atomic_swap_ulong
pte = atomic_swap_ulong(&pq->pq_pte, 0);
atomic_swap_ulong(&ci->ci_vmcs_pa, VMX_VMCS_PA_CLEAR);
atomic_swap_ulong(&ci->ci_vmcs_pa, vcpu->vc_control_pa);
pending = atomic_swap_ulong(&revents[row], 0);
selector = atomic_swap_ulong(&v->evtchn_pending_sel, 0);
pending = atomic_swap_ulong(&sc->sc_ipg->evtchn_pending[row],
#ifndef atomic_swap_ulong