stgi

Set Global Interrupt Flag

STGI

Enables global interrupts (AMD SVM).

Pseudocode Operation

GIF ← 1; // Global interrupt flag enabled

Encoding

Binary Layout

0F

+0

01

+1

DC

+2

 

Format SVM

Opcode 0F 01 DC

Extension SVM

Operands

Related

More in SVM

Reference

View in Intel® 64 and IA-32 Architectures SDM ↗ AMD APM

Instruction Forms

Opcode	Instruction	Op/En	64/32-bit Mode	CPUID	Description
0F 01 DC	STGI				Sets the global interrupt flag (GIF).

Description

Sets the global interrupt flag (GIF) to 1. While GIF is zero, all external interrupts are disabled. This is a Secure Virtual Machine (SVM) instruction. Attempted execution of this instruction causes a #UD exception if SVM is not enabled and neither SVM Lock nor the device exclusion vector (DEV) are supported. Support for SVM Lock is indicated by CPUID Fn8000_000A_EDX[SVML] = 1. Support for DEV is part of the SKINIT architecture and is indicated by CPUID Fn8000_0001_ECX[SKINIT] = 1. For more information on using the CPUID instruction, see the description of the CPUID instruction on page 165. For information on enabling SVM, see “Enabling SVM” in APM Volume 2.

Flags Affected

None.

Exceptions

Exceptions

Virtual Exception Real 8086 Protected Cause of Exception Secure Virtual Machine was not enabled (EFER.SVME=0) and both of the following conditions were true: • SVM Lock is not available, as indicated by X CPUID Fn8000_000A_EDX[SVML] = 0. Invalid opcode, #UD • DEV is not available, as indicated by CPUID Fn8000_0001_ECX[SKINIT] = 0. X X Instruction is only recognized in protected mode. General protection, X CPL was not 0. #GP System Instruction Reference 469