/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, see <http://www.gnu.org/licenses/>.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/atomic.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <net/arp.h>
#include <net/route.h>
#include <net/sock.h>
#include <net/pkt_sched.h>

#include "hyperv_net.h"


#define RING_SIZE_MIN 64
#define LINKCHANGE_INT (2 * HZ)
#define NETVSC_HW_FEATURES      (NETIF_F_RXCSUM | \
                                 NETIF_F_SG | \
                                 NETIF_F_TSO | \
                                 NETIF_F_TSO6 | \
                                 NETIF_F_HW_CSUM)
static int ring_size = 128;
module_param(ring_size, int, S_IRUGO);
MODULE_PARM_DESC(ring_size, "Ring buffer size (# of pages)");

static int max_num_vrss_chns = 8;

static const u32 default_msg = NETIF_MSG_DRV | NETIF_MSG_PROBE |
                                NETIF_MSG_LINK | NETIF_MSG_IFUP |
                                NETIF_MSG_IFDOWN | NETIF_MSG_RX_ERR |
                                NETIF_MSG_TX_ERR;

static int debug = -1;
module_param(debug, int, S_IRUGO);
MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");

static void do_set_multicast(struct work_struct *w)
{
        struct net_device_context *ndevctx =
                container_of(w, struct net_device_context, work);
        struct netvsc_device *nvdev;
        struct rndis_device *rdev;

        nvdev = hv_get_drvdata(ndevctx->device_ctx);
        if (nvdev == NULL || nvdev->ndev == NULL)
                return;

        rdev = nvdev->extension;
        if (rdev == NULL)
                return;

        if (nvdev->ndev->flags & IFF_PROMISC)
                rndis_filter_set_packet_filter(rdev,
                        NDIS_PACKET_TYPE_PROMISCUOUS);
        else
                rndis_filter_set_packet_filter(rdev,
                        NDIS_PACKET_TYPE_BROADCAST |
                        NDIS_PACKET_TYPE_ALL_MULTICAST |
                        NDIS_PACKET_TYPE_DIRECTED);
}

static void netvsc_set_multicast_list(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);

        schedule_work(&net_device_ctx->work);
}

static int netvsc_open(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_device *device_obj = net_device_ctx->device_ctx;
        struct netvsc_device *nvdev;
        struct rndis_device *rdev;
        int ret = 0;

        netif_carrier_off(net);

        /* Open up the device */
        ret = rndis_filter_open(device_obj);
        if (ret != 0) {
                netdev_err(net, "unable to open device (ret %d).\n", ret);
                return ret;
        }

        netif_tx_wake_all_queues(net);

        nvdev = hv_get_drvdata(device_obj);
        rdev = nvdev->extension;
        if (!rdev->link_state)
                netif_carrier_on(net);

        return ret;
}

static int netvsc_close(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_device *device_obj = net_device_ctx->device_ctx;
        struct netvsc_device *nvdev = hv_get_drvdata(device_obj);
        int ret;
        u32 aread, awrite, i, msec = 10, retry = 0, retry_max = 20;
        struct vmbus_channel *chn;

        netif_tx_disable(net);

        /* Make sure netvsc_set_multicast_list doesn't re-enable filter! */
        cancel_work_sync(&net_device_ctx->work);
        ret = rndis_filter_close(device_obj);
        if (ret != 0) {
                netdev_err(net, "unable to close device (ret %d).\n", ret);
                return ret;
        }

        /* Ensure pending bytes in ring are read */
        while (true) {
                aread = 0;
                for (i = 0; i < nvdev->num_chn; i++) {
                        chn = nvdev->chn_table[i];
                        if (!chn)
                                continue;

                        hv_get_ringbuffer_availbytes(&chn->inbound, &aread,
                                                     &awrite);

                        if (aread)
                                break;

                        hv_get_ringbuffer_availbytes(&chn->outbound, &aread,
                                                     &awrite);

