vmm: api: Introduce new "add-device" HTTP endpoint

This commit introduces the new command "add-device" that will let a user
hotplug a VFIO PCI device to an already running VM.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/api/http.rs

@@ -4,7 +4,7 @@
 //
 
 use crate::api::http_endpoint::{
-    VmActionHandler, VmCreate, VmInfo, VmResize, VmmPing, VmmShutdown,
+    VmActionHandler, VmAddDevice, VmCreate, VmInfo, VmResize, VmmPing, VmmShutdown,
 };
 use crate::api::{ApiRequest, VmAction};
 use crate::{Error, Result};
@@ -62,6 +62,7 @@ lazy_static! {
         r.routes.insert(endpoint!("/vmm.shutdown"), Box::new(VmmShutdown {}));
         r.routes.insert(endpoint!("/vmm.ping"), Box::new(VmmPing {}));
         r.routes.insert(endpoint!("/vm.resize"), Box::new(VmResize {}));
+        r.routes.insert(endpoint!("/vm.add-device"), Box::new(VmAddDevice {}));
 
         r
     };

vmm/src/api/http_endpoint.rs

@@ -5,8 +5,9 @@
 
 use crate::api::http::EndpointHandler;
 use crate::api::{
-    vm_boot, vm_create, vm_delete, vm_info, vm_pause, vm_reboot, vm_resize, vm_resume, vm_shutdown,
-    vmm_ping, vmm_shutdown, ApiError, ApiRequest, ApiResult, VmAction, VmConfig, VmResizeData,
+    vm_add_device, vm_boot, vm_create, vm_delete, vm_info, vm_pause, vm_reboot, vm_resize,
+    vm_resume, vm_shutdown, vmm_ping, vmm_shutdown, ApiError, ApiRequest, ApiResult, VmAction,
+    VmAddDeviceData, VmConfig, VmResizeData,
 };
 use micro_http::{Body, Method, Request, Response, StatusCode, Version};
 use serde_json::Error as SerdeError;
@@ -47,6 +48,9 @@ pub enum HttpError {
     /// Could not resize a VM
     VmResize(ApiError),
 
+    /// Could not add a device to a VM
+    VmAddDevice(ApiError),
+
     /// Could not shut the VMM down
     VmmShutdown(ApiError),
 
@@ -261,3 +265,43 @@ impl EndpointHandler for VmResize {
         }
     }
 }
+
+// /api/v1/vm.add-device handler
+pub struct VmAddDevice {}
+
+impl EndpointHandler for VmAddDevice {
+    fn handle_request(
+        &self,
+        req: &Request,
+        api_notifier: EventFd,
+        api_sender: Sender<ApiRequest>,
+    ) -> Response {
+        match req.method() {
+            Method::Put => {
+                match &req.body {
+                    Some(body) => {
+                        // Deserialize into a VmAddDeviceData
+                        let vm_add_device_data: VmAddDeviceData =
+                            match serde_json::from_slice(body.raw())
+                                .map_err(HttpError::SerdeJsonDeserialize)
+                            {
+                                Ok(config) => config,
+                                Err(e) => return error_response(e, StatusCode::BadRequest),
+                            };
+
+                        // Call vm_add_device()
+                        match vm_add_device(api_notifier, api_sender, Arc::new(vm_add_device_data))
+                            .map_err(HttpError::VmAddDevice)
+                        {
+                            Ok(_) => Response::new(Version::Http11, StatusCode::NoContent),
+                            Err(e) => error_response(e, StatusCode::InternalServerError),
+                        }
+                    }
+
+                    None => Response::new(Version::Http11, StatusCode::BadRequest),
+                }
+            }
+            _ => Response::new(Version::Http11, StatusCode::BadRequest),
+        }
+    }
+}

vmm/src/api/mod.rs

@@ -99,6 +99,9 @@ pub enum ApiError {
 
     /// The VM could not be resized
     VmResize(VmError),
+
+    /// The device could not be added to the VM.
+    VmAddDevice(VmError),
 }
 pub type ApiResult<T> = std::result::Result<T, ApiError>;
 
@@ -119,6 +122,11 @@ pub struct VmResizeData {
     pub desired_ram: Option<u64>,
 }
 
