VMCS结构
VMCS是保持在内存中的数据结构,包含了虚拟cpu的相关寄存器的内容和虚拟cpu相关的控制信息,每个VMCS对应一个虚拟CPU。
VMCS在使用时需要与物理CPU绑定。在任意给定时候,VMCS与物理CPU是一对一的绑定关系,即一个物理CPU只能绑定一个VMCS,一个VMCS也只能与一个物理CPU绑定。VMCS在不同的时候可以绑定到不同的物理CPU,如在某个VMCS先和物理CPU1绑定,并在某个时候解除绑定关系,并重新绑定到物理CPU2.这种绑定关系的变化称为VMCS的迁移。
VT-x提供了二条指令用于VMCS的绑定与解除绑定。
VMPTRLD
VMCLEAR: 将执行该指令的物理CPU与它的VMCS解除绑定。该指令会将物理CPU缓存中的VMCS结构同步到内存中去,从而保证VMCS和新的物理CPU绑定时,内存中的值是最新的。
VT-x定义了VMCS的具体格式和内容。规定它是一个最大不超过4KB的内存块,并且要求是4KB对齐。VMCS的格式,各域描述如下:
偏移0处是VMCS版本标识,表示VMCS数据格式的版本号。
偏移4处是VMX中止指示,VM-Exit执行不成功时产生VMX中止,CPU会在此处存入VMX中止的原因,以方便调试。
偏移8处时VMCS数据域,该域的格式是CPU相关的,不同型号的CPU可能使用不同格式,具体使用哪种格式由VMCS版本标识确定。
VMCS主要的信息存放在VMCS数据域,VT-x提供了二条指令用于访问VMCS。
VMREAD < 索引>:读VMCS 中索引 指定的域。
VMWRITE <索引><数据>:写VMCS中索引指定的域。
VT-x为VMCS数据域的每个字段也定义了相应的索引,通过上述二条指令也可以直接访问VMCS数据域中的各个域。
具体而言,VMCS数据域包括下列六大类信息。
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VM-Exit信息域:提供VM-Exit事件的原因及明细信息,VMM利用这些信息来决定如何管理和控制VM,VM-Exit信息域只是只读的。
VMCS中各个域的详细分析:
VM-execution控制类字段
VIRTUAL_PROCESSOR_ID = 0x00000000, /SECONDARY_EXEC_ENABLE_VPID为1,有效,提供16位的VPID/
POSTED_INTR_NV = 0x00000002, /PIN_BASED_POSTED_INTR为1时有效/
IO_BITMAP_A = 0x00002000, /CPU_BASED_USE_IO_BITMAPS启用时,该字段生效/
IO_BITMAP_A_HIGH = 0x00002001,
IO_BITMAP_B = 0x00002002,
IO_BITMAP_B_HIGH = 0x00002003,
/当CPU_BASED_USE_MSR_BITMAPS为1时有效,当某位1时,访问该位所对应的MSR将产生VM-exit,MSR bitmap区域为4k,
低半部分read bitmap,对应MSR范围从00000000H到00001FFFH,用来控制MSR的读访问;
高半部分read bitmap,对应MSR范围从C0000000H到C0001FFFH,用来控制MSR的读访问;
低半部分write bitmap,对应MSR范围从00000000H到00001FFFH,用来控制MSR的写访问;
高半部分write bitmap,对应MSR范围从C0000000H到C0001FFFH,用来控制MSR的写访问;
MSR bitmap的某位为0时,访问该位所对应的MSR不会产生VM-exit/
MSR_BITMAP = 0x00002004,
MSR_BITMAP_HIGH = 0x00002005,
EXCUTIVE_VMCSP = 0x0000200c,
EXCUTIVE_VMCSP_HIGH = 0x0000200d,
/CPU_BASED_USE_TSC_OFFSETING为1时,该字段提供64位的偏移值,执行RDTSC,RDTSCP,RDMSR指令
读取TSC时,返回的值为TSC+TSC offset/
TSC_OFFSET = 0x00002010,
TSC_OFFSET_HIGH = 0x00002011,
/当CPU_BASED_TPR_SHADOW为1时,该字段有效,需要提供一个物理地址作为4k的页面/
VIRTUAL_APIC_PAGE_ADDR = 0x00002012, /Virtual-APIC address (full)/
VIRTUAL_APIC_PAGE_ADDR_HIGH = 0x00002013, /Virtual-APIC address (high)/
/当SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES为1时,该字段有效,需要提供一个物理地址
作为4k的页面/
APIC_ACCESS_ADDR = 0x00002014, /APIC-access address (full)/
APIC_ACCESS_ADDR_HIGH = 0x00002015, /APIC-access address (high)/
POSTED_INTR_DESC_ADDR = 0x00002016,
POSTED_INTR_DESC_ADDR_HIGH = 0x00002017,
