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

Table Of Contents
Vol. 3 23-19
VM EXITS
10 Cleared to 0.
11 Undefined.
13:12 Operand size:
1: 16-bit
2: 32-bit
Other values not used. Undefined for VM exits from 64-bit mode.
14 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)
26:23 BaseReg (encoded as IndexReg above)
Undefined for instructions with no base register (bit 27 is set).
27 BaseReg invalid (0 = valid; 1 = invalid)
Table 23-9. Format of the VM-Exit Instruction-Information Field as Used for LIDT,
LGDT, SIDT, or SGDT (Contd.)
Bit Position(s) Content