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

Table Of Contents
Vol. 3 23-9
VM EXITS
For MOV DR, the exit qualification contains information about the instruction
and has the format given in Table 23-4.
For an I/O instruction, the exit qualification contains information about the
instruction and has the format given in Table 23-5.
Table 23-4. Exit Qualification for MOV DR
Bit Position(s) Contents
2:0 Number of debug register
3 Reserved (cleared to 0)
4 Direction of access (0
= MOV to DR; 1 = MOV from DR)
7:5 Reserved (cleared to 0)
11:8 General-purpose register:
0 = RAX
1= RCX
2= RDX
3= RBX
4= RSP
5= RBP
6= RSI
7= RDI
8 –15 = R8 – R15, respectively
63:12 Reserved (cleared to 0)
Table 23-5. Exit Qualification for I/O Instructions
Bit Position(s) Contents
2:0 Size of access:
0= 1-byte
1= 2-byte
3= 4-byte
Other values not used
3 Direction of the attempted access (0
= OUT, 1 = IN)
4 String instruction (0 = not string; 1 = string)