/* sunvnet.c: Sun LDOM Virtual Network Driver.
 *
 * Copyright (C) 2007, 2008 David S. Miller <davem@davemloft.net>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/ethtool.h>
#include <linux/etherdevice.h>
#include <linux/mutex.h>
#include <linux/highmem.h>
#include <linux/if_vlan.h>

#if IS_ENABLED(CONFIG_IPV6)
#include <linux/icmpv6.h>
#endif

#include <net/ip.h>
#include <net/icmp.h>
#include <net/route.h>

#include <asm/vio.h>
#include <asm/ldc.h>

#include "sunvnet.h"

#define DRV_MODULE_NAME         "sunvnet"
#define DRV_MODULE_VERSION      "1.0"
#define DRV_MODULE_RELDATE      "June 25, 2007"

static char version[] =
        DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")\n";
MODULE_AUTHOR("David S. Miller (davem@davemloft.net)");
MODULE_DESCRIPTION("Sun LDOM virtual network driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_MODULE_VERSION);

#define VNET_MAX_TXQS           16

/* Heuristic for the number of times to exponentially backoff and
 * retry sending an LDC trigger when EAGAIN is encountered
 */
#define VNET_MAX_RETRIES        10

static int __vnet_tx_trigger(struct vnet_port *port, u32 start);
static void vnet_port_reset(struct vnet_port *port);

/* Ordered from largest major to lowest */
static struct vio_version vnet_versions[] = {
        { .major = 1, .minor = 8 },
        { .major = 1, .minor = 7 },
        { .major = 1, .minor = 6 },
        { .major = 1, .minor = 0 },
};

static inline u32 vnet_tx_dring_avail(struct vio_dring_state *dr)
{
        return vio_dring_avail(dr, VNET_TX_RING_SIZE);
}

static int vnet_handle_unknown(struct vnet_port *port, void *arg)
{
        struct vio_msg_tag *pkt = arg;

        pr_err("Received unknown msg [%02x:%02x:%04x:%08x]\n",
               pkt->type, pkt->stype, pkt->stype_env, pkt->sid);
        pr_err("Resetting connection\n");

        ldc_disconnect(port->vio.lp);

        return -ECONNRESET;
}

static int vnet_port_alloc_tx_ring(struct vnet_port *port);

static int vnet_send_attr(struct vio_driver_state *vio)
{
        struct vnet_port *port = to_vnet_port(vio);
        struct net_device *dev = port->vp->dev;
        struct vio_net_attr_info pkt;
        int framelen = ETH_FRAME_LEN;
        int i, err;

        err = vnet_port_alloc_tx_ring(to_vnet_port(vio));
        if (err)
                return err;

        memset(&pkt, 0, sizeof(pkt));
        pkt.tag.type = VIO_TYPE_CTRL;
        pkt.tag.stype = VIO_SUBTYPE_INFO;
        pkt.tag.stype_env = VIO_ATTR_INFO;
        pkt.tag.sid = vio_send_sid(vio);
        if (vio_version_before(vio, 1, 2))
                pkt.xfer_mode = VIO_DRING_MODE;
        else
                pkt.xfer_mode = VIO_NEW_DRING_MODE;
        pkt.addr_type = VNET_ADDR_ETHERMAC;
        pkt.ack_freq = 0;
        for (i = 0; i < 6; i++)
                pkt.addr |= (u64)dev->dev_addr[i] << ((5 - i) * 8);
        if (vio_version_after(vio, 1, 3)) {
                if (port->rmtu) {
                        port->rmtu = min(VNET_MAXPACKET, port->rmtu);
                        pkt.mtu = port->rmtu;
                } else {
                        port->rmtu = VNET_MAXPACKET;
                        pkt.mtu = port->rmtu;
                }
                if (vio_version_after_eq(vio, 1, 6))
                        pkt.options = VIO_TX_DRING;
        } else if (vio_version_before(vio, 1, 3)) {
                pkt.mtu = framelen;
        } else { /* v1.3 */
                pkt.mtu = framelen + VLAN_HLEN;
        }

        pkt.cflags = 0;
        if (vio_version_after_eq(vio, 1, 7) && port->tso) {
                pkt.cflags |= VNET_LSO_IPV4_CAPAB;
                if (!port->tsolen)
                        port->tsolen = VNET_MAXTSO;
                pkt.ipv4_lso_maxlen = port->tsolen;
        }

        pkt.plnk_updt = PHYSLINK_UPDATE_NONE;

        viodbg(HS, "SEND NET ATTR xmode[0x%x] atype[0x%x] addr[%llx] "
               "ackfreq[%u] plnk_updt[0x%02x] opts[0x%02x] mtu[%llu] "
               "cflags[0x%04x] lso_max[%u]\n",
               pkt.xfer_mode, pkt.addr_type,
               (unsigned long long)pkt.addr,
               pkt.ack_freq, pkt.plnk_updt, pkt.options,
               (unsigned long long)pkt.mtu, pkt.cflags, pkt.ipv4_lso_maxlen);


        return vio_ldc_send(vio, &pkt, sizeof(pkt));
}

static int handle_attr_info(struct vio_driver_state *vio,
                            struct vio_net_attr_info *pkt)
{
        struct vnet_port *port = to_vnet_port(vio);
        u64     localmtu;
        u8      xfer_mode;

        viodbg(HS, "GOT NET ATTR xmode[0x%x] atype[0x%x] addr[%llx] "
               "ackfreq[%u] plnk_updt[0x%02x] opts[0x%02x] mtu[%llu] "
               " (rmtu[%llu]) cflags[0x%04x] lso_max[%u]\n",
               pkt->xfer_mode, pkt->addr_type,
               (unsigned long long)pkt->addr,
               pkt->ack_freq, pkt->plnk_updt, pkt->options,
               (unsigned long long)pkt->mtu, port->rmtu, pkt->cflags,
               pkt->ipv4_lso_maxlen);

        pkt->tag.sid = vio_send_sid(vio);

        xfer_mode = pkt->xfer_mode;
        /* for version < 1.2, VIO_DRING_MODE = 0x3 and no bitmask */
        if (vio_version_before(vio, 1, 2) && xfer_mode == VIO_DRING_MODE)
                xfer_mode = VIO_NEW_DRING_MODE;

        /* MTU negotiation:
         *      < v1.3 - ETH_FRAME_LEN exactly
         *      > v1.3 - MIN(pkt.mtu, VNET_MAXPACKET, port->rmtu) and change
         *                      pkt->mtu for ACK
         *      = v1.3 - ETH_FRAME_LEN + VLAN_HLEN exactly
         */
        if (vio_version_before(vio, 1, 3)) {
                localmtu = ETH_FRAME_LEN;
        } else if (vio_version_after(vio, 1, 3)) {
                localmtu = port->rmtu ? port->rmtu : VNET_MAXPACKET;
                localmtu = min(pkt->mtu, localmtu);
                pkt->mtu = localmtu;
        } else { /* v1.3 */
                localmtu = ETH_FRAME_LEN + VLAN_HLEN;
        }
        port->rmtu = localmtu;

        /* LSO negotiation */
        if (vio_version_after_eq(vio, 1, 7))
                port->tso &= !!(pkt->cflags & VNET_LSO_IPV4_CAPAB);
        else
                port->tso = false;
        if (port->tso) {
                if (!port->tsolen)
                        port->tsolen = VNET_MAXTSO;
                port->tsolen = min(port->tsolen, pkt->ipv4_lso_maxlen);
                if (port->tsolen < VNET_MINTSO) {
                        port->tso = false;
                        port->tsolen = 0;
                        pkt->cflags &= ~VNET_LSO_IPV4_CAPAB;
                }
                pkt->ipv4_lso_maxlen = port->tsolen;
        } else {
                pkt->cflags &= ~VNET_LSO_IPV4_CAPAB;
                pkt->ipv4_lso_maxlen = 0;
        }

        /* for version >= 1.6, ACK packet mode we support */
        if (vio_version_after_eq(vio, 1, 6)) {
                pkt->xfer_mode = VIO_NEW_DRING_MODE;
                pkt->options = VIO_TX_DRING;
        }

        if (!(xfer_mode | VIO_NEW_DRING_MODE) ||
            pkt->addr_type != VNET_ADDR_ETHERMAC ||
            pkt->mtu != localmtu) {
                viodbg(HS, "SEND NET ATTR NACK\n");

                pkt->tag.stype = VIO_SUBTYPE_NACK;

