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qemu/hw/xen/xen-bus.c
Paul Durrant 240cc11369 hw/xen: Avoid crash when backend watch fires too early 
The xen-block code ends up calling aio_poll() through blkconf_geometry(),
which means we see watch events during the indirect call to
xendev_class->realize() in xen_device_realize(). Unfortunately this call
is made before populating the initial frontend and backend device nodes
in xenstore and hence xen_block_frontend_changed() (which is called from
a watch event) fails to read the frontend's 'state' node, and hence
believes the device is being torn down. This in-turn sets the backend
state to XenbusStateClosed and causes the device to be deleted before it
is fully set up, leading to the crash.
By simply moving the call to xendev_class->realize() after the initial
xenstore nodes are populated, this sorry state of affairs is avoided.

Reported-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
2023-03-07 17:04:30 +00:00

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/*
* 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.
*/
#include "qemu/osdep.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
#include "qemu/uuid.h"
#include "hw/qdev-properties.h"
#include "hw/sysbus.h"
#include "hw/xen/xen.h"
#include "hw/xen/xen-backend.h"
#include "hw/xen/xen-bus.h"
#include "hw/xen/xen-bus-helper.h"
#include "monitor/monitor.h"
#include "qapi/error.h"
#include "qapi/qmp/qdict.h"
#include "sysemu/sysemu.h"
#include "trace.h"
static char *xen_device_get_backend_path(XenDevice *xendev)
{
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);
const char *type = object_get_typename(OBJECT(xendev));
const char *backend = xendev_class->backend;
if (!backend) {
backend = type;
}
return g_strdup_printf("/local/domain/%u/backend/%s/%u/%s",
xenbus->backend_id, backend, xendev->frontend_id,
xendev->name);
}
static char *xen_device_get_frontend_path(XenDevice *xendev)
{
XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);
const char *type = object_get_typename(OBJECT(xendev));
const char *device = xendev_class->device;
if (!device) {
device = type;
}
return g_strdup_printf("/local/domain/%u/device/%s/%s",
xendev->frontend_id, device, xendev->name);
}
static void xen_device_unplug(XenDevice *xendev, Error **errp)
{
ERRP_GUARD();
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
const char *type = object_get_typename(OBJECT(xendev));
xs_transaction_t tid;
trace_xen_device_unplug(type, xendev->name);
/* Mimic the way the Xen toolstack does an unplug */
again:
tid = qemu_xen_xs_transaction_start(xenbus->xsh);
if (tid == XBT_NULL) {
error_setg_errno(errp, errno, "failed xs_transaction_start");
return;
}
xs_node_printf(xenbus->xsh, tid, xendev->backend_path, "online",
errp, "%u", 0);
if (*errp) {
goto abort;
}
xs_node_printf(xenbus->xsh, tid, xendev->backend_path, "state",
errp, "%u", XenbusStateClosing);
if (*errp) {
goto abort;
}
if (!qemu_xen_xs_transaction_end(xenbus->xsh, tid, false)) {
if (errno == EAGAIN) {
goto again;
}
error_setg_errno(errp, errno, "failed xs_transaction_end");
}
return;
abort:
/*
* We only abort if there is already a failure so ignore any error
* from ending the transaction.
*/
qemu_xen_xs_transaction_end(xenbus->xsh, tid, true);
}
static void xen_bus_print_dev(Monitor *mon, DeviceState *dev, int indent)
{
XenDevice *xendev = XEN_DEVICE(dev);
monitor_printf(mon, "%*sname = '%s' frontend_id = %u\n",
indent, "", xendev->name, xendev->frontend_id);
}
static char *xen_bus_get_dev_path(DeviceState *dev)
{
return xen_device_get_backend_path(XEN_DEVICE(dev));
}
static void xen_bus_backend_create(XenBus *xenbus, const char *type,
const char *name, char *path,
Error **errp)
{
ERRP_GUARD();
xs_transaction_t tid;
char **key;
QDict *opts;
unsigned int i, n;
trace_xen_bus_backend_create(type, path);
again:
tid = qemu_xen_xs_transaction_start(xenbus->xsh);
if (tid == XBT_NULL) {
error_setg(errp, "failed xs_transaction_start");
return;
}
key = qemu_xen_xs_directory(xenbus->xsh, tid, path, &n);
if (!key) {
if (!qemu_xen_xs_transaction_end(xenbus->xsh, tid, true)) {
error_setg_errno(errp, errno, "failed xs_transaction_end");
}
return;
}
opts = qdict_new();
for (i = 0; i < n; i++) {
char *val;
/*
* Assume anything found in the xenstore backend area, other than
* the keys created for a generic XenDevice, are parameters
* to be used to configure the backend.
