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VT的特殊功能--EPT [复制链接]

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只看楼主 倒序阅读 使用道具 楼主  发表于: 2016-02-02


VT的特殊功能--EPT

发表于 2016 年 1 月 3 日

28.2 THE EXTENDED PAGE TABLE MECHANISM (EPT)
   The extended page-table mechanism (EPT) is a feature that can be used to support the virtualization of physical memory. When EPT is in use, certain addresses that would normally be treated as physical addresses (and used to access memory) are instead treated as guest-physical addresses. Guest-physical addresses are translated by traversing a set of EPT paging structures to produce physical addresses that are used to access memory.
扩展页表是VT的一个特殊的功能,用于支持物理内存的虚拟化,当使用EPT的时候,某些正常的物理地址将被作为客户机物理地址,通过遍历一组EPT页表结构来翻译客户机物理地址,其产生的物理地址可以用于访问内存
28.2.1 EPT Overview
    EPT is used when the “enable EPT” VM-execution control is 1  It translates the guest-physical addresses used in VMX non-root operation and those used by VM entry for event injection.
只有enable EPT为1的时候,EPT才能被使用 (enable EPT在Secondary字段,只有Primary的bit 31为1的时候,Secondary才有效,如果Primary的bit 31为0,那么就默认Secondary字段的所有值为0) ,它用来翻译的客户机物理地址是在VMX非根模式中使用的,并且用于VMM-Entry的事件注入
The translation from guest-physical address to physical address is determined by a set of EPT paging structures. The EPT paging structures are similar to those used to translate linear address while the processor is in IA-32e mode. Section 28.2.2 gives the details of the EPT paging structures
   客户机物理地址到物理地址的翻译是由一组EPT页表结构决定的,EPT 页表结构的翻译类似于IA-32e模式下处理器对线性地址的翻译,28.2.2节详述了EPT页表结构
    If CR0.PG=1, linear address are translated through paging structures referenced through control register CR3,While the "enable EPT" VM-execution control is 1,these are called guest paging structures. There are no guest paging structures if CR0.PG=0
    如果CR0.PG为1,线性地址的翻译将通过控制寄存器CR3引用的页表结构,当“enable EPT”是1的时候,被引用的页表结构叫做客户机页表结构,如果CR0.PG为0,将没有客户机分页结构
    When the "enable EPT" VM-execution control is 1, the identity of guest-physical address depends on the value of CR0.PG
    1. If CR0.PG=0, each linear address is treated as a guest-physical address
    2. If CR0.PG=1, guest-physical addresses are those derived from the contents of control register CR3 and the guest paging structures, The latter includes the addresses to which linear addresses are translated by the guest paging structures
   当“enable EPT”是1的时候,客户机物理地址的身份由CR0.PG决定
   1. 如果CR0.PG=0,线性地址将被作为客户机物理地址
    2. 如果CR0.PG=1, 客户机物理地址将来源于CR3和分页结构的共同作用,线性地址的翻译通过客户机分页结构

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