qemu-e2k/include/hw/xen/xen-bus.h
Paul Durrant 32d0b7be68 xen-bus/block: explicitly assign event channels to an AioContext
It is not safe to close an event channel from the QEMU main thread when
that channel's poller is running in IOThread context.

This patch adds a new xen_device_set_event_channel_context() function
to explicitly assign the channel AioContext, and modifies
xen_device_bind_event_channel() to initially assign the channel's poller
to the QEMU main thread context. The code in xen-block's dataplane is
then modified to assign the channel to IOThread context during
xen_block_dataplane_start() and de-assign it during in
xen_block_dataplane_stop(), such that the channel is always assigned
back to main thread context before it is closed. aio_set_fd_handler()
already deals with all the necessary synchronization when moving an fd
between AioContext-s so no extra code is needed to manage this.

Reported-by: Julien Grall <jgrall@amazon.com>
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20191216143451.19024-1-pdurrant@amazon.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
2020-02-27 11:50:30 +00:00

146 lines
4.9 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 XenWatchList XenWatchList;
typedef struct XenWatch XenWatch;
typedef struct XenEventChannel XenEventChannel;
typedef struct XenDevice {
DeviceState qdev;
domid_t frontend_id;
char *name;
struct xs_handle *xsh;
XenWatchList *watch_list;
char *backend_path, *frontend_path;
enum xenbus_state backend_state, frontend_state;
Notifier exit;
XenWatch *backend_state_watch, *frontend_state_watch;
bool backend_online;
XenWatch *backend_online_watch;
xengnttab_handle *xgth;
bool feature_grant_copy;
bool inactive;
QLIST_HEAD(, XenEventChannel) event_channels;
QLIST_ENTRY(XenDevice) list;
} 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;
XenWatchList *watch_list;
XenWatch *backend_watch;
QLIST_HEAD(, XenDevice) inactive_devices;
} 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);
void xen_device_backend_printf(XenDevice *xendev, const char *key,
const char *fmt, ...)
GCC_FMT_ATTR(3, 4);
void xen_device_frontend_printf(XenDevice *xendev, const char *key,
const char *fmt, ...)
GCC_FMT_ATTR(3, 4);
int xen_device_frontend_scanf(XenDevice *xendev, const char *key,
const char *fmt, ...);
void xen_device_set_max_grant_refs(XenDevice *xendev, unsigned int nr_refs,
Error **errp);
void *xen_device_map_grant_refs(XenDevice *xendev, uint32_t *refs,
unsigned int nr_refs, int prot,
Error **errp);
void xen_device_unmap_grant_refs(XenDevice *xendev, void *map,
unsigned int nr_refs, Error **errp);
typedef struct XenDeviceGrantCopySegment {
union {
void *virt;
struct {
uint32_t ref;
off_t offset;
} foreign;
} source, dest;
size_t len;
} XenDeviceGrantCopySegment;
void xen_device_copy_grant_refs(XenDevice *xendev, bool to_domain,
XenDeviceGrantCopySegment segs[],
unsigned int nr_segs, Error **errp);
typedef bool (*XenEventHandler)(void *opaque);
XenEventChannel *xen_device_bind_event_channel(XenDevice *xendev,
unsigned int port,
XenEventHandler handler,
void *opaque, Error **errp);
void xen_device_set_event_channel_context(XenDevice *xendev,
XenEventChannel *channel,
AioContext *ctx,
Error **errp);
void xen_device_notify_event_channel(XenDevice *xendev,
XenEventChannel *channel,
Error **errp);
void xen_device_unbind_event_channel(XenDevice *xendev,
XenEventChannel *channel,
Error **errp);
#endif /* HW_XEN_BUS_H */