Fix compile errors

Author: ValentaTomas

src/firecracker/src/main.rs

@@ -337,6 +337,7 @@ fn main_exec() -> Result<(), MainError> {
         state: VmState::NotStarted,
         vmm_version: FIRECRACKER_VERSION.to_string(),
         app_name: "Firecracker".to_string(),
+        memory_regions: None,
     };
 
     if let Some(metrics_path) = arguments.single_value("metrics-path") {

src/vmm/src/lib.rs

@@ -466,6 +466,7 @@ impl Vmm {
         &self.guest_memory
     }
 
+    /// Returns the memory mappings for the guest memory.
     pub fn guest_memory_mappings(&self, vm_info: &VmInfo) -> Vec<GuestMemoryRegionMapping> {
         let mut offset = 0;
         let mut mappings = Vec::new();

src/vmm/src/rpc_interface.rs

@@ -652,7 +652,7 @@ impl RuntimeApiController {
                 let mut instance_info = locked_vmm.instance_info();
 
                 instance_info.memory_regions =
-                    locked_vmm.guest_memory_mappings(&VmInfo::from(&self.vm_resources));
+                    Some(locked_vmm.guest_memory_mappings(&VmInfo::from(&self.vm_resources)));
 
                 Ok(VmmData::InstanceInformation(instance_info))
             }