> While debugging a kernel issue, I found that QEMU always reboots when an
> x86 triple fault occurs, which complicates debugging. QEMU and libvirt
> have a facility for creating a dump when KVM reports
> KVM_SYSTEM_EVENT_CRASH. So change the VMX triple fault handler to do
> that. This gives user space the ability to decide whether to dump,
> pause, shutdown, or reboot.
You probably want QEMU's -no-reboot option.
Triple faults are already reported to userspace with KVM_EXIT_SHUTDOWN,
and it's up to userspace to decide what to do with it. This patch cannot
be applied, because there are guests that do a triple-fault intentionally
in order to reset the machine.
Paolo
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 3 ++-
> include/trace/events/kvm.h | 3 ++-
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 3acde66..1f2694c 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -5731,7 +5731,8 @@ static int handle_external_interrupt(struct kvm_vcpu
> *vcpu)
>
> static int handle_triple_fault(struct kvm_vcpu *vcpu)
> {
> - vcpu->run->exit_reason = KVM_EXIT_SHUTDOWN;
> + vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
> + vcpu->run->system_event.type = KVM_SYSTEM_EVENT_CRASH;
> return 0;
> }
>
> diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
> index 8ade3eb..200a3d7 100644
> --- a/include/trace/events/kvm.h
> +++ b/include/trace/events/kvm.h
> @@ -14,7 +14,8 @@
> ERSN(SHUTDOWN), ERSN(FAIL_ENTRY), ERSN(INTR), ERSN(SET_TPR), \
> ERSN(TPR_ACCESS), ERSN(S390_SIEIC), ERSN(S390_RESET), ERSN(DCR),\
> ERSN(NMI), ERSN(INTERNAL_ERROR), ERSN(OSI), ERSN(PAPR_HCALL), \
> - ERSN(S390_UCONTROL), ERSN(WATCHDOG), ERSN(S390_TSCH)
> + ERSN(S390_UCONTROL), ERSN(WATCHDOG), ERSN(S390_TSCH), \
> + ERSN(SYSTEM_EVENT)
>
> TRACE_EVENT(kvm_userspace_exit,
> TP_PROTO(__u32 reason, int errno),
> --
> 2.7.4
>
>
