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

Table Of Contents
Vol. 3 24-9
SUPPORT FOR ADDRESS TRANSLATION
Note that, if bits 2:0 of an EPT PDE are all 0, the entry is considered to be “not
present”; the logical processor ignores bits 63:3 (including bit 7) of such an entry
and will use it neither to reference an EPT page table nor to map a 2-MByte page.
24.2.3.4 EPT Page-Table Entries
An EPT page-table entry (PTE) is identified using bits 47:12 of the guest-physical
address (see Section 24.2.2) and thus maps a 4-Kbyte page. Table 24-3 shows the
format of an EPT PDE.
7 Must be 1 (otherwise, this entry references an EPT page table)
11:8 Ignored
20:12 Reserved (must be 0)
N–1:21 Physical address of the 2-MByte page referenced by this entry
1
51:N Reserved (must be 0)
63:52 Ignored
NOTES:
1. N is the physical-address width supported by the logical processor.
Table 24-5. Format of an EPT Page-Table Entry
Bit
Position(s)
Contents
0 Read access; indicates whether reads are allowed from the 4-KByte page
referenced by this entry
1 Write access; indicates whether writes are allowed to the 4-KByte page
referenced by this entry
2 Execute access; indicates whether instruction fetches are allowed from the 4-
KByte page referenced by this entry
5:3 EPT memory type for this 4-KByte page (see Section 24.2.5)
6 Ignore PAT memory type for this 4-KByte page (see Section 24.2.5)
11:7 Ignored
Table 24-4. Format of an EPT Page-Directory Entry that Maps a 2-MByte Page
Bit
Position(s)
Contents