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

Table Of Contents
Vol. 3 22-15
VM ENTRIES
The activity-state field must indicate the active state if the interruptibility-
state field indicates blocking by either MOV-SS or by STI (if either bit 0 or
bit 1 in that field is 1).
If the valid bit (bit 31) in the VM-entry interruption-information field is 1, the
interruption to be delivered (as defined by interruption type and vector) must
not be one that would normally be blocked while a logical processor is in the
activity state corresponding to the contents of the activity-state field. The
following items enumerate the interruptions (as specified in the VM-entry
interruption-information field) whose injection is allowed for the different
activity states:
Active. Any interruption is allowed.
HLT. The only events allowed are the following:
Those with interruption type external interrupt or non-maskable
interrupt (NMI).
Those with interruption type hardware exception and vector 1
(debug exception) or vector 18 (machine-check exception).
Those with interruption type other event and vector 0 (pending MTF
VM exit).
See Table 20-12 in Section 20.8.3 for details regarding the format of the
VM-entry interruption-information field.
Shutdown. Only NMIs and machine-check exceptions are allowed.
Wait-for-SIPI. No interruptions are allowed.
The activity-state field must not indicate the wait-for-SIPI state if the “entry
to SMM” VM-entry control is 1.
Interruptibility state.
The reserved bits (bits 31:4) must be 0.
The field cannot indicate blocking by both STI and MOV SS (bits 0 and 1
cannot both be 1).
Bit 0 (blocking by STI) must be 0 if the IF flag (bit 9) is 0 in the RFLAGS field.
Bit 0 (blocking by STI) and bit 1 (blocking by MOV-SS) must both be 0 if the
valid bit (bit 31) in the VM-entry interruption-information field is 1 and the
interruption type (bits 10:8) in that field has value 0, indicating external
interrupt.
Bit 1 (blocking by MOV-SS) must be 0 if the valid bit (bit 31) in the VM-entry
interruption-information field is 1 and the interruption type (bits 10:8) in that
field has value 2, indicating non-maskable interrupt (NMI).
2. As noted in Section 20.4.1, SS.DPL corresponds to the logical processor’s current privilege level
(CPL).