[PATCH v10 3/8] qmp: add QMP command x-query-virtio

[Jonah Palmer <jonah.palmer@oracle.com>]

From: Laurent Vivier <lvivier@redhat.com>

This new command lists all the instances of VirtIODevices with
their canonical QOM path and name.

Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
---
 hw/virtio/meson.build      |  2 ++
 hw/virtio/virtio-stub.c    | 14 ++++++++++
 hw/virtio/virtio.c         | 27 ++++++++++++++++++
 include/hw/virtio/virtio.h |  1 +
 qapi/meson.build           |  1 +
 qapi/qapi-schema.json      |  1 +
 qapi/virtio.json           | 68 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/qtest/qmp-cmd-test.c |  1 +
 8 files changed, 115 insertions(+)
 create mode 100644 hw/virtio/virtio-stub.c
 create mode 100644 qapi/virtio.json

diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index 521f7d6..d893f5f 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -6,8 +6,10 @@ softmmu_virtio_ss.add(when: 'CONFIG_VHOST', if_false: files('vhost-stub.c'))
 
 softmmu_ss.add_all(when: 'CONFIG_VIRTIO', if_true: softmmu_virtio_ss)
 softmmu_ss.add(when: 'CONFIG_VIRTIO', if_false: files('vhost-stub.c'))
+softmmu_ss.add(when: 'CONFIG_VIRTIO', if_false: files('virtio-stub.c'))
 
 softmmu_ss.add(when: 'CONFIG_ALL', if_true: files('vhost-stub.c'))
+softmmu_ss.add(when: 'CONFIG_ALL', if_true: files('virtio-stub.c'))
 
 virtio_ss = ss.source_set()
 virtio_ss.add(files('virtio.c'))
diff --git a/hw/virtio/virtio-stub.c b/hw/virtio/virtio-stub.c
new file mode 100644
index 0000000..05a81ed
--- /dev/null
+++ b/hw/virtio/virtio-stub.c
@@ -0,0 +1,14 @@
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-virtio.h"
+
+static void *qmp_virtio_unsupported(Error **errp)
+{
+    error_setg(errp, "Virtio is disabled");
+    return NULL;
+}
+
+VirtioInfoList *qmp_x_query_virtio(Error **errp)
+{
+    return qmp_virtio_unsupported(errp);
+}
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 867834d..76a63a0 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -13,6 +13,8 @@
 
 #include "qemu/osdep.h"
 #include "qapi/error.h"
+#include "qapi/qapi-commands-virtio.h"
+#include "qapi/qapi-visit-virtio.h"
 #include "cpu.h"
 #include "trace.h"
 #include "qemu/error-report.h"
@@ -29,6 +31,9 @@
 #include "sysemu/runstate.h"
 #include "standard-headers/linux/virtio_ids.h"
 
+/* QAPI list of realized VirtIODevices */
+static QTAILQ_HEAD(, VirtIODevice) virtio_list;
+
 /*
  * The alignment to use between consumer and producer parts of vring.
  * x86 pagesize again. This is the default, used by transports like PCI
@@ -3700,6 +3705,7 @@ static void virtio_device_realize(DeviceState *dev, Error **errp)
     vdev->listener.commit = virtio_memory_listener_commit;
     vdev->listener.name = "virtio";
     memory_listener_register(&vdev->listener, vdev->dma_as);
+    QTAILQ_INSERT_TAIL(&virtio_list, vdev, next);
 }
 
 static void virtio_device_unrealize(DeviceState *dev)
@@ -3714,6 +3720,7 @@ static void virtio_device_unrealize(DeviceState *dev)
         vdc->unrealize(dev);
     }
 
+    QTAILQ_REMOVE(&virtio_list, vdev, next);
     g_free(vdev->bus_name);
     vdev->bus_name = NULL;
 }
@@ -3887,6 +3894,8 @@ static void virtio_device_class_init(ObjectClass *klass, void *data)
     vdc->stop_ioeventfd = virtio_device_stop_ioeventfd_impl;
 
     vdc->legacy_features |= VIRTIO_LEGACY_FEATURES;
+
+    QTAILQ_INIT(&virtio_list);
 }
 
 bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev)
@@ -3897,6 +3906,24 @@ bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev)
     return virtio_bus_ioeventfd_enabled(vbus);
 }
 
