device_manager: AArch64: add a field to set/get GIC device entity

In AArch64 systems, the state of GIC device can only be
retrieved from `KVM_GET_DEVICE_ATTR` ioctl. Therefore to implement
saving/restoring the GIC states, we need to make sure that the
GIC object (either the file descriptor or the device itself) can
be extracted after the VM is started.

This commit refactors the code of GIC creation by adding a new
field `gic_device_entity` in device manager and methods to set/get
this field. The GIC object can be therefore saved in the device
manager after calling `arch::configure_system`.

Signed-off-by: Henry Wang <Henry.Wang@arm.com>

vmm/src/device_manager.rs

@@ -27,6 +27,8 @@ use crate::{device_node, DEVICE_MANAGER_SNAPSHOT_ID};
 use acpi_tables::{aml, aml::Aml};
 use anyhow::anyhow;
 #[cfg(target_arch = "aarch64")]
+use arch::aarch64::gic::GICDevice;
+#[cfg(target_arch = "aarch64")]
 use arch::aarch64::DeviceInfoForFDT;
 #[cfg(feature = "acpi")]
 use arch::layout;
@@ -727,6 +729,9 @@ pub struct DeviceManager {
     #[cfg(target_arch = "aarch64")]
     interrupt_controller: Option<Arc<Mutex<gic::Gic>>>,
 
+    #[cfg(target_arch = "aarch64")]
+    gic_device_entity: Option<Arc<Mutex<Box<dyn GICDevice>>>>,
+
     // Things to be added to the commandline (i.e. for virtio-mmio)
     cmdline_additions: Vec<String>,
 
@@ -853,6 +858,8 @@ impl DeviceManager {
             address_manager: Arc::clone(&address_manager),
             console: Arc::new(Console::default()),
             interrupt_controller: None,
+            #[cfg(target_arch = "aarch64")]
+            gic_device_entity: None,
             cmdline_additions: Vec::new(),
             #[cfg(feature = "acpi")]
             ged_notification_device: None,
@@ -1155,6 +1162,16 @@ impl DeviceManager {
         Ok(interrupt_controller)
     }
 
+    #[cfg(target_arch = "aarch64")]
+    pub fn set_gic_device_entity(&mut self, device_entity: Arc<Mutex<Box<dyn GICDevice>>>) {
+        self.gic_device_entity = Some(device_entity);
+    }
+
+    #[cfg(target_arch = "aarch64")]
+    pub fn get_gic_device_entity(&self) -> Option<&Arc<Mutex<Box<dyn GICDevice>>>> {
+        self.gic_device_entity.as_ref()
+    }
+
     #[cfg(target_arch = "aarch64")]
     pub fn enable_interrupt_controller(&self) -> DeviceManagerResult<()> {
         if let Some(interrupt_controller) = &self.interrupt_controller {

vmm/src/vm.rs

@@ -801,7 +801,9 @@ impl Vm {
             None
         };
 
-        arch::configure_system(
+        // Call `configure_system` and pass the GIC devices out, so that
+        // we can register the GIC device to the device manager.
+        let gic_device = arch::configure_system(
             &self.memory_manager.lock().as_ref().unwrap().vm,
             &mem,
             &cmdline_cstring,
@@ -813,6 +815,12 @@ impl Vm {
         )
         .map_err(Error::ConfigureSystem)?;
 
+        // Update the GIC entity in device manager
+        self.device_manager
+            .lock()
+            .unwrap()
+            .set_gic_device_entity(Arc::new(Mutex::new(gic_device)));
+
         self.device_manager
             .lock()
             .unwrap()