pvclock_scale_delta
u64 offset = pvclock_scale_delta(delta, src->tsc_to_system_mul,
u64 tsc = pvclock_scale_delta(kernel_ns-vcpu->arch.this_tsc_nsec,
return pvclock_scale_delta(nsec, vcpu->arch.virtual_tsc_mult,
u64 offset = pvclock_scale_delta(delta, src->tsc_to_system_mul,