Linux 2.6.34-rc3

[pohmelfs.git] / drivers / vhost / net.c

/* 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.
 *
 * virtio-net server in host kernel.
 */

#include <linux/compat.h>
#include <linux/eventfd.h>
#include <linux/vhost.h>
#include <linux/virtio_net.h>
#include <linux/mmu_context.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/net.h>
#include <linux/if_packet.h>
#include <linux/if_arp.h>
#include <linux/if_tun.h>
#include <linux/if_macvlan.h>

#include <net/sock.h>

#include "vhost.h"

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

enum {
        VHOST_NET_VQ_RX = 0,
        VHOST_NET_VQ_TX = 1,
        VHOST_NET_VQ_MAX = 2,
};

enum vhost_net_poll_state {
        VHOST_NET_POLL_DISABLED = 0,
        VHOST_NET_POLL_STARTED = 1,
        VHOST_NET_POLL_STOPPED = 2,
};

struct vhost_net {
        struct vhost_dev dev;
        struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
        struct vhost_poll poll[VHOST_NET_VQ_MAX];
        /* Tells us whether we are polling a socket for TX.
         * We only do this when socket buffer fills up.
         * Protected by tx vq lock. */
        enum vhost_net_poll_state tx_poll_state;
};

/* Pop first len bytes from iovec. Return number of segments used. */
static int move_iovec_hdr(struct iovec *from, struct iovec *to,
                          size_t len, int iov_count)
{
        int seg = 0;
        size_t size;
        while (len && seg < iov_count) {
                size = min(from->iov_len, len);
                to->iov_base = from->iov_base;
                to->iov_len = size;
                from->iov_len -= size;
                from->iov_base += size;
                len -= size;
                ++from;
                ++to;
                ++seg;
        }
        return seg;
}

/* Caller must have TX VQ lock */
static void tx_poll_stop(struct vhost_net *net)
{
        if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
                return;
        vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
        net->tx_poll_state = VHOST_NET_POLL_STOPPED;
}

/* Caller must have TX VQ lock */
static void tx_poll_start(struct vhost_net *net, struct socket *sock)
{
        if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
                return;
        vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
        net->tx_poll_state = VHOST_NET_POLL_STARTED;
}

/* Expects to be always run from workqueue - which acts as
 * read-size critical section for our kind of RCU. */
static void handle_tx(struct vhost_net *net)
{
        struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
        unsigned head, out, in, s;
        struct msghdr msg = {
                .msg_name = NULL,
                .msg_namelen = 0,
                .msg_control = NULL,
                .msg_controllen = 0,
                .msg_iov = vq->iov,
                .msg_flags = MSG_DONTWAIT,
        };
        size_t len, total_len = 0;
        int err, wmem;
        size_t hdr_size;
        struct socket *sock = rcu_dereference(vq->private_data);
        if (!sock)
                return;

        wmem = atomic_read(&sock->sk->sk_wmem_alloc);
        if (wmem >= sock->sk->sk_sndbuf) {
                mutex_lock(&vq->mutex);
                tx_poll_start(net, sock);
                mutex_unlock(&vq->mutex);
                return;
        }

        use_mm(net->dev.mm);
        mutex_lock(&vq->mutex);
        vhost_disable_notify(vq);

        if (wmem < sock->sk->sk_sndbuf / 2)
                tx_poll_stop(net);
        hdr_size = vq->hdr_size;

        for (;;) {
                head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
                                         ARRAY_SIZE(vq->iov),
                                         &out, &in,
                                         NULL, NULL);
                /* Nothing new?  Wait for eventfd to tell us they refilled. */
                if (head == vq->num) {
                        wmem = atomic_read(&sock->sk->sk_wmem_alloc);
                        if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
                                tx_poll_start(net, sock);
                                set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
                                break;
                        }
                        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;
                }
                /* Skip header. TODO: support TSO. */
                s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
                msg.msg_iovlen = out;
                len = iov_length(vq->iov, out);
                /* Sanity check */
                if (!len) {
                        vq_err(vq, "Unexpected header len for TX: "
                               "%zd expected %zd\n",
                               iov_length(vq->hdr, s), hdr_size);
                        break;
                }
                /* TODO: Check specific error and bomb out unless ENOBUFS? */
                err = sock->ops->sendmsg(NULL, sock, &msg, len);
                if (unlikely(err < 0)) {
                        vhost_discard_vq_desc(vq);
                        tx_poll_start(net, sock);
                        break;
                }
                if (err != len)
                        pr_err("Truncated TX packet: "
                               " len %d != %zd\n", err, len);
                vhost_add_used_and_signal(&net->dev, vq, head, 0);
                total_len += len;
                if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
                        vhost_poll_queue(&vq->poll);
                        break;
                }
        }

