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/api/mod.rs

@@ -96,6 +96,9 @@ pub enum ApiError {
 
     /// The VMM could not shutdown.
     VmmShutdown(VmError),
+
+    /// The VM could not be resized
+    VmResize(VmError),
 }
 pub type ApiResult<T> = std::result::Result<T, ApiError>;
 
@@ -110,6 +113,11 @@ pub struct VmmPingResponse {
     pub version: String,
 }
 
+#[derive(Clone, Deserialize, Serialize)]
+pub struct VmResizeData {
+    pub desired_vcpus: u8,
+}
+
 pub enum ApiResponsePayload {
     /// No data is sent on the channel.
     Empty,
@@ -169,6 +177,9 @@ pub enum ApiRequest {
     /// This will shutdown and delete the current VM, if any, and then exit the
     /// VMM process.
     VmmShutdown(Sender<ApiResponse>),
+
+    //// Resuze the VMM
+    VmResize(Arc<VmResizeData>, Sender<ApiResponse>),
 }
 
 pub fn vm_create(
@@ -303,3 +314,21 @@ pub fn vmm_shutdown(api_evt: EventFd, api_sender: Sender<ApiRequest>) -> ApiResu
 
     Ok(())
 }
+
+pub fn vm_resize(
+    api_evt: EventFd,
+    api_sender: Sender<ApiRequest>,
+    data: Arc<VmResizeData>,
+) -> ApiResult<()> {
+    let (response_sender, response_receiver) = channel();
+
+    // Send the VM creation request.
+    api_sender
+        .send(ApiRequest::VmResize(data, response_sender))
+        .map_err(ApiError::RequestSend)?;
+    api_evt.write(1).map_err(ApiError::EventFdWrite)?;
+
+    response_receiver.recv().map_err(ApiError::ResponseRecv)??;
+
+    Ok(())
+}