                (void) vio_ldc_send(vio, pkt, sizeof(*pkt));

                return -ECONNRESET;
        } else {
                viodbg(HS, "SEND NET ATTR ACK xmode[0x%x] atype[0x%x] "
                       "addr[%llx] ackfreq[%u] plnk_updt[0x%02x] opts[0x%02x] "
                       "mtu[%llu] (rmtu[%llu]) cflags[0x%04x] lso_max[%u]\n",
                       pkt->xfer_mode, pkt->addr_type,
                       (unsigned long long)pkt->addr,
                       pkt->ack_freq, pkt->plnk_updt, pkt->options,
                       (unsigned long long)pkt->mtu, port->rmtu, pkt->cflags,
                       pkt->ipv4_lso_maxlen);

                pkt->tag.stype = VIO_SUBTYPE_ACK;

                return vio_ldc_send(vio, pkt, sizeof(*pkt));
        }

}

static int handle_attr_ack(struct vio_driver_state *vio,
                           struct vio_net_attr_info *pkt)
{
        viodbg(HS, "GOT NET ATTR ACK\n");

        return 0;
}

static int handle_attr_nack(struct vio_driver_state *vio,
                            struct vio_net_attr_info *pkt)
{
        viodbg(HS, "GOT NET ATTR NACK\n");

        return -ECONNRESET;
}

static int vnet_handle_attr(struct vio_driver_state *vio, void *arg)
{
        struct vio_net_attr_info *pkt = arg;

        switch (pkt->tag.stype) {
        case VIO_SUBTYPE_INFO:
                return handle_attr_info(vio, pkt);

        case VIO_SUBTYPE_ACK:
                return handle_attr_ack(vio, pkt);

        case VIO_SUBTYPE_NACK:
                return handle_attr_nack(vio, pkt);

        default:
                return -ECONNRESET;
        }
}

static void vnet_handshake_complete(struct vio_driver_state *vio)
{
        struct vio_dring_state *dr;

        dr = &vio->drings[VIO_DRIVER_RX_RING];
        dr->snd_nxt = dr->rcv_nxt = 1;

        dr = &vio->drings[VIO_DRIVER_TX_RING];
        dr->snd_nxt = dr->rcv_nxt = 1;
}

/* The hypervisor interface that implements copying to/from imported
 * memory from another domain requires that copies are done to 8-byte
 * aligned buffers, and that the lengths of such copies are also 8-byte
 * multiples.
 *
 * So we align skb->data to an 8-byte multiple and pad-out the data
 * area so we can round the copy length up to the next multiple of
 * 8 for the copy.
 *
 * The transmitter puts the actual start of the packet 6 bytes into
 * the buffer it sends over, so that the IP headers after the ethernet
 * header are aligned properly.  These 6 bytes are not in the descriptor
 * length, they are simply implied.  This offset is represented using
 * the VNET_PACKET_SKIP macro.
 */
static struct sk_buff *alloc_and_align_skb(struct net_device *dev,
                                           unsigned int len)
{
        struct sk_buff *skb = netdev_alloc_skb(dev, len+VNET_PACKET_SKIP+8+8);
        unsigned long addr, off;

        if (unlikely(!skb))
                return NULL;

        addr = (unsigned long) skb->data;
        off = ((addr + 7UL) & ~7UL) - addr;
        if (off)
                skb_reserve(skb, off);

        return skb;
}

static inline void vnet_fullcsum(struct sk_buff *skb)
{
        struct iphdr *iph = ip_hdr(skb);
        int offset = skb_transport_offset(skb);

        if (skb->protocol != htons(ETH_P_IP))
                return;
        if (iph->protocol != IPPROTO_TCP &&
            iph->protocol != IPPROTO_UDP)
                return;
        skb->ip_summed = CHECKSUM_NONE;
        skb->csum_level = 1;
        skb->csum = 0;
        if (iph->protocol == IPPROTO_TCP) {
                struct tcphdr *ptcp = tcp_hdr(skb);

                ptcp->check = 0;
                skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
                ptcp->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
                                                skb->len - offset, IPPROTO_TCP,
                                                skb->csum);
        } else if (iph->protocol == IPPROTO_UDP) {
                struct udphdr *pudp = udp_hdr(skb);

                pudp->check = 0;
                skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
                pudp->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
                                                skb->len - offset, IPPROTO_UDP,
                                                skb->csum);
        }
}

static int vnet_rx_one(struct vnet_port *port, struct vio_net_desc *desc)
{
        struct net_device *dev = port->vp->dev;
        unsigned int len = desc->size;
        unsigned int copy_len;
        struct sk_buff *skb;
        int maxlen;
        int err;

        err = -EMSGSIZE;
        if (port->tso && port->tsolen > port->rmtu)
                maxlen = port->tsolen;
        else
                maxlen = port->rmtu;
        if (unlikely(len < ETH_ZLEN || len > maxlen)) {
                dev->stats.rx_length_errors++;
                goto out_dropped;
        }

        skb = alloc_and_align_skb(dev, len);
        err = -ENOMEM;
        if (unlikely(!skb)) {
                dev->stats.rx_missed_errors++;
                goto out_dropped;
        }

        copy_len = (len + VNET_PACKET_SKIP + 7U) & ~7U;
        skb_put(skb, copy_len);
        err = ldc_copy(port->vio.lp, LDC_COPY_IN,
                       skb->data, copy_len, 0,
                       desc->cookies, desc->ncookies);
        if (unlikely(err < 0)) {
                dev->stats.rx_frame_errors++;
                goto out_free_skb;
        }

        skb_pull(skb, VNET_PACKET_SKIP);
        skb_trim(skb, len);
        skb->protocol = eth_type_trans(skb, dev);

        if (vio_version_after_eq(&port->vio, 1, 8)) {
                struct vio_net_dext *dext = vio_net_ext(desc);

                if (dext->flags & VNET_PKT_HCK_IPV4_HDRCKSUM) {
                        if (skb->protocol == ETH_P_IP) {
                                struct iphdr *iph = (struct iphdr *)skb->data;

                                iph->check = 0;
                                ip_send_check(iph);
                        }
                }
                if ((dext->flags & VNET_PKT_HCK_FULLCKSUM) &&
                    skb->ip_summed == CHECKSUM_NONE)
                        vnet_fullcsum(skb);
                if (dext->flags & VNET_PKT_HCK_IPV4_HDRCKSUM_OK) {
                        skb->ip_summed = CHECKSUM_PARTIAL;
                        skb->csum_level = 0;
                        if (dext->flags & VNET_PKT_HCK_FULLCKSUM_OK)
                                skb->csum_level = 1;
                }
        }

        skb->ip_summed = port->switch_port ? CHECKSUM_NONE : CHECKSUM_PARTIAL;

        dev->stats.rx_packets++;
        dev->stats.rx_bytes += len;
        napi_gro_receive(&port->napi, skb);
        return 0;

out_free_skb:
        kfree_skb(skb);

out_dropped:
        dev->stats.rx_dropped++;
        return err;
}

static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr,
                         u32 start, u32 end, u8 vio_dring_state)
{
        struct vio_dring_data hdr = {
                .tag = {
                        .type           = VIO_TYPE_DATA,
                        .stype          = VIO_SUBTYPE_ACK,
                        .stype_env      = VIO_DRING_DATA,
                        .sid            = vio_send_sid(&port->vio),
                },
                .dring_ident            = dr->ident,
                .start_idx              = start,
                .end_idx                = end,
                .state                  = vio_dring_state,
        };
        int err, delay;
        int retries = 0;

        hdr.seq = dr->snd_nxt;
        delay = 1;
        do {
                err = vio_ldc_send(&port->vio, &hdr, sizeof(hdr));
                if (err > 0) {
                        dr->snd_nxt++;
                        break;
                }
                udelay(delay);
                if ((delay <<= 1) > 128)
                        delay = 128;
                if (retries++ > VNET_MAX_RETRIES) {
                        pr_info("ECONNRESET %x:%x:%x:%x:%x:%x\n",
                                port->raddr[0], port->raddr[1],
                                port->raddr[2], port->raddr[3],
                                port->raddr[4], port->raddr[5]);
                        break;
                }
        } while (err == -EAGAIN);

        if (err <= 0 && vio_dring_state == VIO_DRING_STOPPED) {
                port->stop_rx_idx = end;
                port->stop_rx = true;
        } else {
                port->stop_rx_idx = 0;
                port->stop_rx = false;
        }

        return err;
}

static struct vio_net_desc *get_rx_desc(struct vnet_port *port,
                                        struct vio_dring_state *dr,
                                        u32 index)
{
        struct vio_net_desc *desc = port->vio.desc_buf;
        int err;

        err = ldc_get_dring_entry(port->vio.lp, desc, dr->entry_size,
                                  (index * dr->entry_size),
                                  dr->cookies, dr->ncookies);
        if (err < 0)
                return ERR_PTR(err);

        return desc;
}

static int put_rx_desc(struct vnet_port *port,
                       struct vio_dring_state *dr,
                       struct vio_net_desc *desc,
                       u32 index)
{
        int err;

        err = ldc_put_dring_entry(port->vio.lp, desc, dr->entry_size,
                                  (index * dr->entry_size),
                                  dr->cookies, dr->ncookies);
        if (err < 0)
                return err;

        return 0;
}

static int vnet_walk_rx_one(struct vnet_port *port,
                            struct vio_dring_state *dr,
                            u32 index, int *needs_ack)
{
        struct vio_net_desc *desc = get_rx_desc(port, dr, index);
        struct vio_driver_state *vio = &port->vio;
        int err;