/当SECONDARY_EXEC_ENABLE_EPT为1时,支持guest端物理地址转换为host端的最终物理地址
bit2:0指示EPT paging-structure的内存类型(uc或WB);bit5:3指示EPT页表结构层级,这个值加1才是真正的级数;
bit6 =1指示EPT页表结构项里的access与dirty标志位有效(EPT表项的bit8:9),处理器会更新EPT表项的这二个标志位
bit N-1:12提供EPT PML4T表的物理地址。
EPT 页表被载入专门的 EPT 页表指针寄存器 EPTP。EPT 页表对地址的映射机理与客户机页表对地址的映射机理相同 /
EPT_POINTER = 0x0000201a, /EPT pointer (EPTP; full)/
EPT_POINTER_HIGH = 0x0000201b, /EPT pointer (EPTP; high)/
/当SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY为1时,该字段有效,用于控制发送EOI命令时是否
产生VM-exit,对应的位为1时,将产生VM-exit/
EOI_EXIT_BITMAP0 = 0x0000201c, /对应向量号从0H到3FH/
EOI_EXIT_BITMAP0_HIGH = 0x0000201d,
EOI_EXIT_BITMAP1 = 0x0000201e, /对应向量号从40H到7FH/
EOI_EXIT_BITMAP1_HIGH = 0x0000201f,
EOI_EXIT_BITMAP2 = 0x00002020, /对应向量号从80H到BFH/
EOI_EXIT_BITMAP2_HIGH = 0x00002021,
EOI_EXIT_BITMAP3 = 0x00002022, /对应向量号从C0H到FFH/
EOI_EXIT_BITMAP3_HIGH = 0x00002023,
/VMCS Shadowing Bitmap Addresses/
VMREAD_BITMAP = 0x00002026,
VMWRITE_BITMAP = 0x00002028,
/ bit0 =1 发生外部中断则产生VM-exit;bit2:1 保留位,固定为1;
bit3 =1 发生NMI则产生VM-exit;bit4 保留位,固定为1;
bit5 =1 定义virtual NMI;bit6 =1 启用VMX-preemption定时器;
bit7 =1 启用posted-interrupt processing机制处理虚拟中断;
bit31:8 保留位,固定为0/
PIN_BASED_VM_EXEC_CONTROL = 0x00004000, /Pin-based VM-execution controls/
/bit0 保留位,固定为0;bit1 保留位,固定为1;
bit2 =1在IF=1并且中断没被阻塞时,产生VM-exit;bit3 =1读取TSC值时,返回TSC值加上偏移值;
bit6:4 保留值,固定为1;bit7 =1执行HLT指令产生VM-exit;bit8 保留值,固定为1;
bit9 =1执行INVLPG指令产生VM-exit;bit10 =1执行MWAIT指令产生VM-exit;
bit11 =1执行RDPMC指令产生VM-exit;bit12 =1执行RDTSC指令产生VM-exit;bit14:13保留值,固定为1;
bit15 =1写CR3寄存器产生VM-exit;bit16 =1读CR3寄存器产生VM-exit;bit18:17保留值,固定为1;
bit19 =1写CR8寄存器产生VM-exit;bit20 =1读CR8寄存器产生VM-exit;bit21 =1启用virtual-APIC page页面虚拟化local APIC;
bit22 =1开virtual-NMI window时产生VM-exit;bit23 =1读写DR寄存器产生VM-exit;
bit24 =1执行IN/OUT或INS/OUTS类指令产生VM-exit;bit25 =1启用I/O bitmap;bit26 保留位,固定为1;
bit27 =1启用MTF调试功能;bit28 =1启用MSR bitmap;bit29 =1执行MONITOR指令产生VM-exit;
bit30 =1执行PAUSE指令产生VM-exit;bit31 =1Secondary processor-based VM-execution controls字段有效/
CPU_BASED_VM_EXEC_CONTROL = 0x00004002, /Primary processor-based VM-execution controls/
/EXCEPTION_BITMAP字段是一个32位的值,每位对应一个异常向量,在VMX non-root中,如果发生异常, 处理器检查EXCEPTION_BITMAP相应的位,该位为1时则产生VM-exit,为0时通过guest-IDT执行异常处理例程,当triple-fault发生时,直接产生VM-exit/
EXCEPTION_BITMAP = 0x00004004, /Exception bitmap,异常控制/
PAGE_FAULT_ERROR_CODE_MASK = 0x00004006,
PAGE_FAULT_ERROR_CODE_MATCH = 0x00004008,
/最大值为4/
