vmm: device_manager: Add a PCI devices creation routine

In order to reduce the DeviceManager's new() complexity, we can move the
PCI devices creation code into its own routine.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

vmm/src/device_manager.rs

@@ -463,6 +463,59 @@ impl DeviceManager {
         )?;
 
         if cfg!(feature = "pci_support") {
+            DeviceManager::add_pci_devices(
+                vm_info,
+                &address_manager,
+                mem_slots,
+                &mut virt_iommu,
+                virtio_devices,
+                &interrupt_info,
+            )?;
+        } else if cfg!(feature = "mmio_support") {
+            #[cfg(feature = "mmio_support")]
+            {
+                for (device, _) in virtio_devices {
+                    let mmio_addr = address_manager
+                        .allocator
+                        .lock()
+                        .unwrap()
+                        .allocate_mmio_addresses(None, MMIO_LEN, Some(MMIO_LEN));
+                    if let Some(addr) = mmio_addr {
+                        DeviceManager::add_virtio_mmio_device(
+                            device,
+                            vm_info.memory,
+                            &address_manager,
+                            vm_info.vm_fd,
+                            &interrupt_info,
+                            addr,
+                            &mut cmdline_additions,
+                        )?;
+                    } else {
+                        error!("Unable to allocate MMIO address!");
+                    }
+                }
+            }
+        }
+
+        Ok(DeviceManager {
+            address_manager,
+            console,
+            ioapic,
+            mmap_regions,
+            cmdline_additions,
+            virt_iommu,
+        })
+    }
+
+    #[allow(unused_variables)]
+    fn add_pci_devices(
+        vm_info: &VmInfo,
+        address_manager: &Arc<AddressManager>,
+        mem_slots: u32,
+        virt_iommu: &mut Option<(u32, Vec<u32>)>,
+        virtio_devices: Vec<(Box<dyn vm_virtio::VirtioDevice>, bool)>,
+        interrupt_info: &InterruptInfo,
+    ) -> DeviceManagerResult<()> {
         #[cfg(feature = "pci_support")]
         {
             let pci_root = PciRoot::new(None);
@@ -534,7 +587,7 @@ impl DeviceManager {
                     &None,
                 )?;
 
-                    virt_iommu = Some((iommu_id, iommu_attached_devices));
+                *virt_iommu = Some((iommu_id, iommu_attached_devices));
             }
 
             let pci_bus = Arc::new(Mutex::new(pci_bus));
@@ -553,40 +606,8 @@ impl DeviceManager {
                 )
                 .map_err(DeviceManagerError::BusError)?;
         }
-        } else if cfg!(feature = "mmio_support") {
-            #[cfg(feature = "mmio_support")]
-            {
-                for (device, _) in virtio_devices {
-                    let mmio_addr = address_manager
-                        .allocator
-                        .lock()
-                        .unwrap()
-                        .allocate_mmio_addresses(None, MMIO_LEN, Some(MMIO_LEN));
-                    if let Some(addr) = mmio_addr {
-                        DeviceManager::add_virtio_mmio_device(
-                            device,
-                            vm_info.memory,
-                            &address_manager,
-                            vm_info.vm_fd,
-                            &interrupt_info,
-                            addr,
-                            &mut cmdline_additions,
-                        )?;
-                    } else {
-                        error!("Unable to allocate MMIO address!");
-                    }
-                }
-            }
-        }
 
-        Ok(DeviceManager {
+        Ok(())
-            address_manager,
-            console,
-            ioapic,
-            mmap_regions,
-            cmdline_additions,
-            virt_iommu,
-        })
     }
 
     fn make_ioapic(