vhost test module

/* Copyright (C) 2009 Red Hat, Inc.

 * Author: Michael S. Tsirkin <mst@redhat.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2.

 *

 * 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/rcupdate.h>

#include <linux/file.h>

#include <linux/slab.h>

#include "test.h"

#include "vhost.c"

/* Max number of bytes transferred before requeueing the job.

 * Using this limit prevents one virtqueue from starving others. */

#define VHOST_TEST_WEIGHT 0x80000

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->dev.vqs[VHOST_TEST_VQ];

	unsigned out, in;

	int head;

	size_t len, total_len = 0;

	void *private;

	private = rcu_dereference_check(vq->private_data, 1);

	if (!private)

		return;

	mutex_lock(&vq->mutex);

	vhost_disable_notify(vq);

	for (;;) {

		head = vhost_get_vq_desc(&n->dev, 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(vq))) {

				vhost_disable_notify(vq);

				continue;

			}

			break;

		}

		if (in) {

			vq_err(vq, "Unexpected descriptor format for TX: "

			       "out %d, int %d\n", out, in);

			break;

		}

		len = iov_length(vq->iov, out);

		/* Sanity check */

		if (!len) {

			vq_err(vq, "Unexpected 0 len for TX\n");

			break;

		}

		vhost_add_used_and_signal(&n->dev, vq, head, 0);

		total_len += len;

		if (unlikely(total_len >= VHOST_TEST_WEIGHT)) {

			vhost_poll_queue(&vq->poll);

			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;

	int r;

	if (!n)

		return -ENOMEM;

	dev = &n->dev;

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

	r = vhost_dev_init(dev, n->vqs, VHOST_TEST_VQ_MAX);

	if (r < 0) {

		kfree(n);

		return r;

	}

	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 = rcu_dereference_protected(vq->private_data,

					 lockdep_is_held(&vq->mutex));

	rcu_assign_pointer(vq->private_data, 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->dev.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_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 = rcu_dereference_protected(vq->private_data,

						    lockdep_is_held(&vq->mutex));

		rcu_assign_pointer(vq->private_data, priv);

		mutex_unlock(&vq->mutex);

		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;

	mutex_lock(&n->dev.mutex);

	err = vhost_dev_check_owner(&n->dev);

	if (err)

		goto done;

	vhost_test_stop(n, &priv);

	vhost_test_flush(n);

	err = vhost_dev_reset_owner(&n->dev);

done:

	mutex_unlock(&n->dev.mutex);

	return err;

}

static int vhost_test_set_features(struct vhost_test *n, u64 features)

{

	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;

	}

	n->dev.acked_features = features;

	smp_wmb();

	vhost_test_flush(n);

	mutex_unlock(&n->dev.mutex);

	return 0;

}

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

			     unsigned long arg)

{

	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_GET_FEATURES:

		features = VHOST_FEATURES;

		if (copy_to_user(featurep, &features, sizeof features))

			return -EFAULT;

		return 0;

	case VHOST_SET_FEATURES:

		if (copy_from_user(&features, featurep, sizeof features))

			return -EFAULT;

		if (features & ~VHOST_FEATURES)

			return -EOPNOTSUPP;

		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, arg);

		vhost_test_flush(n);

		mutex_unlock(&n->dev.mutex);

		return r;

	}

}

#ifdef CONFIG_COMPAT

static long vhost_test_compat_ioctl(struct file *f, unsigned int ioctl,

				   unsigned long arg)

{

	return vhost_test_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));

}

#endif

static const struct file_operations vhost_test_fops = {

	.owner          = THIS_MODULE,

	.release        = vhost_test_release,

	.unlocked_ioctl = vhost_test_ioctl,

#ifdef CONFIG_COMPAT

	.compat_ioctl   = vhost_test_compat_ioctl,

#endif

	.open           = vhost_test_open,

	.llseek		= noop_llseek,

};

static struct miscdevice vhost_test_misc = {

	MISC_DYNAMIC_MINOR,

	"vhost-test",

	&vhost_test_fops,

};

static int vhost_test_init(void)

{

	return misc_register(&vhost_test_misc);

}

module_init(vhost_test_init);

static void vhost_test_exit(void)

{

	misc_deregister(&vhost_test_misc);

}

module_exit(vhost_test_exit);

MODULE_VERSION("0.0.1");

MODULE_LICENSE("GPL v2");

MODULE_AUTHOR("Michael S. Tsirkin");

MODULE_DESCRIPTION("Host kernel side for virtio simulator");

#ifndef LINUX_VHOST_TEST_H

#define LINUX_VHOST_TEST_H

/* Start a given test on the virtio null device. 0 stops all tests. */

#define VHOST_TEST_RUN _IOW(VHOST_VIRTIO, 0x31, int)

#endif

obj-m += vhost_test.o

EXTRA_CFLAGS += -Idrivers/vhost

#include "test.c"