IST_INDEX_VC
new_ist = old_ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]);
this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], new_ist);
ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]);
this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist);
tss->x86_tss.ist[IST_INDEX_VC] = __this_cpu_ist_top_va(VC);
ISTG(X86_TRAP_VC, asm_exc_vmm_communication, IST_INDEX_VC),