diff --git a/src/dragonball/src/api/v1/vmm_action.rs b/src/dragonball/src/api/v1/vmm_action.rs
index cdaec08a85..a271d04cbf 100644
--- a/src/dragonball/src/api/v1/vmm_action.rs
+++ b/src/dragonball/src/api/v1/vmm_action.rs
@@ -549,7 +549,9 @@ impl VmmService {
                 }
             })?;
 
-        VirtioNetDeviceMgr::insert_device(vm.device_manager_mut(), ctx, config)
+        vm.device_manager_mut()
+            .virtio_net_manager
+            .insert_device(ctx, config)
             .map(|_| VmmData::Empty)
             .map_err(VmmActionError::VirtioNet)
     }
@@ -562,7 +564,9 @@ impl VmmService {
     ) -> VmmRequestResult {
         let vm = vmm.get_vm_mut().ok_or(VmmActionError::InvalidVMID)?;
 
-        VirtioNetDeviceMgr::update_device_ratelimiters(vm.device_manager_mut(), config)
+        vm.device_manager_mut()
+            .virtio_net_manager
+            .update_device_ratelimiters(config)
             .map(|_| VmmData::Empty)
             .map_err(VmmActionError::VirtioNet)
     }
diff --git a/src/dragonball/src/device_manager/virtio_net_dev_mgr.rs b/src/dragonball/src/device_manager/virtio_net_dev_mgr.rs
index c0b0f62daa..bfcc600fb6 100644
--- a/src/dragonball/src/device_manager/virtio_net_dev_mgr.rs
+++ b/src/dragonball/src/device_manager/virtio_net_dev_mgr.rs
@@ -223,7 +223,7 @@ impl VirtioNetDeviceMgr {
 
     /// Insert or update a virtio net device into the manager.
     pub fn insert_device(
-        device_mgr: &mut DeviceManager,
+        &mut self,
         mut ctx: DeviceOpContext,
         config: VirtioNetDeviceConfigInfo,
     ) -> std::result::Result<(), VirtioNetDeviceError> {
@@ -234,8 +234,6 @@ impl VirtioNetDeviceMgr {
             return Err(VirtioNetDeviceError::UpdateNotAllowedPostBoot);
         }
 
-        let mgr = &mut device_mgr.virtio_net_manager;
-
         slog::info!(
             ctx.logger(),
             "add virtio-net device configuration";
@@ -244,7 +242,7 @@ impl VirtioNetDeviceMgr {
             "host_dev_name" => &config.host_dev_name,
         );
 
-        let device_index = mgr.info_list.insert_or_update(&config)?;
+        let device_index = self.info_list.insert_or_update(&config)?;
 
         if ctx.is_hotplug {
             slog::info!(
@@ -260,17 +258,17 @@ impl VirtioNetDeviceMgr {
                     let dev = DeviceManager::create_mmio_virtio_device(
                         device,
                         &mut ctx,
-                        config.use_shared_irq.unwrap_or(mgr.use_shared_irq),
+                        config.use_shared_irq.unwrap_or(self.use_shared_irq),
                         config.use_generic_irq.unwrap_or(USE_GENERIC_IRQ),
                     )
                     .map_err(VirtioNetDeviceError::DeviceManager)?;
                     ctx.insert_hotplug_mmio_device(&dev, None)
                         .map_err(VirtioNetDeviceError::DeviceManager)?;
                     // live-upgrade need save/restore device from info.device.
-                    mgr.info_list[device_index].set_device(dev);
+                    self.info_list[device_index].set_device(dev);
                 }
                 Err(e) => {
-                    mgr.info_list.remove(device_index);
+                    self.info_list.remove(device_index);
                     return Err(VirtioNetDeviceError::Virtio(e));
                 }
             }
@@ -281,16 +279,15 @@ impl VirtioNetDeviceMgr {
 
     /// Update the ratelimiter settings of a virtio net device.
     pub fn update_device_ratelimiters(
-        device_mgr: &mut DeviceManager,
+        &mut self,
         new_cfg: VirtioNetDeviceConfigUpdateInfo,
     ) -> std::result::Result<(), VirtioNetDeviceError> {
-        let mgr = &mut device_mgr.virtio_net_manager;
-        match mgr.get_index_of_iface_id(&new_cfg.iface_id) {
+        match self.get_index_of_iface_id(&new_cfg.iface_id) {
             Some(index) => {
-                let config = &mut mgr.info_list[index].config;
+                let config = &mut self.info_list[index].config;
                 config.rx_rate_limiter = new_cfg.rx_rate_limiter.clone();
                 config.tx_rate_limiter = new_cfg.tx_rate_limiter.clone();
-                let device = mgr.info_list[index].device.as_mut().ok_or_else(|| {
+                let device = self.info_list[index].device.as_mut().ok_or_else(|| {
                     VirtioNetDeviceError::InvalidIfaceId(new_cfg.iface_id.clone())
                 })?;