Add a helper to fetch machine containers.  Add some sanity check around.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/hw/qdev-core.h | 10 ++++++++++
 hw/core/qdev.c         | 11 +++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 5be9844412..dc6cd951fa 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -996,6 +996,16 @@ const char *qdev_fw_name(DeviceState *dev);
 void qdev_assert_realized_properly(void);
 Object *qdev_get_machine(void);
 
+/**
+ * machine_get_container:
+ * @name: The name of container to lookup
+ *
+ * Get a container of the machine (QOM path "/machine/NAME").
+ *
+ * Returns: the machine container object.
+ */
+Object *machine_get_container(const char *name);
+
 /**
  * qdev_get_human_name() - Return a human-readable name for a device
  * @dev: The device. Must be a valid and non-NULL pointer.
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index b622be15ee..fa3bc85d9a 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -828,6 +828,17 @@ Object *qdev_get_machine(void)
     return dev;
 }
 
+Object *machine_get_container(const char *name)
+{
+    Object *container, *machine;
+
+    machine = qdev_get_machine();
+    container = object_resolve_path_component(machine, name);
+    assert(object_dynamic_cast(container, TYPE_CONTAINER));
+
+    return container;
+}
+
 char *qdev_get_human_name(DeviceState *dev)
 {
     g_assert(dev != NULL);
-- 
2.45.0