*/
if (!strcmp(key[i], "state") ||
!strcmp(key[i], "online") ||
!strcmp(key[i], "frontend") ||
!strcmp(key[i], "frontend-id") ||
!strcmp(key[i], "hotplug-status"))
continue;
if (xs_node_scanf(xenbus->xsh, tid, path, key[i], NULL, "%ms",
&val) == 1) {
qdict_put_str(opts, key[i], val);
free(val);
}
}
free(key);
if (!qemu_xen_xs_transaction_end(xenbus->xsh, tid, false)) {
qobject_unref(opts);
if (errno == EAGAIN) {
goto again;
}
error_setg_errno(errp, errno, "failed xs_transaction_end");
return;
}
xen_backend_device_create(xenbus, type, name, opts, errp);
qobject_unref(opts);
if (*errp) {
error_prepend(errp, "failed to create '%s' device '%s': ", type, name);
}
}
static void xen_bus_type_enumerate(XenBus *xenbus, const char *type)
{
char *domain_path = g_strdup_printf("backend/%s/%u", type, xen_domid);
char **backend;
unsigned int i, n;
trace_xen_bus_type_enumerate(type);
backend = qemu_xen_xs_directory(xenbus->xsh, XBT_NULL, domain_path, &n);
if (!backend) {
goto out;
}
for (i = 0; i < n; i++) {
char *backend_path = g_strdup_printf("%s/%s", domain_path,
backend[i]);
enum xenbus_state state;
unsigned int online;
if (xs_node_scanf(xenbus->xsh, XBT_NULL, backend_path, "state",
NULL, "%u", &state) != 1)
state = XenbusStateUnknown;
if (xs_node_scanf(xenbus->xsh, XBT_NULL, backend_path, "online",
NULL, "%u", &online) != 1)
online = 0;
if (online && state == XenbusStateInitialising) {
Error *local_err = NULL;
xen_bus_backend_create(xenbus, type, backend[i], backend_path,
&local_err);
if (local_err) {
error_report_err(local_err);
}
}
g_free(backend_path);
}
free(backend);
out:
g_free(domain_path);
}
static void xen_bus_enumerate(XenBus *xenbus)
{
char **type;
unsigned int i, n;
trace_xen_bus_enumerate();
type = qemu_xen_xs_directory(xenbus->xsh, XBT_NULL, "backend", &n);
if (!type) {
return;
}
for (i = 0; i < n; i++) {
xen_bus_type_enumerate(xenbus, type[i]);
}
free(type);
}
static void xen_bus_device_cleanup(XenDevice *xendev)
{
const char *type = object_get_typename(OBJECT(xendev));
Error *local_err = NULL;
trace_xen_bus_device_cleanup(type, xendev->name);
g_assert(!xendev->backend_online);
if (!xen_backend_try_device_destroy(xendev, &local_err)) {
object_unparent(OBJECT(xendev));
}
if (local_err) {
error_report_err(local_err);
}
}
static void xen_bus_cleanup(XenBus *xenbus)
{
XenDevice *xendev, *next;
trace_xen_bus_cleanup();
QLIST_FOREACH_SAFE(xendev, &xenbus->inactive_devices, list, next) {
g_assert(xendev->inactive);
QLIST_REMOVE(xendev, list);
xen_bus_device_cleanup(xendev);
}
}
static void xen_bus_backend_changed(void *opaque, const char *path)
{
XenBus *xenbus = opaque;
xen_bus_enumerate(xenbus);
xen_bus_cleanup(xenbus);
}
static void xen_bus_unrealize(BusState *bus)
{
XenBus *xenbus = XEN_BUS(bus);
trace_xen_bus_unrealize();
if (xenbus->backend_watch) {
unsigned int i;
for (i = 0; i < xenbus->backend_types; i++) {
if (xenbus->backend_watch[i]) {
xs_node_unwatch(xenbus->xsh, xenbus->backend_watch[i]);
}
}
g_free(xenbus->backend_watch);
xenbus->backend_watch = NULL;
}
if (xenbus->xsh) {
qemu_xen_xs_close(xenbus->xsh);
}
}
static void xen_bus_realize(BusState *bus, Error **errp)
{
char *key = g_strdup_printf("%u", xen_domid);
XenBus *xenbus = XEN_BUS(bus);
unsigned int domid;
const char **type;
unsigned int i;
Error *local_err = NULL;
trace_xen_bus_realize();
xenbus->xsh = qemu_xen_xs_open();
if (!xenbus->xsh) {
