// SPDX-License-Identifier: GPL-2.0-only

  /* Copyright (C) 2009 Red Hat, Inc.
   * Author: Michael S. Tsirkin <mst@redhat.com>
   *

   * test virtio server in host kernel.
   */
  
  #include <linux/compat.h>
  #include <linux/eventfd.h>
  #include <linux/vhost.h>
  #include <linux/miscdevice.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/workqueue.h>

  #include <linux/file.h>
  #include <linux/slab.h>
  
  #include "test.h"

  #include "vhost.h"

  
  /* Max number of bytes transferred before requeueing the job.
   * Using this limit prevents one virtqueue from starving others. */
  #define VHOST_TEST_WEIGHT 0x80000

  /* Max number of packets transferred before requeueing the job.
   * Using this limit prevents one virtqueue from starving others with
   * pkts.
   */
  #define VHOST_TEST_PKT_WEIGHT 256

  enum {
  	VHOST_TEST_VQ = 0,
  	VHOST_TEST_VQ_MAX = 1,
  };
  
  struct vhost_test {
  	struct vhost_dev dev;
  	struct vhost_virtqueue vqs[VHOST_TEST_VQ_MAX];
  };
  
  /* Expects to be always run from workqueue - which acts as
   * read-size critical section for our kind of RCU. */
  static void handle_vq(struct vhost_test *n)
  {

  	struct vhost_virtqueue *vq = &n->vqs[VHOST_TEST_VQ];

  	unsigned out, in;
  	int head;
  	size_t len, total_len = 0;
  	void *private;

  	mutex_lock(&vq->mutex);

  	private = vhost_vq_get_backend(vq);

  	if (!private) {
  		mutex_unlock(&vq->mutex);

  		return;

  	}

  	vhost_disable_notify(&n->dev, vq);

  
  	for (;;) {

  		head = vhost_get_vq_desc(vq, vq->iov,

  					 ARRAY_SIZE(vq->iov),
  					 &out, &in,
  					 NULL, NULL);
  		/* On error, stop handling until the next kick. */
  		if (unlikely(head < 0))
  			break;
  		/* Nothing new?  Wait for eventfd to tell us they refilled. */
  		if (head == vq->num) {

  			if (unlikely(vhost_enable_notify(&n->dev, vq))) {
  				vhost_disable_notify(&n->dev, vq);

  				continue;
  			}
  			break;
  		}
  		if (in) {
  			vq_err(vq, "Unexpected descriptor format for TX: "
  			       "out %d, int %d
  ", out, in);
  			break;
  		}
  		len = iov_length(vq->iov, out);
  		/* Sanity check */
  		if (!len) {
  			vq_err(vq, "Unexpected 0 len for TX
  ");
  			break;
  		}
  		vhost_add_used_and_signal(&n->dev, vq, head, 0);
  		total_len += len;

  		if (unlikely(vhost_exceeds_weight(vq, 0, total_len)))

  			break;

  	}
  
  	mutex_unlock(&vq->mutex);
  }
  
  static void handle_vq_kick(struct vhost_work *work)
  {
  	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
  						  poll.work);
  	struct vhost_test *n = container_of(vq->dev, struct vhost_test, dev);
  
  	handle_vq(n);
  }
  
  static int vhost_test_open(struct inode *inode, struct file *f)
  {
  	struct vhost_test *n = kmalloc(sizeof *n, GFP_KERNEL);
  	struct vhost_dev *dev;

  	struct vhost_virtqueue **vqs;

  
  	if (!n)
  		return -ENOMEM;

  	vqs = kmalloc_array(VHOST_TEST_VQ_MAX, sizeof(*vqs), GFP_KERNEL);

  	if (!vqs) {
  		kfree(n);
  		return -ENOMEM;
  	}

  
  	dev = &n->dev;

  	vqs[VHOST_TEST_VQ] = &n->vqs[VHOST_TEST_VQ];

  	n->vqs[VHOST_TEST_VQ].handle_kick = handle_vq_kick;

  	vhost_dev_init(dev, vqs, VHOST_TEST_VQ_MAX, UIO_MAXIOV,

  		       VHOST_TEST_PKT_WEIGHT, VHOST_TEST_WEIGHT, true, NULL);

