[Qemu-devel] [PATCH] virtio: Mark virtio-device as non-user-creatable

[Eduardo Habkost <ehabkost@redhat.com>]

TYPE_VIRTIO_DEVICE devices are already not usable with -device
and device_add, but they are reported as user-creatable on
"-device help" and through monitor interfaces.

Mark them as not user-creatable to avoid confusing users, and to
allow automated testing (e.g. scripts/device-crash-test) to skip
them.

Before this patch, device-crash-test will try to test
virtio-device devices with all machine-types:

  $ time ./scripts/device-crash-test -D virtio-device -v ./x86_64-softmmu/qemu-system-x86_64
  [...]
  INFO: Total: 1088 test cases
  INFO: Skipped 408 test cases

  real    0m49.775s

After this patch, the script won't try to test virtio-device
devices:

  $ time ./scripts/device-crash-test -D virtio-device -v ./x86_64-softmmu/qemu-system-x86_64
  INFO: Total: 0 test cases

  real    0m0.092s

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 hw/virtio/virtio.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 464947f..c4bdb94 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2653,6 +2653,17 @@ static void virtio_device_class_init(ObjectClass *klass, void *data)
     dc->unrealize = virtio_device_unrealize;
     dc->bus_type = TYPE_VIRTIO_BUS;
     dc->props = virtio_properties;
+    /*
+     * Reason:
+     * - TYPE_VIRTIO_DEVICE devices are not visible to guests
+     *   unless they are created and controlled by transport-specific
+     *   devices (virtio-pci, virtio-mmio, and virtio-ccw).
+     * - A TYPE_VIRTIO_BUS bus is never available for plugging
+     *   using -device/device_add, as virtio-bus buses are
+     *   created on the fly and immediately populated by the
+     *   transport-specific devices' realize methods.
+     */
+    dc->user_creatable = false;
     vdc->start_ioeventfd = virtio_device_start_ioeventfd_impl;
     vdc->stop_ioeventfd = virtio_device_stop_ioeventfd_impl;
 
-- 
2.9.4