test.c

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/* Copyright (C) 2009 Red Hat, Inc.
 * Author: Michael S. Tsirkin <[email protected]>
 *
 * 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(&n->dev, 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(&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\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, false);
    /* 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);

        r = vhost_init_used(&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;
    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_NET_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_NET_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");