text: /*
   * vhost-backend
   *
   * Copyright (c) 2013 Virtual Open Systems Sarl.
   *
   * This work is licensed under the terms of the GNU GPL, version 2 or later.
   * See the COPYING file in the top-level directory.
   *
   */
  
  #include "hw/virtio/vhost.h"
  #include "hw/virtio/vhost-backend.h"
  #include "qemu/error-report.h"
  
  #include <sys/ioctl.h>
  
  extern const VhostOps user_ops;
  
  static int vhost_kernel_call(struct vhost_dev *dev, unsigned long int request,
                               void *arg)
  {
      int fd = (uintptr_t) dev->opaque;
  
      assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_KERNEL);
  
      return ioctl(fd, request, arg);
  }
  
  static int vhost_kernel_init(struct vhost_dev *dev, void *opaque)
  {
      assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_KERNEL);
  
      dev->opaque = opaque;
  
      return 0;
  }
  
  static int vhost_kernel_cleanup(struct vhost_dev *dev)
  {
      int fd = (uintptr_t) dev->opaque;
  
      assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_KERNEL);
  
      return close(fd);
  }
  
  static const VhostOps kernel_ops = {
          .backend_type = VHOST_BACKEND_TYPE_KERNEL,
          .vhost_call = vhost_kernel_call,
          .vhost_backend_init = vhost_kernel_init,
          .vhost_backend_cleanup = vhost_kernel_cleanup
  };
  
  int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type)
  {
      int r = 0;
  
      switch (backend_type) {
      case VHOST_BACKEND_TYPE_KERNEL:
          dev->vhost_ops = &kernel_ops;
          break;
      case VHOST_BACKEND_TYPE_USER:
          dev->vhost_ops = &user_ops;
          break;
      default:
          error_report("Unknown vhost backend type\n");
          r = -1;
      }
  
      return r;
  }
  