On Fri, Dec 03, 2021 at 03:34:04PM +0800, zhenwei pi wrote: > A KVM guest overwrites the '.calibrate_tsc' and '.calibrate_cpu' if kvmclock > is supported: > > in function kvmclock_init(void) (linux/arch/x86/kernel/kvmclock.c) > ... > x86_platform.calibrate_tsc = kvm_get_tsc_khz; > x86_platform.calibrate_cpu = kvm_get_tsc_khz; > ... > > And kvm_get_tsc_khz reads PV data from host side. Before guest reads this, > KVM should writes the frequency into the PV data structure. > > And the problem is that KVM gets tsc_khz directly without aperf/mperf > detection. So user may gets different frequency(cat /proc/cpuinfo) from > guest & host. > > Or is that possible to export function 'aperfmperf_get_khz'? TSC frequency and aperf/mperf are unrelated. You're trying to make apple juice with carrots.