        BUG_ON(desc == NULL);
        if (IS_ERR(desc))
                return PTR_ERR(desc);

        if (desc->hdr.state != VIO_DESC_READY)
                return 1;

        dma_rmb();

        viodbg(DATA, "vio_walk_rx_one desc[%02x:%02x:%08x:%08x:%llx:%llx]\n",
               desc->hdr.state, desc->hdr.ack,
               desc->size, desc->ncookies,
               desc->cookies[0].cookie_addr,
               desc->cookies[0].cookie_size);

        err = vnet_rx_one(port, desc);
        if (err == -ECONNRESET)
                return err;
        desc->hdr.state = VIO_DESC_DONE;
        err = put_rx_desc(port, dr, desc, index);
        if (err < 0)
                return err;
        *needs_ack = desc->hdr.ack;
        return 0;
}

static int vnet_walk_rx(struct vnet_port *port, struct vio_dring_state *dr,
                        u32 start, u32 end, int *npkts, int budget)
{
        struct vio_driver_state *vio = &port->vio;
        int ack_start = -1, ack_end = -1;
        bool send_ack = true;

        end = (end == (u32) -1) ? vio_dring_prev(dr, start)
                                : vio_dring_next(dr, end);

        viodbg(DATA, "vnet_walk_rx start[%08x] end[%08x]\n", start, end);

        while (start != end) {
                int ack = 0, err = vnet_walk_rx_one(port, dr, start, &ack);
                if (err == -ECONNRESET)
                        return err;
                if (err != 0)
                        break;
                (*npkts)++;
                if (ack_start == -1)
                        ack_start = start;
                ack_end = start;
                start = vio_dring_next(dr, start);
                if (ack && start != end) {
                        err = vnet_send_ack(port, dr, ack_start, ack_end,
                                            VIO_DRING_ACTIVE);
                        if (err == -ECONNRESET)
                                return err;
                        ack_start = -1;
                }
                if ((*npkts) >= budget) {
                        send_ack = false;
                        break;
                }
        }
        if (unlikely(ack_start == -1))
                ack_start = ack_end = vio_dring_prev(dr, start);
        if (send_ack) {
                port->napi_resume = false;
                return vnet_send_ack(port, dr, ack_start, ack_end,
                                     VIO_DRING_STOPPED);
        } else  {
                port->napi_resume = true;
                port->napi_stop_idx = ack_end;
                return 1;
        }
}

static int vnet_rx(struct vnet_port *port, void *msgbuf, int *npkts,
                   int budget)
{
        struct vio_dring_data *pkt = msgbuf;
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_RX_RING];
        struct vio_driver_state *vio = &port->vio;

        viodbg(DATA, "vnet_rx stype_env[%04x] seq[%016llx] rcv_nxt[%016llx]\n",
               pkt->tag.stype_env, pkt->seq, dr->rcv_nxt);

        if (unlikely(pkt->tag.stype_env != VIO_DRING_DATA))
                return 0;
        if (unlikely(pkt->seq != dr->rcv_nxt)) {
                pr_err("RX out of sequence seq[0x%llx] rcv_nxt[0x%llx]\n",
                       pkt->seq, dr->rcv_nxt);
                return 0;
        }

        if (!port->napi_resume)
                dr->rcv_nxt++;

        /* XXX Validate pkt->start_idx and pkt->end_idx XXX */

        return vnet_walk_rx(port, dr, pkt->start_idx, pkt->end_idx,
                            npkts, budget);
}

static int idx_is_pending(struct vio_dring_state *dr, u32 end)
{
        u32 idx = dr->cons;
        int found = 0;

        while (idx != dr->prod) {
                if (idx == end) {
                        found = 1;
                        break;
                }
                idx = vio_dring_next(dr, idx);
        }
        return found;
}

static int vnet_ack(struct vnet_port *port, void *msgbuf)
{
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        struct vio_dring_data *pkt = msgbuf;
        struct net_device *dev;
        struct vnet *vp;
        u32 end;
        struct vio_net_desc *desc;
        struct netdev_queue *txq;

        if (unlikely(pkt->tag.stype_env != VIO_DRING_DATA))
                return 0;

        end = pkt->end_idx;
        vp = port->vp;
        dev = vp->dev;
        netif_tx_lock(dev);
        if (unlikely(!idx_is_pending(dr, end))) {
                netif_tx_unlock(dev);
                return 0;
        }

        /* sync for race conditions with vnet_start_xmit() and tell xmit it
         * is time to send a trigger.
         */
        dr->cons = vio_dring_next(dr, end);
        desc = vio_dring_entry(dr, dr->cons);
        if (desc->hdr.state == VIO_DESC_READY && !port->start_cons) {
                /* vnet_start_xmit() just populated this dring but missed
                 * sending the "start" LDC message to the consumer.
                 * Send a "start" trigger on its behalf.
                 */
                if (__vnet_tx_trigger(port, dr->cons) > 0)
                        port->start_cons = false;
                else
                        port->start_cons = true;
        } else {
                port->start_cons = true;
        }
        netif_tx_unlock(dev);

        txq = netdev_get_tx_queue(dev, port->q_index);
        if (unlikely(netif_tx_queue_stopped(txq) &&
                     vnet_tx_dring_avail(dr) >= VNET_TX_WAKEUP_THRESH(dr)))
                return 1;

        return 0;
}

static int vnet_nack(struct vnet_port *port, void *msgbuf)
{
        /* XXX just reset or similar XXX */
        return 0;
}

static int handle_mcast(struct vnet_port *port, void *msgbuf)
{
        struct vio_net_mcast_info *pkt = msgbuf;

        if (pkt->tag.stype != VIO_SUBTYPE_ACK)
                pr_err("%s: Got unexpected MCAST reply [%02x:%02x:%04x:%08x]\n",
                       port->vp->dev->name,
                       pkt->tag.type,
                       pkt->tag.stype,
                       pkt->tag.stype_env,
                       pkt->tag.sid);

        return 0;
}

/* Got back a STOPPED LDC message on port. If the queue is stopped,
 * wake it up so that we'll send out another START message at the
 * next TX.
 */
static void maybe_tx_wakeup(struct vnet_port *port)
{
        struct netdev_queue *txq;

        txq = netdev_get_tx_queue(port->vp->dev, port->q_index);
        __netif_tx_lock(txq, smp_processor_id());
        if (likely(netif_tx_queue_stopped(txq))) {
                struct vio_dring_state *dr;

                dr = &port->vio.drings[VIO_DRIVER_TX_RING];
                netif_tx_wake_queue(txq);
        }
        __netif_tx_unlock(txq);
}

static inline bool port_is_up(struct vnet_port *vnet)
{
        struct vio_driver_state *vio = &vnet->vio;

        return !!(vio->hs_state & VIO_HS_COMPLETE);
}

static int vnet_event_napi(struct vnet_port *port, int budget)
{
        struct vio_driver_state *vio = &port->vio;
        int tx_wakeup, err;
        int npkts = 0;
        int event = (port->rx_event & LDC_EVENT_RESET);

ldc_ctrl:
        if (unlikely(event == LDC_EVENT_RESET ||
                     event == LDC_EVENT_UP)) {
                vio_link_state_change(vio, event);

                if (event == LDC_EVENT_RESET) {
                        vnet_port_reset(port);
                        vio_port_up(vio);
                }
                port->rx_event = 0;
                return 0;
        }
        /* We may have multiple LDC events in rx_event. Unroll send_events() */
        event = (port->rx_event & LDC_EVENT_UP);
        port->rx_event &= ~(LDC_EVENT_RESET|LDC_EVENT_UP);
        if (event == LDC_EVENT_UP)
                goto ldc_ctrl;
        event = port->rx_event;
        if (!(event & LDC_EVENT_DATA_READY))
                return 0;

