Re: [PATCH v2 14/24] vhost-user: introduce vhost_reset_vring() interface

[Jason Wang]

在 2022/8/16 09:06, Kangjie Xu 写道:

Introduce the interface vhost_reset_vring(). The interface is a wrapper
to send a VHOST_USER_RESET_VRING message to the back-end. It will reset
an individual vring in the back-end. Meanwhile, it will wait for a reply
to ensure the reset has been completed.

Signed-off-by: Kangjie Xu <kangjie...@linux.alibaba.com>
Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
---
  hw/virtio/vhost-user.c            | 41 +++++++++++++++++++++++++++++++
  include/hw/virtio/vhost-backend.h |  3 +++
  2 files changed, 44 insertions(+)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 75b8df21a4..56033f7a92 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -126,6 +126,7 @@ typedef enum VhostUserRequest {
      VHOST_USER_GET_MAX_MEM_SLOTS = 36,
      VHOST_USER_ADD_MEM_REG = 37,
      VHOST_USER_REM_MEM_REG = 38,
+    VHOST_USER_RESET_VRING = 41,
      VHOST_USER_MAX
  } VhostUserRequest;

@@ -1498,6 +1499,45 @@ static int vhost_user_get_max_memslots(struct vhost_dev *dev,

      return 0;
  }

+static int vhost_user_reset_vring(struct vhost_dev *dev,

+                                  struct vhost_vring_state *ring)
+{
+    int ret;
+    VhostUserMsg msg = {
+        .hdr.request = VHOST_USER_RESET_VRING,
+        .hdr.flags = VHOST_USER_VERSION,

Do we need VHOST_USER_NEED_REPLY_MASK here?

Other looks good.

Thanks

+        .payload.state = *ring,
+        .hdr.size = sizeof(msg.payload.state),
+    };
+
+    if (!virtio_has_feature(dev->acked_features, VIRTIO_F_RING_RESET)) {
+        return -ENOTSUP;
+    }
+
+    ret = vhost_user_write(dev, &msg, NULL, 0);
+    if (ret < 0) {
+        return ret;
+    }
+
+    ret = vhost_user_read(dev, &msg);
+    if (ret < 0) {
+        return ret;
+    }
+
+    if (msg.hdr.request != VHOST_USER_RESET_VRING) {
+        error_report("Received unexpected msg type. Expected %d received %d",
+                     VHOST_USER_RESET_VRING, msg.hdr.request);
+        return -EPROTO;
+    }
+
+    if (msg.hdr.size != sizeof(msg.payload.state)) {
+        error_report("Received bad msg size.");
+        return -EPROTO;
+    }
+
+    return 0;
+}
+
  static int vhost_user_reset_device(struct vhost_dev *dev)
  {
      VhostUserMsg msg = {
@@ -2625,6 +2665,7 @@ const VhostOps user_ops = {
          .vhost_set_features = vhost_user_set_features,
          .vhost_get_features = vhost_user_get_features,
          .vhost_set_owner = vhost_user_set_owner,
+        .vhost_reset_vring = vhost_user_reset_vring,
          .vhost_reset_device = vhost_user_reset_device,
          .vhost_get_vq_index = vhost_user_get_vq_index,
          .vhost_set_vring_enable = vhost_user_set_vring_enable,
diff --git a/include/hw/virtio/vhost-backend.h 
b/include/hw/virtio/vhost-backend.h
index eab46d7f0b..f23bf71a8d 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -79,6 +79,8 @@ typedef int (*vhost_get_features_op)(struct vhost_dev *dev,
                                       uint64_t *features);
  typedef int (*vhost_set_backend_cap_op)(struct vhost_dev *dev);
  typedef int (*vhost_set_owner_op)(struct vhost_dev *dev);
+typedef int (*vhost_reset_vring_op)(struct vhost_dev *dev,
+                                    struct vhost_vring_state *ring);
  typedef int (*vhost_reset_device_op)(struct vhost_dev *dev);
  typedef int (*vhost_get_vq_index_op)(struct vhost_dev *dev, int idx);
  typedef int (*vhost_set_vring_enable_op)(struct vhost_dev *dev,
@@ -154,6 +156,7 @@ typedef struct VhostOps {
      vhost_set_backend_cap_op vhost_set_backend_cap;
      vhost_set_owner_op vhost_set_owner;
      vhost_reset_device_op vhost_reset_device;
+    vhost_reset_vring_op vhost_reset_vring;
      vhost_get_vq_index_op vhost_get_vq_index;
      vhost_set_vring_enable_op vhost_set_vring_enable;
      vhost_requires_shm_log_op vhost_requires_shm_log;