virtio: introduce virtio_device_ioeventfd_enabled

This will be used to forbid iothread configuration when the
proxy does not allow using ioeventfd.  To simplify the implementation,
change the direction of the ioeventfd_disabled callback too.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

4 files changed, 23 insertions, 7 deletions

diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index a8d2bd89c5..3ffec66d59 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -193,7 +193,7 @@ 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) {
@@ -223,6 +223,14 @@ void virtio_bus_stop_ioeventfd(VirtioBusState *bus)
     bus->ioeventfd_started = false;
 }
 
+bool virtio_bus_ioeventfd_enabled(VirtioBusState *bus)
+{
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
+    DeviceState *proxy = DEVICE(BUS(bus)->parent);
+
+    return k->ioeventfd_assign && 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 04a9655d84..a30270f902 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 f00fc2537c..62001b46d7 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
@@ -2516,7 +2516,7 @@ 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 e2285180c4..138a6444ff 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2247,6 +2247,14 @@ 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,