vmm: Free PCI BARs when unplugging PCI device

Now that PciDevice trait has a dedicated function to remove the bars,
the DeviceManager can invoke this function whenever a PCI device is
unplugged from the VM.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/device_manager.rs

@@ -135,6 +135,10 @@ pub enum DeviceManagerError {
     #[cfg(feature = "pci_support")]
     AllocateBars(pci::PciDeviceError),
 
+    /// Could not free the BARs associated with a PCI device.
+    #[cfg(feature = "pci_support")]
+    FreePciBars(pci::PciDeviceError),
+
     /// Cannot register ioevent.
     RegisterIoevent(kvm_ioctls::Error),
 
@@ -1861,6 +1865,13 @@ impl DeviceManager {
                     return Ok(());
                 };
 
+            // Free the allocated BARs
+            pci_device
+                .lock()
+                .unwrap()
+                .free_bars(&mut self.address_manager.allocator.lock().unwrap())
+                .map_err(DeviceManagerError::FreePciBars)?;
+
             // Remove the device from the PCI bus
             pci.lock()
                 .unwrap()