Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 73 insertions, 0 deletions

diff --git a/hw/core/qdev-hotplug.c b/hw/core/qdev-hotplug.c
new file mode 100644
index 000000000..d495d0e9c
--- /dev/null
+++ b/hw/core/qdev-hotplug.c
@@ -0,0 +1,73 @@
+/*
+ * QDev Hotplug handlers
+ *
+ * Copyright (c) Red Hat
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/qdev-core.h"
+#include "hw/boards.h"
+
+HotplugHandler *qdev_get_machine_hotplug_handler(DeviceState *dev)
+{
+    MachineState *machine;
+    MachineClass *mc;
+    Object *m_obj = qdev_get_machine();
+
+    if (object_dynamic_cast(m_obj, TYPE_MACHINE)) {
+        machine = MACHINE(m_obj);
+        mc = MACHINE_GET_CLASS(machine);
+        if (mc->get_hotplug_handler) {
+            return mc->get_hotplug_handler(machine, dev);
+        }
+    }
+
+    return NULL;
+}
+
+bool qdev_hotplug_allowed(DeviceState *dev, Error **errp)
+{
+    MachineState *machine;
+    MachineClass *mc;
+    Object *m_obj = qdev_get_machine();
+
+    if (object_dynamic_cast(m_obj, TYPE_MACHINE)) {
+        machine = MACHINE(m_obj);
+        mc = MACHINE_GET_CLASS(machine);
+        if (mc->hotplug_allowed) {
+            return mc->hotplug_allowed(machine, dev, errp);
+        }
+    }
+
+    return true;
+}
+
+HotplugHandler *qdev_get_bus_hotplug_handler(DeviceState *dev)
+{
+    if (dev->parent_bus) {
+        return dev->parent_bus->hotplug_handler;
+    }
+    return NULL;
+}
+
+HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
+{
+    HotplugHandler *hotplug_ctrl = qdev_get_machine_hotplug_handler(dev);
+
+    if (hotplug_ctrl == NULL && dev->parent_bus) {
+        hotplug_ctrl = qdev_get_bus_hotplug_handler(dev);
+    }
+    return hotplug_ctrl;
+}
+
+/* can be used as ->unplug() callback for the simple cases */
+void qdev_simple_device_unplug_cb(HotplugHandler *hotplug_dev,
+                                  DeviceState *dev, Error **errp)
+{
+    qdev_unrealize(dev);
+}