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

This commit introduces the new command "remove-device" that will let a
user hot-unplug a VFIO PCI device from 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, VmAddDevice, VmCreate, VmInfo, VmResize, VmmPing, VmmShutdown,
+    VmActionHandler, VmAddDevice, VmCreate, VmInfo, VmRemoveDevice, VmResize, VmmPing, VmmShutdown,
 };
 use crate::api::{ApiRequest, VmAction};
 use crate::{Error, Result};
@@ -63,6 +63,7 @@ lazy_static! {
         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.routes.insert(endpoint!("/vm.remove-device"), Box::new(VmRemoveDevice {}));
 
         r
     };

vmm/src/api/http_endpoint.rs

@@ -5,9 +5,9 @@
 
 use crate::api::http::EndpointHandler;
 use crate::api::{
-    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,
+    vm_add_device, vm_boot, vm_create, vm_delete, vm_info, vm_pause, vm_reboot, vm_remove_device,
+    vm_resize, vm_resume, vm_shutdown, vmm_ping, vmm_shutdown, ApiError, ApiRequest, ApiResult,
+    VmAction, VmAddDeviceData, VmConfig, VmRemoveDeviceData, VmResizeData,
 };
 use micro_http::{Body, Method, Request, Response, StatusCode, Version};
 use serde_json::Error as SerdeError;
@@ -51,6 +51,9 @@ pub enum HttpError {
     /// Could not add a device to a VM
     VmAddDevice(ApiError),
 
+    /// Could not remove a device from a VM
+    VmRemoveDevice(ApiError),
+
     /// Could not shut the VMM down
     VmmShutdown(ApiError),
 
@@ -305,3 +308,47 @@ impl EndpointHandler for VmAddDevice {
         }
     }
 }
+
+// /api/v1/vm.remove-device handler
+pub struct VmRemoveDevice {}
+
+impl EndpointHandler for VmRemoveDevice {
+    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 VmRemoveDeviceData
+                        let vm_remove_device_data: VmRemoveDeviceData =
+                            match serde_json::from_slice(body.raw())
+                                .map_err(HttpError::SerdeJsonDeserialize)
+                            {
+                                Ok(config) => config,
+                                Err(e) => return error_response(e, StatusCode::BadRequest),
+                            };
+
+                        // Call vm_remove_device()
+                        match vm_remove_device(
+                            api_notifier,
+                            api_sender,
+                            Arc::new(vm_remove_device_data),
+                        )
+                        .map_err(HttpError::VmRemoveDevice)
+                        {
+                            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

@@ -102,6 +102,9 @@ pub enum ApiError {
 
     /// The device could not be added to the VM.
     VmAddDevice(VmError),
+
+    /// The device could not be removed from the VM.
+    VmRemoveDevice(VmError),
 }
 pub type ApiResult<T> = std::result::Result<T, ApiError>;
 
@@ -127,6 +130,11 @@ pub struct VmAddDeviceData {
     pub path: String,
 }
 
+#[derive(Clone, Deserialize, Serialize)]
+pub struct VmRemoveDeviceData {
+    pub id: String,
+}
+
 pub enum ApiResponsePayload {
     /// No data is sent on the channel.
     Empty,
@@ -192,6 +200,9 @@ pub enum ApiRequest {
 
     /// Add a device to the VM.
     VmAddDevice(Arc<VmAddDeviceData>, Sender<ApiResponse>),
+
+    /// Remove a device from the VM.
+    VmRemoveDevice(Arc<VmRemoveDeviceData>, Sender<ApiResponse>),
 }
 
 pub fn vm_create(
@@ -362,3 +373,21 @@ pub fn vm_add_device(
 
     Ok(())
 }
+
+pub fn vm_remove_device(
+    api_evt: EventFd,
+    api_sender: Sender<ApiRequest>,
+    data: Arc<VmRemoveDeviceData>,
+) -> ApiResult<()> {
+    let (response_sender, response_receiver) = channel();
+
+    // Send the VM remove-device request.
+    api_sender
+        .send(ApiRequest::VmRemoveDevice(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

@@ -155,6 +155,22 @@ paths:
         404:
           description: The new device could not be added to the VM instance.
 
+  /vm.remove-device:
+    put:
+      summary: Remove a device from the VM
+      requestBody:
+        description: The identifier of the device
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/VmRemoveDevice'
+        required: true
+      responses:
+        204:
+          description: The device was successfully removed from the VM instance.
+        404:
+          description: The device could not be removed from the VM instance.
+
 components:
   schemas:
 
@@ -449,3 +465,9 @@ components:
       properties:
         path:
           type: string
+
+    VmRemoveDevice:
+      type: object
+      properties:
+        id:
+          type: string