error_setg_errno(errp, errno, "failed xs_open");
goto fail;
}
if (xs_node_scanf(xenbus->xsh, XBT_NULL, "", /* domain root node */
"domid", NULL, "%u", &domid) == 1) {
xenbus->backend_id = domid;
} else {
xenbus->backend_id = 0; /* Assume lack of node means dom0 */
}
module_call_init(MODULE_INIT_XEN_BACKEND);
type = xen_backend_get_types(&xenbus->backend_types);
xenbus->backend_watch = g_new(struct qemu_xs_watch *,
xenbus->backend_types);
for (i = 0; i < xenbus->backend_types; i++) {
char *node = g_strdup_printf("backend/%s", type[i]);
xenbus->backend_watch[i] =
xs_node_watch(xenbus->xsh, node, key, xen_bus_backend_changed,
xenbus, &local_err);
if (local_err) {
/* This need not be treated as a hard error so don't propagate */
error_reportf_err(local_err,
"failed to set up '%s' enumeration watch: ",
type[i]);
}
g_free(node);
}
g_free(type);
g_free(key);
return;
fail:
xen_bus_unrealize(bus);
g_free(key);
}
static void xen_bus_unplug_request(HotplugHandler *hotplug,
DeviceState *dev,
Error **errp)
{
XenDevice *xendev = XEN_DEVICE(dev);
xen_device_unplug(xendev, errp);
}
static void xen_bus_class_init(ObjectClass *class, void *data)
{
BusClass *bus_class = BUS_CLASS(class);
HotplugHandlerClass *hotplug_class = HOTPLUG_HANDLER_CLASS(class);
bus_class->print_dev = xen_bus_print_dev;
bus_class->get_dev_path = xen_bus_get_dev_path;
bus_class->realize = xen_bus_realize;
bus_class->unrealize = xen_bus_unrealize;
hotplug_class->unplug_request = xen_bus_unplug_request;
}
static const TypeInfo xen_bus_type_info = {
.name = TYPE_XEN_BUS,
.parent = TYPE_BUS,
.instance_size = sizeof(XenBus),
.class_size = sizeof(XenBusClass),
.class_init = xen_bus_class_init,
.interfaces = (InterfaceInfo[]) {
{ TYPE_HOTPLUG_HANDLER },
{ }
},
};
void xen_device_backend_printf(XenDevice *xendev, const char *key,
const char *fmt, ...)
{
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
Error *local_err = NULL;
va_list ap;
g_assert(xenbus->xsh);
va_start(ap, fmt);
xs_node_vprintf(xenbus->xsh, XBT_NULL, xendev->backend_path, key,
&local_err, fmt, ap);
va_end(ap);
if (local_err) {
error_report_err(local_err);
}
}
G_GNUC_SCANF(3, 4)
static int xen_device_backend_scanf(XenDevice *xendev, const char *key,
const char *fmt, ...)
{
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
va_list ap;
int rc;
g_assert(xenbus->xsh);
va_start(ap, fmt);
rc = xs_node_vscanf(xenbus->xsh, XBT_NULL, xendev->backend_path, key,
NULL, fmt, ap);
va_end(ap);
return rc;
}
void xen_device_backend_set_state(XenDevice *xendev,
enum xenbus_state state)
{
const char *type = object_get_typename(OBJECT(xendev));
if (xendev->backend_state == state) {
return;
}
trace_xen_device_backend_state(type, xendev->name,
xs_strstate(state));
xendev->backend_state = state;
xen_device_backend_printf(xendev, "state", "%u", state);
}
enum xenbus_state xen_device_backend_get_state(XenDevice *xendev)
{
return xendev->backend_state;
}
static void xen_device_backend_set_online(XenDevice *xendev, bool online)
{
const char *type = object_get_typename(OBJECT(xendev));
if (xendev->backend_online == online) {
return;
}
trace_xen_device_backend_online(type, xendev->name, online);
xendev->backend_online = online;
xen_device_backend_printf(xendev, "online", "%u", online);
}
/*
* Tell from the state whether the frontend is likely alive,
* i.e. it will react to a change of state of the backend.
