In nested guest tsc_read_refs always return ULLONG_MAX, and that will call tsc_refine_calibration_work periodly. So nested guest will read acpi timer port 0x608 periodly.
The patch set X86_FEATURE_TSC_KNOWN_FREQ for kvmclock to avoid 'refine' operation. Thanks for PeterZijlstra's advice. Signed-off-by: Peng Hao <[email protected]> --- arch/x86/kernel/kvmclock.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 8b26c9e..fc1562e 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -138,6 +138,7 @@ static unsigned long kvm_get_tsc_khz(void) src = &hv_clock[cpu].pvti; tsc_khz = pvclock_tsc_khz(src); put_cpu(); + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); return tsc_khz; } -- 1.8.3.1
