virtio-devices: Simplify virtio device reset

Rather than having to give and return the ioeventfd used for a device
clone them each time. This will make it simpler when we start handling
the driver enabling fewer queues than advertised by the device.

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

virtio-devices/src/device.rs

@@ -116,7 +116,7 @@ pub trait VirtioDevice: Send {
 
     /// Optionally deactivates this device and returns ownership of the guest memory map, interrupt
     /// event, and queue events.
-    fn reset(&mut self) -> Option<(Arc<dyn VirtioInterrupt>, Vec<EventFd>)> {
+    fn reset(&mut self) -> Option<Arc<dyn VirtioInterrupt>> {
         None
     }
 
@@ -288,7 +288,7 @@ impl VirtioCommon {
         Ok(())
     }
 
-    pub fn reset(&mut self) -> Option<(Arc<dyn VirtioInterrupt>, Vec<EventFd>)> {
+    pub fn reset(&mut self) -> Option<Arc<dyn VirtioInterrupt>> {
         // We first must resume the virtio thread if it was paused.
         if self.pause_evt.take().is_some() {
             self.resume().ok()?;
@@ -307,11 +307,8 @@ impl VirtioCommon {
             }
         }
 
-        // Return the interrupt and queue EventFDs
-        Some((
-            self.interrupt_cb.take().unwrap(),
-            self.queue_evts.take().unwrap(),
-        ))
+        // Return the interrupt
+        Some(self.interrupt_cb.take().unwrap())
     }
 }