CR3_TARGET_COUNT = 0x0000400a,
/当CPU_BASED_TPR_SHADOW为1时,该字段有效,提供中断优先级的门槛值,低于该值,VM-exit/
TPR_THRESHOLD = 0x0000401c,
/*bit0 =1虚拟化访问APIC-access page;bit1 =1启用EPT;bit2 =1访问GDTR,LDTR,IDTR,TR
产生VM-exit;
bit3 =0执行RDTSCP指令产生#UD异常;bit4 =1虚拟化访问x2APIC MSR;bit5 =1启用VPID机制;
bit6 =1执行WBINVD指令产生VM-exit;bit7=1guest可以使用非分页保护模式或者实模式;
bit8 =1支持访问virtual-APIC page内的虚拟寄存器;bit9 =1支持虚拟中断的delivery;
bit10 =1决定PASUE指令是否产生VM-exit;bit11 =1执行RDRAND指令产生VM-exit;
bit12 =1执行INVPCID指令产生#UD异常;bit13 =1VMX non-root operation可以执行VMFUNC指令;
bit31:14保留位,固定为0/
SECONDARY_VM_EXEC_CONTROL= 0x0000401e, /Secondary processor-based VM-execution controls*/
PLE_GAP = 0x00004020,
PLE_WINDOW = 0x00004022,
/位为1时,表示该位权利属于host所有,为0时,表示该位guest有权设置/
CR0_GUEST_HOST_MASK = 0x00006000, /加速客户机写CR0指令/
CR4_GUEST_HOST_MASK = 0x00006002,
CR0_READ_SHADOW = 0x00006004, /加速客户机读CR0指令/
CR4_READ_SHADOW = 0x00006006,
CR3_TARGET_VALUE0 = 0x00006008,
CR3_TARGET_VALUE1 = 0x0000600a,
CR3_TARGET_VALUE2 = 0x0000600c,
CR3_TARGET_VALUE3 = 0x0000600e,
VM-entry控制类字段
VM_ENTRY_MSR_LOAD_ADDR = 0x0000200a,
VM_ENTRY_MSR_LOAD_ADDR_HIGH = 0x0000200b,
/*bit1:0 保留位,固定为1;bit2 =1加载debug寄存器;bit8:3保留位,固定为1;
bit9 =1进入IA-32e模式;bit10 =1进入SMM模式;bit11 =1返回executive monitor,关闭SMM双重监控处理;
bit12保留位,固定为1;bit13 =1加载IA32_PERF_GLOBAL_CTRL;bit14 =1加载IA32_PAT;
bit15 =1加载IA32_EFER;bit31:16保留值,固定为0*/
VM_ENTRY_CONTROLS= 0x00004012, /VM-Entry Controls,由寄存器MSR_IA32_VMX_ENTRY_CTLS控制/
VM_ENTRY_MSR_LOAD_COUNT = 0x00004014,
/*bit7:0中断或异常向量号;
bit10:8Interruption type:
0: External interrupt
1: Reserved
2: Non-maskable interrupt (NMI)
3: Hardware exception
4: Software interrupt
5: Privileged software exception
6: Software exception
7: Other event
bit11 =1指示有错误码需要提交;bit30:12保留位;
bit31 =1指示VM_ENTRY_INTR_INFO_FIELD字段有效*/
VM_ENTRY_INTR_INFO_FIELD = 0x00004016, /事件注入控制字段/
VM_ENTRY_EXCEPTION_ERROR_CODE = 0x00004018, /VM-entry exception error code/
VM_ENTRY_INSTRUCTION_LEN = 0x0000401a, /VM-entry instruction length/
VM-exit控制类字段
VM_EXIT_MSR_STORE_ADDR = 0x00002006,
VM_EXIT_MSR_STORE_ADDR_HIGH = 0x00002007,
VM_EXIT_MSR_LOAD_ADDR = 0x00002008,
VM_EXIT_MSR_LOAD_ADDR_HIGH = 0x00002009,
/bit1:0保留值,固定为1;bit2 =1保存debug寄存器;bit8:3保留值,固定为1;bit9=1返回到
IA-32e模式;
bit11:10保留值,固定为1;bit12=1加载IA32_PERF_GLOBAL_CTRL;bit14:13保留值,固定为1;
bit15=1VM-exit时处理器响应中断控制器,读取中断向量号;bit17:16保留值,固定为1;
bit18=1保存IA32_PAT;bit19=1加载IA32_PAT;bit20=1保存IA32_EFER;bit21=1加载IA32_EFER;
