virtio-net: Gracefully handle passt process quitting

When the process quits, prints an error msg and effectively disables virtio-net.

Signed-off-by: Matej Hrica <[email protected]>

Author: mtjhrc

src/devices/src/virtio/net/device.rs

@@ -176,6 +176,9 @@ impl Net {
             Err(e @ passt::WriteError::Internal(_)) => {
                 log::error!("Failed to finish write: {e:?}");
             }
+            Err(e @ passt::WriteError::ProcessNotRunning) => {
+                log::debug!("Failed to finish write: {e:?}");
+            }
         }
     }
 
@@ -318,7 +321,10 @@ impl Net {
                     dropped_frames += drop_rest_of_frames(tx_queue);
                     break;
                 }
-                Err(e @ passt::WriteError::Internal(_)) => return Err(TxError::Passt(e)),
+
+                Err(
+                    e @ passt::WriteError::Internal(_) | e @ passt::WriteError::ProcessNotRunning,
+                ) => return Err(TxError::Passt(e)),
             }
         }
 

src/devices/src/virtio/net/event_handler.rs

@@ -65,12 +65,19 @@ impl Subscriber for Net {
                     self.process_tx_queue_event();
                 }
                 _ if source == passt_socket => {
-                    if event_set.contains(EventSet::IN) {
-                        self.process_passt_socket_readable()
-                    }
+                    if event_set.contains(EventSet::HANG_UP)
+                        || event_set.contains(EventSet::READ_HANG_UP)
+                    {
+                        log::error!("Got {event_set:?} on passt fd, virtio-net will stop working");
+                        eprintln!("LIBKRUN VIRTIO-NET FATAL: Passt process seems to have quit or crashed! Networking is now disabled!");
+                    } else {
+                        if event_set.contains(EventSet::IN) {
+                            self.process_passt_socket_readable()
+                        }
 
-                    if event_set.contains(EventSet::OUT) {
-                        self.process_passt_socket_writeable()
+                        if event_set.contains(EventSet::OUT) {
+                            self.process_passt_socket_writeable()
+                        }
                     }
                 }
                 _ => {
@@ -95,7 +102,10 @@ impl Subscriber for Net {
                 EpollEvent::new(EventSet::IN, self.queue_evts[RX_INDEX].as_raw_fd() as u64),
                 EpollEvent::new(EventSet::IN, self.queue_evts[TX_INDEX].as_raw_fd() as u64),
                 EpollEvent::new(
-                    EventSet::IN | EventSet::OUT | EventSet::EDGE_TRIGGERED,
+                    EventSet::IN
+                        | EventSet::OUT
+                        | EventSet::EDGE_TRIGGERED
+                        | EventSet::READ_HANG_UP,
                     self.raw_passt_socket_fd() as u64,
                 ),
             ]

src/devices/src/virtio/net/passt.rs

@@ -21,6 +21,8 @@ pub enum WriteError {
     NothingWritten,
     /// Part of the buffer was written, the write has to be finished using try_finish_write
     PartialWrite,
+    /// Passt doesnt seem to be running (received EPIPE)
+    ProcessNotRunning,
     /// Another internal error occurred
     Internal(nix::Error),
 }
@@ -183,6 +185,7 @@ impl Passt {
                         return Err(WriteError::PartialWrite);
                     }
                 }
+                Err(nix::Error::EPIPE) => return Err(WriteError::ProcessNotRunning),
                 Err(e) => return Err(WriteError::Internal(e)),
             }
         }