vl: exit qemu on guest panic if -no-shutdown is not set

For automated testing purposes it can be helpful to exit qemu
(poweroff) when the guest panics. Make this the default unless
-no-shutdown is specified.

For internal-errors like errors from KVM_RUN the behaviour is
not changed, in other words QEMU does not exit to allow debugging
in the QEMU monitor.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Message-Id: <1476775794-108012-1-git-send-email-borntraeger@de.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

qapi-schema.json

@@ -4621,10 +4621,10 @@
 #
 # @pause: system pauses
 #
-# Since: 2.1
+# Since: 2.1 (poweroff since 2.8)
 ##
 { 'enum': 'GuestPanicAction',
-  'data': [ 'pause' ] }
+  'data': [ 'pause', 'poweroff' ] }
 
 ##
 # @rtc-reset-reinjection

vl.c

@@ -1792,6 +1792,11 @@ void qemu_system_guest_panicked(void)
     }
     qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_PAUSE, &error_abort);
     vm_stop(RUN_STATE_GUEST_PANICKED);
+    if (!no_shutdown) {
+        qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_POWEROFF,
+                                       &error_abort);
+        qemu_system_shutdown_request();
+    }
 }
 
 void qemu_system_reset_request(void)