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

Table Of Contents
Vol. 3 22-13
VM ENTRIES
Bit 14 (D/B). For CS, D/B must be 0 if the guest will be IA-32e mode
and the L bit (bit 13) in the access-rights field is 1.
Bit 15 (G). The following checks apply if the register is CS or if the
register is usable:
If any bit in the limit field in the range 11:0 is 0, G must be 0.
If any bit in the limit field in the range 31:20 is 1, G must be 1.
Bits 31:17 (reserved). If the register is CS or if the register is
usable, these bits must all be 0.
TR. The different sub-fields are considered separately:
Bits 3:0 (Type).
If the guest will not be IA-32e mode, the Type must be 3 (16-bit
busy TSS) or 11 (32-bit busy TSS).
If the guest will be IA-32e mode, the Type must be 11 (64-bit busy
TSS).
Bit 4 (S). S must be 0.
Bit 7 (P). P must be 1.
Bits 11:8 (reserved). These bits must all be 0.
Bit 15 (G).
If any bit in the limit field in the range 11:0 is 0, G must be 0.
If any bit in the limit field in the range 31:20 is 1, G must be 1.
Bit 16 (Unusable). The unusable bit must be 0.
Bits 31:17 (reserved). These bits must all be 0.
LDTR. The following checks on the different sub-fields apply only if LDTR is
usable:
Bits 3:0 (Type). The Type must be 2 (LDT).
Bit 4 (S). S must be 0.
Bit 7 (P). P must be 1.
Bits 11:8 (reserved). These bits must all be 0.
Bit 15 (G).
If any bit in the limit field in the range 11:0 is 0, G must be 0.
If any bit in the limit field in the range 31:20 is 1, G must be 1.
Bits 31:17 (reserved). These bits must all be 0.
22.3.1.3 Checks on Guest Descriptor-Table Registers
The following checks are performed on the fields for GDTR and IDTR: