vm-virtio, vmm: Delete unix socket on shutdown

It's not possible to call UnixListener::Bind() on an existing file so
unlink the created socket when shutting down the Vsock device.

This will allow the VM to be rebooted with a vsock device.

Fixes: #1083

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

vm-virtio/src/vsock/device.rs

@@ -40,6 +40,7 @@ use libc::EFD_NONBLOCK;
 use std;
 use std::io;
 use std::os::unix::io::AsRawFd;
+use std::path::PathBuf;
 use std::result;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, RwLock};
@@ -387,6 +388,7 @@ pub struct Vsock<B: VsockBackend> {
     interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
     epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
     paused: Arc<AtomicBool>,
+    path: PathBuf,
 }
 
 impl<B> Vsock<B>
@@ -395,7 +397,13 @@ where
 {
     /// Create a new virtio-vsock device with the given VM CID and vsock
     /// backend.
-    pub fn new(id: String, cid: u64, backend: B, iommu: bool) -> io::Result<Vsock<B>> {
+    pub fn new(
+        id: String,
+        cid: u64,
+        path: PathBuf,
+        backend: B,
+        iommu: bool,
+    ) -> io::Result<Vsock<B>> {
         let mut avail_features = 1u64 << VIRTIO_F_VERSION_1 | 1u64 << VIRTIO_F_IN_ORDER;
 
         if iommu {
@@ -414,6 +422,7 @@ where
             interrupt_cb: None,
             epoll_threads: None,
             paused: Arc::new(AtomicBool::new(false)),
+            path,
         })
     }
 }
@@ -572,6 +581,10 @@ where
             self.queue_evts.take().unwrap(),
         ))
     }
+
+    fn shutdown(&mut self) {
+        std::fs::remove_file(&self.path).ok();
+    }
 }
 
 virtio_pausable!(Vsock, T: 'static + VsockBackend + Sync);

vm-virtio/src/vsock/mod.rs

@@ -166,6 +166,7 @@ mod tests {
     use crate::{VIRTQ_DESC_F_NEXT, VIRTQ_DESC_F_WRITE};
     use libc::EFD_NONBLOCK;
     use std::os::unix::io::AsRawFd;
+    use std::path::PathBuf;
     use std::sync::atomic::AtomicBool;
     use std::sync::{Arc, RwLock};
     use vm_memory::{GuestAddress, GuestMemoryAtomic, GuestMemoryMmap};
@@ -265,7 +266,14 @@ mod tests {
                 cid: CID,
                 mem: GuestMemoryMmap::from_ranges(&[(GuestAddress(0), MEM_SIZE)]).unwrap(),
                 mem_size: MEM_SIZE,
-                device: Vsock::new(String::from("vsock"), CID, TestBackend::new(), false).unwrap(),
+                device: Vsock::new(
+                    String::from("vsock"),
+                    CID,
+                    PathBuf::from("/test/sock"),
+                    TestBackend::new(),
+                    false,
+                )
+                .unwrap(),
             }
         }
 

vmm/src/device_manager.rs

@@ -1714,7 +1714,13 @@ impl DeviceManager {
                 .map_err(DeviceManagerError::CreateVsockBackend)?;
 
         let vsock_device = Arc::new(Mutex::new(
-            vm_virtio::Vsock::new(id.clone(), vsock_cfg.cid, backend, vsock_cfg.iommu)
+            vm_virtio::Vsock::new(
+                id.clone(),
+                vsock_cfg.cid,
+                vsock_cfg.sock.clone(),
+                backend,
+                vsock_cfg.iommu,
+            )
             .map_err(DeviceManagerError::CreateVirtioVsock)?,
         ));