        /* we dont expect any other bits than RESET, UP, DATA_READY */
        BUG_ON(event != LDC_EVENT_DATA_READY);

        tx_wakeup = err = 0;
        while (1) {
                union {
                        struct vio_msg_tag tag;
                        u64 raw[8];
                } msgbuf;

                if (port->napi_resume) {
                        struct vio_dring_data *pkt =
                                (struct vio_dring_data *)&msgbuf;
                        struct vio_dring_state *dr =
                                &port->vio.drings[VIO_DRIVER_RX_RING];

                        pkt->tag.type = VIO_TYPE_DATA;
                        pkt->tag.stype = VIO_SUBTYPE_INFO;
                        pkt->tag.stype_env = VIO_DRING_DATA;
                        pkt->seq = dr->rcv_nxt;
                        pkt->start_idx = vio_dring_next(dr, port->napi_stop_idx);
                        pkt->end_idx = -1;
                        goto napi_resume;
                }
                err = ldc_read(vio->lp, &msgbuf, sizeof(msgbuf));
                if (unlikely(err < 0)) {
                        if (err == -ECONNRESET)
                                vio_conn_reset(vio);
                        break;
                }
                if (err == 0)
                        break;
                viodbg(DATA, "TAG [%02x:%02x:%04x:%08x]\n",
                       msgbuf.tag.type,
                       msgbuf.tag.stype,
                       msgbuf.tag.stype_env,
                       msgbuf.tag.sid);
                err = vio_validate_sid(vio, &msgbuf.tag);
                if (err < 0)
                        break;
napi_resume:
                if (likely(msgbuf.tag.type == VIO_TYPE_DATA)) {
                        if (msgbuf.tag.stype == VIO_SUBTYPE_INFO) {
                                if (!port_is_up(port)) {
                                        /* failures like handshake_failure()
                                         * may have cleaned up dring, but
                                         * NAPI polling may bring us here.
                                         */
                                        err = -ECONNRESET;
                                        break;
                                }
                                err = vnet_rx(port, &msgbuf, &npkts, budget);
                                if (npkts >= budget)
                                        break;
                                if (npkts == 0)
                                        break;
                        } else if (msgbuf.tag.stype == VIO_SUBTYPE_ACK) {
                                err = vnet_ack(port, &msgbuf);
                                if (err > 0)
                                        tx_wakeup |= err;
                        } else if (msgbuf.tag.stype == VIO_SUBTYPE_NACK) {
                                err = vnet_nack(port, &msgbuf);
                        }
                } else if (msgbuf.tag.type == VIO_TYPE_CTRL) {
                        if (msgbuf.tag.stype_env == VNET_MCAST_INFO)
                                err = handle_mcast(port, &msgbuf);
                        else
                                err = vio_control_pkt_engine(vio, &msgbuf);
                        if (err)
                                break;
                } else {
                        err = vnet_handle_unknown(port, &msgbuf);
                }
                if (err == -ECONNRESET)
                        break;
        }
        if (unlikely(tx_wakeup && err != -ECONNRESET))
                maybe_tx_wakeup(port);
        return npkts;
}

static int vnet_poll(struct napi_struct *napi, int budget)
{
        struct vnet_port *port = container_of(napi, struct vnet_port, napi);
        struct vio_driver_state *vio = &port->vio;
        int processed = vnet_event_napi(port, budget);

        if (processed < budget) {
                napi_complete(napi);
                port->rx_event &= ~LDC_EVENT_DATA_READY;
                vio_set_intr(vio->vdev->rx_ino, HV_INTR_ENABLED);
        }
        return processed;
}

static void vnet_event(void *arg, int event)
{
        struct vnet_port *port = arg;
        struct vio_driver_state *vio = &port->vio;

        port->rx_event |= event;
        vio_set_intr(vio->vdev->rx_ino, HV_INTR_DISABLED);
        napi_schedule(&port->napi);

}

static int __vnet_tx_trigger(struct vnet_port *port, u32 start)
{
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        struct vio_dring_data hdr = {
                .tag = {
                        .type           = VIO_TYPE_DATA,
                        .stype          = VIO_SUBTYPE_INFO,
                        .stype_env      = VIO_DRING_DATA,
                        .sid            = vio_send_sid(&port->vio),
                },
                .dring_ident            = dr->ident,
                .start_idx              = start,
                .end_idx                = (u32) -1,
        };
        int err, delay;
        int retries = 0;

        if (port->stop_rx) {
                err = vnet_send_ack(port,
                                    &port->vio.drings[VIO_DRIVER_RX_RING],
                                    port->stop_rx_idx, -1,
                                    VIO_DRING_STOPPED);
                if (err <= 0)
                        return err;
        }

        hdr.seq = dr->snd_nxt;
        delay = 1;
        do {
                err = vio_ldc_send(&port->vio, &hdr, sizeof(hdr));
                if (err > 0) {
                        dr->snd_nxt++;
                        break;
                }
                udelay(delay);
                if ((delay <<= 1) > 128)
                        delay = 128;
                if (retries++ > VNET_MAX_RETRIES)
                        break;
        } while (err == -EAGAIN);

        return err;
}

struct vnet_port *__tx_port_find(struct vnet *vp, struct sk_buff *skb)
{
        unsigned int hash = vnet_hashfn(skb->data);
        struct hlist_head *hp = &vp->port_hash[hash];
        struct vnet_port *port;

        hlist_for_each_entry_rcu(port, hp, hash) {
                if (!port_is_up(port))
                        continue;
                if (ether_addr_equal(port->raddr, skb->data))
                        return port;
        }
        list_for_each_entry_rcu(port, &vp->port_list, list) {
                if (!port->switch_port)
                        continue;
                if (!port_is_up(port))
                        continue;
                return port;
        }
        return NULL;
}

static struct sk_buff *vnet_clean_tx_ring(struct vnet_port *port,
                                          unsigned *pending)
{
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        struct sk_buff *skb = NULL;
        int i, txi;

        *pending = 0;

        txi = dr->prod;
        for (i = 0; i < VNET_TX_RING_SIZE; ++i) {
                struct vio_net_desc *d;

                --txi;
                if (txi < 0)
                        txi = VNET_TX_RING_SIZE-1;

                d = vio_dring_entry(dr, txi);

                if (d->hdr.state == VIO_DESC_READY) {
                        (*pending)++;
                        continue;
                }
                if (port->tx_bufs[txi].skb) {
                        if (d->hdr.state != VIO_DESC_DONE)
                                pr_notice("invalid ring buffer state %d\n",
                                          d->hdr.state);
                        BUG_ON(port->tx_bufs[txi].skb->next);

                        port->tx_bufs[txi].skb->next = skb;
                        skb = port->tx_bufs[txi].skb;
                        port->tx_bufs[txi].skb = NULL;

                        ldc_unmap(port->vio.lp,
                                  port->tx_bufs[txi].cookies,
                                  port->tx_bufs[txi].ncookies);
                } else if (d->hdr.state == VIO_DESC_FREE)
                        break;
                d->hdr.state = VIO_DESC_FREE;
        }
        return skb;
}

static inline void vnet_free_skbs(struct sk_buff *skb)
{
        struct sk_buff *next;

        while (skb) {
                next = skb->next;
                skb->next = NULL;
                dev_kfree_skb(skb);
                skb = next;
        }
}

static void vnet_clean_timer_expire(unsigned long port0)
{
        struct vnet_port *port = (struct vnet_port *)port0;
        struct sk_buff *freeskbs;
        unsigned pending;

        netif_tx_lock(port->vp->dev);
        freeskbs = vnet_clean_tx_ring(port, &pending);
        netif_tx_unlock(port->vp->dev);

        vnet_free_skbs(freeskbs);

        if (pending)
                (void)mod_timer(&port->clean_timer,
                                jiffies + VNET_CLEAN_TIMEOUT);
         else
                del_timer(&port->clean_timer);
}

static inline int vnet_skb_map(struct ldc_channel *lp, struct sk_buff *skb,
                               struct ldc_trans_cookie *cookies, int ncookies,
                               unsigned int map_perm)
{
        int i, nc, err, blen;

