xenbus.c

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/*
 * Xenbus code for netif backend
 *
 * Copyright (C) 2005 Rusty Russell <[email protected]>
 * Copyright (C) 2005 XenSource Ltd
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include "common.h"

struct backend_info {
    struct xenbus_device *dev;
    struct xenvif *vif;
    enum xenbus_state frontend_state;
    struct xenbus_watch hotplug_status_watch;
    u8 have_hotplug_status_watch:1;
};

static int connect_rings(struct backend_info *);
static void connect(struct backend_info *);
static void backend_create_xenvif(struct backend_info *be);
static void unregister_hotplug_status_watch(struct backend_info *be);

static int netback_remove(struct xenbus_device *dev)
{
    struct backend_info *be = dev_get_drvdata(&dev->dev);

    unregister_hotplug_status_watch(be);
    if (be->vif) {
        kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
        xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
        xenvif_disconnect(be->vif);
        be->vif = NULL;
    }
    kfree(be);
    dev_set_drvdata(&dev->dev, NULL);
    return 0;
}


static int netback_probe(struct xenbus_device *dev,
             const struct xenbus_device_id *id)
{
    const char *message;
    struct xenbus_transaction xbt;
    int err;
    int sg;
    struct backend_info *be = kzalloc(sizeof(struct backend_info),
                      GFP_KERNEL);
    if (!be) {
        xenbus_dev_fatal(dev, -ENOMEM,
                 "allocating backend structure");
        return -ENOMEM;
    }

    be->dev = dev;
    dev_set_drvdata(&dev->dev, be);

    sg = 1;

    do {
        err = xenbus_transaction_start(&xbt);
        if (err) {
            xenbus_dev_fatal(dev, err, "starting transaction");
            goto fail;
        }

        err = xenbus_printf(xbt, dev->nodename, "feature-sg", "%d", sg);
        if (err) {
            message = "writing feature-sg";
            goto abort_transaction;
        }

        err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv4",
                    "%d", sg);
        if (err) {
            message = "writing feature-gso-tcpv4";
            goto abort_transaction;
        }

        /* We support rx-copy path. */
        err = xenbus_printf(xbt, dev->nodename,
                    "feature-rx-copy", "%d", 1);
        if (err) {
            message = "writing feature-rx-copy";
            goto abort_transaction;
        }

        /*
         * We don't support rx-flip path (except old guests who don't
         * grok this feature flag).
         */
        err = xenbus_printf(xbt, dev->nodename,
                    "feature-rx-flip", "%d", 0);
        if (err) {
            message = "writing feature-rx-flip";
            goto abort_transaction;
        }

        err = xenbus_transaction_end(xbt, 0);
    } while (err == -EAGAIN);

    if (err) {
        xenbus_dev_fatal(dev, err, "completing transaction");
        goto fail;
    }

    err = xenbus_switch_state(dev, XenbusStateInitWait);
    if (err)
        goto fail;

    /* This kicks hotplug scripts, so do it immediately. */
    backend_create_xenvif(be);

    return 0;

abort_transaction:
    xenbus_transaction_end(xbt, 1);
    xenbus_dev_fatal(dev, err, "%s", message);
fail:
    pr_debug("failed");
    netback_remove(dev);
    return err;
}


/*
 * Handle the creation of the hotplug script environment.  We add the script
 * and vif variables to the environment, for the benefit of the vif-* hotplug
 * scripts.
 */
static int netback_uevent(struct xenbus_device *xdev,
              struct kobj_uevent_env *env)
{
    struct backend_info *be = dev_get_drvdata(&xdev->dev);
    char *val;

    val = xenbus_read(XBT_NIL, xdev->nodename, "script", NULL);
    if (IS_ERR(val)) {
        int err = PTR_ERR(val);
        xenbus_dev_fatal(xdev, err, "reading script");
        return err;
    } else {
        if (add_uevent_var(env, "script=%s", val)) {
            kfree(val);
            return -ENOMEM;
        }
        kfree(val);
    }

    if (!be || !be->vif)
        return 0;