+VirtioInfoList *qmp_x_query_virtio(Error **errp)
+{
+    VirtioInfoList *list = NULL;
+    VirtioInfoList *node;
+    VirtIODevice *vdev;
+
+    QTAILQ_FOREACH(vdev, &virtio_list, next) {
+        DeviceState *dev = DEVICE(vdev);
+        node = g_new0(VirtioInfoList, 1);
+        node->value = g_new(VirtioInfo, 1);
+        node->value->path = g_strdup(dev->canonical_path);
+        node->value->name = g_strdup(vdev->name);
+        QAPI_LIST_PREPEND(list, node->value);
+    }
+
+    return list;
+}
+
 static const TypeInfo virtio_device_info = {
     .name = TYPE_VIRTIO_DEVICE,
     .parent = TYPE_DEVICE,
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 0a12bd5..3b4eb85 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -110,6 +110,7 @@ struct VirtIODevice
     bool use_guest_notifier_mask;
     AddressSpace *dma_as;
     QLIST_HEAD(, VirtQueue) *vector_queues;
+    QTAILQ_ENTRY(VirtIODevice) next;
 };
 
 struct VirtioDeviceClass {
diff --git a/qapi/meson.build b/qapi/meson.build
index c0c49c1..e332f28 100644
--- a/qapi/meson.build
+++ b/qapi/meson.build
@@ -48,6 +48,7 @@ qapi_all_modules = [
   'sockets',
   'trace',
   'transaction',
+  'virtio',
   'yank',
 ]
 if have_system
diff --git a/qapi/qapi-schema.json b/qapi/qapi-schema.json
index 4912b97..1512ada 100644
--- a/qapi/qapi-schema.json
+++ b/qapi/qapi-schema.json
@@ -93,3 +93,4 @@
 { 'include': 'audio.json' }
 { 'include': 'acpi.json' }
 { 'include': 'pci.json' }
+{ 'include': 'virtio.json' }
diff --git a/qapi/virtio.json b/qapi/virtio.json
new file mode 100644
index 0000000..5372cde
--- /dev/null
+++ b/qapi/virtio.json
@@ -0,0 +1,68 @@
+# -*- Mode: Python -*-
+# vim: filetype=python
+#
+
+##
+# = Virtio devices
+##
+
+##
+# @VirtioInfo:
+#
+# Basic information about a given VirtIODevice
+#
+# @path: The VirtIODevice's canonical QOM path
+#
+# @name: Name of the VirtIODevice
+#
+# Since: 7.0
+#
+##
+{ 'struct': 'VirtioInfo',
+  'data': { 'path': 'str',
+            'name': 'str' } }
+
+##
+# @x-query-virtio:
+#
+# Returns a list of all realized VirtIODevices
+#
+# Features:
+# @unstable: This command is meant for debugging
+#
+# Returns: List of gathered VirtIODevices
+#
+# Since: 7.0
+#
+# Example:
+#
+# -> { "execute": "x-query-virtio" }
+# <- { "return": [
+#        {
+#            "path": "/machine/peripheral-anon/device[4]/virtio-backend",
+#            "name": "virtio-input"
+#        },
+#        {
+#            "path": "/machine/peripheral/crypto0/virtio-backend",
+#            "name": "virtio-crypto"
+#        },
+#        {
+#            "path": "/machine/peripheral-anon/device[2]/virtio-backend",
+#            "name": "virtio-scsi"
+#        },
+#        {
+#            "path": "/machine/peripheral-anon/device[1]/virtio-backend",
+#            "name": "virtio-net"
+#        },
+#        {
+#            "path": "/machine/peripheral-anon/device[0]/virtio-backend",
+#            "name": "virtio-serial"
+#        }
+#      ]
+#    }
+#
+##
+
+{ 'command': 'x-query-virtio',
+  'returns': [ 'VirtioInfo' ],
+  'features': [ 'unstable' ] }
diff --git a/tests/qtest/qmp-cmd-test.c b/tests/qtest/qmp-cmd-test.c
index 7f103ea..fd00ee2 100644
--- a/tests/qtest/qmp-cmd-test.c
+++ b/tests/qtest/qmp-cmd-test.c
@@ -103,6 +103,7 @@ static bool query_is_ignored(const char *cmd)
         "query-gic-capabilities", /* arm */
         /* Success depends on target-specific build configuration: */
         "query-pci",              /* CONFIG_PCI */
+        "x-query-virtio",         /* CONFIG_VIRTIO */
         /* Success depends on launching SEV guest */
         "query-sev-launch-measure",
         /* Success depends on Host or Hypervisor SEV support */
-- 
1.8.3.1