                        if (aread)
                                break;
                }

                retry++;
                if (retry > retry_max || aread == 0)
                        break;

                msleep(msec);

                if (msec < 1000)
                        msec *= 2;
        }

        if (aread) {
                netdev_err(net, "Ring buffer not empty after closing rndis\n");
                ret = -ETIMEDOUT;
        }

        return ret;
}

static void *init_ppi_data(struct rndis_message *msg, u32 ppi_size,
                                int pkt_type)
{
        struct rndis_packet *rndis_pkt;
        struct rndis_per_packet_info *ppi;

        rndis_pkt = &msg->msg.pkt;
        rndis_pkt->data_offset += ppi_size;

        ppi = (struct rndis_per_packet_info *)((void *)rndis_pkt +
                rndis_pkt->per_pkt_info_offset + rndis_pkt->per_pkt_info_len);

        ppi->size = ppi_size;
        ppi->type = pkt_type;
        ppi->ppi_offset = sizeof(struct rndis_per_packet_info);

        rndis_pkt->per_pkt_info_len += ppi_size;

        return ppi;
}

static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb,
                        void *accel_priv, select_queue_fallback_t fallback)
{
        struct net_device_context *net_device_ctx = netdev_priv(ndev);
        struct hv_device *hdev =  net_device_ctx->device_ctx;
        struct netvsc_device *nvsc_dev = hv_get_drvdata(hdev);
        u32 hash;
        u16 q_idx = 0;

        if (nvsc_dev == NULL || ndev->real_num_tx_queues <= 1)
                return 0;

        hash = skb_get_hash(skb);
        q_idx = nvsc_dev->send_table[hash % VRSS_SEND_TAB_SIZE] %
                ndev->real_num_tx_queues;

        if (!nvsc_dev->chn_table[q_idx])
                q_idx = 0;

        return q_idx;
}

static u32 fill_pg_buf(struct page *page, u32 offset, u32 len,
                        struct hv_page_buffer *pb)
{
        int j = 0;

        /* Deal with compund pages by ignoring unused part
         * of the page.
         */
        page += (offset >> PAGE_SHIFT);
        offset &= ~PAGE_MASK;

        while (len > 0) {
                unsigned long bytes;

                bytes = PAGE_SIZE - offset;
                if (bytes > len)
                        bytes = len;
                pb[j].pfn = page_to_pfn(page);
                pb[j].offset = offset;
                pb[j].len = bytes;

                offset += bytes;
                len -= bytes;

                if (offset == PAGE_SIZE && len) {
                        page++;
                        offset = 0;
                        j++;
                }
        }

        return j + 1;
}

static u32 init_page_array(void *hdr, u32 len, struct sk_buff *skb,
                           struct hv_netvsc_packet *packet,
                           struct hv_page_buffer **page_buf)
{
        struct hv_page_buffer *pb = *page_buf;
        u32 slots_used = 0;
        char *data = skb->data;
        int frags = skb_shinfo(skb)->nr_frags;
        int i;

        /* The packet is laid out thus:
         * 1. hdr: RNDIS header and PPI
         * 2. skb linear data
         * 3. skb fragment data
         */
        if (hdr != NULL)
                slots_used += fill_pg_buf(virt_to_page(hdr),
                                        offset_in_page(hdr),
                                        len, &pb[slots_used]);

        packet->rmsg_size = len;
        packet->rmsg_pgcnt = slots_used;

        slots_used += fill_pg_buf(virt_to_page(data),
                                offset_in_page(data),
                                skb_headlen(skb), &pb[slots_used]);

        for (i = 0; i < frags; i++) {
                skb_frag_t *frag = skb_shinfo(skb)->frags + i;

                slots_used += fill_pg_buf(skb_frag_page(frag),
                                        frag->page_offset,
                                        skb_frag_size(frag), &pb[slots_used]);
        }
        return slots_used;
}

static int count_skb_frag_slots(struct sk_buff *skb)
{
        int i, frags = skb_shinfo(skb)->nr_frags;
        int pages = 0;

        for (i = 0; i < frags; i++) {
                skb_frag_t *frag = skb_shinfo(skb)->frags + i;
                unsigned long size = skb_frag_size(frag);
                unsigned long offset = frag->page_offset;

                /* Skip unused frames from start of page */
                offset &= ~PAGE_MASK;
                pages += PFN_UP(offset + size);
        }
        return pages;
}

static int netvsc_get_slots(struct sk_buff *skb)
{
        char *data = skb->data;
        unsigned int offset = offset_in_page(data);
        unsigned int len = skb_headlen(skb);
        int slots;
        int frag_slots;

        slots = DIV_ROUND_UP(offset + len, PAGE_SIZE);
        frag_slots = count_skb_frag_slots(skb);
        return slots + frag_slots;
}

static u32 get_net_transport_info(struct sk_buff *skb, u32 *trans_off)
{
        u32 ret_val = TRANSPORT_INFO_NOT_IP;

        if ((eth_hdr(skb)->h_proto != htons(ETH_P_IP)) &&
                (eth_hdr(skb)->h_proto != htons(ETH_P_IPV6))) {
                goto not_ip;
        }

