bool Fence::FenceAwaiter::await_suspend(T awaitingCoroutine) noexcept {
Scheduler* scheduler = nullptr;
if constexpr (std::is_base_of_v<SchedulablePromiseTag, std::decay_t<decltype(awaitingCoroutine.promise())>>) {
scheduler = static_cast<const SchedulablePromiseTag&>(awaitingCoroutine.promise()).m_scheduler;
}
return await_suspend(std::experimental::coroutine_handle<>(awaitingCoroutine), scheduler);
}
static int suspend_evtchn_init(int xc, int domid)
{
struct xs_handle *xs;
char path[128];
char *portstr;
unsigned int plen;
int port;
int rc;
si.xce = -1;
si.suspend_evtchn = -1;
xs = xs_daemon_open();
if (!xs) {
warnx("failed to get xenstore handle");
return -1;
}
sprintf(path, "/local/domain/%d/device/suspend/event-channel", domid);
portstr = xs_read(xs, XBT_NULL, path, &plen);
xs_daemon_close(xs);
if (!portstr || !plen) {
warnx("could not read suspend event channel");
return -1;
}
port = atoi(portstr);
free(portstr);
si.xce = xc_evtchn_open();
if (si.xce < 0) {
warnx("failed to open event channel handle");
goto cleanup;
}
si.suspend_evtchn = xc_evtchn_bind_interdomain(si.xce, domid, port);
if (si.suspend_evtchn < 0) {
warnx("failed to bind suspend event channel: %d", si.suspend_evtchn);
goto cleanup;
}
rc = xc_domain_subscribe_for_suspend(xc, domid, port);
if (rc < 0) {
warnx("failed to subscribe to domain: %d", rc);
goto cleanup;
}
/* event channel is pending immediately after binding */
await_suspend();
return 0;
cleanup:
suspend_evtchn_release();
return -1;
}
/**
* Issue a suspend request to a dedicated event channel in the guest, and
* receive the acknowledgement from the subscribe event channel. */
static int evtchn_suspend(void)
{
int rc;
rc = xc_evtchn_notify(si.xce, si.suspend_evtchn);
if (rc < 0) {
warnx("failed to notify suspend request channel: %d", rc);
return 0;
}
if (await_suspend() < 0) {
warnx("suspend failed");
return 0;
}
/* notify xend that it can do device migration */
printf("suspended\n");
fflush(stdout);
return 1;
}