Paolo Bonzini <pbonzini@xxxxxxxxxx> writes: > On 15/03/21 16:55, Vitaly Kuznetsov wrote: >>> I think we should instead write 0 to the page in kvm_gen_update_masterclock. >> >> We can do that but we will also need to invalidate >> hv->tsc_ref.tsc_sequence to prevent MSR based clocksource >> (HV_X64_MSR_TIME_REF_COUNT -> get_time_ref_counter()) from using stale >> hv->tsc_ref.tsc_scale/tsc_offset values (in case we had them >> calculated). > > Yes, we're talking about the same thing (invalidating tsc_sequence is > done by writing 0 to it). > Yes, 'hv->tsc_ref' is a 'shadow TSC page' which almost always caches what's in the 'real' one. One notable exception is that after migration our cache is out of sync until the first successful kvm_hv_setup_tsc_page() call. What I was trying to say is that we not only need to write '0' to the 'real' TSC page but also invalidate our internal 'hv->tsc_ref'. Anyway, I think we're in a violent agreement here, v2 is coming with this change after I'm done testing it. Thanks! > Paolo > >> Also, we can't really disable TSC page for nested scenario when guest >> opted for reenlightenment (PATCH4) but we're not going to update the >> page anyway so there's not much different. >> > -- Vitaly