        *trans_off = skb_transport_offset(skb);

        if ((eth_hdr(skb)->h_proto == htons(ETH_P_IP))) {
                struct iphdr *iphdr = ip_hdr(skb);

                if (iphdr->protocol == IPPROTO_TCP)
                        ret_val = TRANSPORT_INFO_IPV4_TCP;
                else if (iphdr->protocol == IPPROTO_UDP)
                        ret_val = TRANSPORT_INFO_IPV4_UDP;
        } else {
                if (ipv6_hdr(skb)->nexthdr == IPPROTO_TCP)
                        ret_val = TRANSPORT_INFO_IPV6_TCP;
                else if (ipv6_hdr(skb)->nexthdr == IPPROTO_UDP)
                        ret_val = TRANSPORT_INFO_IPV6_UDP;
        }

not_ip:
        return ret_val;
}

static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_netvsc_packet *packet = NULL;
        int ret;
        unsigned int num_data_pgs;
        struct rndis_message *rndis_msg;
        struct rndis_packet *rndis_pkt;
        u32 rndis_msg_size;
        bool isvlan;
        bool linear = false;
        struct rndis_per_packet_info *ppi;
        struct ndis_tcp_ip_checksum_info *csum_info;
        struct ndis_tcp_lso_info *lso_info;
        int  hdr_offset;
        u32 net_trans_info;
        u32 hash;
        u32 skb_length;
        struct hv_page_buffer page_buf[MAX_PAGE_BUFFER_COUNT];
        struct hv_page_buffer *pb = page_buf;
        struct netvsc_stats *tx_stats = this_cpu_ptr(net_device_ctx->tx_stats);

        /* We will atmost need two pages to describe the rndis
         * header. We can only transmit MAX_PAGE_BUFFER_COUNT number
         * of pages in a single packet. If skb is scattered around
         * more pages we try linearizing it.
         */

check_size:
        skb_length = skb->len;
        num_data_pgs = netvsc_get_slots(skb) + 2;
        if (num_data_pgs > MAX_PAGE_BUFFER_COUNT && linear) {
                net_alert_ratelimited("packet too big: %u pages (%u bytes)\n",
                                      num_data_pgs, skb->len);
                ret = -EFAULT;
                goto drop;
        } else if (num_data_pgs > MAX_PAGE_BUFFER_COUNT) {
                if (skb_linearize(skb)) {
                        net_alert_ratelimited("failed to linearize skb\n");
                        ret = -ENOMEM;
                        goto drop;
                }
                linear = true;
                goto check_size;
        }

        /*
         * Place the rndis header in the skb head room and
         * the skb->cb will be used for hv_netvsc_packet
         * structure.
         */
        ret = skb_cow_head(skb, RNDIS_AND_PPI_SIZE);
        if (ret) {
                netdev_err(net, "unable to alloc hv_netvsc_packet\n");
                ret = -ENOMEM;
                goto drop;
        }
        /* Use the skb control buffer for building up the packet */
        BUILD_BUG_ON(sizeof(struct hv_netvsc_packet) >
                        FIELD_SIZEOF(struct sk_buff, cb));
        packet = (struct hv_netvsc_packet *)skb->cb;


        packet->q_idx = skb_get_queue_mapping(skb);

        packet->total_data_buflen = skb->len;

        rndis_msg = (struct rndis_message *)skb->head;

        memset(rndis_msg, 0, RNDIS_AND_PPI_SIZE);

        isvlan = skb->vlan_tci & VLAN_TAG_PRESENT;

