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

Table Of Contents
20-12 Vol. 3
VIRTUAL-MACHINE CONTROL STRUCTURES
19 CR8-load exiting This control determines whether executions of MOV to CR8
cause VM exits.
This control must be 0 on processors that do not support
Intel 64 architecture.
20 CR8-store exiting This control determines whether executions of MOV from
CR8 cause VM exits.
This control must be 0 on processors that do not support
Intel 64 architecture.
21 Use TPR shadow Setting this control to 1 activates the TPR shadow, which is
maintained in a page of memory addressed by the virtual-
APIC address. See Section 21.4.
This control must be 0 on processors that do not support
Intel 64 architecture.
22 NMI-window
exiting
If this control is 1, a VM exit occurs at the beginning of any
instruction if there is no virtual-NMI blocking (see Section
20.4.2).
This control can be set only if the “virtual NMIs” VM-execution
control (see Section 20.6.1) is 1.
23 MOV-DR exiting This control determines whether executions of MOV DR
cause VM exits.
24 Unconditional I/O
exiting
This control determines whether executions of I/O
instructions (IN, INS/INSB/INSW/INSD, OUT, and
OUTS/OUTSB/OUTSW/OUTSD) cause VM exits.
This control is ignored if the “use I/O bitmaps” control is 1.
25 Use I/O bitmaps This control determines whether I/O bitmaps are used to
restrict executions of I/O instructions (see Section 20.6.4 and
Section 21.1.3).
For this control, “0” means “do not use I/O bitmaps” and “1”
means “use I/O bitmaps.” If the I/O bitmaps are used, the
setting of the “unconditional I/O exiting” control is ignored.
27 Monitor trap flag If this control is 1, the monitor trap flag debugging feature is
enabled. See Section 21.7.2.
Table 20-6. Definitions of Primary Processor-Based VM-Execution Controls (Contd.)
Bit Position(s) Name Description