*/
static bool xen_device_frontend_is_active(XenDevice *xendev)
{
switch (xendev->frontend_state) {
case XenbusStateInitWait:
case XenbusStateInitialised:
case XenbusStateConnected:
case XenbusStateClosing:
return true;
default:
return false;
}
}
static void xen_device_backend_changed(void *opaque, const char *path)
{
XenDevice *xendev = opaque;
const char *type = object_get_typename(OBJECT(xendev));
enum xenbus_state state;
unsigned int online;
trace_xen_device_backend_changed(type, xendev->name);
if (xen_device_backend_scanf(xendev, "state", "%u", &state) != 1) {
state = XenbusStateUnknown;
}
xen_device_backend_set_state(xendev, state);
if (xen_device_backend_scanf(xendev, "online", "%u", &online) != 1) {
online = 0;
}
xen_device_backend_set_online(xendev, !!online);
/*
* If the toolstack (or unplug request callback) has set the backend
* state to Closing, but there is no active frontend then set the
* backend state to Closed.
*/
if (state == XenbusStateClosing &&
!xen_device_frontend_is_active(xendev)) {
xen_device_backend_set_state(xendev, XenbusStateClosed);
}
/*
* If a backend is still 'online' then we should leave it alone but,
* if a backend is not 'online', then the device is a candidate
* for destruction. Hence add it to the 'inactive' list to be cleaned
* by xen_bus_cleanup().
*/
if (!online &&
(state == XenbusStateClosed || state == XenbusStateInitialising ||
state == XenbusStateInitWait || state == XenbusStateUnknown) &&
!xendev->inactive) {
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
xendev->inactive = true;
QLIST_INSERT_HEAD(&xenbus->inactive_devices, xendev, list);
/*
* Re-write the state to cause a XenBus backend_watch notification,
* resulting in a call to xen_bus_cleanup().
*/
xen_device_backend_printf(xendev, "state", "%u", state);
}
}
static void xen_device_backend_create(XenDevice *xendev, Error **errp)
{
ERRP_GUARD();
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
xendev->backend_path = xen_device_get_backend_path(xendev);
g_assert(xenbus->xsh);
xs_node_create(xenbus->xsh, XBT_NULL, xendev->backend_path,
xenbus->backend_id, xendev->frontend_id, XS_PERM_READ, errp);
if (*errp) {
error_prepend(errp, "failed to create backend: ");
return;
}
xendev->backend_state_watch =
xs_node_watch(xendev->xsh, xendev->backend_path,
"state", xen_device_backend_changed, xendev,
errp);
if (*errp) {
error_prepend(errp, "failed to watch backend state: ");
return;
}
xendev->backend_online_watch =
xs_node_watch(xendev->xsh, xendev->backend_path,
"online", xen_device_backend_changed, xendev,
errp);
if (*errp) {
error_prepend(errp, "failed to watch backend online: ");
return;
}
}
static void xen_device_backend_destroy(XenDevice *xendev)
{
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
Error *local_err = NULL;
if (xendev->backend_online_watch) {
xs_node_unwatch(xendev->xsh, xendev->backend_online_watch);
xendev->backend_online_watch = NULL;
}
if (xendev->backend_state_watch) {
xs_node_unwatch(xendev->xsh, xendev->backend_state_watch);
xendev->backend_state_watch = NULL;
}
if (!xendev->backend_path) {
return;
}
g_assert(xenbus->xsh);
xs_node_destroy(xenbus->xsh, XBT_NULL, xendev->backend_path,
&local_err);
g_free(xendev->backend_path);
xendev->backend_path = NULL;
if (local_err) {
error_report_err(local_err);
}
}
void xen_device_frontend_printf(XenDevice *xendev, const char *key,
const char *fmt, ...)
{
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
Error *local_err = NULL;
va_list ap;
g_assert(xenbus->xsh);
va_start(ap, fmt);
xs_node_vprintf(xenbus->xsh, XBT_NULL, xendev->frontend_path, key,
&local_err, fmt, ap);
va_end(ap);
if (local_err) {
error_report_err(local_err);
}
}
int xen_device_frontend_scanf(XenDevice *xendev, const char *key,
const char *fmt, ...)
