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

Table Of Contents
20-8 Vol. 3
VIRTUAL-MACHINE CONTROL STRUCTURES
exceptions without immediately delivering them.
1
This field contains information
about such exceptions. This field is described in Table 20-4.
VMCS link pointer (64 bits). This field is included for future expansion. Software
should set this field to FFFFFFFF_FFFFFFFFH to avoid VM-entry failures (see
Section 22.3.1.5).
VMX-preemption timer value (32 bits). This field is supported only on logical
processors that support the 1-setting of the “activate VMX-preemption timer
VM-execution control. This field contains the value that the VMX-preemption
timer will use following the next VM entry with that setting. See Section 21.7.1
and Section 22.6.4.
Page-directory-pointer-table entries (PDPTEs; 64 bits each). These four (4)
fields (PDPTE0, PDPTE1, PDPTE2, and PDPTE3) are supported only on logical
processors that support the 1-setting of the “enable EPT” VM-execution control.
They correspond to the PDPTEs referenced by CR3 when PAE paging is in use (see
Section 3.8 in the Intel® 64 and IA-32 Architectures Software Developer’s
1. For example, execution of a MOV to SS or a POP to SS may inhibit some debug exceptions for one
instruction. See Section 5.8.3 of Intel® 64 and IA-32 Architectures Software Developer’s Manual,
Volume 3A. In addition, certain events incident to an instruction (for example, an INIT signal) may
take priority over debug traps generated by that instruction. See Table 5-2 in the Intel® 64 and
IA-32 Architectures Software Developer’s Manual, Volume 3A.
Table 20-4. Format of Pending-Debug-Exceptions
Bit
Position(s)
Bit Name Notes
3:0 B3 – B0 When set, each of these bits indicates that the corresponding
breakpoint condition was met. Any of these bits may be set
even if the corresponding enabling bit in DR7 is not set.
11:4 Reserved VM entry fails if these bits are not 0. See Section 22.3.1.5.
12 Enabled
breakpoint
When set, this bit indicates that at least one data or I/O
breakpoint was met and was enabled in DR7.
13 Reserved VM entry fails if this bit is not 0. See Section 22.3.1.5.
14 BS When set, this bit indicates that a debug exception would
have been triggered by single-step execution mode.
63:15 Reserved VM entry fails if these bits are not 0. See Section 22.3.1.5.
Bits 63:32 exist only on processors that support Intel 64
architecture.