From 9eb7413fab5d8d38e97803e6a6242df7c68ef526 Mon Sep 17 00:00:00 2001
From: Sebastien Boeuf <sebastien.boeuf@intel.com>
Date: Mon, 27 Apr 2020 11:29:16 +0200
Subject: [PATCH] vm-virtio: net: Expect an identifier upon device creation

This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
---
 vm-virtio/src/net.rs      | 19 ++++++++++---------
 vmm/src/device_manager.rs | 12 +++++++++---
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/vm-virtio/src/net.rs b/vm-virtio/src/net.rs
index 3c7fd1613..65bc99bd4 100644
--- a/vm-virtio/src/net.rs
+++ b/vm-virtio/src/net.rs
@@ -311,6 +311,7 @@ impl NetEpollHandler {
 }
 
 pub struct Net {
+    id: String,
     kill_evt: Option<EventFd>,
     pause_evt: Option<EventFd>,
     taps: Option<Vec<Tap>>,
@@ -336,6 +337,7 @@ pub struct NetState {
 impl Net {
     /// Create a new virtio network device with the given TAP interface.
     pub fn new_with_tap(
+        id: String,
         taps: Vec<Tap>,
         guest_mac: Option<MacAddr>,
         iommu: bool,
@@ -365,6 +367,7 @@ impl Net {
         }
 
         Ok(Net {
+            id,
             kill_evt: None,
             pause_evt: None,
             taps: Some(taps),
@@ -382,7 +385,9 @@ impl Net {
 
     /// Create a new virtio network device with the given IP address and
     /// netmask.
+    #[allow(clippy::too_many_arguments)]
     pub fn new(
+        id: String,
         if_name: Option<&str>,
         ip_addr: Option<Ipv4Addr>,
         netmask: Option<Ipv4Addr>,
@@ -393,7 +398,7 @@ impl Net {
     ) -> Result<Self> {
         let taps = open_tap(if_name, ip_addr, netmask, num_queues / 2).map_err(Error::OpenTap)?;
 
-        Self::new_with_tap(taps, guest_mac, iommu, num_queues, queue_size)
+        Self::new_with_tap(id, taps, guest_mac, iommu, num_queues, queue_size)
     }
 
     fn state(&self) -> NetState {
@@ -611,19 +616,18 @@ impl VirtioDevice for Net {
 }
 
 virtio_ctrl_q_pausable!(Net);
-const NET_SNAPSHOT_ID: &str = "virtio-net";
 impl Snapshottable for Net {
     fn id(&self) -> String {
-        NET_SNAPSHOT_ID.to_string()
+        self.id.clone()
     }
 
     fn snapshot(&self) -> std::result::Result<Snapshot, MigratableError> {
         let snapshot =
             serde_json::to_vec(&self.state()).map_err(|e| MigratableError::Snapshot(e.into()))?;
 
-        let mut net_snapshot = Snapshot::new(NET_SNAPSHOT_ID);
+        let mut net_snapshot = Snapshot::new(self.id.as_str());
         net_snapshot.add_data_section(SnapshotDataSection {
-            id: format!("{}-section", NET_SNAPSHOT_ID),
+            id: format!("{}-section", self.id),
             snapshot,
         });
 
@@ -631,10 +635,7 @@ impl Snapshottable for Net {
     }
 
     fn restore(&mut self, snapshot: Snapshot) -> std::result::Result<(), MigratableError> {
-        if let Some(net_section) = snapshot
-            .snapshot_data
-            .get(&format!("{}-section", NET_SNAPSHOT_ID))
-        {
+        if let Some(net_section) = snapshot.snapshot_data.get(&format!("{}-section", self.id)) {
             let net_state = match serde_json::from_slice(&net_section.snapshot) {
                 Ok(state) => state,
                 Err(error) => {
diff --git a/vmm/src/device_manager.rs b/vmm/src/device_manager.rs
index 46f7db424..36443dd95 100644
--- a/vmm/src/device_manager.rs
+++ b/vmm/src/device_manager.rs
@@ -1340,9 +1340,13 @@ impl DeviceManager {
         &mut self,
         net_cfg: &mut NetConfig,
     ) -> DeviceManagerResult<(VirtioDeviceArc, bool, Option<String>)> {
-        if net_cfg.id.is_none() {
-            net_cfg.id = Some(self.next_device_name(NET_DEVICE_NAME_PREFIX)?);
-        }
+        let id = if let Some(id) = &net_cfg.id {
+            id.clone()
+        } else {
+            let id = self.next_device_name(NET_DEVICE_NAME_PREFIX)?;
+            net_cfg.id = Some(id.clone());
+            id
+        };
 
         if net_cfg.vhost_user {
             let sock = if let Some(sock) = net_cfg.vhost_socket.clone() {
@@ -1371,6 +1375,7 @@ impl DeviceManager {
             let virtio_net_device = if let Some(ref tap_if_name) = net_cfg.tap {
                 Arc::new(Mutex::new(
                     vm_virtio::Net::new(
+                        id,
                         Some(tap_if_name),
                         None,
                         None,
@@ -1384,6 +1389,7 @@ impl DeviceManager {
             } else {
                 Arc::new(Mutex::new(
                     vm_virtio::Net::new(
+                        id,
                         None,
                         Some(net_cfg.ip),
                         Some(net_cfg.mask),