From b48aa97e38206a84bf8485e7c553412274708ce5 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Tue, 27 Nov 2012 23:29:03 -0200 Subject: KVM: x86: require matched TSC offsets for master clock With master clock, a pvclock clock read calculates: ret = system_timestamp + [ (rdtsc + tsc_offset) - tsc_timestamp ] Where 'rdtsc' is the host TSC. system_timestamp and tsc_timestamp are unique, one tuple per VM: the "master clock". Given a host with synchronized TSCs, its obvious that guest TSC must be matched for the above to guarantee monotonicity. Allow master clock usage only if guest TSCs are synchronized. Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/trace.h | 39 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 36 insertions(+), 3 deletions(-) (limited to 'arch/x86/kvm/trace.h') diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h index 1d6526856080..fe5e00ed7036 100644 --- a/arch/x86/kvm/trace.h +++ b/arch/x86/kvm/trace.h @@ -764,21 +764,54 @@ TRACE_EVENT( {VCLOCK_HPET, "hpet"} \ TRACE_EVENT(kvm_update_master_clock, - TP_PROTO(bool use_master_clock, unsigned int host_clock), - TP_ARGS(use_master_clock, host_clock), + TP_PROTO(bool use_master_clock, unsigned int host_clock, bool offset_matched), + TP_ARGS(use_master_clock, host_clock, offset_matched), TP_STRUCT__entry( __field( bool, use_master_clock ) __field( unsigned int, host_clock ) + __field( bool, offset_matched ) ), TP_fast_assign( __entry->use_master_clock = use_master_clock; __entry->host_clock = host_clock; + __entry->offset_matched = offset_matched; ), - TP_printk("masterclock %d hostclock %s", + TP_printk("masterclock %d hostclock %s offsetmatched %u", __entry->use_master_clock, + __print_symbolic(__entry->host_clock, host_clocks), + __entry->offset_matched) +); + +TRACE_EVENT(kvm_track_tsc, + TP_PROTO(unsigned int vcpu_id, unsigned int nr_matched, + unsigned int online_vcpus, bool use_master_clock, + unsigned int host_clock), + TP_ARGS(vcpu_id, nr_matched, online_vcpus, use_master_clock, + host_clock), + + TP_STRUCT__entry( + __field( unsigned int, vcpu_id ) + __field( unsigned int, nr_vcpus_matched_tsc ) + __field( unsigned int, online_vcpus ) + __field( bool, use_master_clock ) + __field( unsigned int, host_clock ) + ), + + TP_fast_assign( + __entry->vcpu_id = vcpu_id; + __entry->nr_vcpus_matched_tsc = nr_matched; + __entry->online_vcpus = online_vcpus; + __entry->use_master_clock = use_master_clock; + __entry->host_clock = host_clock; + ), + + TP_printk("vcpu_id %u masterclock %u offsetmatched %u nr_online %u" + " hostclock %s", + __entry->vcpu_id, __entry->use_master_clock, + __entry->nr_vcpus_matched_tsc, __entry->online_vcpus, __print_symbolic(__entry->host_clock, host_clocks)) ); -- cgit v1.2.2