Merge branch 'upstream/core' into upstream/xen

Merge branch 'upstream/core' into upstream/xen

* upstream/core:
  xen/panic: use xen_reboot and fix smp_send_stop
  Xen: register panic notifier to take crashes of xen guests on panic
  xen: support large numbers of CPUs with vcpu info placement
  xen: drop xen_sched_clock in favour of using plain wallclock time
  pvops: do not notify callers from register_xenstore_notifier
  xen: make sure pages are really part of domain before freeing
  xen: release unused free memory