/*
 * 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/kthread.h>
#include <linux/ethtool.h>
#include <linux/rtnetlink.h>
#include <linux/if_vlan.h>
#include <linux/vmalloc.h>

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

#define XENVIF_QUEUE_LENGTH 32
#define XENVIF_NAPI_WEIGHT  64

static inline void xenvif_stop_queue(struct xenvif_queue *queue)
{
        struct net_device *dev = queue->vif->dev;

        if (!queue->vif->can_queue)
                return;

        netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id));
}

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

static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id)
{
        struct xenvif_queue *queue = dev_id;

        if (RING_HAS_UNCONSUMED_REQUESTS(&queue->tx))
                napi_schedule(&queue->napi);

        return IRQ_HANDLED;
}

int xenvif_poll(struct napi_struct *napi, int budget)
{
        struct xenvif_queue *queue =
                container_of(napi, struct xenvif_queue, napi);
        int work_done;

        /* This vif is rogue, we pretend we've there is nothing to do
         * for this vif to deschedule it from NAPI. But this interface
         * will be turned off in thread context later.
         */
        if (unlikely(queue->vif->disabled)) {
                napi_complete(napi);
                return 0;
        }

        work_done = xenvif_tx_action(queue, budget);

        if (work_done < budget) {
                napi_complete(napi);
                xenvif_napi_schedule_or_enable_events(queue);
        }

        return work_done;
}

static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
{
        struct xenvif_queue *queue = dev_id;

        xenvif_kick_thread(queue);

        return IRQ_HANDLED;
}

static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
{
        xenvif_tx_interrupt(irq, dev_id);
        xenvif_rx_interrupt(irq, dev_id);

        return IRQ_HANDLED;
}

int xenvif_queue_stopped(struct xenvif_queue *queue)
{
        struct net_device *dev = queue->vif->dev;
        unsigned int id = queue->id;
        return netif_tx_queue_stopped(netdev_get_tx_queue(dev, id));
}

void xenvif_wake_queue(struct xenvif_queue *queue)
{
        struct net_device *dev = queue->vif->dev;
        unsigned int id = queue->id;
        netif_tx_wake_queue(netdev_get_tx_queue(dev, id));
}

/* Callback to wake the queue and drain it on timeout */
static void xenvif_wake_queue_callback(unsigned long data)
{
        struct xenvif_queue *queue = (struct xenvif_queue *)data;

        if (xenvif_queue_stopped(queue)) {
                netdev_err(queue->vif->dev, "draining TX queue\n");
                queue->rx_queue_purge = true;
                xenvif_kick_thread(queue);
                xenvif_wake_queue(queue);
        }
}

static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct xenvif *vif = netdev_priv(dev);
        struct xenvif_queue *queue = NULL;
        unsigned int num_queues = vif->num_queues;
        u16 index;
        int min_slots_needed;

        BUG_ON(skb->dev != dev);

        /* Drop the packet if queues are not set up */
        if (num_queues < 1)
                goto drop;

        /* Obtain the queue to be used to transmit this packet */
        index = skb_get_queue_mapping(skb);
        if (index >= num_queues) {
                pr_warn_ratelimited("Invalid queue %hu for packet on interface %s\n.",
                                    index, vif->dev->name);
                index %= num_queues;
        }
        queue = &vif->queues[index];

        /* Drop the packet if queue is not ready */
        if (queue->task == NULL ||
            queue->dealloc_task == NULL ||
            !xenvif_schedulable(vif))
                goto drop;

        /* At best we'll need one slot for the header and one for each
         * frag.
         */
        min_slots_needed = 1 + skb_shinfo(skb)->nr_frags;

        /* If the skb is GSO then we'll also need an extra slot for the
         * metadata.
         */
        if (skb_is_gso(skb))
                min_slots_needed++;

        /* If the skb can't possibly fit in the remaining slots
         * then turn off the queue to give the ring a chance to
         * drain.
         */
        if (!xenvif_rx_ring_slots_available(queue, min_slots_needed)) {
                queue->wake_queue.function = xenvif_wake_queue_callback;
                queue->wake_queue.data = (unsigned long)queue;
                xenvif_stop_queue(queue);
                mod_timer(&queue->wake_queue,
                        jiffies + rx_drain_timeout_jiffies);
        }

        skb_queue_tail(&queue->rx_queue, skb);
        xenvif_kick_thread(queue);

        return NETDEV_TX_OK;

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

static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
{
        struct xenvif *vif = netdev_priv(dev);
        struct xenvif_queue *queue = NULL;
        unsigned int num_queues = vif->num_queues;
        unsigned long rx_bytes = 0;
        unsigned long rx_packets = 0;
        unsigned long tx_bytes = 0;
        unsigned long tx_packets = 0;
        unsigned int index;

        if (vif->queues == NULL)
                goto out;

