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

Table Of Contents
H-8 Vol. 3
FIELD ENCODING IN VMCS
The limit fields for GDTR and IDTR are defined to be 32 bits in width even though
these fields are only 16-bits wide in the Intel 64 and IA-32 architectures. VM entry
ensures that the high 16 bits of both these fields are cleared to 0.
H.3.4 32-Bit Host-State Field
A value of 3 in bits 11:10 of an encoding indicates a field in the host-state area.
There is only one such 32-bit field as given in Table H-11.
H.4 NATURAL-WIDTH FIELDS
A value of 3 in bits 14:13 of an encoding indicates a natural-width field. As noted in
Section 20.10.2, each of these fields allows only full access, meaning that bit 0 of its
encoding is 0. Each such encoding is thus an even number.
H.4.1 Natural-Width Control Fields
A value of 0 in bits 11:10 of an encoding indicates a control field. These fields are
distinguished by their index value in bits 9:1. Table H-12 enumerates the natural-
width control fields.
Guest activity state 000010011B 00004826H
Guest SMBASE 000010100B 00004828H
Guest IA32_SYSENTER_CS 000010101B 0000482AH
VMX-preemption timer value 000010111B 0000482EH
Table H-11. Encoding for 32-Bit Host-State Field (0100_11xx_xxxx_xxx0B)
Field Name Index Encoding
Host IA32_SYSENTER_CS 000000000B 00004C00H
Table H-12. Encodings for Natural-Width Control Fields (0110_00xx_xxxx_xxx0B)
Field Name Index Encoding
CR0 guest/host mask 000000000B 00006000H
CR4 guest/host mask 000000001B 00006002H
CR0 read shadow 000000010B 00006004H
Table H-10. Encodings for 32-Bit Guest-State Fields
(0100_10xx_xxxx_xxx0B) (Contd.)
Field Name Index Encoding