        /* header */
        blen = skb_headlen(skb);
        if (blen < ETH_ZLEN)
                blen = ETH_ZLEN;
        blen += VNET_PACKET_SKIP;
        blen += 8 - (blen & 7);

        err = ldc_map_single(lp, skb->data-VNET_PACKET_SKIP, blen, cookies,
                             ncookies, map_perm);
        if (err < 0)
                return err;
        nc = err;

        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
                skb_frag_t *f = &skb_shinfo(skb)->frags[i];
                u8 *vaddr;

                if (nc < ncookies) {
                        vaddr = kmap_atomic(skb_frag_page(f));
                        blen = skb_frag_size(f);
                        blen += 8 - (blen & 7);
                        err = ldc_map_single(lp, vaddr + f->page_offset,
                                             blen, cookies + nc, ncookies - nc,
                                             map_perm);
                        kunmap_atomic(vaddr);
                } else {
                        err = -EMSGSIZE;
                }

                if (err < 0) {
                        ldc_unmap(lp, cookies, nc);
                        return err;
                }
                nc += err;
        }
        return nc;
}

static inline struct sk_buff *vnet_skb_shape(struct sk_buff *skb, int ncookies)
{
        struct sk_buff *nskb;
        int i, len, pad, docopy;

        len = skb->len;
        pad = 0;
        if (len < ETH_ZLEN) {
                pad += ETH_ZLEN - skb->len;
                len += pad;
        }
        len += VNET_PACKET_SKIP;
        pad += 8 - (len & 7);

        /* make sure we have enough cookies and alignment in every frag */
        docopy = skb_shinfo(skb)->nr_frags >= ncookies;
        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
                skb_frag_t *f = &skb_shinfo(skb)->frags[i];

                docopy |= f->page_offset & 7;
        }
        if (((unsigned long)skb->data & 7) != VNET_PACKET_SKIP ||
            skb_tailroom(skb) < pad ||
            skb_headroom(skb) < VNET_PACKET_SKIP || docopy) {
                int start = 0, offset;
                __wsum csum;

                len = skb->len > ETH_ZLEN ? skb->len : ETH_ZLEN;
                nskb = alloc_and_align_skb(skb->dev, len);
                if (nskb == NULL) {
                        dev_kfree_skb(skb);
                        return NULL;
                }
                skb_reserve(nskb, VNET_PACKET_SKIP);

                nskb->protocol = skb->protocol;
                offset = skb_mac_header(skb) - skb->data;
                skb_set_mac_header(nskb, offset);
                offset = skb_network_header(skb) - skb->data;
                skb_set_network_header(nskb, offset);
                offset = skb_transport_header(skb) - skb->data;
                skb_set_transport_header(nskb, offset);

                offset = 0;
                nskb->csum_offset = skb->csum_offset;
                nskb->ip_summed = skb->ip_summed;

                if (skb->ip_summed == CHECKSUM_PARTIAL)
                        start = skb_checksum_start_offset(skb);
                if (start) {
                        struct iphdr *iph = ip_hdr(nskb);
                        int offset = start + nskb->csum_offset;

                        if (skb_copy_bits(skb, 0, nskb->data, start)) {
                                dev_kfree_skb(nskb);
                                dev_kfree_skb(skb);
                                return NULL;
                        }
                        *(__sum16 *)(skb->data + offset) = 0;
                        csum = skb_copy_and_csum_bits(skb, start,
                                                      nskb->data + start,
                                                      skb->len - start, 0);
                        if (iph->protocol == IPPROTO_TCP ||
                            iph->protocol == IPPROTO_UDP) {
                                csum = csum_tcpudp_magic(iph->saddr, iph->daddr,
                                                         skb->len - start,
                                                         iph->protocol, csum);
                        }
                        *(__sum16 *)(nskb->data + offset) = csum;

                        nskb->ip_summed = CHECKSUM_NONE;
                } else if (skb_copy_bits(skb, 0, nskb->data, skb->len)) {
                        dev_kfree_skb(nskb);
                        dev_kfree_skb(skb);
                        return NULL;
                }
                (void)skb_put(nskb, skb->len);
                if (skb_is_gso(skb)) {
                        skb_shinfo(nskb)->gso_size = skb_shinfo(skb)->gso_size;
                        skb_shinfo(nskb)->gso_type = skb_shinfo(skb)->gso_type;
                }
                nskb->queue_mapping = skb->queue_mapping;
                dev_kfree_skb(skb);
                skb = nskb;
        }
        return skb;
}

static u16
vnet_select_queue(struct net_device *dev, struct sk_buff *skb,
                  void *accel_priv, select_queue_fallback_t fallback)
{
        struct vnet *vp = netdev_priv(dev);
        struct vnet_port *port = __tx_port_find(vp, skb);

        if (port == NULL)
                return 0;
        return port->q_index;
}

static int vnet_start_xmit(struct sk_buff *skb, struct net_device *dev);

static int vnet_handle_offloads(struct vnet_port *port, struct sk_buff *skb)
{
        struct net_device *dev = port->vp->dev;
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        struct sk_buff *segs;
        int maclen, datalen;
        int status;
        int gso_size, gso_type, gso_segs;
        int hlen = skb_transport_header(skb) - skb_mac_header(skb);
        int proto = IPPROTO_IP;

        if (skb->protocol == htons(ETH_P_IP))
                proto = ip_hdr(skb)->protocol;
        else if (skb->protocol == htons(ETH_P_IPV6))
                proto = ipv6_hdr(skb)->nexthdr;

        if (proto == IPPROTO_TCP)
                hlen += tcp_hdr(skb)->doff * 4;
        else if (proto == IPPROTO_UDP)
                hlen += sizeof(struct udphdr);
        else {
                pr_err("vnet_handle_offloads GSO with unknown transport "
                       "protocol %d tproto %d\n", skb->protocol, proto);
                hlen = 128; /* XXX */
        }
        datalen = port->tsolen - hlen;

        gso_size = skb_shinfo(skb)->gso_size;
        gso_type = skb_shinfo(skb)->gso_type;
        gso_segs = skb_shinfo(skb)->gso_segs;

        if (port->tso && gso_size < datalen)
                gso_segs = DIV_ROUND_UP(skb->len - hlen, datalen);

        if (unlikely(vnet_tx_dring_avail(dr) < gso_segs)) {
                struct netdev_queue *txq;

                txq  = netdev_get_tx_queue(dev, port->q_index);
                netif_tx_stop_queue(txq);
                if (vnet_tx_dring_avail(dr) < skb_shinfo(skb)->gso_segs)
                        return NETDEV_TX_BUSY;
                netif_tx_wake_queue(txq);
        }

        maclen = skb_network_header(skb) - skb_mac_header(skb);
        skb_pull(skb, maclen);

        if (port->tso && gso_size < datalen) {
                if (skb_unclone(skb, GFP_ATOMIC))
                        goto out_dropped;

                /* segment to TSO size */
                skb_shinfo(skb)->gso_size = datalen;
                skb_shinfo(skb)->gso_segs = gso_segs;
        }
        segs = skb_gso_segment(skb, dev->features & ~NETIF_F_TSO);
        if (IS_ERR(segs))
                goto out_dropped;

        skb_push(skb, maclen);
        skb_reset_mac_header(skb);

        status = 0;
        while (segs) {
                struct sk_buff *curr = segs;

                segs = segs->next;
                curr->next = NULL;
                if (port->tso && curr->len > dev->mtu) {
                        skb_shinfo(curr)->gso_size = gso_size;
                        skb_shinfo(curr)->gso_type = gso_type;
                        skb_shinfo(curr)->gso_segs =
                                DIV_ROUND_UP(curr->len - hlen, gso_size);
                } else
                        skb_shinfo(curr)->gso_size = 0;

                skb_push(curr, maclen);
                skb_reset_mac_header(curr);
                memcpy(skb_mac_header(curr), skb_mac_header(skb),
                       maclen);
                curr->csum_start = skb_transport_header(curr) - curr->head;
                if (ip_hdr(curr)->protocol == IPPROTO_TCP)
                        curr->csum_offset = offsetof(struct tcphdr, check);
                else if (ip_hdr(curr)->protocol == IPPROTO_UDP)
                        curr->csum_offset = offsetof(struct udphdr, check);

                if (!(status & NETDEV_TX_MASK))
                        status = vnet_start_xmit(curr, dev);
                if (status & NETDEV_TX_MASK)
                        dev_kfree_skb_any(curr);
        }

        if (!(status & NETDEV_TX_MASK))
                dev_kfree_skb_any(skb);
        return status;
out_dropped:
        dev->stats.tx_dropped++;
        dev_kfree_skb_any(skb);
        return NETDEV_TX_OK;
}

static int vnet_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct vnet *vp = netdev_priv(dev);
        struct vnet_port *port = NULL;
        struct vio_dring_state *dr;
        struct vio_net_desc *d;
        unsigned int len;
        struct sk_buff *freeskbs = NULL;
        int i, err, txi;
        unsigned pending = 0;
        struct netdev_queue *txq;

        rcu_read_lock();
        port = __tx_port_find(vp, skb);
        if (unlikely(!port)) {
                rcu_read_unlock();
                goto out_dropped;
        }

        if (skb_is_gso(skb) && skb->len > port->tsolen) {
                err = vnet_handle_offloads(port, skb);
                rcu_read_unlock();
                return err;
        }

        if (!skb_is_gso(skb) && skb->len > port->rmtu) {
                unsigned long localmtu = port->rmtu - ETH_HLEN;

                if (vio_version_after_eq(&port->vio, 1, 3))
                        localmtu -= VLAN_HLEN;

                if (skb->protocol == htons(ETH_P_IP)) {
                        struct flowi4 fl4;
                        struct rtable *rt = NULL;