        /* Aggregate tx and rx stats from each queue */
        for (index = 0; index < num_queues; ++index) {
                queue = &vif->queues[index];
                rx_bytes += queue->stats.rx_bytes;
                rx_packets += queue->stats.rx_packets;
                tx_bytes += queue->stats.tx_bytes;
                tx_packets += queue->stats.tx_packets;
        }

out:
        vif->dev->stats.rx_bytes = rx_bytes;
        vif->dev->stats.rx_packets = rx_packets;
        vif->dev->stats.tx_bytes = tx_bytes;
        vif->dev->stats.tx_packets = tx_packets;

        return &vif->dev->stats;
}

static void xenvif_up(struct xenvif *vif)
{
        struct xenvif_queue *queue = NULL;
        unsigned int num_queues = vif->num_queues;
        unsigned int queue_index;

        for (queue_index = 0; queue_index < num_queues; ++queue_index) {
                queue = &vif->queues[queue_index];
                napi_enable(&queue->napi);
                enable_irq(queue->tx_irq);
                if (queue->tx_irq != queue->rx_irq)
                        enable_irq(queue->rx_irq);
                xenvif_napi_schedule_or_enable_events(queue);
        }
}

static void xenvif_down(struct xenvif *vif)
{
        struct xenvif_queue *queue = NULL;
        unsigned int num_queues = vif->num_queues;
        unsigned int queue_index;

        for (queue_index = 0; queue_index < num_queues; ++queue_index) {
                queue = &vif->queues[queue_index];
                napi_disable(&queue->napi);
                disable_irq(queue->tx_irq);
                if (queue->tx_irq != queue->rx_irq)
                        disable_irq(queue->rx_irq);
                del_timer_sync(&queue->credit_timeout);
        }
}

static int xenvif_open(struct net_device *dev)
{
        struct xenvif *vif = netdev_priv(dev);
        if (netif_carrier_ok(dev))
                xenvif_up(vif);
        netif_tx_start_all_queues(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_tx_stop_all_queues(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_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV4))
                features &= ~NETIF_F_TSO;
        if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV6))
                features &= ~NETIF_F_TSO6;
        if (!vif->ip_csum)
                features &= ~NETIF_F_IP_CSUM;
        if (!vif->ipv6_csum)
                features &= ~NETIF_F_IPV6_CSUM;

        return features;
}

static const struct xenvif_stat {
        char name[ETH_GSTRING_LEN];
        u16 offset;
} xenvif_stats[] = {
        {
                "rx_gso_checksum_fixup",
                offsetof(struct xenvif_stats, rx_gso_checksum_fixup)
        },
        /* If (sent != success + fail), there are probably packets never
         * freed up properly!
         */
        {
                "tx_zerocopy_sent",
                offsetof(struct xenvif_stats, tx_zerocopy_sent),
        },
        {
                "tx_zerocopy_success",
                offsetof(struct xenvif_stats, tx_zerocopy_success),
        },
        {
                "tx_zerocopy_fail",
                offsetof(struct xenvif_stats, tx_zerocopy_fail)
        },
        /* Number of packets exceeding MAX_SKB_FRAG slots. You should use
         * a guest with the same MAX_SKB_FRAG
         */
        {
                "tx_frag_overflow",
                offsetof(struct xenvif_stats, tx_frag_overflow)
        },
};

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)
{
        struct xenvif *vif = netdev_priv(dev);
        unsigned int num_queues = vif->num_queues;
        int i;
        unsigned int queue_index;
        struct xenvif_stats *vif_stats;

        for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++) {
                unsigned long accum = 0;
                for (queue_index = 0; queue_index < num_queues; ++queue_index) {
                        vif_stats = &vif->queues[queue_index].stats;
                        accum += *(unsigned long *)(vif_stats + xenvif_stats[i].offset);
                }
                data[i] = accum;
        }
}

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,
        .ndo_set_mac_address = eth_mac_addr,
        .ndo_validate_addr   = eth_validate_addr,
};

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);
        /* Allocate a netdev with the max. supported number of queues.
         * When the guest selects the desired number, it will be updated
         * via netif_set_real_num_*_queues().
         */
        dev = alloc_netdev_mq(sizeof(struct xenvif), name, ether_setup,
                              xenvif_max_queues);
        if (dev == NULL) {
                pr_warn("Could not allocate netdev for %s\n", name);
                return ERR_PTR(-ENOMEM);
        }