        /* Add the rndis header */
        rndis_msg->ndis_msg_type = RNDIS_MSG_PACKET;
        rndis_msg->msg_len = packet->total_data_buflen;
        rndis_pkt = &rndis_msg->msg.pkt;
        rndis_pkt->data_offset = sizeof(struct rndis_packet);
        rndis_pkt->data_len = packet->total_data_buflen;
        rndis_pkt->per_pkt_info_offset = sizeof(struct rndis_packet);

        rndis_msg_size = RNDIS_MESSAGE_SIZE(struct rndis_packet);

        hash = skb_get_hash_raw(skb);
        if (hash != 0 && net->real_num_tx_queues > 1) {
                rndis_msg_size += NDIS_HASH_PPI_SIZE;
                ppi = init_ppi_data(rndis_msg, NDIS_HASH_PPI_SIZE,
                                    NBL_HASH_VALUE);
                *(u32 *)((void *)ppi + ppi->ppi_offset) = hash;
        }

        if (isvlan) {
                struct ndis_pkt_8021q_info *vlan;

                rndis_msg_size += NDIS_VLAN_PPI_SIZE;
                ppi = init_ppi_data(rndis_msg, NDIS_VLAN_PPI_SIZE,
                                        IEEE_8021Q_INFO);
                vlan = (struct ndis_pkt_8021q_info *)((void *)ppi +
                                                ppi->ppi_offset);
                vlan->vlanid = skb->vlan_tci & VLAN_VID_MASK;
                vlan->pri = (skb->vlan_tci & VLAN_PRIO_MASK) >>
                                VLAN_PRIO_SHIFT;
        }

        net_trans_info = get_net_transport_info(skb, &hdr_offset);
        if (net_trans_info == TRANSPORT_INFO_NOT_IP)
                goto do_send;

        /*
         * Setup the sendside checksum offload only if this is not a
         * GSO packet.
         */
        if (skb_is_gso(skb))
                goto do_lso;

        if ((skb->ip_summed == CHECKSUM_NONE) ||
            (skb->ip_summed == CHECKSUM_UNNECESSARY))
                goto do_send;

        rndis_msg_size += NDIS_CSUM_PPI_SIZE;
        ppi = init_ppi_data(rndis_msg, NDIS_CSUM_PPI_SIZE,
                            TCPIP_CHKSUM_PKTINFO);

        csum_info = (struct ndis_tcp_ip_checksum_info *)((void *)ppi +
                        ppi->ppi_offset);

        if (net_trans_info & (INFO_IPV4 << 16))
                csum_info->transmit.is_ipv4 = 1;
        else
                csum_info->transmit.is_ipv6 = 1;

        if (net_trans_info & INFO_TCP) {
                csum_info->transmit.tcp_checksum = 1;
                csum_info->transmit.tcp_header_offset = hdr_offset;
        } else if (net_trans_info & INFO_UDP) {
                /* UDP checksum offload is not supported on ws2008r2.
                 * Furthermore, on ws2012 and ws2012r2, there are some
                 * issues with udp checksum offload from Linux guests.
                 * (these are host issues).
                 * For now compute the checksum here.
                 */
                struct udphdr *uh;
                u16 udp_len;

                ret = skb_cow_head(skb, 0);
                if (ret)
                        goto drop;

                uh = udp_hdr(skb);
                udp_len = ntohs(uh->len);
                uh->check = 0;
                uh->check = csum_tcpudp_magic(ip_hdr(skb)->saddr,
                                              ip_hdr(skb)->daddr,
                                              udp_len, IPPROTO_UDP,
                                              csum_partial(uh, udp_len, 0));
                if (uh->check == 0)
                        uh->check = CSUM_MANGLED_0;

                csum_info->transmit.udp_checksum = 0;
        }
        goto do_send;

do_lso:
        rndis_msg_size += NDIS_LSO_PPI_SIZE;
        ppi = init_ppi_data(rndis_msg, NDIS_LSO_PPI_SIZE,
                            TCP_LARGESEND_PKTINFO);

        lso_info = (struct ndis_tcp_lso_info *)((void *)ppi +
                        ppi->ppi_offset);

        lso_info->lso_v2_transmit.type = NDIS_TCP_LARGE_SEND_OFFLOAD_V2_TYPE;
        if (net_trans_info & (INFO_IPV4 << 16)) {
                lso_info->lso_v2_transmit.ip_version =
                        NDIS_TCP_LARGE_SEND_OFFLOAD_IPV4;
                ip_hdr(skb)->tot_len = 0;
                ip_hdr(skb)->check = 0;
                tcp_hdr(skb)->check =
                ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
                                   ip_hdr(skb)->daddr, 0, IPPROTO_TCP, 0);
        } else {
                lso_info->lso_v2_transmit.ip_version =
                        NDIS_TCP_LARGE_SEND_OFFLOAD_IPV6;
                ipv6_hdr(skb)->payload_len = 0;
                tcp_hdr(skb)->check =
                ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
                                &ipv6_hdr(skb)->daddr, 0, IPPROTO_TCP, 0);
        }
        lso_info->lso_v2_transmit.tcp_header_offset = hdr_offset;
        lso_info->lso_v2_transmit.mss = skb_shinfo(skb)->gso_size;

