
+    return k->ioeventfd_enabled(proxy);
+}
+
 /*
  * This function switches from/to the generic ioeventfd handler.
  * assign==false means 'use generic ioeventfd handler'.
diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
index 04a9655..a30270f 100644
--- a/hw/virtio/virtio-mmio.c
+++ b/hw/virtio/virtio-mmio.c
@@ -92,9 +92,9 @@  typedef struct {
     bool format_transport_address;
 } VirtIOMMIOProxy;
 
-static bool virtio_mmio_ioeventfd_disabled(DeviceState *d)
+static bool virtio_mmio_ioeventfd_enabled(DeviceState *d)
 {
-    return !kvm_eventfds_enabled();
+    return kvm_eventfds_enabled();
 }
 
 static int virtio_mmio_ioeventfd_assign(DeviceState *d,
@@ -531,7 +531,7 @@  static void virtio_mmio_bus_class_init(ObjectClass *klass, void *data)
     k->save_config = virtio_mmio_save_config;
     k->load_config = virtio_mmio_load_config;
     k->set_guest_notifiers = virtio_mmio_set_guest_notifiers;
-    k->ioeventfd_disabled = virtio_mmio_ioeventfd_disabled;
+    k->ioeventfd_enabled = virtio_mmio_ioeventfd_enabled;
     k->ioeventfd_assign = virtio_mmio_ioeventfd_assign;
     k->has_variable_vring_alignment = true;
     bus_class->max_dev = 1;
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index a5d8c8d..158ffe5 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -262,11 +262,11 @@  static int virtio_pci_load_queue(DeviceState *d, int n, QEMUFile *f)
     return 0;
 }
 
-static bool virtio_pci_ioeventfd_disabled(DeviceState *d)
+static bool virtio_pci_ioeventfd_enabled(DeviceState *d)
 {
     VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
 
-    return !(proxy->flags & VIRTIO_PCI_FLAG_USE_IOEVENTFD);
+    return (proxy->flags & VIRTIO_PCI_FLAG_USE_IOEVENTFD) != 0;
 }
 
 #define QEMU_VIRTIO_PCI_QUEUE_MEM_MULT 0x1000
@@ -2424,7 +2424,7 @@  static void virtio_pci_bus_class_init(ObjectClass *klass, void *data)
     k->device_plugged = virtio_pci_device_plugged;
     k->device_unplugged = virtio_pci_device_unplugged;
     k->query_nvectors = virtio_pci_query_nvectors;
-    k->ioeventfd_disabled = virtio_pci_ioeventfd_disabled;
+    k->ioeventfd_enabled = virtio_pci_ioeventfd_enabled;
     k->ioeventfd_assign = virtio_pci_ioeventfd_assign;
 }
 
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 2919113..84abd08 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2021,6 +2021,14 @@  static void virtio_device_class_init(ObjectClass *klass, void *data)
     vdc->stop_ioeventfd = virtio_device_stop_ioeventfd_impl;
 }
 
+bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev)
+{
+    BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
+    VirtioBusState *vbus = VIRTIO_BUS(qbus);
+
+    return virtio_bus_ioeventfd_enabled(vbus);
+}
+
 static const TypeInfo virtio_device_info = {
     .name = TYPE_VIRTIO_DEVICE,
     .parent = TYPE_DEVICE,
diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
index 01b11c5..0abc890 100644
--- a/include/hw/virtio/virtio-bus.h
+++ b/include/hw/virtio/virtio-bus.h
@@ -71,10 +71,10 @@  typedef struct VirtioBusClass {
     int (*query_nvectors)(DeviceState *d);
     /*
      * ioeventfd handling: if the transport implements ioeventfd_assign,
-     * it must implement ioeventfd_disabled as well.
+     * it must implement ioeventfd_enabled as well.
      */
-    /* Returns true if the ioeventfd has been disabled for the device. */
-    bool (*ioeventfd_disabled)(DeviceState *d);
+    /* Returns true if the ioeventfd is enabled for the device. */
+    bool (*ioeventfd_enabled)(DeviceState *d);
     /*
      * Assigns/deassigns the ioeventfd backing for the transport on
      * the device for queue number n. Returns an error value on
@@ -134,6 +134,8 @@  static inline VirtIODevice *virtio_bus_get_device(VirtioBusState *bus)
     return (VirtIODevice *)qdev;
 }
 
+/* Return whether the proxy allows ioeventfd.  */
+bool virtio_bus_ioeventfd_enabled(VirtioBusState *bus);
 /* Start the ioeventfd. */
 int virtio_bus_start_ioeventfd(VirtioBusState *bus);
 /* Stop the ioeventfd. */
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index f283217..ec50f7a 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -274,6 +274,7 @@  void virtio_queue_set_guest_notifier_fd_handler(VirtQueue *vq, bool assign,
                                                 bool with_irqfd);
 int virtio_device_start_ioeventfd(VirtIODevice *vdev);
 void virtio_device_stop_ioeventfd(VirtIODevice *vdev);
+bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev);
 EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq);
 void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
                                                bool set_handler);