Add a driver with gettime method returning hosts realtime clock.
This allows Chrony to synchronize host and guest clocks with
high precision (see results below).
chronyc> sources
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
To configure Chronyd to use PHC refclock, add the
following line to its configuration file:
refclock PHC /dev/ptpX poll 3 dpoll -2 offset 0
Where /dev/ptpX is the kvmclock PTP clock.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Acked-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>