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

Vol. 3 I-1
APPENDIX I
VMX BASIC EXIT REASONS
Every VM exit writes a 32-bit exit reason to the VMCS (see Section 20.9.1). Certain
VM-entry failures also do this (see Section 22.7). The low 16 bits of the exit-reason
field form the basic exit reason which provides basic information about the cause of
the VM exit or VM-entry failure.
Table I-1 lists values for basic exit reasons and explains their meaning. Entries apply
to VM exits, unless otherwise noted.
Table I-1. Basic Exit Reasons
Basic Exit
Reason Description
0 Exception or non-maskable interrupt (NMI). Either:
1: Guest software caused an exception and the bit in the exception bitmap
associated with exception’s vector was 1.
2: An NMI was delivered to the logical processor and the “NMI exiting”
VM-execution control was 1. This case includes executions of BOUND that cause
#BR, executions of INT3 (they cause #BP), executions of INTO that cause #OF,
and executions of UD2 (they cause #UD).
1 External interrupt. An external interrupt arrived and the “external-interrupt
exiting” VM-execution control was 1.
2 Triple fault. The logical processor encountered an exception while attempting to
call the double-fault handler and that exception did not itself cause a VM exit due
to the exception bitmap.
3 INIT signal. An INIT signal arrived
4 Start-up IPI (SIPI). A SIPI arrived while the logical processor was in the “wait-for-
SIPI” state.
5 I/O system-management interrupt (SMI). An SMI arrived immediately after
retirement of an I/O instruction and caused an SMM VM exit (see Section 25.15.2).
6 Other SMI. An SMI arrived and caused an SMM VM exit (see Section 25.15.2) but
not immediately after retirement of an I/O instruction.
7 Interrupt window. At the beginning of an instruction, RFLAGS.IF was 1; events
were not blocked by STI or by MOV SS; and the “interrupt-window exiting”
VM-execution control was 1.
8 NMI window. At the beginning of an instruction, there was no virtual-NMI blocking;
events were not blocked by MOV SS; and the “NMI-window exiting” VM-execution
control was 1.
9 Task switch. Guest software attempted a task switch.
10 CPUID. Guest software attempted to execute CPUID.