vmm: Add support for hotplugging a vDPA device

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

vmm/src/lib.rs

@@ -18,7 +18,7 @@ use crate::api::{
 };
 use crate::config::{
     add_to_config, DeviceConfig, DiskConfig, FsConfig, NetConfig, PmemConfig, RestoreConfig,
-    UserDeviceConfig, VmConfig, VsockConfig,
+    UserDeviceConfig, VdpaConfig, VmConfig, VsockConfig,
 };
 #[cfg(all(feature = "kvm", target_arch = "x86_64"))]
 use crate::migration::get_vm_snapshot;
@@ -925,6 +925,32 @@ impl Vmm {
         }
     }
 
+    fn vm_add_vdpa(&mut self, vdpa_cfg: VdpaConfig) -> result::Result<Option<Vec<u8>>, VmError> {
+        self.vm_config.as_ref().ok_or(VmError::VmNotCreated)?;
+
+        {
+            // Validate the configuration change in a cloned configuration
+            let mut config = self.vm_config.as_ref().unwrap().lock().unwrap().clone();
+            add_to_config(&mut config.vdpa, vdpa_cfg.clone());
+            config.validate().map_err(VmError::ConfigValidation)?;
+        }
+
+        if let Some(ref mut vm) = self.vm {
+            let info = vm.add_vdpa(vdpa_cfg).map_err(|e| {
+                error!("Error when adding new vDPA device to the VM: {:?}", e);
+                e
+            })?;
+            serde_json::to_vec(&info)
+                .map(Some)
+                .map_err(VmError::SerializeJson)
+        } else {
+            // Update VmConfig by adding the new device.
+            let mut config = self.vm_config.as_ref().unwrap().lock().unwrap();
+            add_to_config(&mut config.vdpa, vdpa_cfg);
+            Ok(None)
+        }
+    }
+
     fn vm_add_vsock(&mut self, vsock_cfg: VsockConfig) -> result::Result<Option<Vec<u8>>, VmError> {
         self.vm_config.as_ref().ok_or(VmError::VmNotCreated)?;
 
@@ -1742,6 +1768,13 @@ impl Vmm {
                                     .map(ApiResponsePayload::VmAction);
                                 sender.send(response).map_err(Error::ApiResponseSend)?;
                             }
+                            ApiRequest::VmAddVdpa(add_vdpa_data, sender) => {
+                                let response = self
+                                    .vm_add_vdpa(add_vdpa_data.as_ref().clone())
+                                    .map_err(ApiError::VmAddVdpa)
+                                    .map(ApiResponsePayload::VmAction);
+                                sender.send(response).map_err(Error::ApiResponseSend)?;
+                            }
                             ApiRequest::VmAddVsock(add_vsock_data, sender) => {
                                 let response = self
                                     .vm_add_vsock(add_vsock_data.as_ref().clone())
@@ -2199,6 +2232,54 @@ mod unit_tests {
         );
     }
 
+    #[test]
+    fn test_vmm_vm_cold_add_vdpa() {
+        let mut vmm = create_dummy_vmm();
+        let vdpa_config = VdpaConfig::parse("path=/dev/vhost-vdpa,num_queues=2").unwrap();
+
+        assert!(matches!(
+            vmm.vm_add_vdpa(vdpa_config.clone()),
+            Err(VmError::VmNotCreated)
+        ));
+
+        let _ = vmm.vm_create(create_dummy_vm_config());
+        assert!(vmm
+            .vm_config
+            .as_ref()
+            .unwrap()
+            .lock()
+            .unwrap()
+            .vdpa
+            .is_none());
+
+        let result = vmm.vm_add_vdpa(vdpa_config.clone());
+        assert!(result.is_ok());
+        assert!(result.unwrap().is_none());
+        assert_eq!(
+            vmm.vm_config
+                .as_ref()
+                .unwrap()
+                .lock()
+                .unwrap()
+                .vdpa
+                .clone()
+                .unwrap()
+                .len(),
+            1
+        );
+        assert_eq!(
+            vmm.vm_config
+                .as_ref()
+                .unwrap()
+                .lock()
+                .unwrap()
+                .vdpa
+                .clone()
+                .unwrap()[0],
+            vdpa_config
+        );
+    }
+
     #[test]
     fn test_vmm_vm_cold_add_vsock() {
         let mut vmm = create_dummy_vmm();