        mutex_unlock(&vq->mutex);
        unuse_mm(net->dev.mm);
}

/* Expects to be always run from workqueue - which acts as
 * read-size critical section for our kind of RCU. */
static void handle_rx(struct vhost_net *net)
{
        struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
        unsigned head, out, in, log, s;
        struct vhost_log *vq_log;
        struct msghdr msg = {
                .msg_name = NULL,
                .msg_namelen = 0,
                .msg_control = NULL, /* FIXME: get and handle RX aux data. */
                .msg_controllen = 0,
                .msg_iov = vq->iov,
                .msg_flags = MSG_DONTWAIT,
        };

        struct virtio_net_hdr hdr = {
                .flags = 0,
                .gso_type = VIRTIO_NET_HDR_GSO_NONE
        };

        size_t len, total_len = 0;
        int err;
        size_t hdr_size;
        struct socket *sock = rcu_dereference(vq->private_data);
        if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
                return;

        use_mm(net->dev.mm);
        mutex_lock(&vq->mutex);
        vhost_disable_notify(vq);
        hdr_size = vq->hdr_size;

        vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
                vq->log : NULL;

        for (;;) {
                head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
                                         ARRAY_SIZE(vq->iov),
                                         &out, &in,
                                         vq_log, &log);
                /* OK, now we need to know about added descriptors. */
                if (head == vq->num) {
                        if (unlikely(vhost_enable_notify(vq))) {
                                /* They have slipped one in as we were
                                 * doing that: check again. */
                                vhost_disable_notify(vq);
                                continue;
                        }
                        /* Nothing new?  Wait for eventfd to tell us
                         * they refilled. */
                        break;
                }
                /* We don't need to be notified again. */
                if (out) {
                        vq_err(vq, "Unexpected descriptor format for RX: "
                               "out %d, int %d\n",
                               out, in);
                        break;
                }
                /* Skip header. TODO: support TSO/mergeable rx buffers. */
                s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
                msg.msg_iovlen = in;
                len = iov_length(vq->iov, in);
                /* Sanity check */
                if (!len) {
                        vq_err(vq, "Unexpected header len for RX: "
                               "%zd expected %zd\n",
                               iov_length(vq->hdr, s), hdr_size);
                        break;
                }
                err = sock->ops->recvmsg(NULL, sock, &msg,
                                         len, MSG_DONTWAIT | MSG_TRUNC);
                /* TODO: Check specific error and bomb out unless EAGAIN? */
                if (err < 0) {
                        vhost_discard_vq_desc(vq);
                        break;
                }
                /* TODO: Should check and handle checksum. */
                if (err > len) {
                        pr_err("Discarded truncated rx packet: "
                               " len %d > %zd\n", err, len);
                        vhost_discard_vq_desc(vq);
                        continue;
                }
                len = err;
                err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size);
                if (err) {
                        vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n",
                               vq->iov->iov_base, err);
                        break;
                }
                len += hdr_size;
                vhost_add_used_and_signal(&net->dev, vq, head, len);
                if (unlikely(vq_log))
                        vhost_log_write(vq, vq_log, log, len);
                total_len += len;
                if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
                        vhost_poll_queue(&vq->poll);
                        break;
                }
        }

        mutex_unlock(&vq->mutex);
        unuse_mm(net->dev.mm);
}

static void handle_tx_kick(struct work_struct *work)
{
        struct vhost_virtqueue *vq;
        struct vhost_net *net;
        vq = container_of(work, struct vhost_virtqueue, poll.work);
        net = container_of(vq->dev, struct vhost_net, dev);
        handle_tx(net);
}

static void handle_rx_kick(struct work_struct *work)
{
        struct vhost_virtqueue *vq;
        struct vhost_net *net;
        vq = container_of(work, struct vhost_virtqueue, poll.work);
        net = container_of(vq->dev, struct vhost_net, dev);
        handle_rx(net);
}