  
  	f->private_data = n;
  
  	return 0;
  }
  
  static void *vhost_test_stop_vq(struct vhost_test *n,
  				struct vhost_virtqueue *vq)
  {
  	void *private;
  
  	mutex_lock(&vq->mutex);

  	private = vhost_vq_get_backend(vq);
  	vhost_vq_set_backend(vq, NULL);

  	mutex_unlock(&vq->mutex);
  	return private;
  }
  
  static void vhost_test_stop(struct vhost_test *n, void **privatep)
  {
  	*privatep = vhost_test_stop_vq(n, n->vqs + VHOST_TEST_VQ);
  }
  
  static void vhost_test_flush_vq(struct vhost_test *n, int index)
  {

  	vhost_poll_flush(&n->vqs[index].poll);

  }
  
  static void vhost_test_flush(struct vhost_test *n)
  {
  	vhost_test_flush_vq(n, VHOST_TEST_VQ);
  }
  
  static int vhost_test_release(struct inode *inode, struct file *f)
  {
  	struct vhost_test *n = f->private_data;
  	void  *private;
  
  	vhost_test_stop(n, &private);
  	vhost_test_flush(n);

  	vhost_dev_stop(&n->dev);

  	vhost_dev_cleanup(&n->dev);

  	/* We do an extra flush before freeing memory,
  	 * since jobs can re-queue themselves. */
  	vhost_test_flush(n);
  	kfree(n);
  	return 0;
  }
  
  static long vhost_test_run(struct vhost_test *n, int test)
  {
  	void *priv, *oldpriv;
  	struct vhost_virtqueue *vq;
  	int r, index;
  
  	if (test < 0 || test > 1)
  		return -EINVAL;
  
  	mutex_lock(&n->dev.mutex);
  	r = vhost_dev_check_owner(&n->dev);
  	if (r)
  		goto err;
  
  	for (index = 0; index < n->dev.nvqs; ++index) {
  		/* Verify that ring has been setup correctly. */
  		if (!vhost_vq_access_ok(&n->vqs[index])) {
  			r = -EFAULT;
  			goto err;
  		}
  	}
  
  	for (index = 0; index < n->dev.nvqs; ++index) {
  		vq = n->vqs + index;
  		mutex_lock(&vq->mutex);
  		priv = test ? n : NULL;
  
  		/* start polling new socket */

  		oldpriv = vhost_vq_get_backend(vq);
  		vhost_vq_set_backend(vq, priv);

  		r = vhost_vq_init_access(&n->vqs[index]);

  		mutex_unlock(&vq->mutex);

  		if (r)
  			goto err;

  		if (oldpriv) {
  			vhost_test_flush_vq(n, index);
  		}
  	}
  
  	mutex_unlock(&n->dev.mutex);
  	return 0;
  
  err:
  	mutex_unlock(&n->dev.mutex);
  	return r;
  }
  
  static long vhost_test_reset_owner(struct vhost_test *n)
  {
  	void *priv = NULL;
  	long err;

  	struct vhost_iotlb *umem;

  	mutex_lock(&n->dev.mutex);
  	err = vhost_dev_check_owner(&n->dev);
  	if (err)
  		goto done;

  	umem = vhost_dev_reset_owner_prepare();
  	if (!umem) {

  		err = -ENOMEM;
  		goto done;
  	}

  	vhost_test_stop(n, &priv);
  	vhost_test_flush(n);

  	vhost_dev_stop(&n->dev);

  	vhost_dev_reset_owner(&n->dev, umem);

  done:
  	mutex_unlock(&n->dev.mutex);
  	return err;
  }
  
  static int vhost_test_set_features(struct vhost_test *n, u64 features)
  {

  	struct vhost_virtqueue *vq;

  	mutex_lock(&n->dev.mutex);
  	if ((features & (1 << VHOST_F_LOG_ALL)) &&
  	    !vhost_log_access_ok(&n->dev)) {
  		mutex_unlock(&n->dev.mutex);
  		return -EFAULT;
  	}

  	vq = &n->vqs[VHOST_TEST_VQ];
  	mutex_lock(&vq->mutex);
  	vq->acked_features = features;
  	mutex_unlock(&vq->mutex);

  	mutex_unlock(&n->dev.mutex);
  	return 0;
  }

  static long vhost_test_set_backend(struct vhost_test *n, unsigned index, int fd)
  {
  	static void *backend;
  
  	const bool enable = fd != -1;
  	struct vhost_virtqueue *vq;
  	int r;
  
  	mutex_lock(&n->dev.mutex);
  	r = vhost_dev_check_owner(&n->dev);
  	if (r)
  		goto err;
  
  	if (index >= VHOST_TEST_VQ_MAX) {
  		r = -ENOBUFS;
  		goto err;
  	}
  	vq = &n->vqs[index];
  	mutex_lock(&vq->mutex);
  
