interface.c

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/*
 * Network-device interface management.
 *
 * Copyright (c) 2004-2005, Keir Fraser
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "common.h"

#include <linux/ethtool.h>
#include <linux/rtnetlink.h>
#include <linux/if_vlan.h>

#include <xen/events.h>
#include <asm/xen/hypercall.h>

#define XENVIF_QUEUE_LENGTH 32

void xenvif_get(struct xenvif *vif)
{
    atomic_inc(&vif->refcnt);
}

void xenvif_put(struct xenvif *vif)
{
    if (atomic_dec_and_test(&vif->refcnt))
        wake_up(&vif->waiting_to_free);
}

int xenvif_schedulable(struct xenvif *vif)
{
    return netif_running(vif->dev) && netif_carrier_ok(vif->dev);
}

static int xenvif_rx_schedulable(struct xenvif *vif)
{
    return xenvif_schedulable(vif) && !xen_netbk_rx_ring_full(vif);
}

static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
{
    struct xenvif *vif = dev_id;

    if (vif->netbk == NULL)
        return IRQ_NONE;

    xen_netbk_schedule_xenvif(vif);

    if (xenvif_rx_schedulable(vif))
        netif_wake_queue(vif->dev);

    return IRQ_HANDLED;
}

static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
    struct xenvif *vif = netdev_priv(dev);

    BUG_ON(skb->dev != dev);

    if (vif->netbk == NULL)
        goto drop;

    /* Drop the packet if the target domain has no receive buffers. */
    if (!xenvif_rx_schedulable(vif))
        goto drop;

    /* Reserve ring slots for the worst-case number of fragments. */
    vif->rx_req_cons_peek += xen_netbk_count_skb_slots(vif, skb);
    xenvif_get(vif);

    if (vif->can_queue && xen_netbk_must_stop_queue(vif))
        netif_stop_queue(dev);

    xen_netbk_queue_tx_skb(vif, skb);

    return NETDEV_TX_OK;

 drop:
    vif->dev->stats.tx_dropped++;
    dev_kfree_skb(skb);
    return NETDEV_TX_OK;
}

void xenvif_receive_skb(struct xenvif *vif, struct sk_buff *skb)
{
    netif_rx_ni(skb);
}

void xenvif_notify_tx_completion(struct xenvif *vif)
{
    if (netif_queue_stopped(vif->dev) && xenvif_rx_schedulable(vif))
        netif_wake_queue(vif->dev);
}

static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
{
    struct xenvif *vif = netdev_priv(dev);
    return &vif->dev->stats;
}

static void xenvif_up(struct xenvif *vif)
{
    xen_netbk_add_xenvif(vif);
    enable_irq(vif->irq);
    xen_netbk_check_rx_xenvif(vif);
}

static void xenvif_down(struct xenvif *vif)
{
    disable_irq(vif->irq);
    xen_netbk_deschedule_xenvif(vif);
    xen_netbk_remove_xenvif(vif);
}

static int xenvif_open(struct net_device *dev)
{
    struct xenvif *vif = netdev_priv(dev);
    if (netif_carrier_ok(dev))
        xenvif_up(vif);
    netif_start_queue(dev);
    return 0;
}

static int xenvif_close(struct net_device *dev)
{
    struct xenvif *vif = netdev_priv(dev);
    if (netif_carrier_ok(dev))
        xenvif_down(vif);
    netif_stop_queue(dev);
    return 0;
}

static int xenvif_change_mtu(struct net_device *dev, int mtu)
{
    struct xenvif *vif = netdev_priv(dev);
    int max = vif->can_sg ? 65535 - VLAN_ETH_HLEN : ETH_DATA_LEN;

    if (mtu > max)
        return -EINVAL;
    dev->mtu = mtu;
    return 0;
}

static netdev_features_t xenvif_fix_features(struct net_device *dev,
    netdev_features_t features)
{
    struct xenvif *vif = netdev_priv(dev);

    if (!vif->can_sg)
        features &= ~NETIF_F_SG;
    if (!vif->gso && !vif->gso_prefix)
        features &= ~NETIF_F_TSO;
    if (!vif->csum)
        features &= ~NETIF_F_IP_CSUM;

    return features;
}

static const struct xenvif_stat {
    char name[ETH_GSTRING_LEN];
    u16 offset;
} xenvif_stats[] = {
    {
        "rx_gso_checksum_fixup",
        offsetof(struct xenvif, rx_gso_checksum_fixup)
    },
};

static int xenvif_get_sset_count(struct net_device *dev, int string_set)
{
    switch (string_set) {
    case ETH_SS_STATS:
        return ARRAY_SIZE(xenvif_stats);
    default:
        return -EINVAL;
    }
}

static void xenvif_get_ethtool_stats(struct net_device *dev,
                     struct ethtool_stats *stats, u64 * data)
{
    void *vif = netdev_priv(dev);
    int i;

    for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
        data[i] = *(unsigned long *)(vif + xenvif_stats[i].offset);
}

static void xenvif_get_strings(struct net_device *dev, u32 stringset, u8 * data)
{
    int i;

    switch (stringset) {
    case ETH_SS_STATS:
        for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
            memcpy(data + i * ETH_GSTRING_LEN,
                   xenvif_stats[i].name, ETH_GSTRING_LEN);
        break;
    }
}

static const struct ethtool_ops xenvif_ethtool_ops = {
    .get_link   = ethtool_op_get_link,