                        memset(&fl4, 0, sizeof(fl4));
                        fl4.flowi4_oif = dev->ifindex;
                        fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
                        fl4.daddr = ip_hdr(skb)->daddr;
                        fl4.saddr = ip_hdr(skb)->saddr;

                        rt = ip_route_output_key(dev_net(dev), &fl4);
                        rcu_read_unlock();
                        if (!IS_ERR(rt)) {
                                skb_dst_set(skb, &rt->dst);
                                icmp_send(skb, ICMP_DEST_UNREACH,
                                          ICMP_FRAG_NEEDED,
                                          htonl(localmtu));
                        }
                }
#if IS_ENABLED(CONFIG_IPV6)
                else if (skb->protocol == htons(ETH_P_IPV6))
                        icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, localmtu);
#endif
                goto out_dropped;
        }

        skb = vnet_skb_shape(skb, 2);

        if (unlikely(!skb))
                goto out_dropped;

        if (skb->ip_summed == CHECKSUM_PARTIAL)
                vnet_fullcsum(skb);

        dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        i = skb_get_queue_mapping(skb);
        txq = netdev_get_tx_queue(dev, i);
        if (unlikely(vnet_tx_dring_avail(dr) < 1)) {
                if (!netif_tx_queue_stopped(txq)) {
                        netif_tx_stop_queue(txq);

                        /* This is a hard error, log it. */
                        netdev_err(dev, "BUG! Tx Ring full when queue awake!\n");
                        dev->stats.tx_errors++;
                }
                rcu_read_unlock();
                return NETDEV_TX_BUSY;
        }

        d = vio_dring_cur(dr);

        txi = dr->prod;

        freeskbs = vnet_clean_tx_ring(port, &pending);

        BUG_ON(port->tx_bufs[txi].skb);

        len = skb->len;
        if (len < ETH_ZLEN)
                len = ETH_ZLEN;

        err = vnet_skb_map(port->vio.lp, skb, port->tx_bufs[txi].cookies, 2,
                           (LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_RW));
        if (err < 0) {
                netdev_info(dev, "tx buffer map error %d\n", err);
                goto out_dropped;
        }

        port->tx_bufs[txi].skb = skb;
        skb = NULL;
        port->tx_bufs[txi].ncookies = err;

        /* We don't rely on the ACKs to free the skb in vnet_start_xmit(),
         * thus it is safe to not set VIO_ACK_ENABLE for each transmission:
         * the protocol itself does not require it as long as the peer
         * sends a VIO_SUBTYPE_ACK for VIO_DRING_STOPPED.
         *
         * An ACK for every packet in the ring is expensive as the
         * sending of LDC messages is slow and affects performance.
         */
        d->hdr.ack = VIO_ACK_DISABLE;
        d->size = len;
        d->ncookies = port->tx_bufs[txi].ncookies;
        for (i = 0; i < d->ncookies; i++)
                d->cookies[i] = port->tx_bufs[txi].cookies[i];
        if (vio_version_after_eq(&port->vio, 1, 7)) {
                struct vio_net_dext *dext = vio_net_ext(d);

                memset(dext, 0, sizeof(*dext));
                if (skb_is_gso(port->tx_bufs[txi].skb)) {
                        dext->ipv4_lso_mss = skb_shinfo(port->tx_bufs[txi].skb)
                                             ->gso_size;
                        dext->flags |= VNET_PKT_IPV4_LSO;
                }
                if (vio_version_after_eq(&port->vio, 1, 8) &&
                    !port->switch_port) {
                        dext->flags |= VNET_PKT_HCK_IPV4_HDRCKSUM_OK;
                        dext->flags |= VNET_PKT_HCK_FULLCKSUM_OK;
                }
        }

        /* This has to be a non-SMP write barrier because we are writing
         * to memory which is shared with the peer LDOM.
         */
        dma_wmb();

        d->hdr.state = VIO_DESC_READY;

        /* Exactly one ldc "start" trigger (for dr->cons) needs to be sent
         * to notify the consumer that some descriptors are READY.
         * After that "start" trigger, no additional triggers are needed until
         * a DRING_STOPPED is received from the consumer. The dr->cons field
         * (set up by vnet_ack()) has the value of the next dring index
         * that has not yet been ack-ed. We send a "start" trigger here
         * if, and only if, start_cons is true (reset it afterward). Conversely,
         * vnet_ack() should check if the dring corresponding to cons
         * is marked READY, but start_cons was false.
         * If so, vnet_ack() should send out the missed "start" trigger.
         *
         * Note that the dma_wmb() above makes sure the cookies et al. are
         * not globally visible before the VIO_DESC_READY, and that the
         * stores are ordered correctly by the compiler. The consumer will
         * not proceed until the VIO_DESC_READY is visible assuring that
         * the consumer does not observe anything related to descriptors
         * out of order. The HV trap from the LDC start trigger is the
         * producer to consumer announcement that work is available to the
         * consumer
         */
        if (!port->start_cons)
                goto ldc_start_done; /* previous trigger suffices */

        err = __vnet_tx_trigger(port, dr->cons);
        if (unlikely(err < 0)) {
                netdev_info(dev, "TX trigger error %d\n", err);
                d->hdr.state = VIO_DESC_FREE;
                skb = port->tx_bufs[txi].skb;
                port->tx_bufs[txi].skb = NULL;
                dev->stats.tx_carrier_errors++;
                goto out_dropped;
        }

ldc_start_done:
        port->start_cons = false;

        dev->stats.tx_packets++;
        dev->stats.tx_bytes += port->tx_bufs[txi].skb->len;

        dr->prod = (dr->prod + 1) & (VNET_TX_RING_SIZE - 1);
        if (unlikely(vnet_tx_dring_avail(dr) < 1)) {
                netif_tx_stop_queue(txq);
                if (vnet_tx_dring_avail(dr) > VNET_TX_WAKEUP_THRESH(dr))
                        netif_tx_wake_queue(txq);
        }

        (void)mod_timer(&port->clean_timer, jiffies + VNET_CLEAN_TIMEOUT);
        rcu_read_unlock();

        vnet_free_skbs(freeskbs);

        return NETDEV_TX_OK;

out_dropped:
        if (pending)
                (void)mod_timer(&port->clean_timer,
                                jiffies + VNET_CLEAN_TIMEOUT);
        else if (port)
                del_timer(&port->clean_timer);
        if (port)
                rcu_read_unlock();
        if (skb)
                dev_kfree_skb(skb);
        vnet_free_skbs(freeskbs);
        dev->stats.tx_dropped++;
        return NETDEV_TX_OK;
}

static void vnet_tx_timeout(struct net_device *dev)
{
        /* XXX Implement me XXX */
}

static int vnet_open(struct net_device *dev)
{
        netif_carrier_on(dev);
        netif_tx_start_all_queues(dev);

        return 0;
}

static int vnet_close(struct net_device *dev)
{
        netif_tx_stop_all_queues(dev);
        netif_carrier_off(dev);

        return 0;
}

static struct vnet_mcast_entry *__vnet_mc_find(struct vnet *vp, u8 *addr)
{
        struct vnet_mcast_entry *m;

        for (m = vp->mcast_list; m; m = m->next) {
                if (ether_addr_equal(m->addr, addr))
                        return m;
        }
        return NULL;
}

static void __update_mc_list(struct vnet *vp, struct net_device *dev)
{
        struct netdev_hw_addr *ha;

        netdev_for_each_mc_addr(ha, dev) {
                struct vnet_mcast_entry *m;

                m = __vnet_mc_find(vp, ha->addr);
                if (m) {
                        m->hit = 1;
                        continue;
                }

                if (!m) {
                        m = kzalloc(sizeof(*m), GFP_ATOMIC);
                        if (!m)
                                continue;
                        memcpy(m->addr, ha->addr, ETH_ALEN);
                        m->hit = 1;