  	/* Verify that ring has been setup correctly. */
  	if (!vhost_vq_access_ok(vq)) {
  		r = -EFAULT;
  		goto err_vq;
  	}
  	if (!enable) {
  		vhost_poll_stop(&vq->poll);
  		backend = vhost_vq_get_backend(vq);
  		vhost_vq_set_backend(vq, NULL);
  	} else {
  		vhost_vq_set_backend(vq, backend);
  		r = vhost_vq_init_access(vq);
  		if (r == 0)
  			r = vhost_poll_start(&vq->poll, vq->kick);
  	}
  
  	mutex_unlock(&vq->mutex);
  
  	if (enable) {
  		vhost_test_flush_vq(n, index);
  	}
  
  	mutex_unlock(&n->dev.mutex);
  	return 0;
  
  err_vq:
  	mutex_unlock(&vq->mutex);
  err:
  	mutex_unlock(&n->dev.mutex);
  	return r;
  }

  static long vhost_test_ioctl(struct file *f, unsigned int ioctl,
  			     unsigned long arg)
  {

  	struct vhost_vring_file backend;

  	struct vhost_test *n = f->private_data;
  	void __user *argp = (void __user *)arg;
  	u64 __user *featurep = argp;
  	int test;
  	u64 features;
  	int r;
  	switch (ioctl) {
  	case VHOST_TEST_RUN:
  		if (copy_from_user(&test, argp, sizeof test))
  			return -EFAULT;
  		return vhost_test_run(n, test);

  	case VHOST_TEST_SET_BACKEND:
  		if (copy_from_user(&backend, argp, sizeof backend))
  			return -EFAULT;
  		return vhost_test_set_backend(n, backend.index, backend.fd);

  	case VHOST_GET_FEATURES:

  		features = VHOST_FEATURES;

  		if (copy_to_user(featurep, &features, sizeof features))
  			return -EFAULT;
  		return 0;
  	case VHOST_SET_FEATURES:

  		printk(KERN_ERR "1
  ");

  		if (copy_from_user(&features, featurep, sizeof features))
  			return -EFAULT;

  		printk(KERN_ERR "2
  ");

  		if (features & ~VHOST_FEATURES)

  			return -EOPNOTSUPP;

  		printk(KERN_ERR "3
  ");

  		return vhost_test_set_features(n, features);
  	case VHOST_RESET_OWNER:
  		return vhost_test_reset_owner(n);
  	default:
  		mutex_lock(&n->dev.mutex);

  		r = vhost_dev_ioctl(&n->dev, ioctl, argp);
                  if (r == -ENOIOCTLCMD)
                          r = vhost_vring_ioctl(&n->dev, ioctl, argp);

  		vhost_test_flush(n);
  		mutex_unlock(&n->dev.mutex);
  		return r;
  	}
  }

  static const struct file_operations vhost_test_fops = {
  	.owner          = THIS_MODULE,
  	.release        = vhost_test_release,
  	.unlocked_ioctl = vhost_test_ioctl,

  	.compat_ioctl   = compat_ptr_ioctl,

  	.open           = vhost_test_open,
  	.llseek		= noop_llseek,
  };
  
  static struct miscdevice vhost_test_misc = {
  	MISC_DYNAMIC_MINOR,
  	"vhost-test",
  	&vhost_test_fops,
  };

  module_misc_device(vhost_test_misc);

  
  MODULE_VERSION("0.0.1");
  MODULE_LICENSE("GPL v2");
  MODULE_AUTHOR("Michael S. Tsirkin");
  MODULE_DESCRIPTION("Host kernel side for virtio simulator");