bit22=1VM-exit时保存VMX定时器计数值;bit31:23保留值,固定为0/
VM_EXIT_CONTROLS = 0x0000400c, /VM-exit controls/
VM_EXIT_MSR_STORE_COUNT = 0x0000400e,
VM_EXIT_MSR_LOAD_COUNT = 0x00004010,
VM-exit信息类字段
VM_INSTRUCTION_ERROR = 0x00004400, /指令失败类/
/基本信息类/
GUEST_PHYSICAL_ADDRESS = 0x00002400, /Guest-physical address保存由于EPT violation或者/
GUEST_PHYSICAL_ADDRESS_HIGH= 0x00002401,/EPT misconfiguration故障引起VM-exit时的GPA值/
VM_EXIT_REASON = 0x00004402, /Exit reason/
EXIT_QUALIFICATION = 0x00006400, /执行指令VM-exit原因,不同指令,该字段有不同的格式/
GUEST_LINEAR_ADDRESS = 0x0000640a, /保存导致VM-exit的某些事件的线性地址值/
/直接向量事件类/
VM_EXIT_INTR_INFO = 0x00004404, /VM-exit interruption information虚拟机退出原因/
VM_EXIT_INTR_ERROR_CODE = 0x00004406,
/间接向量事件类信息字段/
IDT_VECTORING_INFO_FIELD = 0x00004408,
IDT_VECTORING_ERROR_CODE = 0x0000440a,
/指令信息类/
VM_EXIT_INSTRUCTION_LEN = 0x0000440c,
VMX_INSTRUCTION_INFO = 0x0000440e,
/end VM-exit信息类字段/
/start guest-state区域字段/
GUEST_DR7 = 0x0000681a, /调试寄存器/
GUEST_RSP = 0x0000681c, /栈指针/
GUEST_RIP = 0x0000681e, /指令指针/
GUEST_RFLAGS = 0x00006820, /标志寄存器/
/控制寄存器/
GUEST_CR0 = 0x00006800,
GUEST_CR3 = 0x00006802,
GUEST_CR4 = 0x00006804,
/6个数据/代码段寄存器字段,分别为ES,CS,SS,DS,FS,GS寄存器,2个系统段寄存器,分别是
LDTR和TR寄存器。
每个段寄存器有4个字段对应,分别描述段寄存器的各个域:
selector:16位字段;base:64位系统为64位,否则为32位;
limit:32位;access right:32位
access right字段格式:
bit3:0 type段类型值;bit4 0=system,1=code/data;bit6:5段的访问权限;
bit7: 0=no present,1=present;bit11:8 保留;bit12 系统软件可用;
bit13在IA-32e模式下为L标志,在legacy下为保留位;bit14默认操作数size,0=16位,1=32位;
bit15段limit粒度,0=1byte,1=4kb;bit16 0=usable,1=unusable;bit31:17保留/
/ES/
GUEST_ES_SELECTOR = 0x00000800,
GUEST_ES_LIMIT = 0x00004800,
GUEST_ES_AR_BYTES = 0x00004814,
GUEST_ES_BASE = 0x00006806,
/CS/
GUEST_CS_SELECTOR = 0x00000802,
GUEST_CS_LIMIT = 0x00004802,
GUEST_CS_AR_BYTES = 0x00004816,
GUEST_CS_BASE = 0x00006808,
/SS/
GUEST_SS_SELECTOR = 0x00000804,
GUEST_SS_LIMIT = 0x00004804,
GUEST_SS_AR_BYTES = 0x00004818,
GUEST_SS_BASE = 0x0000680a,
/DS/
GUEST_DS_SELECTOR = 0x00000806,
GUEST_DS_LIMIT = 0x00004806,
GUEST_DS_AR_BYTES = 0x0000481a,
GUEST_DS_BASE = 0x0000680c,
/FS/
GUEST_FS_SELECTOR = 0x00000808,
GUEST_FS_LIMIT = 0x00004808,
GUEST_FS_AR_BYTES = 0x0000481c,
GUEST_FS_BASE = 0x0000680e,
/GS/
GUEST_GS_SELECTOR = 0x0000080a,
GUEST_GS_LIMIT = 0x0000480a,
GUEST_GS_AR_BYTES = 0x0000481e,
GUEST_GS_BASE = 0x00006810,
/LDTR局部描述符表寄存器,指令LLDT指令装载到LDTR/
