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

Table Of Contents
20-18 Vol. 3
VIRTUAL-MACHINE CONTROL STRUCTURES
A logical processor uses these bitmaps if and only if the “use MSR bitmaps” control
is 1. If the bitmaps are used, an execution of RDMSR or WRMSR causes a VM exit if
the value of RCX is in neither of the ranges covered by the bitmaps or if the appro-
priate bit in the MSR bitmaps (corresponding to the instruction and the RCX value) is
1. See Section 21.1.3 for details. If the bitmaps are used, their address must be 4-
KByte aligned.
20.6.10 Executive-VMCS Pointer
The executive-VMCS pointer is a 64-bit field used in the dual-monitor treatment of
system-management interrupts (SMIs) and system-management mode (SMM). SMM
VM exits save this field as described in Section 25.15.2. VM entries that return from
SMM use this field as described in Section 25.15.4.
20.6.11 Extended-Page-Table Pointer (EPTP)
The extended-page-table pointer (EPTP) contains the address of the base of
EPML4 table (see Chapter 24), as well as other EPT configuration information. The
format of this field is shown in Table 20-8.
Table 20-8. Format of Extended-Page-Table Pointer
Bit Position(s) Field
2:0 EPT paging-structure memory type (see Section 24.2.5):
0 = Uncacheable (UC)
6= Write-back (WB)
Other values are reserved.
1
NOTES:
1. Software should read the VMX capability MSR IA32_VMX_EPT_VPID_CAP (see Appendix G.10) to
determine what EPT paging-structure memory types are supported.
5:3 This value is 1 less than the EPT page-walk length (see Section 24.2.2)
11:6 Reserved
N–1:12 Bits N–1:12 of the physical address of the 4-KByte aligned EPT PML4 table
2
2. N is the physical-address width supported by the logical processor. Software can determine a pro-
cessor’s physical-address width by executing CPUID with 80000008H in EAX. The physical-
address width is returned in bits 7:0 of EAX.
51:N Reserved
63:52 Reserved