vmm: Add HTTP API to resize the VM

Currently only increasing the number of vCPUs is supported but in the
future it will be extended.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vmm/src/lib.rs

@@ -328,6 +328,14 @@ impl Vmm {
         self.vm_delete()
     }
 
+    fn vm_resize(&mut self, desired_vcpus: u8) -> result::Result<(), VmError> {
+        if let Some(ref mut vm) = self.vm {
+            vm.resize(desired_vcpus)
+        } else {
+            Err(VmError::VmNotRunning)
+        }
+    }
+
     fn control_loop(&mut self, api_receiver: Arc<Receiver<ApiRequest>>) -> Result<()> {
         const EPOLL_EVENTS_LEN: usize = 100;
 
@@ -473,6 +481,13 @@ impl Vmm {
 
                                     break 'outer;
                                 }
+                                ApiRequest::VmResize(resize_data, sender) => {
+                                    let response = self
+                                        .vm_resize(resize_data.desired_vcpus)
+                                        .map_err(ApiError::VmResize)
+                                        .map(|_| ApiResponsePayload::Empty);
+                                    sender.send(response).map_err(Error::ApiResponseSend)?;
+                                }
                             }
                         }
                     }