Ubuntu
linux package

  1. Xenial (16.04)
  2. Bug #1822821
  3. Comment #0

Comment 0 for bug 1822821

Revision history for this message
Heitor Alves de Siqueira (halves) wrote :

[Impact]
 * TSC clocksource not available in nested guests

[Test Case]
 * Spin up a nested Xenial/Bionic guest and check for 'tsc' at
   /sys/devices/system/clocksource/clocksource0/available_clocksource

[Regression Potential]
 * The regression potential is low. Upstream code still maintains this
   behaviour of skipping calibration on guests, and tsc code verifies if
   the frequency is known before registering the clocksource

 * Patches were verified against the above test case, and also tested
   with stress-ng in both nested and non-nested guest scenarios

[Fix]
 * By applying the upstream commits, we skip refined calibration and
   register TSC as a clocksource directly if its frequency is known (via
   MSR or CPUID)