vmm: device_manager: Map MMIO regions to the guest correctly

To correctly map MMIO regions to the guest, we will need to wait for valid
MMIO region information which is generated from 'PciDevice::allocate_bars()'
(as a part of 'DeviceManager::add_pci_device()').

Signed-off-by: Bo Chen <[email protected]>

Author: likebreath

vmm/src/device_manager.rs

@@ -3345,12 +3345,6 @@ impl DeviceManager {
         )
         .map_err(DeviceManagerError::VfioUserCreate)?;
 
-        vfio_user_pci_device
-            .map_mmio_regions(&self.address_manager.vm, || {
-                self.memory_manager.lock().unwrap().allocate_memory_slot()
-            })
-            .map_err(DeviceManagerError::VfioUserMapRegion)?;
-
         let memory = self.memory_manager.lock().unwrap().guest_memory();
         let vfio_user_mapping = Arc::new(VfioUserDmaMapping::new(client, Arc::new(memory)));
         for virtio_mem_device in self.virtio_mem_devices.iter() {
@@ -3382,6 +3376,14 @@ impl DeviceManager {
             resources,
         )?;
 
+        vfio_user_pci_device
+            .lock()
+            .unwrap()
+            .map_mmio_regions(&self.address_manager.vm, || {
+                self.memory_manager.lock().unwrap().allocate_memory_slot()
+            })
+            .map_err(DeviceManagerError::VfioUserMapRegion)?;
+
         let mut node = device_node!(vfio_user_name);
 
         // Update the device tree with correct resource information.