GUEST_LDTR_SELECTOR = 0x0000080c,
GUEST_LDTR_LIMIT = 0x0000480c,
GUEST_LDTR_AR_BYTES = 0x00004820,
GUEST_LDTR_BASE = 0x00006812,
/TR任务寄存器/
GUEST_TR_SELECTOR = 0x0000080e,
GUEST_TR_LIMIT = 0x0000480e,
GUEST_TR_AR_BYTES = 0x00004822,
GUEST_TR_BASE = 0x00006814,
/二个描述符寄存器,GDTR和IDTR.由二个字段组成: base:提供描述符表基地址;limit:提供描述符表的长度. GDTR全局描述符表寄存器,LGDT指令将GDT的入口地址装入此寄存器。/
GUEST_GDTR_LIMIT = 0x00004810,
GUEST_GDTR_BASE = 0x00006816,
/IDTR中断描述符表寄存器/
GUEST_IDTR_LIMIT = 0x00004812,
GUEST_IDTR_BASE = 0x00006818,
/MSR/
GUEST_IA32_DEBUGCTL = 0x00002802,
GUEST_IA32_DEBUGCTL_HIGH = 0x00002803,
GUEST_IA32_PAT = 0x00002804,
GUEST_IA32_PAT_HIGH = 0x00002805,
GUEST_IA32_EFER = 0x00002806,
GUEST_IA32_EFER_HIGH = 0x00002807,
GUEST_IA32_PERF_GLOBAL_CTRL = 0x00002808,
GUEST_IA32_PERF_GLOBAL_CTRL_HIGH= 0x00002809,
GUEST_SYSENTER_CS = 0x0000482A,
GUEST_SYSENTER_ESP = 0x00006824,
GUEST_SYSENTER_EIP = 0x00006826,
非寄存器类字段
GUEST_INTR_STATUS = 0x00000810,/指示虚拟中断的状态/
VMCS_LINK_POINTER = 0x00002800,
VMCS_LINK_POINTER_HIGH = 0x00002801,
GUEST_PDPTR0 = 0x0000280a, /开启EPT使用的字段/
GUEST_PDPTR0_HIGH = 0x0000280b,
GUEST_PDPTR1 = 0x0000280c,
GUEST_PDPTR1_HIGH = 0x0000280d,
GUEST_PDPTR2 = 0x0000280e,
GUEST_PDPTR2_HIGH = 0x0000280f,
GUEST_PDPTR3 = 0x00002810,
GUEST_PDPTR3_HIGH = 0x00002811,
GUEST_ACTIVITY_STATE = 0X00004826,/guest-state指示虚拟机进入/退出,虚拟处理器活动状态/
GUEST_INTERRUPTIBILITY_INFO = 0x00004824,/当前虚拟处理器的可中断性/
VMX_PREEMPTION_TIMER_VALUE = 0x0000482E,
GUEST_PENDING_DBG_EXCEPTIONS = 0x00006822,/pending debug exceptions/
host-state区域字段
HOST_RSP = 0x00006c14, /栈指针/
HOST_RIP = 0x00006c16, /指令指针/
/控制寄存器/
HOST_CR0 = 0x00006c00,
HOST_CR3 = 0x00006c02,
HOST_CR4 = 0x00006c04,
/段选择寄存器/
HOST_ES_SELECTOR = 0x00000c00,
HOST_CS_SELECTOR = 0x00000c02,
HOST_SS_SELECTOR = 0x00000c04,
HOST_DS_SELECTOR = 0x00000c06,
HOST_FS_SELECTOR = 0x00000c08,
HOST_GS_SELECTOR = 0x00000c0a,
HOST_TR_SELECTOR = 0x00000c0c,
/段基址寄存器/
HOST_FS_BASE = 0x00006c06,
HOST_GS_BASE = 0x00006c08,
HOST_TR_BASE = 0x00006c0a,
HOST_GDTR_BASE = 0x00006c0c,
HOST_IDTR_BASE = 0x00006c0e,
/MSR寄存器/
HOST_IA32_PAT = 0x00002c00,
HOST_IA32_PAT_HIGH = 0x00002c01,
HOST_IA32_EFER = 0x00002c02,
HOST_IA32_EFER_HIGH = 0x00002c03,
HOST_IA32_PERF_GLOBAL_CTRL = 0x00002c04,
HOST_IA32_PERF_GLOBAL_CTRL_HIGH = 0x00002c05,
HOST_IA32_SYSENTER_CS = 0x00004c00,
HOST_IA32_SYSENTER_ESP = 0x00006c10,
HOST_IA32_SYSENTER_EIP = 0x00006c12,