From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] kvm/x86/vmx: report KVM_SYSTEM_EVENT_CRASH on triple fault Date: Tue, 28 Mar 2017 03:51:01 -0400 (EDT) Message-ID: <2101391670.8452799.1490687461888.JavaMail.zimbra@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: rkrcmar@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org To: Josh Poimboeuf Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48692 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754563AbdC1H5X (ORCPT ); Tue, 28 Mar 2017 03:57:23 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: > 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 > --- > 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 > >