Intel 64 and IA-32 Architectures Software Developers Manual Volume 2A, Instruction Set Reference, A-M

3-110 Vol. 2
INSTRUCTION SET REFERENCE, A-M
Operation
IF PE = 0
THEN
IF
← 0; (* Reset Interrupt Flag *)
ELSE
IF VM
= 0;
THEN
IF IOPL
← CPL
THEN
IF
← 0; (* Reset Interrupt Flag *)
ELSE
IF ((IOPL
< CPL) and (CPL = 3) and (PVI = 1))
THEN
VIF
← 0; (* Reset Virtual Interrupt Flag *)
ELSE
#GP(0);
FI;
FI;
ELSE (* VM = 1 *)
IF IOPL
= 3
THEN
IF
← 0; (* Reset Interrupt Flag *)
ELSE
IF (IOPL
< 3) AND (VME = 1)
THEN
VIF
← 0; (* Reset Virtual Interrupt Flag *)
ELSE
#GP(0);
FI;
FI;
FI;
FI;
Flags Affected
If protected-mode virtual interrupts are not enabled, IF is set to 0 if the CPL is equal
to or less than the IOPL; otherwise, it is not affected. The other flags in the EFLAGS
register are unaffected.
When protected-mode virtual interrupts are enabled, CPL is 3, and IOPL is less than
3; CLI clears the VIF flag in the EFLAGS register, leaving IF unaffected.