{
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
va_list ap;
int rc;
g_assert(xenbus->xsh);
va_start(ap, fmt);
rc = xs_node_vscanf(xenbus->xsh, XBT_NULL, xendev->frontend_path, key,
NULL, fmt, ap);
va_end(ap);
return rc;
}
static void xen_device_frontend_set_state(XenDevice *xendev,
enum xenbus_state state,
bool publish)
{
const char *type = object_get_typename(OBJECT(xendev));
if (xendev->frontend_state == state) {
return;
}
trace_xen_device_frontend_state(type, xendev->name,
xs_strstate(state));
xendev->frontend_state = state;
if (publish) {
xen_device_frontend_printf(xendev, "state", "%u", state);
}
}
static void xen_device_frontend_changed(void *opaque, const char *path)
{
XenDevice *xendev = opaque;
XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);
const char *type = object_get_typename(OBJECT(xendev));
enum xenbus_state state;
trace_xen_device_frontend_changed(type, xendev->name);
if (xen_device_frontend_scanf(xendev, "state", "%u", &state) != 1) {
state = XenbusStateUnknown;
}
xen_device_frontend_set_state(xendev, state, false);
if (state == XenbusStateInitialising &&
xendev->backend_state == XenbusStateClosed &&
xendev->backend_online) {
/*
* The frontend is re-initializing so switch back to
* InitWait.
*/
xen_device_backend_set_state(xendev, XenbusStateInitWait);
return;
}
if (xendev_class->frontend_changed) {
Error *local_err = NULL;
xendev_class->frontend_changed(xendev, state, &local_err);
if (local_err) {
error_reportf_err(local_err, "frontend change error: ");
}
}
}
static bool xen_device_frontend_exists(XenDevice *xendev)
{
enum xenbus_state state;
return (xen_device_frontend_scanf(xendev, "state", "%u", &state) == 1);
}
static void xen_device_frontend_create(XenDevice *xendev, Error **errp)
{
ERRP_GUARD();
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
xendev->frontend_path = xen_device_get_frontend_path(xendev);
/*
* The frontend area may have already been created by a legacy
* toolstack.
*/
if (!xen_device_frontend_exists(xendev)) {
g_assert(xenbus->xsh);
xs_node_create(xenbus->xsh, XBT_NULL, xendev->frontend_path,
xendev->frontend_id, xenbus->backend_id,
XS_PERM_READ | XS_PERM_WRITE, errp);
if (*errp) {
error_prepend(errp, "failed to create frontend: ");
return;
}
}
xendev->frontend_state_watch =
xs_node_watch(xendev->xsh, xendev->frontend_path, "state",
xen_device_frontend_changed, xendev, errp);
if (*errp) {
error_prepend(errp, "failed to watch frontend state: ");
}
}
static void xen_device_frontend_destroy(XenDevice *xendev)
{
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
Error *local_err = NULL;
if (xendev->frontend_state_watch) {
xs_node_unwatch(xendev->xsh, xendev->frontend_state_watch);
xendev->frontend_state_watch = NULL;
}
if (!xendev->frontend_path) {
return;
}
g_assert(xenbus->xsh);
xs_node_destroy(xenbus->xsh, XBT_NULL, xendev->frontend_path,
&local_err);
g_free(xendev->frontend_path);
xendev->frontend_path = NULL;
if (local_err) {
error_report_err(local_err);
}
}
void xen_device_set_max_grant_refs(XenDevice *xendev, unsigned int nr_refs,
Error **errp)
{
if (qemu_xen_gnttab_set_max_grants(xendev->xgth, nr_refs)) {
error_setg_errno(errp, errno, "xengnttab_set_max_grants failed");
}
}
void *xen_device_map_grant_refs(XenDevice *xendev, uint32_t *refs,
unsigned int nr_refs, int prot,
Error **errp)
{
void *map = qemu_xen_gnttab_map_refs(xendev->xgth, nr_refs,
xendev->frontend_id, refs, prot);
if (!map) {
error_setg_errno(errp, errno,
"xengnttab_map_domain_grant_refs failed");
}
return map;
}
void xen_device_unmap_grant_refs(XenDevice *xendev, void *map, uint32_t *refs,
unsigned int nr_refs, Error **errp)
{
if (qemu_xen_gnttab_unmap(xendev->xgth, map, refs, nr_refs)) {
