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

Table Of Contents
Vol. 3 20-19
VIRTUAL-MACHINE CONTROL STRUCTURES
The EPTP exists only on processors that support the 1-setting of the “enable EPT”
VM-execution control.
20.6.12 Virtual-Processor Identifier (VPID)
The virtual-processor identifier (VPID) is a 16-bit field. It exists only on proces-
sors that support the 1-setting of the “enable VPID” VM-execution control. See
Chapter 24.1 for details regarding the use of this field.
20.7 VM-EXIT CONTROL FIELDS
The VM-exit control fields govern the behavior of VM exits. They are discussed in
Section 20.7.1 and Section 20.7.2.
20.7.1 VM-Exit Controls
The VM-exit controls constitute a 32-bit vector that governs the basic operation of
VM exits. Table 20-9 lists the controls supported. See Chapter 23 for complete details
of how these controls affect VM exits.
Table 20-9. Definitions of VM-Exit Controls
Bit Position(s) Name Description
2 Save debug
controls
This control determines whether DR7 and the
IA32_DEBUGCTL MSR are saved on VM exit.
Note that the first processors to support the virtual-
machine extensions supported only the 1-setting of this
control.
9Host address-
space size
On processors that support Intel 64 architecture, this
control determines whether a logical processor is in 64-bit
mode after the next VM exit. Its value is loaded into CS.L,
IA32_EFER.LME, and IA32_EFER.LMA on every VM exit.
1
This control must be 0 on processors that do not support
Intel 64 architecture.
12 Load
IA32_PERF_GLOB
AL_CTRL
This control determines whether the
IA32_PERF_GLOBAL_CTRL MSR is loaded on VM exit.