    return add_uevent_var(env, "vif=%s", be->vif->dev->name);
}


static void backend_create_xenvif(struct backend_info *be)
{
    int err;
    long handle;
    struct xenbus_device *dev = be->dev;

    if (be->vif != NULL)
        return;

    err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%li", &handle);
    if (err != 1) {
        xenbus_dev_fatal(dev, err, "reading handle");
        return;
    }

    be->vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
    if (IS_ERR(be->vif)) {
        err = PTR_ERR(be->vif);
        be->vif = NULL;
        xenbus_dev_fatal(dev, err, "creating interface");
        return;
    }

    kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
}


static void disconnect_backend(struct xenbus_device *dev)
{
    struct backend_info *be = dev_get_drvdata(&dev->dev);

    if (be->vif) {
        xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
        xenvif_disconnect(be->vif);
        be->vif = NULL;
    }
}

static void frontend_changed(struct xenbus_device *dev,
                 enum xenbus_state frontend_state)
{
    struct backend_info *be = dev_get_drvdata(&dev->dev);

    pr_debug("frontend state %s", xenbus_strstate(frontend_state));

    be->frontend_state = frontend_state;

    switch (frontend_state) {
    case XenbusStateInitialising:
        if (dev->state == XenbusStateClosed) {
            printk(KERN_INFO "%s: %s: prepare for reconnect\n",
                   __func__, dev->nodename);
            xenbus_switch_state(dev, XenbusStateInitWait);
        }
        break;

    case XenbusStateInitialised:
        break;

    case XenbusStateConnected:
        if (dev->state == XenbusStateConnected)
            break;
        backend_create_xenvif(be);
        if (be->vif)
            connect(be);
        break;

    case XenbusStateClosing:
        if (be->vif)
            kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
        disconnect_backend(dev);
        xenbus_switch_state(dev, XenbusStateClosing);
        break;

    case XenbusStateClosed:
        xenbus_switch_state(dev, XenbusStateClosed);
        if (xenbus_dev_is_online(dev))
            break;
        /* fall through if not online */
    case XenbusStateUnknown:
        device_unregister(&dev->dev);
        break;

    default:
        xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
                 frontend_state);
        break;
    }
}


static void xen_net_read_rate(struct xenbus_device *dev,
                  unsigned long *bytes, unsigned long *usec)
{
    char *s, *e;
    unsigned long b, u;
    char *ratestr;

    /* Default to unlimited bandwidth. */
    *bytes = ~0UL;
    *usec = 0;

    ratestr = xenbus_read(XBT_NIL, dev->nodename, "rate", NULL);
    if (IS_ERR(ratestr))
        return;

    s = ratestr;
    b = simple_strtoul(s, &e, 10);
    if ((s == e) || (*e != ','))
        goto fail;

    s = e + 1;
    u = simple_strtoul(s, &e, 10);
    if ((s == e) || (*e != '\0'))
        goto fail;

    *bytes = b;
    *usec = u;

    kfree(ratestr);
    return;

 fail:
    pr_warn("Failed to parse network rate limit. Traffic unlimited.\n");
    kfree(ratestr);
}

static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
{
    char *s, *e, *macstr;
    int i;

    macstr = s = xenbus_read(XBT_NIL, dev->nodename, "mac", NULL);
    if (IS_ERR(macstr))
        return PTR_ERR(macstr);

    for (i = 0; i < ETH_ALEN; i++) {
        mac[i] = simple_strtoul(s, &e, 16);
        if ((s == e) || (*e != ((i == ETH_ALEN-1) ? '\0' : ':'))) {
            kfree(macstr);
            return -ENOENT;
        }
        s = e+1;
    }

    kfree(macstr);
    return 0;
}

static void unregister_hotplug_status_watch(struct backend_info *be)
{
    if (be->have_hotplug_status_watch) {
        unregister_xenbus_watch(&be->hotplug_status_watch);
        kfree(be->hotplug_status_watch.node);
    }
    be->have_hotplug_status_watch = 0;
}

