virtio-mmio: support device mode

With device mode, the virtio-mmio behaves like the device side of the
virtio-mmio transport layer instead of the driver side

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/hw/virtio/vhost-user-scmi.c b/hw/virtio/vhost-user-scmi.c
index 10ead3c3e7..2bede14b88 100644
--- a/hw/virtio/vhost-user-scmi.c
+++ b/hw/virtio/vhost-user-scmi.c
@@ -90,6 +90,15 @@ static void vu_scmi_set_status(VirtIODevice *vdev, uint8_t status)
     VHostUserSCMI *scmi = VHOST_USER_SCMI(vdev);
     bool should_start = status & VIRTIO_CONFIG_S_DRIVER_OK;
 
+    /*
+     * When emulating device mode, we start backend as soon as features have
+     * been set in order to be notified when guest will set vring and flags
+     * like VIRTIO_CONFIG_S_DRIVER_OK
+     */
+    if (vdev->device_mode) {
+	should_start = status & VIRTIO_CONFIG_S_FEATURES_OK;
+    }
+
     if (!vdev->vm_running) {
         should_start = false;
     }