Xen devel - May 2013 - [PATCH 0/3] x86, time, xen: maintain an accurate persistent clock in more cases

The kernel has limited support for updating the persistent clock or
RTC when NTP is synced.  This has the following limitations:

* The persistent clock is not updated on step changes.  This leaves a
  window where it will be incorrect (while NTP resyncs).

* On x86, the virtual platforms have persistent clocks with nanosecond
  precision but this is lost in the x86_platform.set/get_wallclock()
  calls.  Guests may see wallclocks that are out by up to 1 second.

* Xen guests use the Xen wallclock as their persistent clock.  dom0
  maintains this clock so it is persistent for domUs and not dom0
  itself.

These series fixes the above limitations.

Each patch in the series is independent so may be applied to their
respective trees separately.

David