virtio-input: add live migration support

virtio-input is simple enough that it doesn't need to xfer any state.
Still we have to wire up savevm manually, so the generic pci and virtio
are saved correctly.

Additionally we need to do some post-load processing to figure whenever
the guest uses the device or not, so we can give input routing hints to
the qemu input layer using qemu_input_handler_{activate,deactivate}.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1459859501-16965-1-git-send-email-kraxel@redhat.com

hw/input/virtio-input.c

@@ -14,6 +14,8 @@
 
 #include "standard-headers/linux/input.h"
 
+#define VIRTIO_INPUT_VM_VERSION 1
+
 /* ----------------------------------------------------------------- */
 
 void virtio_input_send(VirtIOInput *vinput, virtio_input_event *event)
@@ -214,6 +216,38 @@ static void virtio_input_reset(VirtIODevice *vdev)
     }
 }
 
+static void virtio_input_save(QEMUFile *f, void *opaque)
+{
+    VirtIOInput *vinput = opaque;
+    VirtIODevice *vdev = VIRTIO_DEVICE(vinput);
+
+    virtio_save(vdev, f);
+}
+
+static int virtio_input_load(QEMUFile *f, void *opaque, int version_id)
+{
+    VirtIOInput *vinput = opaque;
+    VirtIOInputClass *vic = VIRTIO_INPUT_GET_CLASS(vinput);
+    VirtIODevice *vdev = VIRTIO_DEVICE(vinput);
+    int ret;
+
+    if (version_id != VIRTIO_INPUT_VM_VERSION) {
+        return -EINVAL;
+    }
+
+    ret = virtio_load(vdev, f, version_id);
+    if (ret) {
+        return ret;
+    }
+
+    /* post_load() */
+    vinput->active = vdev->status & VIRTIO_CONFIG_S_DRIVER_OK;
+    if (vic->change_active) {
+        vic->change_active(vinput);
+    }
+    return 0;
+}
+
 static void virtio_input_device_realize(DeviceState *dev, Error **errp)
 {
     VirtIOInputClass *vic = VIRTIO_INPUT_GET_CLASS(dev);
@@ -245,14 +279,20 @@ static void virtio_input_device_realize(DeviceState *dev, Error **errp)
                 vinput->cfg_size);
     vinput->evt = virtio_add_queue(vdev, 64, virtio_input_handle_evt);
     vinput->sts = virtio_add_queue(vdev, 64, virtio_input_handle_sts);
+
+    register_savevm(dev, "virtio-input", -1, VIRTIO_INPUT_VM_VERSION,
+                    virtio_input_save, virtio_input_load, vinput);
 }
 
 static void virtio_input_device_unrealize(DeviceState *dev, Error **errp)
 {
     VirtIOInputClass *vic = VIRTIO_INPUT_GET_CLASS(dev);
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VirtIOInput *vinput = VIRTIO_INPUT(dev);
     Error *local_err = NULL;
 
+    unregister_savevm(dev, "virtio-input", vinput);
+
     if (vic->unrealize) {
         vic->unrealize(dev, &local_err);
         if (local_err) {