static void hotplug_status_changed(struct xenbus_watch *watch,
                   const char **vec,
                   unsigned int vec_size)
{
    struct backend_info *be = container_of(watch,
                           struct backend_info,
                           hotplug_status_watch);
    char *str;
    unsigned int len;

    str = xenbus_read(XBT_NIL, be->dev->nodename, "hotplug-status", &len);
    if (IS_ERR(str))
        return;
    if (len == sizeof("connected")-1 && !memcmp(str, "connected", len)) {
        xenbus_switch_state(be->dev, XenbusStateConnected);
        /* Not interested in this watch anymore. */
        unregister_hotplug_status_watch(be);
    }
    kfree(str);
}

static void connect(struct backend_info *be)
{
    int err;
    struct xenbus_device *dev = be->dev;

    err = connect_rings(be);
    if (err)
        return;

    err = xen_net_read_mac(dev, be->vif->fe_dev_addr);
    if (err) {
        xenbus_dev_fatal(dev, err, "parsing %s/mac", dev->nodename);
        return;
    }

    xen_net_read_rate(dev, &be->vif->credit_bytes,
              &be->vif->credit_usec);
    be->vif->remaining_credit = be->vif->credit_bytes;

    unregister_hotplug_status_watch(be);
    err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
                   hotplug_status_changed,
                   "%s/%s", dev->nodename, "hotplug-status");
    if (err) {
        /* Switch now, since we can't do a watch. */
        xenbus_switch_state(dev, XenbusStateConnected);
    } else {
        be->have_hotplug_status_watch = 1;
    }

    netif_wake_queue(be->vif->dev);
}


static int connect_rings(struct backend_info *be)
{
    struct xenvif *vif = be->vif;
    struct xenbus_device *dev = be->dev;
    unsigned long tx_ring_ref, rx_ring_ref;
    unsigned int evtchn, rx_copy;
    int err;
    int val;

    err = xenbus_gather(XBT_NIL, dev->otherend,
                "tx-ring-ref", "%lu", &tx_ring_ref,
                "rx-ring-ref", "%lu", &rx_ring_ref,
                "event-channel", "%u", &evtchn, NULL);
    if (err) {
        xenbus_dev_fatal(dev, err,
                 "reading %s/ring-ref and event-channel",
                 dev->otherend);
        return err;
    }

    err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
               &rx_copy);
    if (err == -ENOENT) {
        err = 0;
        rx_copy = 0;
    }
    if (err < 0) {
        xenbus_dev_fatal(dev, err, "reading %s/request-rx-copy",
                 dev->otherend);
        return err;
    }
    if (!rx_copy)
        return -EOPNOTSUPP;

    if (vif->dev->tx_queue_len != 0) {
        if (xenbus_scanf(XBT_NIL, dev->otherend,
                 "feature-rx-notify", "%d", &val) < 0)
            val = 0;
        if (val)
            vif->can_queue = 1;
        else
            /* Must be non-zero for pfifo_fast to work. */
            vif->dev->tx_queue_len = 1;
    }

    if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
             "%d", &val) < 0)
        val = 0;
    vif->can_sg = !!val;

    if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
             "%d", &val) < 0)
        val = 0;
    vif->gso = !!val;

    if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
             "%d", &val) < 0)
        val = 0;
    vif->gso_prefix = !!val;

    if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
             "%d", &val) < 0)
        val = 0;
    vif->csum = !val;

    /* Map the shared frame, irq etc. */
    err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref, evtchn);
    if (err) {
        xenbus_dev_fatal(dev, err,
                 "mapping shared-frames %lu/%lu port %u",
                 tx_ring_ref, rx_ring_ref, evtchn);
        return err;
    }
    return 0;
}


/* ** Driver Registration ** */


static const struct xenbus_device_id netback_ids[] = {
    { "vif" },
    { "" }
};


static DEFINE_XENBUS_DRIVER(netback, ,
    .probe = netback_probe,
    .remove = netback_remove,
    .uevent = netback_uevent,
    .otherend_changed = frontend_changed,
);

int xenvif_xenbus_init(void)
{
    return xenbus_register_backend(&netback_driver);
}