vmm: Unpark the DeviceManager threads in shutdown

To ensure that the DeviceManager threads (such as those used for virtio
devices) are cleaned up it is necessary to unpark them so that they get
cleanly terminated as part of the shutdown.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vmm/src/vm.rs

@@ -608,6 +608,13 @@ impl Vm {
             signals.close();
         }
 
+        // Wake up the DeviceManager threads so they will get terminated cleanly
+        self.device_manager
+            .lock()
+            .unwrap()
+            .resume()
+            .map_err(Error::Resume)?;
+
         self.cpu_manager
             .lock()
             .unwrap()