qmp: add QMP command x-query-virtio-status

This new command shows the status of a VirtIODevice, including
its corresponding vhost device's status (if active).

Next patch will improve output by decoding feature bits, including
vhost device's feature bits (backend, protocol, acked, and features).
Also will decode status bits of a VirtIODevice.

[Jonah: From patch v12; added a check to @virtio_device_find to ensure
 synchronicity between @virtio_list and the devices in the QOM
 composition tree.]

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
Message-Id: <1660220684-24909-3-git-send-email-jonah.palmer@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

3 files changed, 331 insertions, 0 deletions

diff --git a/hw/virtio/virtio-stub.c b/hw/virtio/virtio-stub.c
index 05a81edc92..0b432e8de7 100644
--- a/hw/virtio/virtio-stub.c
+++ b/hw/virtio/virtio-stub.c
@@ -12,3 +12,8 @@ VirtioInfoList *qmp_x_query_virtio(Error **errp)
 {
     return qmp_virtio_unsupported(errp);
 }
+
+VirtioStatus *qmp_x_query_virtio_status(const char *path, Error **errp)
+{
+    return qmp_virtio_unsupported(errp);
+}
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 4fc7c80d3f..696e19126a 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -3948,6 +3948,110 @@ VirtioInfoList *qmp_x_query_virtio(Error **errp)
     return list;
 }
 
