[PATCH 11/16] vhost: introduce restart and release for vhost_dev's vqs

[Kangjie Xu]

Introduce vhost_dev_virtqueue_restart(), which can restart the
virtqueue when the vhost has already started running.

Meanwhile, vhost_dev_virtqueue_release(), which can ummap the
vrings and the desc of a specific vq of a device.

Combining the two functions, we can reset a virtqueue with a
started vhost.

Signed-off-by: Kangjie Xu <kangjie.xu@linux.alibaba.com>
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 hw/virtio/vhost.c         | 29 +++++++++++++++++++++++++++++
 include/hw/virtio/vhost.h |  6 ++++++
 2 files changed, 35 insertions(+)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index e467dfc7bc..d158d71866 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1904,3 +1904,32 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
 
     return -ENOSYS;
 }
+
+void vhost_dev_virtqueue_release(struct vhost_dev *hdev, VirtIODevice *vdev,
+                                 int vq_index)
+{
+    int idx = vq_index - hdev->vq_index;
+
+    idx = hdev->vhost_ops->vhost_get_vq_index(hdev, idx);
+
+    vhost_virtqueue_unmap(hdev,
+                          vdev,
+                          hdev->vqs + idx,
+                          hdev->vq_index + idx);
+}
+
+int vhost_dev_virtqueue_restart(struct vhost_dev *hdev, VirtIODevice *vdev,
+                                int vq_index)
+{
+    int idx = vq_index - hdev->vq_index;
+    int r = 0;
+
+    idx = hdev->vhost_ops->vhost_get_vq_index(hdev, idx);
+
+    r = vhost_virtqueue_start(hdev,
+                              vdev,
+                              hdev->vqs + idx,
+                              hdev->vq_index + idx);
+
+    return r;
+}
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index a346f23d13..7df7dbe24d 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -277,6 +277,12 @@ bool vhost_has_free_slot(void);
 int vhost_net_set_backend(struct vhost_dev *hdev,
                           struct vhost_vring_file *file);
 
+
+void vhost_dev_virtqueue_release(struct vhost_dev *hdev, VirtIODevice *vdev,
+                                 int vq_index);
+int vhost_dev_virtqueue_restart(struct vhost_dev *hdev, VirtIODevice *vdev,
+                                int vq_index);
+
 int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write);
 
 void vhost_dev_reset_inflight(struct vhost_inflight *inflight);
-- 
2.32.0