        SET_NETDEV_DEV(dev, parent);

        vif = netdev_priv(dev);

        vif->domid  = domid;
        vif->handle = handle;
        vif->can_sg = 1;
        vif->ip_csum = 1;
        vif->dev = dev;
        vif->disabled = false;

        /* Start out with no queues. */
        vif->queues = NULL;
        vif->num_queues = 0;

        dev->netdev_ops = &xenvif_netdev_ops;
        dev->hw_features = NETIF_F_SG |
                NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
                NETIF_F_TSO | NETIF_F_TSO6;
        dev->features = dev->hw_features | NETIF_F_RXCSUM;
        dev->ethtool_ops = &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");

        __module_get(THIS_MODULE);

        return vif;
}

int xenvif_init_queue(struct xenvif_queue *queue)
{
        int err, i;

        queue->credit_bytes = queue->remaining_credit = ~0UL;
        queue->credit_usec  = 0UL;
        init_timer(&queue->credit_timeout);
        queue->credit_window_start = get_jiffies_64();

        skb_queue_head_init(&queue->rx_queue);
        skb_queue_head_init(&queue->tx_queue);

        queue->pending_cons = 0;
        queue->pending_prod = MAX_PENDING_REQS;
        for (i = 0; i < MAX_PENDING_REQS; ++i)
                queue->pending_ring[i] = i;

        spin_lock_init(&queue->callback_lock);
        spin_lock_init(&queue->response_lock);

        /* If ballooning is disabled, this will consume real memory, so you
         * better enable it. The long term solution would be to use just a
         * bunch of valid page descriptors, without dependency on ballooning
         */
        err = alloc_xenballooned_pages(MAX_PENDING_REQS,
                                       queue->mmap_pages,
                                       false);
        if (err) {
                netdev_err(queue->vif->dev, "Could not reserve mmap_pages\n");
                return -ENOMEM;
        }

        for (i = 0; i < MAX_PENDING_REQS; i++) {
                queue->pending_tx_info[i].callback_struct = (struct ubuf_info)
                        { .callback = xenvif_zerocopy_callback,
                          .ctx = NULL,
                          .desc = i };
                queue->grant_tx_handle[i] = NETBACK_INVALID_HANDLE;
        }

        init_timer(&queue->wake_queue);

        netif_napi_add(queue->vif->dev, &queue->napi, xenvif_poll,
                        XENVIF_NAPI_WEIGHT);

        return 0;
}

void xenvif_carrier_on(struct xenvif *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();
}

int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref,
                   unsigned long rx_ring_ref, unsigned int tx_evtchn,
                   unsigned int rx_evtchn)
{
        struct task_struct *task;
        int err = -ENOMEM;

        BUG_ON(queue->tx_irq);
        BUG_ON(queue->task);
        BUG_ON(queue->dealloc_task);

        err = xenvif_map_frontend_rings(queue, tx_ring_ref, rx_ring_ref);
        if (err < 0)
                goto err;

        init_waitqueue_head(&queue->wq);
        init_waitqueue_head(&queue->dealloc_wq);

        if (tx_evtchn == rx_evtchn) {
                /* feature-split-event-channels == 0 */
                err = bind_interdomain_evtchn_to_irqhandler(
                        queue->vif->domid, tx_evtchn, xenvif_interrupt, 0,
                        queue->name, queue);
                if (err < 0)
                        goto err_unmap;
                queue->tx_irq = queue->rx_irq = err;
                disable_irq(queue->tx_irq);
        } else {
                /* feature-split-event-channels == 1 */
                snprintf(queue->tx_irq_name, sizeof(queue->tx_irq_name),
                         "%s-tx", queue->name);
                err = bind_interdomain_evtchn_to_irqhandler(
                        queue->vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
                        queue->tx_irq_name, queue);
                if (err < 0)
                        goto err_unmap;
                queue->tx_irq = err;
                disable_irq(queue->tx_irq);

                snprintf(queue->rx_irq_name, sizeof(queue->rx_irq_name),
                         "%s-rx", queue->name);
                err = bind_interdomain_evtchn_to_irqhandler(
                        queue->vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
                        queue->rx_irq_name, queue);
                if (err < 0)
                        goto err_tx_unbind;
                queue->rx_irq = err;
                disable_irq(queue->rx_irq);
        }

        task = kthread_create(xenvif_kthread_guest_rx,
                              (void *)queue, "%s-guest-rx", queue->name);
        if (IS_ERR(task)) {
                pr_warn("Could not allocate kthread for %s\n", queue->name);
                err = PTR_ERR(task);
                goto err_rx_unbind;
        }
        queue->task = task;