    .get_sset_count = xenvif_get_sset_count,
    .get_ethtool_stats = xenvif_get_ethtool_stats,
    .get_strings = xenvif_get_strings,
};

static const struct net_device_ops xenvif_netdev_ops = {
    .ndo_start_xmit = xenvif_start_xmit,
    .ndo_get_stats  = xenvif_get_stats,
    .ndo_open   = xenvif_open,
    .ndo_stop   = xenvif_close,
    .ndo_change_mtu = xenvif_change_mtu,
    .ndo_fix_features = xenvif_fix_features,
};

struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
                unsigned int handle)
{
    int err;
    struct net_device *dev;
    struct xenvif *vif;
    char name[IFNAMSIZ] = {};

    snprintf(name, IFNAMSIZ - 1, "vif%u.%u", domid, handle);
    dev = alloc_netdev(sizeof(struct xenvif), name, ether_setup);
    if (dev == NULL) {
        pr_warn("Could not allocate netdev\n");
        return ERR_PTR(-ENOMEM);
    }

    SET_NETDEV_DEV(dev, parent);

    vif = netdev_priv(dev);
    vif->domid  = domid;
    vif->handle = handle;
    vif->netbk  = NULL;
    vif->can_sg = 1;
    vif->csum = 1;
    atomic_set(&vif->refcnt, 1);
    init_waitqueue_head(&vif->waiting_to_free);
    vif->dev = dev;
    INIT_LIST_HEAD(&vif->schedule_list);
    INIT_LIST_HEAD(&vif->notify_list);

    vif->credit_bytes = vif->remaining_credit = ~0UL;
    vif->credit_usec  = 0UL;
    init_timer(&vif->credit_timeout);
    /* Initialize 'expires' now: it's used to track the credit window. */
    vif->credit_timeout.expires = jiffies;

    dev->netdev_ops = &xenvif_netdev_ops;
    dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO;
    dev->features = dev->hw_features;
    SET_ETHTOOL_OPS(dev, &xenvif_ethtool_ops);

    dev->tx_queue_len = XENVIF_QUEUE_LENGTH;

    /*
     * Initialise a dummy MAC address. We choose the numerically
     * largest non-broadcast address to prevent the address getting
     * stolen by an Ethernet bridge for STP purposes.
     * (FE:FF:FF:FF:FF:FF)
     */
    memset(dev->dev_addr, 0xFF, ETH_ALEN);
    dev->dev_addr[0] &= ~0x01;

    netif_carrier_off(dev);

    err = register_netdev(dev);
    if (err) {
        netdev_warn(dev, "Could not register device: err=%d\n", err);
        free_netdev(dev);
        return ERR_PTR(err);
    }

    netdev_dbg(dev, "Successfully created xenvif\n");
    return vif;
}

int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
           unsigned long rx_ring_ref, unsigned int evtchn)
{
    int err = -ENOMEM;

    /* Already connected through? */
    if (vif->irq)
        return 0;

    err = xen_netbk_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
    if (err < 0)
        goto err;

    err = bind_interdomain_evtchn_to_irqhandler(
        vif->domid, evtchn, xenvif_interrupt, 0,
        vif->dev->name, vif);
    if (err < 0)
        goto err_unmap;
    vif->irq = err;
    disable_irq(vif->irq);

    xenvif_get(vif);

    rtnl_lock();
    if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)
        dev_set_mtu(vif->dev, ETH_DATA_LEN);
    netdev_update_features(vif->dev);
    netif_carrier_on(vif->dev);
    if (netif_running(vif->dev))
        xenvif_up(vif);
    rtnl_unlock();

    return 0;
err_unmap:
    xen_netbk_unmap_frontend_rings(vif);
err:
    return err;
}

void xenvif_disconnect(struct xenvif *vif)
{
    struct net_device *dev = vif->dev;
    if (netif_carrier_ok(dev)) {
        rtnl_lock();
        netif_carrier_off(dev); /* discard queued packets */
        if (netif_running(dev))
            xenvif_down(vif);
        rtnl_unlock();
        xenvif_put(vif);
    }

    atomic_dec(&vif->refcnt);
    wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0);

    del_timer_sync(&vif->credit_timeout);

    if (vif->irq)
        unbind_from_irqhandler(vif->irq, vif);

    unregister_netdev(vif->dev);

    xen_netbk_unmap_frontend_rings(vif);

    free_netdev(vif->dev);
}