                        m->next = vp->mcast_list;
                        vp->mcast_list = m;
                }
        }
}

static void __send_mc_list(struct vnet *vp, struct vnet_port *port)
{
        struct vio_net_mcast_info info;
        struct vnet_mcast_entry *m, **pp;
        int n_addrs;

        memset(&info, 0, sizeof(info));

        info.tag.type = VIO_TYPE_CTRL;
        info.tag.stype = VIO_SUBTYPE_INFO;
        info.tag.stype_env = VNET_MCAST_INFO;
        info.tag.sid = vio_send_sid(&port->vio);
        info.set = 1;

        n_addrs = 0;
        for (m = vp->mcast_list; m; m = m->next) {
                if (m->sent)
                        continue;
                m->sent = 1;
                memcpy(&info.mcast_addr[n_addrs * ETH_ALEN],
                       m->addr, ETH_ALEN);
                if (++n_addrs == VNET_NUM_MCAST) {
                        info.count = n_addrs;

                        (void) vio_ldc_send(&port->vio, &info,
                                            sizeof(info));
                        n_addrs = 0;
                }
        }
        if (n_addrs) {
                info.count = n_addrs;
                (void) vio_ldc_send(&port->vio, &info, sizeof(info));
        }

        info.set = 0;

        n_addrs = 0;
        pp = &vp->mcast_list;
        while ((m = *pp) != NULL) {
                if (m->hit) {
                        m->hit = 0;
                        pp = &m->next;
                        continue;
                }

                memcpy(&info.mcast_addr[n_addrs * ETH_ALEN],
                       m->addr, ETH_ALEN);
                if (++n_addrs == VNET_NUM_MCAST) {
                        info.count = n_addrs;
                        (void) vio_ldc_send(&port->vio, &info,
                                            sizeof(info));
                        n_addrs = 0;
                }

                *pp = m->next;
                kfree(m);
        }
        if (n_addrs) {
                info.count = n_addrs;
                (void) vio_ldc_send(&port->vio, &info, sizeof(info));
        }
}

static void vnet_set_rx_mode(struct net_device *dev)
{
        struct vnet *vp = netdev_priv(dev);
        struct vnet_port *port;

        rcu_read_lock();
        list_for_each_entry_rcu(port, &vp->port_list, list) {

                if (port->switch_port) {
                        __update_mc_list(vp, dev);
                        __send_mc_list(vp, port);
                        break;
                }
        }
        rcu_read_unlock();
}

static int vnet_change_mtu(struct net_device *dev, int new_mtu)
{
        if (new_mtu < 68 || new_mtu > 65535)
                return -EINVAL;

        dev->mtu = new_mtu;
        return 0;
}

static int vnet_set_mac_addr(struct net_device *dev, void *p)
{
        return -EINVAL;
}

static void vnet_get_drvinfo(struct net_device *dev,
                             struct ethtool_drvinfo *info)
{
        strlcpy(info->driver, DRV_MODULE_NAME, sizeof(info->driver));
        strlcpy(info->version, DRV_MODULE_VERSION, sizeof(info->version));
}

static u32 vnet_get_msglevel(struct net_device *dev)
{
        struct vnet *vp = netdev_priv(dev);
        return vp->msg_enable;
}

static void vnet_set_msglevel(struct net_device *dev, u32 value)
{
        struct vnet *vp = netdev_priv(dev);
        vp->msg_enable = value;
}

static const struct ethtool_ops vnet_ethtool_ops = {
        .get_drvinfo            = vnet_get_drvinfo,
        .get_msglevel           = vnet_get_msglevel,
        .set_msglevel           = vnet_set_msglevel,
        .get_link               = ethtool_op_get_link,
};

static void vnet_port_free_tx_bufs(struct vnet_port *port)
{
        struct vio_dring_state *dr;
        int i;

        dr = &port->vio.drings[VIO_DRIVER_TX_RING];

        if (dr->base == NULL)
                return;

        for (i = 0; i < VNET_TX_RING_SIZE; i++) {
                struct vio_net_desc *d;
                void *skb = port->tx_bufs[i].skb;

                if (!skb)
                        continue;

                d = vio_dring_entry(dr, i);

                ldc_unmap(port->vio.lp,
                          port->tx_bufs[i].cookies,
                          port->tx_bufs[i].ncookies);
                dev_kfree_skb(skb);
                port->tx_bufs[i].skb = NULL;
                d->hdr.state = VIO_DESC_FREE;
        }
        ldc_free_exp_dring(port->vio.lp, dr->base,
                           (dr->entry_size * dr->num_entries),
                           dr->cookies, dr->ncookies);
        dr->base = NULL;
        dr->entry_size = 0;
        dr->num_entries = 0;
        dr->pending = 0;
        dr->ncookies = 0;
}

static void vnet_port_reset(struct vnet_port *port)
{
        del_timer(&port->clean_timer);
        vnet_port_free_tx_bufs(port);
        port->rmtu = 0;
        port->tso = true;
        port->tsolen = 0;
}

static int vnet_port_alloc_tx_ring(struct vnet_port *port)
{
        struct vio_dring_state *dr;
        unsigned long len, elen;
        int i, err, ncookies;
        void *dring;

        dr = &port->vio.drings[VIO_DRIVER_TX_RING];

        elen = sizeof(struct vio_net_desc) +
               sizeof(struct ldc_trans_cookie) * 2;
        if (vio_version_after_eq(&port->vio, 1, 7))
                elen += sizeof(struct vio_net_dext);
        len = VNET_TX_RING_SIZE * elen;

        ncookies = VIO_MAX_RING_COOKIES;
        dring = ldc_alloc_exp_dring(port->vio.lp, len,
                                    dr->cookies, &ncookies,
                                    (LDC_MAP_SHADOW |
                                     LDC_MAP_DIRECT |
                                     LDC_MAP_RW));
        if (IS_ERR(dring)) {
                err = PTR_ERR(dring);
                goto err_out;
        }

        dr->base = dring;
        dr->entry_size = elen;
        dr->num_entries = VNET_TX_RING_SIZE;
        dr->prod = dr->cons = 0;
        port->start_cons  = true; /* need an initial trigger */
        dr->pending = VNET_TX_RING_SIZE;
        dr->ncookies = ncookies;

        for (i = 0; i < VNET_TX_RING_SIZE; ++i) {
                struct vio_net_desc *d;

                d = vio_dring_entry(dr, i);
                d->hdr.state = VIO_DESC_FREE;
        }
        return 0;

err_out:
        vnet_port_free_tx_bufs(port);

        return err;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
static void vnet_poll_controller(struct net_device *dev)
{
        struct vnet *vp = netdev_priv(dev);
        struct vnet_port *port;
        unsigned long flags;

        spin_lock_irqsave(&vp->lock, flags);
        if (!list_empty(&vp->port_list)) {
                port = list_entry(vp->port_list.next, struct vnet_port, list);
                napi_schedule(&port->napi);
        }
        spin_unlock_irqrestore(&vp->lock, flags);
}
#endif
static LIST_HEAD(vnet_list);
static DEFINE_MUTEX(vnet_list_mutex);

static const struct net_device_ops vnet_ops = {
        .ndo_open               = vnet_open,
        .ndo_stop               = vnet_close,
        .ndo_set_rx_mode        = vnet_set_rx_mode,
        .ndo_set_mac_address    = vnet_set_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_tx_timeout         = vnet_tx_timeout,
        .ndo_change_mtu         = vnet_change_mtu,
        .ndo_start_xmit         = vnet_start_xmit,
        .ndo_select_queue       = vnet_select_queue,
#ifdef CONFIG_NET_POLL_CONTROLLER
        .ndo_poll_controller    = vnet_poll_controller,
#endif
};

static struct vnet *vnet_new(const u64 *local_mac)
{
        struct net_device *dev;
        struct vnet *vp;
        int err, i;

        dev = alloc_etherdev_mqs(sizeof(*vp), VNET_MAX_TXQS, 1);
        if (!dev)
                return ERR_PTR(-ENOMEM);
        dev->needed_headroom = VNET_PACKET_SKIP + 8;
        dev->needed_tailroom = 8;

        for (i = 0; i < ETH_ALEN; i++)
                dev->dev_addr[i] = (*local_mac >> (5 - i) * 8) & 0xff;

        vp = netdev_priv(dev);

        spin_lock_init(&vp->lock);
        vp->dev = dev;

