linux-kernel - [PATCH] kvm/x86/vmx: report KVM_SYSTEM_EVENT

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Message-Id: <f6ad65ee00ce0207701293200f6aa4d691cac3f8.1490642724.git.jpoimboe@redhat.com>
Date:   Mon, 27 Mar 2017 14:25:35 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, rkrcmar@...hat.com
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: [PATCH] kvm/x86/vmx: report KVM_SYSTEM_EVENT_CRASH on triple fault

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.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 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