rdtsc
tsc = rdtsc();
t.u64 += rdtsc(); /* potential vmexit latency */
last_count = rdtsc();
count = rdtsc();
st->pctr_tsc = rdtsc();
st->pctr_tsc = rdtsc();
(void)rdtsc();
pvclock_ti->ti_tsc_timestamp = rdtsc();
tsc = rdtsc();
r += rdtsc(); /* potential vmexit latency */
st->pctr_tsc = rdtsc();
st->pctr_tsc = rdtsc();
st->pctr_tsc = rdtsc();