error_setg_errno(errp, errno, "xengnttab_unmap failed");
}
}
void xen_device_copy_grant_refs(XenDevice *xendev, bool to_domain,
XenDeviceGrantCopySegment segs[],
unsigned int nr_segs, Error **errp)
{
qemu_xen_gnttab_grant_copy(xendev->xgth, to_domain, xendev->frontend_id,
(XenGrantCopySegment *)segs, nr_segs, errp);
}
struct XenEventChannel {
QLIST_ENTRY(XenEventChannel) list;
AioContext *ctx;
xenevtchn_handle *xeh;
evtchn_port_t local_port;
XenEventHandler handler;
void *opaque;
};
static bool xen_device_poll(void *opaque)
{
XenEventChannel *channel = opaque;
return channel->handler(channel->opaque);
}
static void xen_device_event(void *opaque)
{
XenEventChannel *channel = opaque;
unsigned long port = qemu_xen_evtchn_pending(channel->xeh);
if (port == channel->local_port) {
xen_device_poll(channel);
qemu_xen_evtchn_unmask(channel->xeh, port);
}
}
void xen_device_set_event_channel_context(XenDevice *xendev,
XenEventChannel *channel,
AioContext *ctx,
Error **errp)
{
if (!channel) {
error_setg(errp, "bad channel");
return;
}
if (channel->ctx)
aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh), true,
NULL, NULL, NULL, NULL, NULL);
channel->ctx = ctx;
aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh), true,
xen_device_event, NULL, xen_device_poll, NULL, channel);
}
XenEventChannel *xen_device_bind_event_channel(XenDevice *xendev,
unsigned int port,
XenEventHandler handler,
void *opaque, Error **errp)
{
XenEventChannel *channel = g_new0(XenEventChannel, 1);
xenevtchn_port_or_error_t local_port;
channel->xeh = qemu_xen_evtchn_open();
if (!channel->xeh) {
error_setg_errno(errp, errno, "failed xenevtchn_open");
goto fail;
}
local_port = qemu_xen_evtchn_bind_interdomain(channel->xeh,
xendev->frontend_id,
port);
if (local_port < 0) {
error_setg_errno(errp, errno, "xenevtchn_bind_interdomain failed");
goto fail;
}
channel->local_port = local_port;
channel->handler = handler;
channel->opaque = opaque;
/* Only reason for failure is a NULL channel */
xen_device_set_event_channel_context(xendev, channel,
qemu_get_aio_context(),
&error_abort);
QLIST_INSERT_HEAD(&xendev->event_channels, channel, list);
return channel;
fail:
if (channel->xeh) {
qemu_xen_evtchn_close(channel->xeh);
}
g_free(channel);
return NULL;
}
void xen_device_notify_event_channel(XenDevice *xendev,
XenEventChannel *channel,
Error **errp)
{
if (!channel) {
error_setg(errp, "bad channel");
return;
}
if (qemu_xen_evtchn_notify(channel->xeh, channel->local_port) < 0) {
error_setg_errno(errp, errno, "xenevtchn_notify failed");
}
}
void xen_device_unbind_event_channel(XenDevice *xendev,
XenEventChannel *channel,
Error **errp)
{
if (!channel) {
error_setg(errp, "bad channel");
return;
}
QLIST_REMOVE(channel, list);
aio_set_fd_handler(channel->ctx, qemu_xen_evtchn_fd(channel->xeh), true,
NULL, NULL, NULL, NULL, NULL);
if (qemu_xen_evtchn_unbind(channel->xeh, channel->local_port) < 0) {
error_setg_errno(errp, errno, "xenevtchn_unbind failed");
}
qemu_xen_evtchn_close(channel->xeh);
g_free(channel);
}
static void xen_device_unrealize(DeviceState *dev)
{
XenDevice *xendev = XEN_DEVICE(dev);
XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);
const char *type = object_get_typename(OBJECT(xendev));
XenEventChannel *channel, *next;
if (!xendev->name) {
return;
}
trace_xen_device_unrealize(type, xendev->name);
if (xendev->exit.notify) {
qemu_remove_exit_notifier(&xendev->exit);
xendev->exit.notify = NULL;
}
if (xendev_class->unrealize) {
xendev_class->unrealize(xendev);
}
/* Make sure all event channels are cleaned up */
QLIST_FOREACH_SAFE(channel, &xendev->event_channels, list, next) {
xen_device_unbind_event_channel(xendev, channel, NULL);
}
