virtio: Introduce started flag to VirtioDevice

The virtio 1.0 transitional devices support driver uses the device
before setting the DRIVER_OK status bit. So we introduce a started
flag to indicate whether driver has started the device or not.

Signed-off-by: Xie Yongji <xieyongji@baidu.com>
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Message-Id: <20190320112646.3712-2-xieyongji@baidu.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/virtio.c

@@ -1162,10 +1162,16 @@ int virtio_set_status(VirtIODevice *vdev, uint8_t val)
             }
         }
     }
+    vdev->started = val & VIRTIO_CONFIG_S_DRIVER_OK;
+    if (unlikely(vdev->start_on_kick && vdev->started)) {
+        vdev->start_on_kick = false;
+    }
+
     if (k->set_status) {
         k->set_status(vdev, val);
     }
     vdev->status = val;
+
     return 0;
 }
 
@@ -1208,6 +1214,9 @@ void virtio_reset(void *opaque)
         k->reset(vdev);
     }
 
+    vdev->start_on_kick = (virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1) &&
+                          !virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1));
+    vdev->started = false;
     vdev->broken = false;
     vdev->guest_features = 0;
     vdev->queue_sel = 0;
@@ -1518,14 +1527,21 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n, int align)
 
 static bool virtio_queue_notify_aio_vq(VirtQueue *vq)
 {
+    bool ret = false;
+
     if (vq->vring.desc && vq->handle_aio_output) {
         VirtIODevice *vdev = vq->vdev;
 
         trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
-        return vq->handle_aio_output(vdev, vq);
+        ret = vq->handle_aio_output(vdev, vq);
+
+        if (unlikely(vdev->start_on_kick)) {
+            vdev->started = true;
+            vdev->start_on_kick = false;
+        }
     }
 
-    return false;
+    return ret;
 }
 
 static void virtio_queue_notify_vq(VirtQueue *vq)
@@ -1539,6 +1555,11 @@ static void virtio_queue_notify_vq(VirtQueue *vq)
 
         trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
         vq->handle_output(vdev, vq);
+
+        if (unlikely(vdev->start_on_kick)) {
+            vdev->started = true;
+            vdev->start_on_kick = false;
+        }
     }
 }
 
@@ -1556,6 +1577,11 @@ void virtio_queue_notify(VirtIODevice *vdev, int n)
     } else if (vq->handle_output) {
         vq->handle_output(vdev, vq);
     }
+
+    if (unlikely(vdev->start_on_kick)) {
+        vdev->started = true;
+        vdev->start_on_kick = false;
+    }
 }
 
 uint16_t virtio_queue_vector(VirtIODevice *vdev, int n)
@@ -1770,6 +1796,13 @@ static bool virtio_broken_needed(void *opaque)
     return vdev->broken;
 }
 
+static bool virtio_started_needed(void *opaque)
+{
+    VirtIODevice *vdev = opaque;
+
+    return vdev->started;
+}
+
 static const VMStateDescription vmstate_virtqueue = {
     .name = "virtqueue_state",
     .version_id = 1,
@@ -1898,6 +1931,17 @@ static const VMStateDescription vmstate_virtio_broken = {
     }
 };
 
+static const VMStateDescription vmstate_virtio_started = {
+    .name = "virtio/started",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = &virtio_started_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_BOOL(started, VirtIODevice),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription vmstate_virtio = {
     .name = "virtio",
     .version_id = 1,
@@ -1913,6 +1957,7 @@ static const VMStateDescription vmstate_virtio = {
         &vmstate_virtio_ringsize,
         &vmstate_virtio_broken,
         &vmstate_virtio_extra_state,
+        &vmstate_virtio_started,
         NULL
     }
 };
@@ -2286,6 +2331,9 @@ void virtio_init(VirtIODevice *vdev, const char *name,
             g_malloc0(sizeof(*vdev->vector_queues) * nvectors);
     }
 
+    vdev->start_on_kick = (virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1) &&
+                          !virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1));
+    vdev->started = false;
     vdev->device_id = device_id;
     vdev->status = 0;
     atomic_set(&vdev->isr, 0);

include/hw/virtio/virtio.h

@@ -105,6 +105,8 @@ struct VirtIODevice
     uint16_t device_id;
     bool vm_running;
     bool broken; /* device in invalid state, needs reset */
+    bool started;
+    bool start_on_kick; /* virtio 1.0 transitional devices support that */
     VMChangeStateEntry *vmstate;
     char *bus_name;
     uint8_t device_endian;