[RFC 3/5] qmp: add QMP command virtio-queue-status

[Laurent Vivier]

This new command shows internal status of a VirtQueue.
(vrings and indexes).

Signed-off-by: Laurent Vivier <address@hidden>
---
 hw/virtio/virtio-stub.c |  6 +++
 hw/virtio/virtio.c      | 35 +++++++++++++++
 qapi/virtio.json        | 98 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 139 insertions(+)

diff --git a/hw/virtio/virtio-stub.c b/hw/virtio/virtio-stub.c
index 8fe2d6cd8892..5b4ed6fd531e 100644
--- a/hw/virtio/virtio-stub.c
+++ b/hw/virtio/virtio-stub.c
@@ -17,3 +17,9 @@ VirtioStatus *qmp_virtio_status(const char* path, Error 
**errp)
 {
     return qmp_virtio_unsupported(errp);
 }
+
+VirtQueueStatus *qmp_virtio_queue_status(const char *path, uint16_t queue,
+                                         Error **errp)
+{
+    return qmp_virtio_unsupported(errp);
+}
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 7f6e21e4ab2c..271d4ca3417f 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -3855,6 +3855,41 @@ static VirtIODevice *virtio_device_find(const char *path)
     return NULL;
 }
 
+VirtQueueStatus *qmp_virtio_queue_status(const char *path, uint16_t queue,
+                                         Error **errp)
+{
+    VirtIODevice *vdev;
+    VirtQueueStatus *status;
+
+    vdev = virtio_device_find(path);
+    if (vdev == NULL) {
+        error_setg(errp, "Path %s is not a VirtIO device", path);
+        return NULL;
+    }
+
+    if (queue >= VIRTIO_QUEUE_MAX || !virtio_queue_get_num(vdev, queue)) {
+        error_setg(errp, "Invalid virtqueue number %d", queue);
+        return NULL;
+    }
+
+    status = g_new0(VirtQueueStatus, 1);
+    status->queue_index = vdev->vq[queue].queue_index;
+    status->inuse = vdev->vq[queue].inuse;
+    status->vring_num = vdev->vq[queue].vring.num;
+    status->vring_num_default = vdev->vq[queue].vring.num_default;
+    status->vring_align = vdev->vq[queue].vring.align;
+    status->vring_desc = vdev->vq[queue].vring.desc;
+    status->vring_avail = vdev->vq[queue].vring.avail;
+    status->vring_used = vdev->vq[queue].vring.used;
+    status->last_avail_idx = vdev->vq[queue].last_avail_idx;
+    status->shadow_avail_idx = vdev->vq[queue].shadow_avail_idx;
+    status->used_idx = vdev->vq[queue].used_idx;
+    status->signalled_used = vdev->vq[queue].signalled_used;
+    status->signalled_used_valid = vdev->vq[queue].signalled_used_valid;
+
+    return status;
+}
+
 VirtioStatus *qmp_virtio_status(const char* path, Error **errp)
 {
     VirtIODevice *vdev;
diff --git a/qapi/virtio.json b/qapi/virtio.json
index 2af4d95b9893..ab70500d919b 100644
--- a/qapi/virtio.json
+++ b/qapi/virtio.json
@@ -117,3 +117,101 @@
   'data': { 'path': 'str' },
   'returns': 'VirtioStatus'
 }
+
+##
+# @VirtQueueStatus:
+#
+# Status of a VirtQueue
+#
+# @queue_index: VirtQueue queue_index
+#
+# @inuse: VirtQueue inuse
+#
+# @vring_num: VirtQueue vring.num
+#
+# @vring_num_default: VirtQueue vring.num_default
+#
+# @vring_align: VirtQueue vring.align
+#
+# @vring_desc: VirtQueue vring.desc
+#
+# @vring_avail: VirtQueue vring.avail
+#
+# @vring_used: VirtQueue vring.used
+#
+# @last_avail_idx: VirtQueue last_avail_idx
+#
+# @shadow_avail_idx: VirtQueue shadow_avail_idx
+#
+# @used_idx: VirtQueue used_idx
+#
+# @signalled_used: VirtQueue signalled_used
+#
+# @signalled_used_valid: VirtQueue signalled_used_valid
+#
+# Since: 5.1
+#
+##
+
+{ 'struct': 'VirtQueueStatus',
+  'data': {
+    'queue_index': 'uint16',
+    'inuse': 'uint32',
+    'vring_num': 'int',
+    'vring_num_default': 'int',
+    'vring_align': 'int',
+    'vring_desc': 'uint64',
+    'vring_avail': 'uint64',
+    'vring_used': 'uint64',
+    'last_avail_idx': 'uint16',
+    'shadow_avail_idx': 'uint16',
+    'used_idx': 'uint16',
+    'signalled_used': 'uint16',
+    'signalled_used_valid': 'uint16'
+  }
+}
+
+##
+# @virtio-queue-status:
+#
+# Return the status of a given VirtQueue
+#
+# @path: QOBject path of the VirtIODevice
+#
+# @queue: queue number to examine
+#
+# Returns: Status of the VirtQueue
+#
+# Since: 5.1
+#
+# Example:
+#
+# -> { "execute": "virtio-queue-status",
+#      "arguments": {
+#          "path": "/machine/peripheral-anon/device[3]/virtio-backend",
+#          "queue": 0
+#      }
+#   }
+# <- { "return": {
+#      "signalled_used": 373,
+#      "inuse": 0,
+#      "vring_desc": 864411648,
+#      "vring_num_default": 256,
+#      "signalled_used_valid": 1,
+#      "vring_avail": 864415744,
+#      "last_avail_idx": 373,
+#      "queue_index": 0,
+#      "vring_used": 864416320,
+#      "shadow_avail_idx": 619,
+#      "used_idx": 373,
+#      "vring_num": 256,
+#      "vring_align": 4096
+#      }
+#    }
+#
+##
+
+{ 'command': 'virtio-queue-status',
+  'data': { 'path': 'str', 'queue': 'uint16' },
+  'returns': 'VirtQueueStatus'
+}
-- 
2.25.1