diff --git a/src/dragonball/src/api/v1/vmm_action.rs b/src/dragonball/src/api/v1/vmm_action.rs
index 586b998cb..e687bc1df 100644
--- a/src/dragonball/src/api/v1/vmm_action.rs
+++ b/src/dragonball/src/api/v1/vmm_action.rs
@@ -281,6 +281,8 @@ pub enum VmmData {
     MachineConfiguration(Box<VmConfigInfo>),
     /// Prometheus Metrics represented by String.
     HypervisorMetrics(String),
+    /// Return vfio device's slot number in guest.
+    VfioDeviceData(Option<u8>),
     /// Sync Hotplug
     SyncHotplug((Sender<Option<i32>>, Receiver<Option<i32>>)),
 }
@@ -398,7 +400,9 @@ impl VmmService {
                 self.add_balloon_device(vmm, event_mgr, balloon_cfg)
             }
             #[cfg(feature = "host-device")]
-            VmmAction::InsertHostDevice(hostdev_cfg) => self.add_vfio_device(vmm, hostdev_cfg),
+            VmmAction::InsertHostDevice(mut hostdev_cfg) => {
+                self.add_vfio_device(vmm, &mut hostdev_cfg)
+            }
             #[cfg(feature = "host-device")]
             VmmAction::PrepareRemoveHostDevice(hostdev_id) => {
                 self.prepare_remove_vfio_device(vmm, &hostdev_id)
@@ -850,7 +854,7 @@ impl VmmService {
     }
 
     #[cfg(feature = "host-device")]
-    fn add_vfio_device(&self, vmm: &mut Vmm, config: HostDeviceConfig) -> VmmRequestResult {
+    fn add_vfio_device(&self, vmm: &mut Vmm, config: &mut HostDeviceConfig) -> VmmRequestResult {
         let vm = vmm.get_vm_mut().ok_or(VmmActionError::HostDeviceConfig(
             VfioDeviceError::InvalidVMID,
         ))?;
@@ -873,7 +877,8 @@ impl VmmService {
             .unwrap()
             .insert_device(&mut ctx, config)
             .map_err(VmmActionError::HostDeviceConfig)?;
-        Ok(VmmData::Empty)
+
+        Ok(VmmData::VfioDeviceData(config.dev_config.guest_dev_id))
     }
 
     // using upcall to unplug the pci device in the guest
diff --git a/src/dragonball/src/device_manager/mod.rs b/src/dragonball/src/device_manager/mod.rs
index 169e8cb14..c8ebeb3b2 100644
--- a/src/dragonball/src/device_manager/mod.rs
+++ b/src/dragonball/src/device_manager/mod.rs
@@ -553,7 +553,7 @@ impl DeviceOpContext {
         &self,
         dev: &Arc<dyn DeviceIo>,
         callback: Option<Box<dyn Fn(UpcallClientResponse) + Send>>,
-    ) -> Result<()> {
+    ) -> Result<u8> {
         if !self.is_hotplug || !self.pci_hotplug_enabled {
             return Err(DeviceMgrError::InvalidOperation);
         }
@@ -561,7 +561,12 @@ impl DeviceOpContext {
         let (busno, devfn) = DeviceManager::get_pci_device_info(dev)?;
         let req = DevMgrRequest::AddPciDev(PciDevRequest { busno, devfn });
 
-        self.call_hotplug_device(req, callback)
+        self.call_hotplug_device(req, callback)?;
+
+        // Extract the slot number from devfn
+        // Right shift by 3 to remove function bits (2:0) and
+        // align slot bits (7:3) to the least significant position
+        Ok(devfn >> 3)
     }
 
     #[cfg(feature = "host-device")]
diff --git a/src/dragonball/src/device_manager/vfio_dev_mgr/mod.rs b/src/dragonball/src/device_manager/vfio_dev_mgr/mod.rs
index c3c3b6bac..d70106e27 100644
--- a/src/dragonball/src/device_manager/vfio_dev_mgr/mod.rs
+++ b/src/dragonball/src/device_manager/vfio_dev_mgr/mod.rs
@@ -255,7 +255,7 @@ impl VfioDeviceMgr {
     pub fn insert_device(
         &mut self,
         ctx: &mut DeviceOpContext,
-        config: HostDeviceConfig,
+        config: &mut HostDeviceConfig,
     ) -> Result<()> {
         if !cfg!(feature = "hotplug") && ctx.is_hotplug {
             return Err(VfioDeviceError::UpdateNotAllowedPostBoot);
@@ -267,7 +267,7 @@ impl VfioDeviceMgr {
             "hostdev_id" => &config.hostdev_id,
             "bdf" => &config.dev_config.bus_slot_func,
         );
-        let device_index = self.info_list.insert_or_update(&config)?;
+        let device_index = self.info_list.insert_or_update(config)?;
         // Handle device hotplug case
         if ctx.is_hotplug {
             slog::info!(
@@ -277,7 +277,7 @@ impl VfioDeviceMgr {
                 "hostdev_id" => &config.hostdev_id,
                 "bdf" => &config.dev_config.bus_slot_func,
             );
-            self.add_device(ctx, &config, device_index)?;
+            self.add_device(ctx, config, device_index)?;
         }
 
         Ok(())
@@ -438,7 +438,7 @@ impl VfioDeviceMgr {
     fn add_device(
         &mut self,
         ctx: &mut DeviceOpContext,
-        cfg: &HostDeviceConfig,
+        cfg: &mut HostDeviceConfig,
         idx: usize,
     ) -> Result<()> {
         let dev = self.create_device(cfg, ctx, idx)?;
@@ -450,8 +450,13 @@ impl VfioDeviceMgr {
 
             self.register_memory(vm_memory.deref())?;
         }
-        ctx.insert_hotplug_pci_device(&dev, None)
-            .map_err(VfioDeviceError::VfioDeviceMgr)
+        let slot = ctx
+            .insert_hotplug_pci_device(&dev, None)
+            .map_err(VfioDeviceError::VfioDeviceMgr)?;
+
+        cfg.dev_config.guest_dev_id = Some(slot);
+
+        Ok(())
     }
 
     /// Gets the index of the device with the specified `hostdev_id` if it exists in the list.