接前一篇文章：
本文内容参考：
《 QEMU /KVM》源码解析与应用 —— 李强，机械工业出版社
特此致谢！
一、CPU虚拟化介绍
上一回讲解了VMCS数据区总的前3个区域，分别是：Guest-state区域、Host-state区域、VM-execution控制区域。VMCS数据区总共有6个区域，下面对余下的区域分别做简要介绍。
3. VMCS介绍
（4）VM Exit控制区域
VM Exit控制区域用来指定 虚拟机 在发生VM Exit时的行为，如一些寄存器的保存。
完整的VM Exit control区域如下表所示：
| VM-Exit Controls | Save debug controls | Host Address space size | Load IA32_PERF_GLOBAL_CTRL | ||
| Acknowledge interrupt on exit | Save IA32_PAT | Load IA32_PAT | Save IA32_EFER | Load IA32_EFER | |
| Save VMX preemption timer value | Clear IA32_BNDFGS | Conceal VM exits from Intel PT | |||
| VM-Exit Controls for MSRs | VM-exit MSR-strore count | VM-entry MSR-load address | |||
| VM-exit MSR-load count | VM-exit MSR-load address | ||||
（5）VM Entry控制区域
VM Entry区域用来指定虚拟机在发生VM Entry时的行为，如一些寄存器的加载，还有一些虚拟机的事件注入。
完整的VM Entry control区域如下图所示：
| VM-Entry Controls | Load debug controls | IA-32e mode guest | Entry to SMM | ||
| Deactivate dual-monitor treatment | Load IA32_PERF_GLOBAL_CTRL | Load IA32_PAT | |||
| Load IA32_EFER | Load IA32_BNDCFGS | Conceal VMX from PT | |||
| VM-Exit Controls for MSRs | VM-entry MSR-load count | VM-entry MSR-load address | |||
| VM-Entry for Event Injection | VM-entry interruption-ubfirnatuib fuekd | VM-entry exception error code | VM-entry instruction length | ||
（6）VM Exit信息区域
VM Exit信息区域包含了最近产生的VM Exit信息，典型的信息包括退出的原因以及相应的数据，如指令执行的退出会记录指令的长度等。
完整的VM Exit信息区域如下表所示：
| Base VM-Exit information | Exit reason | Exit qualification | ||
| Guest-linear address | Guest-physical address | |||
| VM Exits Due to Vectored Events | VM-exit interruption information | VM-exit interruption error code | ||
| VM Exits That Occur During Event Delivery | IDT-vectoring information | IDT-vectoring error code | ||
| VM Exits Due to instruction Execution | VM-exiting instruction length | VM-exiting instruction information | ||
| I/O RCX | I/O RSI | I/O RDI | I/O RIP | |
| VM-instruction error field | ||||
至此，VMCS数据区的6个区域就全部介绍完了。
