[PATCH v7 6/8] qmp: add QMP commands for virtio/vhost queue-status

[Jonah Palmer]

From: Laurent Vivier <lvivier@redhat.com>

These new commands show the internal status of a VirtIODevice's
VirtQueue and a vhost device's vhost_virtqueue (if active).

Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
---
 hw/virtio/virtio-stub.c |  14 +++
 hw/virtio/virtio.c      | 103 +++++++++++++++++++
 qapi/virtio.json        | 262 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 379 insertions(+)

 [Jonah: Added vhost support for qmp_x_debug_virtio_queue_status such
  that if a VirtIODevice's vhost device is active, shadow_avail_idx
  is hidden and last_avail_idx is retrieved from the vhost op
  vhost_get_vring_base().

  Also added a new QMP command qmp_x_debug_virtio_vhost_queue_status
  that shows the interal status of a VirtIODevice's vhost device if
  it's active.]

diff --git a/hw/virtio/virtio-stub.c b/hw/virtio/virtio-stub.c
index ddb592f..387803d 100644
--- a/hw/virtio/virtio-stub.c
+++ b/hw/virtio/virtio-stub.c
@@ -17,3 +17,17 @@ VirtioStatus *qmp_x_debug_virtio_status(const char* path, 
Error **errp)
 {
     return qmp_virtio_unsupported(errp);
 }
+
+VirtVhostQueueStatus *qmp_x_debug_virtio_vhost_queue_status(const char *path,
+                                                            uint16_t queue,
+                                                            Error **errp)
+{
+    return qmp_virtio_unsupported(errp);
+}
+
+VirtQueueStatus *qmp_x_debug_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 f0e2b40..8d74dbf 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -4284,6 +4284,109 @@ VirtioStatus *qmp_x_debug_virtio_status(const char 
*path, Error **errp)
     return status;
 }
 
