Commit 03fcbd9d authored by Thomas Huth's avatar Thomas Huth Committed by Eduardo Habkost
Browse files

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 4c939506
or 84ebd3e8 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: default avatarIgor Mammedov <imammedo@redhat.com>
Signed-off-by: default avatarThomas Huth <thuth@redhat.com>
Message-Id: <1509617407-21191-3-git-send-email-thuth@redhat.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Signed-off-by: default avatarEduardo Habkost <ehabkost@redhat.com>
parent 58346214

hw/core/qdev.c

+20 −8
Original line number Diff line number Diff line
@@ -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;

}

include/hw/qdev-core.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

qdev-monitor.c

+5 −0
Original line number Diff line number Diff line
@@ -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));