[Qemu-devel] [PATCH v5 3/9] qdev: add "hotpluggable" property to Device

[Igor Mammedov <imammedo@redhat.com>]

Currently it's possible to make PCIDevice not hotpluggable
by using no_hotplug field of PCIDeviceClass. However it
limits this only to PCI devices and prevents from
generalizing hotplug code.

So add similar field to DeviceClass so it could be reused
with other Devices and would allow to replace PCI specific
hotplug callbacks with generic implementation. Following
patches will replace PCIDeviceClass.no_hotplug with this
new property.

In addition expose field as "hotpluggable" readonly property,
to make it possible to read its value via QOM interface.

Make DeviceClass hotpluggable by default as it was assumed
before.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
v5:
* drop 'boolean' from doc comment of hotpluggable field
v4:
* s/hotplugable/hotpluggable/

v3:
* make DeviceClass hotpluggable by default
  Since PCIDevice still uses internal no_hotlpug checks it shouldn't
  reggress. And follow up patch that converts PCIDevices to use
  "hotpluggable" property will take care about not hotpluggable PCI
  devices explicitly setting "hotpluggable" to false in their class_init().

* move generic hotplug checks from
  "7/11 qdev:pci: refactor PCIDevice to use generic "hotplugable" property"
  to this patch
---
 hw/core/qdev.c         |   29 +++++++++++++++++++++++++++++
 include/hw/qdev-core.h |    3 +++
 2 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index c9f0c33..d8b83f1 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -215,6 +215,12 @@ void qdev_unplug(DeviceState *dev, Error **errp)
     }
     assert(dc->unplug != NULL);
 
+    if (!dc->hotpluggable) {
+        error_set(errp, QERR_DEVICE_NO_HOTPLUG,
+                  object_get_typename(OBJECT(dev)));
+        return;
+    }
+
     qdev_hot_removed = true;
 
     if (dc->unplug(dev) < 0) {
@@ -694,6 +700,11 @@ static void device_set_realized(Object *obj, bool value, Error **err)
     DeviceClass *dc = DEVICE_GET_CLASS(dev);
     Error *local_err = NULL;
 
+    if (dev->hotplugged && !dc->hotpluggable) {
+        error_set(err, QERR_DEVICE_NO_HOTPLUG, object_get_typename(obj));
+        return;
+    }
+
     if (value && !dev->realized) {
         if (!obj->parent && local_err == NULL) {
             static int unattached_count;
@@ -734,6 +745,14 @@ static void device_set_realized(Object *obj, bool value, Error **err)
     dev->realized = value;
 }
 
+static bool device_get_hotpluggable(Object *obj, Error **err)
+{
+    DeviceClass *dc = DEVICE_GET_CLASS(obj);
+    DeviceState *dev = DEVICE(obj);
+
+    return dc->hotpluggable && dev->parent_bus->allow_hotplug;
+}
+
 static void device_initfn(Object *obj)
 {
     DeviceState *dev = DEVICE(obj);
@@ -750,6 +769,8 @@ static void device_initfn(Object *obj)
 
     object_property_add_bool(obj, "realized",
                              device_get_realized, device_set_realized, NULL);
+    object_property_add_bool(obj, "hotpluggable",
+                             device_get_hotpluggable, NULL, NULL);
 
     class = object_get_class(OBJECT(dev));
     do {
@@ -786,6 +807,14 @@ static void device_class_base_init(ObjectClass *class, void *data)
      * so do not propagate them to the subclasses.
      */
     klass->props = NULL;
+
+    /* by default all devices were considered as hotpluggable,
+     * so with intent to check it in generic qdev_unplug() /
+     * device_set_realized() functions make every device
+     * hotpluggable. Devices that shouldn't be hoplugable,
+     * should override it in their class_init()
+     */
+    klass->hotpluggable = true;
 }
 
 static void device_unparent(Object *obj)
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 41ec533..08d329d 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -50,6 +50,8 @@ struct VMStateDescription;
  * is changed to %true. Deprecated, new types inheriting directly from
  * TYPE_DEVICE should use @realize instead, new leaf types should consult
  * their respective parent type.
+ * @hotpluggable: indicates if #DeviceClass is hotpluggable, available
+ * as readonly "hotpluggable" property of #DeviceState instance
  *
  * # Realization #
  * Devices are constructed in two stages,
@@ -110,6 +112,7 @@ typedef struct DeviceClass {
      * TODO remove once we're there
      */
     bool cannot_instantiate_with_device_add_yet;
+    bool hotpluggable;
 
     /* callbacks */
     void (*reset)(DeviceState *dev);
-- 
1.7.1