+VirtVhostQueueStatus *qmp_x_debug_virtio_vhost_queue_status(const char *path,
+                                                            uint16_t queue,
+                                                            Error **errp)
+{
+    VirtIODevice *vdev;
+    VirtVhostQueueStatus *status;
+
+    vdev = virtio_device_find(path);
+    if (vdev == NULL) {
+        error_setg(errp, "Path %s is not a VirtIODevice", path);
+        return NULL;
+    }
+
+    if (!vdev->vhost_started) {
+        error_setg(errp, "Error: vhost device has not started yet");
+        return NULL;
+    }
+
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
+    struct vhost_dev *hdev = vdc->get_vhost(vdev);
+
+    if (queue < hdev->vq_index || queue >= hdev->vq_index + hdev->nvqs) {
+        error_setg(errp, "Invalid vhost virtqueue number %d", queue);
+        return NULL;
+    }
+
+    status = g_new0(VirtVhostQueueStatus, 1);
+    status->device_name = g_strdup(vdev->name);
+    status->kick = hdev->vqs[queue].kick;
+    status->call = hdev->vqs[queue].call;
+    status->desc = (uint64_t)(unsigned long)hdev->vqs[queue].desc;
+    status->avail = (uint64_t)(unsigned long)hdev->vqs[queue].avail;
+    status->used = (uint64_t)(unsigned long)hdev->vqs[queue].used;
+    status->num = hdev->vqs[queue].num;
+    status->desc_phys = hdev->vqs[queue].desc_phys;
+    status->desc_size = hdev->vqs[queue].desc_size;
+    status->avail_phys = hdev->vqs[queue].avail_phys;
+    status->avail_size = hdev->vqs[queue].avail_size;
+    status->used_phys = hdev->vqs[queue].used_phys;
+    status->used_size = hdev->vqs[queue].used_size;
+
+    return status;
+}
+
+VirtQueueStatus *qmp_x_debug_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 VirtIODevice", 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->device_name = g_strdup(vdev->name);
+    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->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;
+
+    if (vdev->vhost_started) {
+        VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
+        struct vhost_dev *hdev = vdc->get_vhost(vdev);
+
+        /* check if vq index exists for vhost as well  */
+        if (queue >= hdev->vq_index && queue < hdev->vq_index + hdev->nvqs) {
+            status->has_last_avail_idx = true;
+
+            int vhost_vq_index =
+                hdev->vhost_ops->vhost_get_vq_index(hdev, queue);
+            struct vhost_vring_state state = {
+                .index = vhost_vq_index,
+            };
+
+            status->last_avail_idx =
+                hdev->vhost_ops->vhost_get_vring_base(hdev, &state);
+        }
+    } else {
+        status->has_shadow_avail_idx = true;
+        status->has_last_avail_idx = true;
+        status->last_avail_idx = vdev->vq[queue].last_avail_idx;
+        status->shadow_avail_idx = vdev->vq[queue].shadow_avail_idx;
+    }
+
+    return status;
+}
+
 static const TypeInfo virtio_device_info = {
     .name = TYPE_VIRTIO_DEVICE,
     .parent = TYPE_DEVICE,
diff --git a/qapi/virtio.json b/qapi/virtio.json
index 678bfe8..de09d0e 100644
--- a/qapi/virtio.json
+++ b/qapi/virtio.json
@@ -815,3 +815,265 @@
   'data': { 'path': 'str' },
   'returns': 'VirtioStatus'
 }
+
+##
+# @VirtQueueStatus:
+#
+# Status of a VirtIODevice VirtQueue
+#
+# @device-name: VirtIODevice name
+#
+# @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 or return of vhost_dev
+#                  vhost_get_vring_base (if vhost active)
+#
+# @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: 6.2
+#
+##
+
+{ 'struct': 'VirtQueueStatus',
+    'data': {
+      'device-name': 'str',
+      'queue-index': 'uint16',
+      'inuse': 'uint32',
+      'vring-num': 'uint32',
+      'vring-num-default': 'uint32',
+      'vring-align': 'uint32',
+      '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': 'bool'
+    }
+}
+
+##
+# @x-debug-virtio-queue-status:
+#
+# Return the status of a given VirtIODevice VirtQueue
+#
+# @path: VirtIO device canonical QOM path
+#
+# @queue: VirtQueue number to examine
+#
+# Returns: Status of the VirtQueue
+#
+# Notes: last_avail_idx will not be displayed in the case where
+#        the selected VirtIODevice has a running vhost device
+#        and the VirtIODevice VirtQueue index (queue) does not
+#        exist for the corresponding vhost device vhost_virtqueue.
+#        Also, shadow_avail_idx will not be displayed in the case
+#        where the selected VirtIODevice has a running vhost device.
+#
+# Since: 6.2
+#
+# Examples:
+#
