From KVM

KVM PVclock

Linux guests only.

Testing

You can verify kvm-clock is enable by checking

/sys/devices/system/clocksource/clocksource0/current_clocksource

Output should say "kvm-clock"

Some basic mechanism to make sure it works:

* Try guests without kvm-clock too. Make sure they at least boot
* make sure successive gettimeofday calls never go backwards (testing this can take days)
* make sure that calls to different time sources (like gettimeofday and monotonic) do not deviate too much, nor go backwards.