+#[derive(Clone, Deserialize, Serialize)]
+pub struct VmAddDeviceData {
+    pub path: String,
+}
+
 pub enum ApiResponsePayload {
     /// No data is sent on the channel.
     Empty,
@@ -179,8 +187,11 @@ pub enum ApiRequest {
     /// VMM process.
     VmmShutdown(Sender<ApiResponse>),
 
-    /// Resize the VMM
+    /// Resize the VM.
     VmResize(Arc<VmResizeData>, Sender<ApiResponse>),
+
+    /// Add a device to the VM.
+    VmAddDevice(Arc<VmAddDeviceData>, Sender<ApiResponse>),
 }
 
 pub fn vm_create(
@@ -333,3 +344,21 @@ pub fn vm_resize(
 
     Ok(())
 }
+
+pub fn vm_add_device(
+    api_evt: EventFd,
+    api_sender: Sender<ApiRequest>,
+    data: Arc<VmAddDeviceData>,
+) -> ApiResult<()> {
+    let (response_sender, response_receiver) = channel();
+
+    // Send the VM add-device request.
+    api_sender
+        .send(ApiRequest::VmAddDevice(data, response_sender))
+        .map_err(ApiError::RequestSend)?;
+    api_evt.write(1).map_err(ApiError::EventFdWrite)?;
+
+    response_receiver.recv().map_err(ApiError::ResponseRecv)??;
+
+    Ok(())
+}

vmm/src/api/openapi/cloud-hypervisor.yaml

@@ -139,6 +139,22 @@ paths:
         404:
           description: The VM instance could not be resized because it is not created.
 
+  /vm.add-device:
+    put:
+      summary: Add a new device to the VM
+      requestBody:
+        description: The path of the new device
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/VmAddDevice'
+        required: true
+      responses:
+        204:
+          description: The new device was successfully added to the VM instance.
+        404:
+          description: The new device could not be added to the VM instance.
+
 components:
   schemas:
 
@@ -427,3 +443,9 @@ components:
           type: integer
         desired_ram:
           type: integer
+
+    VmAddDevice:
+      type: object
+      properties:
+        path:
+          type: string

vmm/src/device_manager.rs

@@ -1585,6 +1585,10 @@ impl DeviceManager {
         #[cfg(not(feature = "acpi"))]
         return Ok(());
     }
+
+    pub fn add_device(&self, _path: String) -> DeviceManagerResult<()> {
+        Ok(())
+    }
 }
 
 #[cfg(feature = "acpi")]

vmm/src/lib.rs

@@ -372,6 +372,19 @@ impl Vmm {
         }
     }
 
+    fn vm_add_device(&mut self, path: String) -> result::Result<(), VmError> {
+        if let Some(ref mut vm) = self.vm {
+            if let Err(e) = vm.add_device(path) {
+                error!("Error when adding new device to the VM: {:?}", e);
+                Err(e)
+            } else {
+                Ok(())
+            }
+        } else {
+            Err(VmError::VmNotRunning)
+        }
+    }
+
     fn control_loop(&mut self, api_receiver: Arc<Receiver<ApiRequest>>) -> Result<()> {
         const EPOLL_EVENTS_LEN: usize = 100;
 
@@ -527,6 +540,13 @@ impl Vmm {
                                         .map(|_| ApiResponsePayload::Empty);
                                     sender.send(response).map_err(Error::ApiResponseSend)?;
                                 }
+                                ApiRequest::VmAddDevice(add_device_data, sender) => {
+                                    let response = self
+                                        .vm_add_device(add_device_data.path.clone())
+                                        .map_err(ApiError::VmAddDevice)
+                                        .map(|_| ApiResponsePayload::Empty);
+                                    sender.send(response).map_err(Error::ApiResponseSend)?;
+                                }
                             }
                         }
                     }

vmm/src/vm.rs

@@ -540,6 +540,16 @@ impl Vm {
         Ok(())
     }
 
+    pub fn add_device(&mut self, path: String) -> Result<()> {
+        self.devices
+            .lock()
+            .unwrap()
+            .add_device(path)
+            .map_err(Error::DeviceManager)?;
+
+        Ok(())
+    }
+
     fn os_signal_handler(signals: Signals, console_input_clone: Arc<Console>, on_tty: bool) {
         for signal in signals.forever() {
             match signal {