watchdog/diag288: don't reset for action=none|debug|pause

If the watchdog expires and the guest is not notified (NONE, DEBUG, PAUSE),
we must not reset the watchdog device, otherwise watchdog_ping() and
watchdog_stop() will fail when triggered by the guest. This reset behavior
matches to the z/VM behavior when a custom command is to be executed
on expiry.

Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Bo Tu <tubo@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

hw/watchdog/wdt_diag288.c

@@ -51,6 +51,13 @@ static void diag288_timer_expired(void *dev)
 {
     qemu_log_mask(CPU_LOG_RESET, "Watchdog timer expired.\n");
     watchdog_perform_action();
+    /* Reset the watchdog only if the guest was notified about expiry. */
+    switch (get_watchdog_action()) {
+    case WDT_DEBUG:
+    case WDT_NONE:
+    case WDT_PAUSE:
+         return;
+    }
     wdt_diag288_reset(dev);
 }