xen_device_frontend_destroy(xendev);
xen_device_backend_destroy(xendev);
if (xendev->xgth) {
qemu_xen_gnttab_close(xendev->xgth);
xendev->xgth = NULL;
}
if (xendev->xsh) {
qemu_xen_xs_close(xendev->xsh);
xendev->xsh = NULL;
}
g_free(xendev->name);
xendev->name = NULL;
}
static void xen_device_exit(Notifier *n, void *data)
{
XenDevice *xendev = container_of(n, XenDevice, exit);
xen_device_unrealize(DEVICE(xendev));
}
static void xen_device_realize(DeviceState *dev, Error **errp)
{
ERRP_GUARD();
XenDevice *xendev = XEN_DEVICE(dev);
XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
const char *type = object_get_typename(OBJECT(xendev));
if (xendev->frontend_id == DOMID_INVALID) {
xendev->frontend_id = xen_domid;
}
if (xendev->frontend_id >= DOMID_FIRST_RESERVED) {
error_setg(errp, "invalid frontend-id");
goto unrealize;
}
if (!xendev_class->get_name) {
error_setg(errp, "get_name method not implemented");
goto unrealize;
}
xendev->name = xendev_class->get_name(xendev, errp);
if (*errp) {
error_prepend(errp, "failed to get device name: ");
goto unrealize;
}
trace_xen_device_realize(type, xendev->name);
xendev->xsh = qemu_xen_xs_open();
if (!xendev->xsh) {
error_setg_errno(errp, errno, "failed xs_open");
goto unrealize;
}
xendev->xgth = qemu_xen_gnttab_open();
if (!xendev->xgth) {
error_setg_errno(errp, errno, "failed xengnttab_open");
goto unrealize;
}
xen_device_backend_create(xendev, errp);
if (*errp) {
goto unrealize;
}
xen_device_frontend_create(xendev, errp);
if (*errp) {
goto unrealize;
}
xen_device_backend_printf(xendev, "frontend", "%s",
xendev->frontend_path);
xen_device_backend_printf(xendev, "frontend-id", "%u",
xendev->frontend_id);
xen_device_backend_printf(xendev, "hotplug-status", "connected");
xen_device_backend_set_online(xendev, true);
xen_device_backend_set_state(xendev, XenbusStateInitWait);
if (!xen_device_frontend_exists(xendev)) {
xen_device_frontend_printf(xendev, "backend", "%s",
xendev->backend_path);
xen_device_frontend_printf(xendev, "backend-id", "%u",
xenbus->backend_id);
xen_device_frontend_set_state(xendev, XenbusStateInitialising, true);
}
if (xendev_class->realize) {
xendev_class->realize(xendev, errp);
if (*errp) {
goto unrealize;
}
}
xendev->exit.notify = xen_device_exit;
qemu_add_exit_notifier(&xendev->exit);
return;
unrealize:
xen_device_unrealize(dev);
}
static Property xen_device_props[] = {
DEFINE_PROP_UINT16("frontend-id", XenDevice, frontend_id,
DOMID_INVALID),
DEFINE_PROP_END_OF_LIST()
};
static void xen_device_class_init(ObjectClass *class, void *data)
{
DeviceClass *dev_class = DEVICE_CLASS(class);
dev_class->realize = xen_device_realize;
dev_class->unrealize = xen_device_unrealize;
device_class_set_props(dev_class, xen_device_props);
dev_class->bus_type = TYPE_XEN_BUS;
}
static const TypeInfo xen_device_type_info = {
.name = TYPE_XEN_DEVICE,
.parent = TYPE_DEVICE,
.instance_size = sizeof(XenDevice),
.abstract = true,
.class_size = sizeof(XenDeviceClass),
.class_init = xen_device_class_init,
};
typedef struct XenBridge {
SysBusDevice busdev;
} XenBridge;
#define TYPE_XEN_BRIDGE "xen-bridge"
static const TypeInfo xen_bridge_type_info = {
.name = TYPE_XEN_BRIDGE,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(XenBridge),
};
static void xen_register_types(void)
{
type_register_static(&xen_bridge_type_info);
type_register_static(&xen_bus_type_info);
type_register_static(&xen_device_type_info);
}
type_init(xen_register_types)
void xen_bus_init(void)
{
DeviceState *dev = qdev_new(TYPE_XEN_BRIDGE);
BusState *bus = qbus_new(TYPE_XEN_BUS, dev, NULL);
sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
qbus_set_bus_hotplug_handler(bus);
}
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