Re: [Qemu-devel] [PATCH v5 1/2] Add device listener interface

[Paul Durrant]

> -----Original Message-----
> From: Paolo Bonzini [mailto:address@hidden
> Sent: 05 December 2014 11:45
> To: Paul Durrant; address@hidden
> Cc: Michael S. Tsirkin; Andreas Faerber"; Peter Crosthwaite; Igor
> Mammedov; Markus Armbruster; Thomas Huth; Christian Borntraeger
> Subject: Re: [PATCH v5 1/2] Add device listener interface
> 
> 
> 
> On 05/12/2014 11:50, Paul Durrant wrote:
> > The Xen ioreq-server API, introduced in Xen 4.5, requires that PCI device
> > models explicitly register with Xen for config space accesses. This patch
> > adds a listener interface into qdev-core which can be used by the Xen
> > interface code to monitor for arrival and departure of PCI devices.
> >
> > Signed-off-by: Paul Durrant <address@hidden>
> > Cc: Michael S. Tsirkin <address@hidden>
> > Cc: Andreas Faerber" <address@hidden>
> > Cc: Paolo Bonzini <address@hidden>
> > Cc: Peter Crosthwaite <address@hidden>
> > Cc: Igor Mammedov <address@hidden>
> > Cc: Markus Armbruster <address@hidden>
> > Cc: Thomas Huth <address@hidden>
> > Cc: Christian Borntraeger <address@hidden>
> > ---
> >  hw/core/qdev.c          |   53
> +++++++++++++++++++++++++++++++++++++++++++++++
> >  include/hw/qdev-core.h  |   10 +++++++++
> >  include/qemu/typedefs.h |    1 +
> >  3 files changed, 64 insertions(+)
> >
> > diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> > index 35fd00d..76ff9ef 100644
> > --- a/hw/core/qdev.c
> > +++ b/hw/core/qdev.c
> > @@ -189,6 +189,56 @@ int qdev_init(DeviceState *dev)
> >      return 0;
> >  }
> >
> > +static QTAILQ_HEAD(device_listeners, DeviceListener) device_listeners
> > +    = QTAILQ_HEAD_INITIALIZER(device_listeners);
> > +
> > +enum ListenerDirection { Forward, Reverse };
> > +
> > +#define DEVICE_LISTENER_CALL(_callback, _direction, _args...)     \
> > +    do {                                                          \
> > +        DeviceListener *_listener;                                \
> > +                                                                  \
> > +        switch (_direction) {                                     \
> > +        case Forward:                                             \
> > +            QTAILQ_FOREACH(_listener, &device_listeners, link) {  \
> > +                if (_listener->_callback) {                       \
> > +                    _listener->_callback(_listener, ##_args);     \
> > +                }                                                 \
> > +            }                                                     \
> > +            break;                                                \
> > +        case Reverse:                                             \
> > +            QTAILQ_FOREACH_REVERSE(_listener, &device_listeners,  \
> > +                                   device_listeners, link) {      \
> > +                if (_listener->_callback) {                       \
> > +                    _listener->_callback(_listener, ##_args);     \
> > +                }                                                 \
> > +            }                                                     \
> > +            break;                                                \
> > +        default:                                                  \
> > +            abort();                                              \
> > +        }                                                         \
> > +    } while (0)
> > +
> > +static int device_listener_add(DeviceState *dev, void *opaque)
> > +{
> > +    DEVICE_LISTENER_CALL(realize, Forward, dev);
> > +
> > +    return 0;
> > +}
> > +
> > +void device_listener_register(DeviceListener *listener)
> > +{
> > +    QTAILQ_INSERT_TAIL(&device_listeners, listener, link);
> > +
> > +    qbus_walk_children(sysbus_get_default(), NULL, NULL,
> device_listener_add,
> > +                       NULL, NULL);
> > +}
> > +
> > +void device_listener_unregister(DeviceListener *listener)
> > +{
> > +    QTAILQ_REMOVE(&device_listeners, listener, link);
> > +}
> > +
> >  static void device_realize(DeviceState *dev, Error **errp)
> >  {
> >      DeviceClass *dc = DEVICE_GET_CLASS(dev);
> > @@ -994,6 +1044,8 @@ static void device_set_realized(Object *obj, bool
> value, Error **errp)
> >              goto fail;
> >          }
> >
> > +        DEVICE_LISTENER_CALL(realize, Forward, dev);
> > +
> >          hotplug_ctrl = qdev_get_hotplug_handler(dev);
> >          if (hotplug_ctrl) {
> >              hotplug_handler_plug(hotplug_ctrl, dev, &local_err);
> > @@ -1035,6 +1087,7 @@ static void device_set_realized(Object *obj, bool
> value, Error **errp)
> >              dc->unrealize(dev, local_errp);
> >          }
> >          dev->pending_deleted_event = true;
> > +        DEVICE_LISTENER_CALL(unrealize, Reverse, dev);
> >      }
> >
> >      if (local_err != NULL) {
> > diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> > index 589bbe7..15a226f 100644
> > --- a/include/hw/qdev-core.h
> > +++ b/include/hw/qdev-core.h
> > @@ -165,6 +165,12 @@ struct DeviceState {
> >      int alias_required_for_version;
> >  };
> >
> > +struct DeviceListener {
> > +    void (*realize)(DeviceListener *listener, DeviceState *dev);
> > +    void (*unrealize)(DeviceListener *listener, DeviceState *dev);
> > +    QTAILQ_ENTRY(DeviceListener) link;
> > +};
> > +
> >  #define TYPE_BUS "bus"
> >  #define BUS(obj) OBJECT_CHECK(BusState, (obj), TYPE_BUS)
> >  #define BUS_CLASS(klass) OBJECT_CLASS_CHECK(BusClass, (klass),
> TYPE_BUS)
> > @@ -376,4 +382,8 @@ static inline bool qbus_is_hotpluggable(BusState
> *bus)
> >  {
> >     return bus->hotplug_handler;
> >  }
> > +
> > +void device_listener_register(DeviceListener *listener);
> > +void device_listener_unregister(DeviceListener *listener);
> > +
> >  #endif
> > diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
> > index 3475177..4bb4938 100644
> > --- a/include/qemu/typedefs.h
> > +++ b/include/qemu/typedefs.h
> > @@ -20,6 +20,7 @@ typedef struct Property Property;
> >  typedef struct PropertyInfo PropertyInfo;
> >  typedef struct CompatProperty CompatProperty;
> >  typedef struct DeviceState DeviceState;
> > +typedef struct DeviceListener DeviceListener;
> >  typedef struct BusState BusState;
> >  typedef struct BusClass BusClass;
> >
> >
> 
> Reviewed-by: Paolo Bonzini <address@hidden>
> 

Great. Thanks for that. All I need now is an ack on this from a maintainer.

  Paul

> Thanks!
> 
> Paolo