// 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

static const int vhost_test_bits[] = {
        VHOST_FEATURES
};

#define VHOST_TEST_FEATURES VHOST_FEATURES_U64(vhost_test_bits, 0)

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\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(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_obj(*n);
        struct vhost_dev *dev;
        struct vhost_virtqueue **vqs;

        if (!n)
                return -ENOMEM;
        vqs = kmalloc_objs(*vqs, VHOST_TEST_VQ_MAX);
        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(struct vhost_test *n)
{
        vhost_dev_flush(&n->dev);
}

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);
        kfree(n->dev.vqs);
        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(n);
                }
        }

        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(n);
        }

        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_TEST_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_TEST_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, 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");