pci, vmm: Extend PciDevice trait to support BAR relocation

By adding a new method id() to the PciDevice trait, we allow the caller
to retrieve a unique identifier. This is used in the context of BAR
relocation to identify the device being relocated, so that we can update
the DeviceTree resources for all PCI devices (and not only
VirtioPciDevice).

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

pci/src/vfio.rs

@@ -976,6 +976,7 @@ impl VfioCommon {
 /// The VMM creates a VfioDevice, then assigns it to a VfioPciDevice,
 /// which then gets added to the PCI bus.
 pub struct VfioPciDevice {
+    id: String,
     vm: Arc<dyn hypervisor::Vm>,
     device: Arc<VfioDevice>,
     container: Arc<VfioContainer>,
@@ -986,7 +987,9 @@ pub struct VfioPciDevice {
 
 impl VfioPciDevice {
     /// Constructs a new Vfio Pci device for the given Vfio device
+    #[allow(clippy::too_many_arguments)]
     pub fn new(
+        id: String,
         vm: &Arc<dyn hypervisor::Vm>,
         device: VfioDevice,
         container: Arc<VfioContainer>,
@@ -1027,6 +1030,7 @@ impl VfioPciDevice {
         common.initialize_legacy_interrupt(legacy_interrupt_group, &vfio_wrapper)?;
 
         let vfio_pci_device = VfioPciDevice {
+            id,
             vm: vm.clone(),
             device,
             container,
@@ -1438,4 +1442,8 @@ impl PciDevice for VfioPciDevice {
     fn as_any(&mut self) -> &mut dyn Any {
         self
     }
+
+    fn id(&self) -> Option<String> {
+        Some(self.id.clone())
+    }
 }