hv_vcpu_is_preempted
PV_CALLEE_SAVE_REGS_THUNK(hv_vcpu_is_preempted);
pv_ops_lock.vcpu_is_preempted = PV_CALLEE_SAVE(hv_vcpu_is_preempted);
bool hv_vcpu_is_preempted(int vcpu);