static void handle_tx_net(struct work_struct *work)
{
        struct vhost_net *net;
        net = container_of(work, struct vhost_net, poll[VHOST_NET_VQ_TX].work);
        handle_tx(net);
}

static void handle_rx_net(struct work_struct *work)
{
        struct vhost_net *net;
        net = container_of(work, struct vhost_net, poll[VHOST_NET_VQ_RX].work);
        handle_rx(net);
}

static int vhost_net_open(struct inode *inode, struct file *f)
{
        struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
        int r;
        if (!n)
                return -ENOMEM;
        n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
        n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
        r = vhost_dev_init(&n->dev, n->vqs, VHOST_NET_VQ_MAX);
        if (r < 0) {
                kfree(n);
                return r;
        }

        vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT);
        vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN);
        n->tx_poll_state = VHOST_NET_POLL_DISABLED;

        f->private_data = n;

        return 0;
}

static void vhost_net_disable_vq(struct vhost_net *n,
                                 struct vhost_virtqueue *vq)
{
        if (!vq->private_data)
                return;
        if (vq == n->vqs + VHOST_NET_VQ_TX) {
                tx_poll_stop(n);
                n->tx_poll_state = VHOST_NET_POLL_DISABLED;
        } else
                vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
}

static void vhost_net_enable_vq(struct vhost_net *n,
                                struct vhost_virtqueue *vq)
{
        struct socket *sock = vq->private_data;
        if (!sock)
                return;
        if (vq == n->vqs + VHOST_NET_VQ_TX) {
                n->tx_poll_state = VHOST_NET_POLL_STOPPED;
                tx_poll_start(n, sock);
        } else
                vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
}

static struct socket *vhost_net_stop_vq(struct vhost_net *n,
                                        struct vhost_virtqueue *vq)
{
        struct socket *sock;

        mutex_lock(&vq->mutex);
        sock = vq->private_data;
        vhost_net_disable_vq(n, vq);
        rcu_assign_pointer(vq->private_data, NULL);
        mutex_unlock(&vq->mutex);
        return sock;
}

static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
                           struct socket **rx_sock)
{
        *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
        *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
}

static void vhost_net_flush_vq(struct vhost_net *n, int index)
{
        vhost_poll_flush(n->poll + index);
        vhost_poll_flush(&n->dev.vqs[index].poll);
}

static void vhost_net_flush(struct vhost_net *n)
{
        vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
        vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
}

static int vhost_net_release(struct inode *inode, struct file *f)
{
        struct vhost_net *n = f->private_data;
        struct socket *tx_sock;
        struct socket *rx_sock;

        vhost_net_stop(n, &tx_sock, &rx_sock);
        vhost_net_flush(n);
        vhost_dev_cleanup(&n->dev);
        if (tx_sock)
                fput(tx_sock->file);
        if (rx_sock)
                fput(rx_sock->file);
        /* We do an extra flush before freeing memory,
         * since jobs can re-queue themselves. */
        vhost_net_flush(n);
        kfree(n);
        return 0;
}

static struct socket *get_raw_socket(int fd)
{
        struct {
                struct sockaddr_ll sa;
                char  buf[MAX_ADDR_LEN];
        } uaddr;
        int uaddr_len = sizeof uaddr, r;
        struct socket *sock = sockfd_lookup(fd, &r);
        if (!sock)
                return ERR_PTR(-ENOTSOCK);

        /* Parameter checking */
        if (sock->sk->sk_type != SOCK_RAW) {
                r = -ESOCKTNOSUPPORT;
                goto err;
        }

        r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
                               &uaddr_len, 0);
        if (r)
                goto err;

        if (uaddr.sa.sll_family != AF_PACKET) {
                r = -EPFNOSUPPORT;
                goto err;
        }
        return sock;
err:
        fput(sock->file);
        return ERR_PTR(r);
}

static struct socket *get_tap_socket(int fd)
{
        struct file *file = fget(fd);
        struct socket *sock;
        if (!file)
                return ERR_PTR(-EBADF);
        sock = tun_get_socket(file);
        if (!IS_ERR(sock))
                return sock;
        sock = macvtap_get_socket(file);
        if (IS_ERR(sock))
                fput(file);
        return sock;
}

static struct socket *get_socket(int fd)
{
        struct socket *sock;
        /* special case to disable backend */
        if (fd == -1)
                return NULL;
        sock = get_raw_socket(fd);
        if (!IS_ERR(sock))
                return sock;
        sock = get_tap_socket(fd);
        if (!IS_ERR(sock))
                return sock;
        return ERR_PTR(-ENOTSOCK);
}

static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
{
        struct socket *sock, *oldsock;
        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_NET_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;
        }
        sock = get_socket(fd);
        if (IS_ERR(sock)) {
                r = PTR_ERR(sock);
                goto err_vq;
        }

