qemu/include/hw/xen/xen-bus.h
Paul Durrant 82a29e3048 xen: add xenstore watcher infrastructure
A Xen PV frontend communicates its state to the PV backend by writing to
the 'state' key in the frontend area in xenstore. It is therefore
necessary for a XenDevice implementation to be notified whenever the
value of this key changes.

This patch adds code to do this as follows:

- an 'fd handler' is registered on the libxenstore handle which will be
  triggered whenever a 'watch' event occurs
- primitives are added to xen-bus-helper to add or remove watch events
- a list of Notifier objects is added to XenBus to provide a mechanism
  to call the appropriate 'watch handler' when its associated event
  occurs

The xen-block implementation is extended with a 'frontend_changed' method,
which calls as-yet stub 'connect' and 'disconnect' functions when the
relevant frontend state transitions occur. A subsequent patch will supply
a full implementation for these functions.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
2019-01-14 13:45:40 +00:00

83 lines
2.3 KiB
C

/*
* Copyright (c) 2018 Citrix Systems Inc.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef HW_XEN_BUS_H
#define HW_XEN_BUS_H
#include "hw/xen/xen_common.h"
#include "hw/sysbus.h"
#include "qemu/notify.h"
typedef void (*XenWatchHandler)(void *opaque);
typedef struct XenWatch XenWatch;
typedef struct XenDevice {
DeviceState qdev;
domid_t frontend_id;
char *name;
char *backend_path, *frontend_path;
enum xenbus_state backend_state, frontend_state;
Notifier exit;
XenWatch *frontend_state_watch;
} XenDevice;
typedef char *(*XenDeviceGetName)(XenDevice *xendev, Error **errp);
typedef void (*XenDeviceRealize)(XenDevice *xendev, Error **errp);
typedef void (*XenDeviceFrontendChanged)(XenDevice *xendev,
enum xenbus_state frontend_state,
Error **errp);
typedef void (*XenDeviceUnrealize)(XenDevice *xendev, Error **errp);
typedef struct XenDeviceClass {
/*< private >*/
DeviceClass parent_class;
/*< public >*/
const char *backend;
const char *device;
XenDeviceGetName get_name;
XenDeviceRealize realize;
XenDeviceFrontendChanged frontend_changed;
XenDeviceUnrealize unrealize;
} XenDeviceClass;
#define TYPE_XEN_DEVICE "xen-device"
#define XEN_DEVICE(obj) \
OBJECT_CHECK(XenDevice, (obj), TYPE_XEN_DEVICE)
#define XEN_DEVICE_CLASS(class) \
OBJECT_CLASS_CHECK(XenDeviceClass, (class), TYPE_XEN_DEVICE)
#define XEN_DEVICE_GET_CLASS(obj) \
OBJECT_GET_CLASS(XenDeviceClass, (obj), TYPE_XEN_DEVICE)
typedef struct XenBus {
BusState qbus;
domid_t backend_id;
struct xs_handle *xsh;
NotifierList watch_notifiers;
} XenBus;
typedef struct XenBusClass {
/*< private >*/
BusClass parent_class;
} XenBusClass;
#define TYPE_XEN_BUS "xen-bus"
#define XEN_BUS(obj) \
OBJECT_CHECK(XenBus, (obj), TYPE_XEN_BUS)
#define XEN_BUS_CLASS(class) \
OBJECT_CLASS_CHECK(XenBusClass, (class), TYPE_XEN_BUS)
#define XEN_BUS_GET_CLASS(obj) \
OBJECT_GET_CLASS(XenBusClass, (obj), TYPE_XEN_BUS)
void xen_bus_init(void);
void xen_device_backend_set_state(XenDevice *xendev,
enum xenbus_state state);
enum xenbus_state xen_device_backend_get_state(XenDevice *xendev);
#endif /* HW_XEN_BUS_H */