Intel 64 and IA-32 Architectures Software Developers Manual Volume 2B, Instruction Set Reference, N-Z

Vol. 2B 5-25

VMX INSTRUCTION REFERENCE

VMXOFF—Leave VMX Operation

Description

Takes the logical processor out of VMX operation, unblocks INIT signals, re-enables

A20M, and clears any address-range monitoring.

Operation

IF (not in VMX operation) or (RFLAGS.VM = 1) or

(IA32_EFER.LMA = 1 and CS.L = 0)

THEN #UD;

ELSIF in VMX non-root operation

THEN VMexit;

ELSIF CPL > 0

THEN #GP(0);

ELSIF dual-monitor treatment of SMIs and SMM is active

THEN VMfail(VMXOFF under dual-monitor treatment of SMIs and SMM);

ELSE

leave VMX operation;

unblock INIT;

unblock and enable A20M;

clear address-range monitoring;

VMsucceed;

FI;

Flags Affected

See the operation section and Section 5.2.

Use of Prefixes

LOCK Causes #UD

REP* Cause #UD (includes REPNE/REPNZ and REP/REPE/REPZ)

Segment overrides Ignored

Operand size Causes #UD

Opcode Instruction Description

0F 01 C4 VMXOFF Leaves VMX operation.

1. See the information on MONITOR/MWAIT in Chapter 7, “Multiple-Processor Management,” of the

Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3A.