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

[Paolo Bonzini <pbonzini@redhat.com>]

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 <paul.durrant@citrix.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Andreas Faerber" <afaerber@suse.de>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> Cc: Igor Mammedov <imammedo@redhat.com>
> Cc: Markus Armbruster <armbru@redhat.com>
> Cc: Thomas Huth <thuth@linux.vnet.ibm.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  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 <pbonzini@redhat.com>

Thanks!

Paolo