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qdev: Check for the availability of a hotplug controller before adding a device 

The qdev_unplug() function contains a g_assert(hotplug_ctrl) statement,
so QEMU crashes when the user tries to device_add + device_del a device
that does not have a corresponding hotplug controller. This could be
provoked for a couple of devices in the past (see commit 4c93950659
or 84ebd3e8c7 for example), and can currently for example also be
triggered like this:

$ s390x-softmmu/qemu-system-s390x -M none -nographic
QEMU 2.10.50 monitor - type 'help' for more information
(qemu) device_add qemu-s390x-cpu,id=x
(qemu) device_del x
**
ERROR:qemu/qdev-monitor.c:872:qdev_unplug: assertion failed: (hotplug_ctrl)
Aborted (core dumped)

So devices clearly need a hotplug controller when they should be usable
with device_add.
The code in qdev_device_add() already checks whether the bus has a proper
hotplug controller, but for devices that do not have a corresponding bus,
there is no appropriate check available yet. In that case we should check
whether the machine itself provides a suitable hotplug controller and
refuse to plug the device if none is available.

Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1509617407-21191-3-git-send-email-thuth@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Thomas Huth 2017-11-02 11:10:06 +01:00 committed by Eduardo Habkost
parent 58346214d0
commit 03fcbd9dc5
3 changed files with 26 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
hw/core/qdev.c
View File

@ -253,19 +253,31 @@ void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
dev->alias_required_for_version = required_for_version;
}
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;
}
HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
{
HotplugHandler *hotplug_ctrl = NULL;
HotplugHandler *hotplug_ctrl;
if (dev->parent_bus && dev->parent_bus->hotplug_handler) {
hotplug_ctrl = dev->parent_bus->hotplug_handler;
} else if (object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) {
MachineState *machine = MACHINE(qdev_get_machine());
MachineClass *mc = MACHINE_GET_CLASS(machine);
if (mc->get_hotplug_handler) {
hotplug_ctrl = mc->get_hotplug_handler(machine, dev);
}
} else {
hotplug_ctrl = qdev_get_machine_hotplug_handler(dev);
}
return hotplug_ctrl;
}

1
include/hw/qdev-core.h
View File

@ -286,6 +286,7 @@ DeviceState *qdev_try_create(BusState *bus, const char *name);
void qdev_init_nofail(DeviceState *dev);
void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
int required_for_version);
HotplugHandler *qdev_get_machine_hotplug_handler(DeviceState *dev);
HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev);
void qdev_unplug(DeviceState *dev, Error **errp);
void qdev_simple_device_unplug_cb(HotplugHandler *hotplug_dev,

5
qdev-monitor.c
View File

@ -613,6 +613,11 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
if (bus) {
qdev_set_parent_bus(dev, bus);
} else if (qdev_hotplug && !qdev_get_machine_hotplug_handler(dev)) {
/* No bus, no machine hotplug handler --> device is not hotpluggable */
error_setg(&err, "Device '%s' can not be hotplugged on this machine",
driver);
goto err_del_dev;
}
qdev_set_id(dev, qemu_opts_id(opts));