+static VirtIODevice *virtio_device_find(const char *path)
+{
+    VirtIODevice *vdev;
+
+    QTAILQ_FOREACH(vdev, &virtio_list, next) {
+        DeviceState *dev = DEVICE(vdev);
+
+        if (strcmp(dev->canonical_path, path) != 0) {
+            continue;
+        }
+
+        Error *err = NULL;
+        QObject *obj = qmp_qom_get(dev->canonical_path, "realized", &err);
+        if (err == NULL) {
+            GString *is_realized = qobject_to_json_pretty(obj, true);
+            /* virtio device is NOT realized, remove it from list */
+            if (!strncmp(is_realized->str, "false", 4)) {
+                g_string_free(is_realized, true);
+                qobject_unref(obj);
+                QTAILQ_REMOVE(&virtio_list, vdev, next);
+                return NULL;
+            }
+            g_string_free(is_realized, true);
+        } else {
+            /* virtio device doesn't exist in QOM tree */
+            QTAILQ_REMOVE(&virtio_list, vdev, next);
+            qobject_unref(obj);
+            return NULL;
+        }
+        /* device exists in QOM tree & is realized */
+        qobject_unref(obj);
+        return vdev;
+    }
+    return NULL;
+}
+
+VirtioStatus *qmp_x_query_virtio_status(const char *path, Error **errp)
+{
+    VirtIODevice *vdev;
+    VirtioStatus *status;
+
+    vdev = virtio_device_find(path);
+    if (vdev == NULL) {
+        error_setg(errp, "Path %s is not a VirtIODevice", path);
+        return NULL;
+    }
+
+    status = g_new0(VirtioStatus, 1);
+    status->name = g_strdup(vdev->name);
+    status->device_id = vdev->device_id;
+    status->vhost_started = vdev->vhost_started;
+    status->guest_features = vdev->guest_features;
+    status->host_features = vdev->host_features;
+    status->backend_features = vdev->backend_features;
+
+    switch (vdev->device_endian) {
+    case VIRTIO_DEVICE_ENDIAN_LITTLE:
+        status->device_endian = g_strdup("little");
+        break;
+    case VIRTIO_DEVICE_ENDIAN_BIG:
+        status->device_endian = g_strdup("big");
+        break;
+    default:
+        status->device_endian = g_strdup("unknown");
+        break;
+    }
+
+    status->num_vqs = virtio_get_num_queues(vdev);
+    status->status = vdev->status;
+    status->isr = vdev->isr;
+    status->queue_sel = vdev->queue_sel;
+    status->vm_running = vdev->vm_running;
+    status->broken = vdev->broken;
+    status->disabled = vdev->disabled;
+    status->use_started = vdev->use_started;
+    status->started = vdev->started;
+    status->start_on_kick = vdev->start_on_kick;
+    status->disable_legacy_check = vdev->disable_legacy_check;
+    status->bus_name = g_strdup(vdev->bus_name);
+    status->use_guest_notifier_mask = vdev->use_guest_notifier_mask;
+    status->has_vhost_dev = vdev->vhost_started;
+
+    if (vdev->vhost_started) {
+        VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
+        struct vhost_dev *hdev = vdc->get_vhost(vdev);
+
+        status->vhost_dev = g_new0(VhostStatus, 1);
+        status->vhost_dev->n_mem_sections = hdev->n_mem_sections;
+        status->vhost_dev->n_tmp_sections = hdev->n_tmp_sections;
+        status->vhost_dev->nvqs = hdev->nvqs;
+        status->vhost_dev->vq_index = hdev->vq_index;
+        status->vhost_dev->features = hdev->features;
+        status->vhost_dev->acked_features = hdev->acked_features;
+        status->vhost_dev->backend_features = hdev->backend_features;
+        status->vhost_dev->protocol_features = hdev->protocol_features;
+        status->vhost_dev->max_queues = hdev->max_queues;
+        status->vhost_dev->backend_cap = hdev->backend_cap;
+        status->vhost_dev->log_enabled = hdev->log_enabled;
+        status->vhost_dev->log_size = hdev->log_size;
+    }
+
+    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 03896e423f..c86b3bc635 100644
--- a/qapi/virtio.json
+++ b/qapi/virtio.json
@@ -66,3 +66,225 @@
 { 'command': 'x-query-virtio',
   'returns': [ 'VirtioInfo' ],
   'features': [ 'unstable' ] }
+
+##
+# @VhostStatus:
+#
+# Information about a vhost device. This information will only be
+# displayed if the vhost device is active.
+#
+# @n-mem-sections: vhost_dev n_mem_sections
+#
+# @n-tmp-sections: vhost_dev n_tmp_sections
+#
+# @nvqs: vhost_dev nvqs (number of virtqueues being used)
+#
+# @vq-index: vhost_dev vq_index
+#
+# @features: vhost_dev features
+#
+# @acked-features: vhost_dev acked_features
+#
+# @backend-features: vhost_dev backend_features
+#
+# @protocol-features: vhost_dev protocol_features
+#
+# @max-queues: vhost_dev max_queues
+#
+# @backend-cap: vhost_dev backend_cap
+#
+# @log-enabled: vhost_dev log_enabled flag
+#
+# @log-size: vhost_dev log_size
+#
+# Since: 7.1
+#
+##
+
+{ 'struct': 'VhostStatus',
+  'data': { 'n-mem-sections': 'int',
+            'n-tmp-sections': 'int',
+            'nvqs': 'uint32',
+            'vq-index': 'int',
+            'features': 'uint64',
+            'acked-features': 'uint64',
+            'backend-features': 'uint64',
+            'protocol-features': 'uint64',
+            'max-queues': 'uint64',