do_send:
        /* Start filling in the page buffers with the rndis hdr */
        rndis_msg->msg_len += rndis_msg_size;
        packet->total_data_buflen = rndis_msg->msg_len;
        packet->page_buf_cnt = init_page_array(rndis_msg, rndis_msg_size,
                                               skb, packet, &pb);

        /* timestamp packet in software */
        skb_tx_timestamp(skb);
        ret = netvsc_send(net_device_ctx->device_ctx, packet,
                          rndis_msg, &pb, skb);

drop:
        if (ret == 0) {
                u64_stats_update_begin(&tx_stats->syncp);
                tx_stats->packets++;
                tx_stats->bytes += skb_length;
                u64_stats_update_end(&tx_stats->syncp);
        } else {
                if (ret != -EAGAIN) {
                        dev_kfree_skb_any(skb);
                        net->stats.tx_dropped++;
                }
        }

        return (ret == -EAGAIN) ? NETDEV_TX_BUSY : NETDEV_TX_OK;
}

/*
 * netvsc_linkstatus_callback - Link up/down notification
 */
void netvsc_linkstatus_callback(struct hv_device *device_obj,
                                struct rndis_message *resp)
{
        struct rndis_indicate_status *indicate = &resp->msg.indicate_status;
        struct net_device *net;
        struct net_device_context *ndev_ctx;
        struct netvsc_device *net_device;
        struct netvsc_reconfig *event;
        unsigned long flags;

        /* Handle link change statuses only */
        if (indicate->status != RNDIS_STATUS_NETWORK_CHANGE &&
            indicate->status != RNDIS_STATUS_MEDIA_CONNECT &&
            indicate->status != RNDIS_STATUS_MEDIA_DISCONNECT)
                return;

        net_device = hv_get_drvdata(device_obj);
        net = net_device->ndev;

        if (!net || net->reg_state != NETREG_REGISTERED)
                return;

        ndev_ctx = netdev_priv(net);

        event = kzalloc(sizeof(*event), GFP_ATOMIC);
        if (!event)
                return;
        event->event = indicate->status;

        spin_lock_irqsave(&ndev_ctx->lock, flags);
        list_add_tail(&event->list, &ndev_ctx->reconfig_events);
        spin_unlock_irqrestore(&ndev_ctx->lock, flags);

        schedule_delayed_work(&ndev_ctx->dwork, 0);
}

/*
 * netvsc_recv_callback -  Callback when we receive a packet from the
 * "wire" on the specified device.
 */
int netvsc_recv_callback(struct hv_device *device_obj,
                                struct hv_netvsc_packet *packet,
                                void **data,
                                struct ndis_tcp_ip_checksum_info *csum_info,
                                struct vmbus_channel *channel,
                                u16 vlan_tci)
{
        struct net_device *net;
        struct net_device_context *net_device_ctx;
        struct sk_buff *skb;
        struct netvsc_stats *rx_stats;

        net = ((struct netvsc_device *)hv_get_drvdata(device_obj))->ndev;
        if (!net || net->reg_state != NETREG_REGISTERED) {
                return NVSP_STAT_FAIL;
        }
        net_device_ctx = netdev_priv(net);
        rx_stats = this_cpu_ptr(net_device_ctx->rx_stats);

        /* Allocate a skb - TODO direct I/O to pages? */
        skb = netdev_alloc_skb_ip_align(net, packet->total_data_buflen);
        if (unlikely(!skb)) {
                ++net->stats.rx_dropped;
                return NVSP_STAT_FAIL;
        }

