Intel 64 and IA-32 Architectures Software Developers Manual Volume 3B, System Programming Guide Part 2

Table Of Contents
23-22 Vol. 3
VM EXITS
Table 23-11. Format of the VM-Exit Instruction-Information Field as Used for
VMCLEAR, VMPTRLD, VMPTRST, and VMXON
Bit Position(s) Content
1:0 Scaling:
0: no scaling
1: scale by 2
2: scale by 4
3: scale by 8 (used only on processors that support Intel 64 architecture)
Undefined for instructions with no index register (bit 22 is set).
6:2 Undefined.
9:7 Address size:
0: 16-bit
1: 32-bit
2: 64-bit (used only on processors that support Intel 64 architecture)
Other values not used.
10 Cleared to 0.
14:11 Undefined.
17:15 Segment register:
0: ES
1: CS
2: SS
3: DS
4: FS
5: GS
Other values not used.
21:18 IndexReg:
0 = RAX
1= RCX
2= RDX
3= RBX
4= RSP
5= RBP
6= RSI
7= RDI
8–15 represent R8–R15, respectively (used only on processors that support
Intel 64 architecture)
Undefined for instructions with no index register (bit 22 is set).
22 IndexReg invalid (0 = valid; 1 = invalid)