        task = kthread_create(xenvif_dealloc_kthread,
                              (void *)queue, "%s-dealloc", queue->name);
        if (IS_ERR(task)) {
                pr_warn("Could not allocate kthread for %s\n", queue->name);
                err = PTR_ERR(task);
                goto err_rx_unbind;
        }
        queue->dealloc_task = task;

        wake_up_process(queue->task);
        wake_up_process(queue->dealloc_task);

        return 0;

err_rx_unbind:
        unbind_from_irqhandler(queue->rx_irq, queue);
        queue->rx_irq = 0;
err_tx_unbind:
        unbind_from_irqhandler(queue->tx_irq, queue);
        queue->tx_irq = 0;
err_unmap:
        xenvif_unmap_frontend_rings(queue);
err:
        module_put(THIS_MODULE);
        return err;
}

void xenvif_carrier_off(struct xenvif *vif)
{
        struct net_device *dev = vif->dev;

        rtnl_lock();
        netif_carrier_off(dev); /* discard queued packets */
        if (netif_running(dev))
                xenvif_down(vif);
        rtnl_unlock();
}

static void xenvif_wait_unmap_timeout(struct xenvif_queue *queue,
                                      unsigned int worst_case_skb_lifetime)
{
        int i, unmap_timeout = 0;

        for (i = 0; i < MAX_PENDING_REQS; ++i) {
                if (queue->grant_tx_handle[i] != NETBACK_INVALID_HANDLE) {
                        unmap_timeout++;
                        schedule_timeout(msecs_to_jiffies(1000));
                        if (unmap_timeout > worst_case_skb_lifetime &&
                            net_ratelimit())
                                netdev_err(queue->vif->dev,
                                           "Page still granted! Index: %x\n",
                                           i);
                        i = -1;
                }
        }
}

void xenvif_disconnect(struct xenvif *vif)
{
        struct xenvif_queue *queue = NULL;
        unsigned int num_queues = vif->num_queues;
        unsigned int queue_index;

        if (netif_carrier_ok(vif->dev))
                xenvif_carrier_off(vif);

        for (queue_index = 0; queue_index < num_queues; ++queue_index) {
                queue = &vif->queues[queue_index];

                if (queue->task) {
                        del_timer_sync(&queue->wake_queue);
                        kthread_stop(queue->task);
                        queue->task = NULL;
                }

                if (queue->dealloc_task) {
                        kthread_stop(queue->dealloc_task);
                        queue->dealloc_task = NULL;
                }

                if (queue->tx_irq) {
                        if (queue->tx_irq == queue->rx_irq)
                                unbind_from_irqhandler(queue->tx_irq, queue);
                        else {
                                unbind_from_irqhandler(queue->tx_irq, queue);
                                unbind_from_irqhandler(queue->rx_irq, queue);
                        }
                        queue->tx_irq = 0;
                }

                xenvif_unmap_frontend_rings(queue);
        }
}

/* Reverse the relevant parts of xenvif_init_queue().
 * Used for queue teardown from xenvif_free(), and on the
 * error handling paths in xenbus.c:connect().
 */
void xenvif_deinit_queue(struct xenvif_queue *queue)
{
        free_xenballooned_pages(MAX_PENDING_REQS, queue->mmap_pages);
        netif_napi_del(&queue->napi);
}

void xenvif_free(struct xenvif *vif)
{
        struct xenvif_queue *queue = NULL;
        unsigned int num_queues = vif->num_queues;
        unsigned int queue_index;
        /* Here we want to avoid timeout messages if an skb can be legitimately
         * stuck somewhere else. Realistically this could be an another vif's
         * internal or QDisc queue. That another vif also has this
         * rx_drain_timeout_msecs timeout, but the timer only ditches the
         * internal queue. After that, the QDisc queue can put in worst case
         * XEN_NETIF_RX_RING_SIZE / MAX_SKB_FRAGS skbs into that another vif's
         * internal queue, so we need several rounds of such timeouts until we
         * can be sure that no another vif should have skb's from us. We are
         * not sending more skb's, so newly stuck packets are not interesting
         * for us here.
         */
        unsigned int worst_case_skb_lifetime = (rx_drain_timeout_msecs/1000) *
                DIV_ROUND_UP(XENVIF_QUEUE_LENGTH, (XEN_NETIF_RX_RING_SIZE / MAX_SKB_FRAGS));

        unregister_netdev(vif->dev);

        for (queue_index = 0; queue_index < num_queues; ++queue_index) {
                queue = &vif->queues[queue_index];
                xenvif_wait_unmap_timeout(queue, worst_case_skb_lifetime);
                xenvif_deinit_queue(queue);
        }

        vfree(vif->queues);
        vif->queues = NULL;
        vif->num_queues = 0;

        free_netdev(vif->dev);

        module_put(THIS_MODULE);
}