        /*
         * Copy to skb. This copy is needed here since the memory pointed by
         * hv_netvsc_packet cannot be deallocated
         */
        memcpy(skb_put(skb, packet->total_data_buflen), *data,
                packet->total_data_buflen);

        skb->protocol = eth_type_trans(skb, net);
        if (csum_info) {
                /* We only look at the IP checksum here.
                 * Should we be dropping the packet if checksum
                 * failed? How do we deal with other checksums - TCP/UDP?
                 */
                if (csum_info->receive.ip_checksum_succeeded)
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                else
                        skb->ip_summed = CHECKSUM_NONE;
        }

        if (vlan_tci & VLAN_TAG_PRESENT)
                __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
                                       vlan_tci);

        skb_record_rx_queue(skb, channel->
                            offermsg.offer.sub_channel_index);

        u64_stats_update_begin(&rx_stats->syncp);
        rx_stats->packets++;
        rx_stats->bytes += packet->total_data_buflen;
        u64_stats_update_end(&rx_stats->syncp);

        /*
         * Pass the skb back up. Network stack will deallocate the skb when it
         * is done.
         * TODO - use NAPI?
         */
        netif_rx(skb);

        return 0;
}

static void netvsc_get_drvinfo(struct net_device *net,
                               struct ethtool_drvinfo *info)
{
        strlcpy(info->driver, KBUILD_MODNAME, sizeof(info->driver));
        strlcpy(info->fw_version, "N/A", sizeof(info->fw_version));
}

static void netvsc_get_channels(struct net_device *net,
                                struct ethtool_channels *channel)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_device *dev = net_device_ctx->device_ctx;
        struct netvsc_device *nvdev = hv_get_drvdata(dev);

        if (nvdev) {
                channel->max_combined   = nvdev->max_chn;
                channel->combined_count = nvdev->num_chn;
        }
}

static int netvsc_set_channels(struct net_device *net,
                               struct ethtool_channels *channels)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_device *dev = net_device_ctx->device_ctx;
        struct netvsc_device *nvdev = hv_get_drvdata(dev);
        struct netvsc_device_info device_info;
        u32 num_chn;
        u32 max_chn;
        int ret = 0;
        bool recovering = false;

        if (!nvdev || nvdev->destroy)
                return -ENODEV;

        num_chn = nvdev->num_chn;
        max_chn = min_t(u32, nvdev->max_chn, num_online_cpus());

        if (nvdev->nvsp_version < NVSP_PROTOCOL_VERSION_5) {
                pr_info("vRSS unsupported before NVSP Version 5\n");
                return -EINVAL;
        }

        /* We do not support rx, tx, or other */
        if (!channels ||
            channels->rx_count ||
            channels->tx_count ||
            channels->other_count ||
            (channels->combined_count < 1))
                return -EINVAL;

        if (channels->combined_count > max_chn) {
                pr_info("combined channels too high, using %d\n", max_chn);
                channels->combined_count = max_chn;
        }

        ret = netvsc_close(net);
        if (ret)
                goto out;

 do_set:
        nvdev->start_remove = true;
        rndis_filter_device_remove(dev);

        nvdev->num_chn = channels->combined_count;

        net_device_ctx->device_ctx = dev;
        hv_set_drvdata(dev, net);

        memset(&device_info, 0, sizeof(device_info));
        device_info.num_chn = nvdev->num_chn; /* passed to RNDIS */
        device_info.ring_size = ring_size;
        device_info.max_num_vrss_chns = max_num_vrss_chns;

        ret = rndis_filter_device_add(dev, &device_info);
        if (ret) {
                if (recovering) {
                        netdev_err(net, "unable to add netvsc device (ret %d)\n", ret);
                        return ret;
                }
                goto recover;
        }

        nvdev = hv_get_drvdata(dev);

        ret = netif_set_real_num_tx_queues(net, nvdev->num_chn);
        if (ret) {
                if (recovering) {
                        netdev_err(net, "could not set tx queue count (ret %d)\n", ret);
                        return ret;
                }
                goto recover;
        }

        ret = netif_set_real_num_rx_queues(net, nvdev->num_chn);
        if (ret) {
                if (recovering) {
                        netdev_err(net, "could not set rx queue count (ret %d)\n", ret);
                        return ret;
                }
                goto recover;
        }

 out:
        netvsc_open(net);

        return ret;

 recover:
        /* If the above failed, we attempt to recover through the same
         * process but with the original number of channels.
         */
        netdev_err(net, "could not set channels, recovering\n");
        recovering = true;
        channels->combined_count = num_chn;
        goto do_set;
}

static bool netvsc_validate_ethtool_ss_cmd(const struct ethtool_cmd *cmd)
{
        struct ethtool_cmd diff1 = *cmd;
        struct ethtool_cmd diff2 = {};

