vmm,devices: Change Gic snapshot and restore path

The snapshot and restore of AArch64 Gic was done in Vm. Now it is moved
to DeviceManager.

The benefit is that the restore can be done while the Gic is created in
DeviceManager.

While the moving of state data from Vm snapshot to DeviceManager
snapshot breaks the compatability of migration from older versions.

Signed-off-by: Michael Zhao <michael.zhao@arm.com>

vmm/src/device_manager.rs

@@ -1381,10 +1381,35 @@ impl DeviceManager {
 
         self.interrupt_controller = Some(interrupt_controller.clone());
 
-        // Unlike x86_64, the "interrupt_controller" here for AArch64 is only
-        // a `Gic` object that implements the `InterruptController` to provide
-        // interrupt delivery service. This is not the real GIC device so that
-        // we do not need to insert it to the device tree.
+        // Restore the vGic if this is in the process of restoration
+        let id = String::from(gic::GIC_SNAPSHOT_ID);
+        if let Some(vgic_snapshot) = snapshot_from_id(self.snapshot.as_ref(), &id) {
+            // PMU support is optional. Nothing should be impacted if the PMU initialization failed.
+            if self
+                .cpu_manager
+                .lock()
+                .unwrap()
+                .init_pmu(arch::aarch64::fdt::AARCH64_PMU_IRQ + 16)
+                .is_err()
+            {
+                info!("Failed to initialize PMU");
+            }
+
+            let vgic_state = vgic_snapshot
+                .to_state(&id)
+                .map_err(DeviceManagerError::RestoreGetState)?;
+            let saved_vcpu_states = self.cpu_manager.lock().unwrap().get_saved_states();
+            interrupt_controller
+                .lock()
+                .unwrap()
+                .restore_vgic(vgic_state, &saved_vcpu_states)
+                .unwrap();
+        }
+
+        self.device_tree
+            .lock()
+            .unwrap()
+            .insert(id.clone(), device_node!(id, interrupt_controller));
 
         Ok(interrupt_controller)
     }