+# 1. Get VirtQueue status for virtio-vsock (vhost-vsock running)
+#
+# -> { "execute": "x-debug-virtio-queue-status",
+#      "arguments": {
+#          "path": "/machine/peripheral/vsock0/virtio-backend",
+#          "queue": 1
+#      }
+#    }
+# <- { "return": {
+#          "signalled-used": 0,
+#          "inuse": 0,
+#          "vring-align": 4096,
+#          "vring-desc": 5217370112,
+#          "signalled-used-valid": false,
+#          "vring-num-default": 128,
+#          "vring-avail": 5217372160,
+#          "queue-index": 1,
+#          "last-avail-idx": 0,
+#          "vring-used": 5217372480,
+#          "used-idx": 0,
+#          "device-name": "vhost-vsock",
+#          "vring-num": 128
+#      }
+#    }
+#
+# 2. Get VirtQueue status for virtio-serial (no vhost)
+#
+# -> { "execute": "x-debug-virtio-queue-status",
+#      "arguments": {
+#          "path": "/machine/peripheral-anon/device[0]/virtio-backend",
+#          "queue": 20
+#       }
+#    }
+# <- { "return": {
+#          "signalled-used": 0,
+#          "inuse": 0,
+#          "vring-align": 4096,
+#          "vring-desc": 5182074880,
+#          "signalled-used-valid": false,
+#          "vring-num-default": 128,
+#          "vring-avail": 5182076928,
+#          "queue-index": 20,
+#          "last-avail-idx": 0,
+#          "vring-used": 5182077248,
+#          "used-idx": 0,
+#          "device-name": "virtio-serial",
+#          "shadow-avail-idx": 0,
+#          "vring-num": 128
+#      }
+#    }
+#
+##
+
+{ 'command': 'x-debug-virtio-queue-status',
+  'data': { 'path': 'str', 'queue': 'uint16' },
+  'returns': 'VirtQueueStatus'
+}
+
+##
+# @VirtVhostQueueStatus:
+#
+# Status of a vhost device vhost_virtqueue
+#
+# @device-name: VirtIODevice name
+#
+# @kick: vhost_virtqueue kick
+#
+# @call: vhost_virtqueue call
+#
+# @desc: vhost_virtqueue desc
+#
+# @avail: vhost_virtqueue avail
+#
+# @used: vhost_virtqueue used
+#
+# @num: vhost_virtqueue num
+#
+# @desc-phys: vhost_virtqueue desc_phys
+#
+# @desc-size: vhost_virtqueue desc_size
+#
+# @avail-phys: vhost_virtqueue avail_phys
+#
+# @avail-size: vhost_virtqueue avail_size
+#
+# @used-phys: vhost_virtqueue used_phys
+#
+# @used-size: vhost_virtqueue used_size
+#
+# Since: 6.2
+#
+##
+
+{ 'struct': 'VirtVhostQueueStatus',
+    'data': {
+      'device-name': 'str',
+      'kick': 'int',
+      'call': 'int',
+      'desc': 'uint64',
+      'avail': 'uint64',
+      'used': 'uint64',
+      'num': 'int',
+      'desc-phys': 'uint64',
+      'desc-size': 'uint32',
+      'avail-phys': 'uint64',
+      'avail-size': 'uint32',
+      'used-phys': 'uint64',
+      'used-size': 'uint32'
+    }
+}
+
+##
+# @x-debug-virtio-vhost-queue-status:
+#
+# Return the status of a given vhost device vhost_virtqueue
+#
+# @path: VirtIO device canonical QOM path
+#
+# @queue: vhost_virtqueue number to examine
+#
+# Returns: Status of the vhost_virtqueue
+#
+# Since: 6.2
+#
+# Examples:
+#
+# 1. Get vhost_virtqueue status for vhost-crypto
+#
+# -> { "execute": "x-debug-virtio-vhost-queue-status",
+#      "arguments": {
+#          "path": "/machine/peripheral/crypto0/virtio-backend",
+#          "queue": 0
+#      }
+#    }
+# <- { "return": {
+#          "avail-phys": 5216124928,
+#          "used-phys": 5216127040,
+#          "avail-size": 2054,
+#          "desc-size": 16384,
+#          "used-size": 8198,
+#          "desc": 140141447430144,
+#          "num": 1024,
+#          "device-name": "virtio-crypto",
+#          "call": 0,
+#          "avail": 140141447446528,
+#          "desc-phys": 5216108544,
+#          "used": 140141447448640,
+#          "kick": 0
+#      }
+#    }
+#
+# 2. Get vhost_virtqueue status for vhost-vsock
+#
+# -> { "execute": "x-debug-virtio-vhost-queue-status",
+#      "arguments": {
+#          "path": "/machine/peripheral/vsock0/virtio-backend",
+#          "queue": 0
+#      }
+#    }
+# <- { "return": {
+#          "avail-phys": 5182261248,
+#          "used-phys": 5182261568,
+#          "avail-size": 262,
+#          "desc-size": 2048,
+#          "used-size": 1030,
+#          "desc": 140141413580800,
+#          "num": 128,
+#          "device-name": "vhost-vsock",
+#          "call": 0,
+#          "avail": 140141413582848,
+#          "desc-phys": 5182259200,
+#          "used": 140141413583168,
+#          "kick": 0
+#      }
+#    }
+#
+##
+
+{ 'command': 'x-debug-virtio-vhost-queue-status',
+  'data': { 'path': 'str', 'queue': 'uint16' },
+  'returns': 'VirtVhostQueueStatus'
+}
-- 
1.8.3.1