+            'backend-cap': 'uint64',
+            'log-enabled': 'bool',
+            'log-size': 'uint64' } }
+
+##
+# @VirtioStatus:
+#
+# Full status of the virtio device with most VirtIODevice members.
+# Also includes the full status of the corresponding vhost device
+# if the vhost device is active.
+#
+# @name: VirtIODevice name
+#
+# @device-id: VirtIODevice ID
+#
+# @vhost-started: VirtIODevice vhost_started flag
+#
+# @guest-features: VirtIODevice guest_features
+#
+# @host-features: VirtIODevice host_features
+#
+# @backend-features: VirtIODevice backend_features
+#
+# @device-endian: VirtIODevice device_endian
+#
+# @num-vqs: VirtIODevice virtqueue count. This is the number of active
+#           virtqueues being used by the VirtIODevice.
+#
+# @status: VirtIODevice configuration status (VirtioDeviceStatus)
+#
+# @isr: VirtIODevice ISR
+#
+# @queue-sel: VirtIODevice queue_sel
+#
+# @vm-running: VirtIODevice vm_running flag
+#
+# @broken: VirtIODevice broken flag
+#
+# @disabled: VirtIODevice disabled flag
+#
+# @use-started: VirtIODevice use_started flag
+#
+# @started: VirtIODevice started flag
+#
+# @start-on-kick: VirtIODevice start_on_kick flag
+#
+# @disable-legacy-check: VirtIODevice disabled_legacy_check flag
+#
+# @bus-name: VirtIODevice bus_name
+#
+# @use-guest-notifier-mask: VirtIODevice use_guest_notifier_mask flag
+#
+# @vhost-dev: Corresponding vhost device info for a given VirtIODevice.
+#             Present if the given VirtIODevice has an active vhost
+#             device.
+#
+# Since: 7.1
+#
+##
+
+{ 'struct': 'VirtioStatus',
+  'data': { 'name': 'str',
+            'device-id': 'uint16',
+            'vhost-started': 'bool',
+            'device-endian': 'str',
+            'guest-features': 'uint64',
+            'host-features': 'uint64',
+            'backend-features': 'uint64',
+            'num-vqs': 'int',
+            'status': 'uint8',
+            'isr': 'uint8',
+            'queue-sel': 'uint16',
+            'vm-running': 'bool',
+            'broken': 'bool',
+            'disabled': 'bool',
+            'use-started': 'bool',
+            'started': 'bool',
+            'start-on-kick': 'bool',
+            'disable-legacy-check': 'bool',
+            'bus-name': 'str',
+            'use-guest-notifier-mask': 'bool',
+            '*vhost-dev': 'VhostStatus' } }
+
+##
+# @x-query-virtio-status:
+#
+# Poll for a comprehensive status of a given virtio device
+#
+# @path: Canonical QOM path of the VirtIODevice
+#
+# Features:
+# @unstable: This command is meant for debugging.
+#
+# Returns: VirtioStatus of the virtio device
+#
+# Since: 7.1
+#
+# Examples:
+#
+# 1. Poll for the status of virtio-crypto (no vhost-crypto active)
+#
+# -> { "execute": "x-query-virtio-status",
+#      "arguments": { "path": "/machine/peripheral/crypto0/virtio-backend" }
+#    }
+# <- { "return": {
+#          "device-endian": "little",
+#          "bus-name": "",
+#          "disable-legacy-check": false,
+#          "name": "virtio-crypto",
+#          "started": true,
+#          "device-id": 20,
+#          "backend-features": 0,
+#          "start-on-kick": false,
+#          "isr": 1,
+#          "broken": false,
+#          "status": 15,
+#          "num-vqs": 2,
+#          "guest-features": 5100273664,
+#          "host-features": 6325010432,
+#          "use-guest-notifier-mask": true,
+#          "vm-running": true,
+#          "queue-sel": 1,
+#          "disabled": false,
+#          "vhost-started": false,
+#          "use-started": true
+#      }
+#    }
+#
+# 2. Poll for the status of virtio-net (vhost-net is active)
+#
+# -> { "execute": "x-query-virtio-status",
+#      "arguments": { "path": "/machine/peripheral-anon/device[1]/virtio-backend" }
+#    }
+# <- { "return": {
+#          "device-endian": "little",
+#          "bus-name": "",
+#          "disabled-legacy-check": false,
+#          "name": "virtio-net",
+#          "started": true,
+#          "device-id": 1,
+#          "vhost-dev": {
+#              "n-tmp-sections": 4,
+#              "n-mem-sections": 4,
+#              "max-queues": 1,
+#              "backend-cap": 2,
+#              "log-size": 0,
+#              "backend-features": 0,
+#              "nvqs": 2,
+#              "protocol-features": 0,
+#              "vq-index": 0,
+#              "log-enabled": false,
+#              "acked-features": 5100306432,
+#              "features": 13908344832
+#          },
+#          "backend-features": 6337593319,
+#          "start-on-kick": false,
+#          "isr": 1,
+#          "broken": false,
+#          "status": 15,
+#          "num-vqs": 3,
+#          "guest-features": 5111807911,
+#          "host-features": 6337593319,
+#          "use-guest-notifier-mask": true,
+#          "vm-running": true,
+#          "queue-sel": 2,
+#          "disabled": false,
+#          "vhost-started": true,
+#          "use-started": true
+#      }
+#    }
+#
+##
+
+{ 'command': 'x-query-virtio-status',
+  'data': { 'path': 'str' },
+  'returns': 'VirtioStatus',
+  'features': [ 'unstable' ] }