        INIT_LIST_HEAD(&vp->port_list);
        for (i = 0; i < VNET_PORT_HASH_SIZE; i++)
                INIT_HLIST_HEAD(&vp->port_hash[i]);
        INIT_LIST_HEAD(&vp->list);
        vp->local_mac = *local_mac;

        dev->netdev_ops = &vnet_ops;
        dev->ethtool_ops = &vnet_ethtool_ops;
        dev->watchdog_timeo = VNET_TX_TIMEOUT;

        dev->hw_features = NETIF_F_TSO | NETIF_F_GSO | NETIF_F_GSO_SOFTWARE |
                           NETIF_F_HW_CSUM | NETIF_F_SG;
        dev->features = dev->hw_features;

        err = register_netdev(dev);
        if (err) {
                pr_err("Cannot register net device, aborting\n");
                goto err_out_free_dev;
        }

        netdev_info(dev, "Sun LDOM vnet %pM\n", dev->dev_addr);

        list_add(&vp->list, &vnet_list);

        return vp;

err_out_free_dev:
        free_netdev(dev);

        return ERR_PTR(err);
}

static struct vnet *vnet_find_or_create(const u64 *local_mac)
{
        struct vnet *iter, *vp;

        mutex_lock(&vnet_list_mutex);
        vp = NULL;
        list_for_each_entry(iter, &vnet_list, list) {
                if (iter->local_mac == *local_mac) {
                        vp = iter;
                        break;
                }
        }
        if (!vp)
                vp = vnet_new(local_mac);
        mutex_unlock(&vnet_list_mutex);

        return vp;
}

static void vnet_cleanup(void)
{
        struct vnet *vp;
        struct net_device *dev;

        mutex_lock(&vnet_list_mutex);
        while (!list_empty(&vnet_list)) {
                vp = list_first_entry(&vnet_list, struct vnet, list);
                list_del(&vp->list);
                dev = vp->dev;
                /* vio_unregister_driver() should have cleaned up port_list */
                BUG_ON(!list_empty(&vp->port_list));
                unregister_netdev(dev);
                free_netdev(dev);
        }
        mutex_unlock(&vnet_list_mutex);
}

static const char *local_mac_prop = "local-mac-address";

static struct vnet *vnet_find_parent(struct mdesc_handle *hp,
                                                u64 port_node)
{
        const u64 *local_mac = NULL;
        u64 a;

        mdesc_for_each_arc(a, hp, port_node, MDESC_ARC_TYPE_BACK) {
                u64 target = mdesc_arc_target(hp, a);
                const char *name;

                name = mdesc_get_property(hp, target, "name", NULL);
                if (!name || strcmp(name, "network"))
                        continue;

                local_mac = mdesc_get_property(hp, target,
                                               local_mac_prop, NULL);
                if (local_mac)
                        break;
        }
        if (!local_mac)
                return ERR_PTR(-ENODEV);

        return vnet_find_or_create(local_mac);
}

static struct ldc_channel_config vnet_ldc_cfg = {
        .event          = vnet_event,
        .mtu            = 64,
        .mode           = LDC_MODE_UNRELIABLE,
};

static struct vio_driver_ops vnet_vio_ops = {
        .send_attr              = vnet_send_attr,
        .handle_attr            = vnet_handle_attr,
        .handshake_complete     = vnet_handshake_complete,
};

static void print_version(void)
{
        printk_once(KERN_INFO "%s", version);
}

const char *remote_macaddr_prop = "remote-mac-address";

static void
vnet_port_add_txq(struct vnet_port *port)
{
        struct vnet *vp = port->vp;
        int n;

        n = vp->nports++;
        n = n & (VNET_MAX_TXQS - 1);
        port->q_index = n;
        netif_tx_wake_queue(netdev_get_tx_queue(vp->dev, port->q_index));
}

static void
vnet_port_rm_txq(struct vnet_port *port)
{
        port->vp->nports--;
        netif_tx_stop_queue(netdev_get_tx_queue(port->vp->dev, port->q_index));
}

static int vnet_port_probe(struct vio_dev *vdev, const struct vio_device_id *id)
{
        struct mdesc_handle *hp;
        struct vnet_port *port;
        unsigned long flags;
        struct vnet *vp;
        const u64 *rmac;
        int len, i, err, switch_port;

        print_version();

        hp = mdesc_grab();

        vp = vnet_find_parent(hp, vdev->mp);
        if (IS_ERR(vp)) {
                pr_err("Cannot find port parent vnet\n");
                err = PTR_ERR(vp);
                goto err_out_put_mdesc;
        }

        rmac = mdesc_get_property(hp, vdev->mp, remote_macaddr_prop, &len);
        err = -ENODEV;
        if (!rmac) {
                pr_err("Port lacks %s property\n", remote_macaddr_prop);
                goto err_out_put_mdesc;
        }

        port = kzalloc(sizeof(*port), GFP_KERNEL);
        err = -ENOMEM;
        if (!port)
                goto err_out_put_mdesc;

        for (i = 0; i < ETH_ALEN; i++)
                port->raddr[i] = (*rmac >> (5 - i) * 8) & 0xff;

        port->vp = vp;

        err = vio_driver_init(&port->vio, vdev, VDEV_NETWORK,
                              vnet_versions, ARRAY_SIZE(vnet_versions),
                              &vnet_vio_ops, vp->dev->name);
        if (err)
                goto err_out_free_port;

        err = vio_ldc_alloc(&port->vio, &vnet_ldc_cfg, port);
        if (err)
                goto err_out_free_port;

        netif_napi_add(port->vp->dev, &port->napi, vnet_poll, NAPI_POLL_WEIGHT);

        INIT_HLIST_NODE(&port->hash);
        INIT_LIST_HEAD(&port->list);

        switch_port = 0;
        if (mdesc_get_property(hp, vdev->mp, "switch-port", NULL) != NULL)
                switch_port = 1;
        port->switch_port = switch_port;
        port->tso = true;
        port->tsolen = 0;

        spin_lock_irqsave(&vp->lock, flags);
        if (switch_port)
                list_add_rcu(&port->list, &vp->port_list);
        else
                list_add_tail_rcu(&port->list, &vp->port_list);
        hlist_add_head_rcu(&port->hash,
                           &vp->port_hash[vnet_hashfn(port->raddr)]);
        vnet_port_add_txq(port);
        spin_unlock_irqrestore(&vp->lock, flags);

        dev_set_drvdata(&vdev->dev, port);

        pr_info("%s: PORT ( remote-mac %pM%s )\n",
                vp->dev->name, port->raddr, switch_port ? " switch-port" : "");

        setup_timer(&port->clean_timer, vnet_clean_timer_expire,
                    (unsigned long)port);

        napi_enable(&port->napi);
        vio_port_up(&port->vio);

        mdesc_release(hp);

        return 0;

err_out_free_port:
        kfree(port);

err_out_put_mdesc:

        mdesc_release(hp);
        return err;
}

static int vnet_port_remove(struct vio_dev *vdev)
{
        struct vnet_port *port = dev_get_drvdata(&vdev->dev);

        if (port) {

                del_timer_sync(&port->vio.timer);

                napi_disable(&port->napi);

                list_del_rcu(&port->list);
                hlist_del_rcu(&port->hash);

                synchronize_rcu();
                del_timer_sync(&port->clean_timer);
                vnet_port_rm_txq(port);
                netif_napi_del(&port->napi);
                vnet_port_free_tx_bufs(port);
                vio_ldc_free(&port->vio);

                dev_set_drvdata(&vdev->dev, NULL);

                kfree(port);

        }
        return 0;
}

static const struct vio_device_id vnet_port_match[] = {
        {
                .type = "vnet-port",
        },
        {},
};
MODULE_DEVICE_TABLE(vio, vnet_port_match);

static struct vio_driver vnet_port_driver = {
        .id_table       = vnet_port_match,
        .probe          = vnet_port_probe,
        .remove         = vnet_port_remove,
        .name           = "vnet_port",
};

static int __init vnet_init(void)
{
        return vio_register_driver(&vnet_port_driver);
}

static void __exit vnet_exit(void)
{
        vio_unregister_driver(&vnet_port_driver);
        vnet_cleanup();
}

module_init(vnet_init);
module_exit(vnet_exit);