        /* start polling new socket */
        oldsock = vq->private_data;
        if (sock == oldsock)
                goto done;

        vhost_net_disable_vq(n, vq);
        rcu_assign_pointer(vq->private_data, sock);
        vhost_net_enable_vq(n, vq);
done:
        if (oldsock) {
                vhost_net_flush_vq(n, index);
                fput(oldsock->file);
        }

err_vq:
        mutex_unlock(&vq->mutex);
err:
        mutex_unlock(&n->dev.mutex);
        return r;
}

static long vhost_net_reset_owner(struct vhost_net *n)
{
        struct socket *tx_sock = NULL;
        struct socket *rx_sock = NULL;
        long err;
        mutex_lock(&n->dev.mutex);
        err = vhost_dev_check_owner(&n->dev);
        if (err)
                goto done;
        vhost_net_stop(n, &tx_sock, &rx_sock);
        vhost_net_flush(n);
        err = vhost_dev_reset_owner(&n->dev);
done:
        mutex_unlock(&n->dev.mutex);
        if (tx_sock)
                fput(tx_sock->file);
        if (rx_sock)
                fput(rx_sock->file);
        return err;
}

static int vhost_net_set_features(struct vhost_net *n, u64 features)
{
        size_t hdr_size = features & (1 << VHOST_NET_F_VIRTIO_NET_HDR) ?
                sizeof(struct virtio_net_hdr) : 0;
        int i;
        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();
        for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
                mutex_lock(&n->vqs[i].mutex);
                n->vqs[i].hdr_size = hdr_size;
                mutex_unlock(&n->vqs[i].mutex);
        }
        vhost_net_flush(n);
        mutex_unlock(&n->dev.mutex);
        return 0;
}

static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
                            unsigned long arg)
{
        struct vhost_net *n = f->private_data;
        void __user *argp = (void __user *)arg;
        u64 __user *featurep = argp;
        struct vhost_vring_file backend;
        u64 features;
        int r;
        switch (ioctl) {
        case VHOST_NET_SET_BACKEND:
                r = copy_from_user(&backend, argp, sizeof backend);
                if (r < 0)
                        return r;
                return vhost_net_set_backend(n, backend.index, backend.fd);
        case VHOST_GET_FEATURES:
                features = VHOST_FEATURES;
                return copy_to_user(featurep, &features, sizeof features);
        case VHOST_SET_FEATURES:
                r = copy_from_user(&features, featurep, sizeof features);
                if (r < 0)
                        return r;
                if (features & ~VHOST_FEATURES)
                        return -EOPNOTSUPP;
                return vhost_net_set_features(n, features);
        case VHOST_RESET_OWNER:
                return vhost_net_reset_owner(n);
        default:
                mutex_lock(&n->dev.mutex);
                r = vhost_dev_ioctl(&n->dev, ioctl, arg);
                vhost_net_flush(n);
                mutex_unlock(&n->dev.mutex);
                return r;
        }
}

#ifdef CONFIG_COMPAT
static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
                                   unsigned long arg)
{
        return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
}
#endif

const static struct file_operations vhost_net_fops = {
        .owner          = THIS_MODULE,
        .release        = vhost_net_release,
        .unlocked_ioctl = vhost_net_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = vhost_net_compat_ioctl,
#endif
        .open           = vhost_net_open,
};

static struct miscdevice vhost_net_misc = {
        VHOST_NET_MINOR,
        "vhost-net",
        &vhost_net_fops,
};

int vhost_net_init(void)
{
        int r = vhost_init();
        if (r)
                goto err_init;
        r = misc_register(&vhost_net_misc);
        if (r)
                goto err_reg;
        return 0;
err_reg:
        vhost_cleanup();
err_init:
        return r;

}
module_init(vhost_net_init);

void vhost_net_exit(void)
{
        misc_deregister(&vhost_net_misc);
        vhost_cleanup();
}
module_exit(vhost_net_exit);

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