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

Table Of Contents
Vol. 3 24-5
SUPPORT FOR ADDRESS TRANSLATION
Bits 63:52 are all 0.
Bits 51:12 are from the EPT PDE.
Bits 11:3 are bits 20:12 of the guest-physical address.
Bits 2:0 are all 0.
The final physical address is computed as follows:
Bits 63:52 are all 0.
Bits 51:12 are from the EPT PTE (see Table 24-5).
Bits 11:0 are from the original guest-physical address.
If bit 7 of the EPT PDE is 1, the final physical address is computed as follows:
Bits 63:52 are all 0.
Bits 51:21 are from the EPT PDE (see Table 24-4).
Bits 20:0 are from the original guest-physical address.
If bits 2:0 of an EPT paging-structure entry are all 0, the entry is not present and is
used neither to reference another EPT paging-structure entry nor to produce a phys-
ical address. A reference using a guest-physical address whose translation encoun-
ters an EPT paging-structure that is not present causes an EPT violation.
The discussion above describes how the EPT paging structures reference each other
and how the logical processor traverses those structures when translating a guest-
physical address. It does not cover all details of the translation process. Additional
details are provided as follows:
Details of the EPT paging-structure entries are given in Section 24.2.3.
Situations in which the translation process may lead to VM exits (sometimes
before the process completes) are described in Section 24.2.4.
Interactions between the EPT translation mechanism and memory typing are
described in Section 24.2.5.
24.2.3 EPT Paging Structures
Each EPT paging structure is 4 KBytes in size and comprises 512 8-Byte entries. This
section specifies the formats of these entries.