        ethtool_cmd_speed_set(&diff1, 0);
        diff1.duplex = 0;
        /* advertising and cmd are usually set */
        diff1.advertising = 0;
        diff1.cmd = 0;
        /* We set port to PORT_OTHER */
        diff2.port = PORT_OTHER;

        return !memcmp(&diff1, &diff2, sizeof(diff1));
}

static void netvsc_init_settings(struct net_device *dev)
{
        struct net_device_context *ndc = netdev_priv(dev);

        ndc->speed = SPEED_UNKNOWN;
        ndc->duplex = DUPLEX_UNKNOWN;
}

static int netvsc_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
{
        struct net_device_context *ndc = netdev_priv(dev);

        ethtool_cmd_speed_set(cmd, ndc->speed);
        cmd->duplex = ndc->duplex;
        cmd->port = PORT_OTHER;

        return 0;
}

static int netvsc_set_settings(struct net_device *dev, struct ethtool_cmd *cmd)
{
        struct net_device_context *ndc = netdev_priv(dev);
        u32 speed;

        speed = ethtool_cmd_speed(cmd);
        if (!ethtool_validate_speed(speed) ||
            !ethtool_validate_duplex(cmd->duplex) ||
            !netvsc_validate_ethtool_ss_cmd(cmd))
                return -EINVAL;

        ndc->speed = speed;
        ndc->duplex = cmd->duplex;

        return 0;
}

static int netvsc_change_mtu(struct net_device *ndev, int mtu)
{
        struct net_device_context *ndevctx = netdev_priv(ndev);
        struct hv_device *hdev =  ndevctx->device_ctx;
        struct netvsc_device *nvdev = hv_get_drvdata(hdev);
        struct netvsc_device_info device_info;
        int limit = ETH_DATA_LEN;
        u32 num_chn;
        int ret = 0;

        if (nvdev == NULL || nvdev->destroy)
                return -ENODEV;

        if (nvdev->nvsp_version >= NVSP_PROTOCOL_VERSION_2)
                limit = NETVSC_MTU - ETH_HLEN;

        if (mtu < NETVSC_MTU_MIN || mtu > limit)
                return -EINVAL;

        ret = netvsc_close(ndev);
        if (ret)
                goto out;

        num_chn = nvdev->num_chn;

        nvdev->start_remove = true;
        rndis_filter_device_remove(hdev);

        ndev->mtu = mtu;

        ndevctx->device_ctx = hdev;
        hv_set_drvdata(hdev, ndev);

        memset(&device_info, 0, sizeof(device_info));
        device_info.ring_size = ring_size;
        device_info.num_chn = num_chn;
        device_info.max_num_vrss_chns = max_num_vrss_chns;
        rndis_filter_device_add(hdev, &device_info);

out:
        netvsc_open(ndev);

        return ret;
}

static struct rtnl_link_stats64 *netvsc_get_stats64(struct net_device *net,
                                                    struct rtnl_link_stats64 *t)
{
        struct net_device_context *ndev_ctx = netdev_priv(net);
        int cpu;

        for_each_possible_cpu(cpu) {
                struct netvsc_stats *tx_stats = per_cpu_ptr(ndev_ctx->tx_stats,
                                                            cpu);
                struct netvsc_stats *rx_stats = per_cpu_ptr(ndev_ctx->rx_stats,
                                                            cpu);
                u64 tx_packets, tx_bytes, rx_packets, rx_bytes;
                unsigned int start;

                do {
                        start = u64_stats_fetch_begin_irq(&tx_stats->syncp);
                        tx_packets = tx_stats->packets;
                        tx_bytes = tx_stats->bytes;
                } while (u64_stats_fetch_retry_irq(&tx_stats->syncp, start));

                do {
                        start = u64_stats_fetch_begin_irq(&rx_stats->syncp);
                        rx_packets = rx_stats->packets;
                        rx_bytes = rx_stats->bytes;
                } while (u64_stats_fetch_retry_irq(&rx_stats->syncp, start));

                t->tx_bytes     += tx_bytes;
                t->tx_packets   += tx_packets;
                t->rx_bytes     += rx_bytes;
                t->rx_packets   += rx_packets;
        }

        t->tx_dropped   = net->stats.tx_dropped;
        t->tx_errors    = net->stats.tx_dropped;

        t->rx_dropped   = net->stats.rx_dropped;
        t->rx_errors    = net->stats.rx_errors;

        return t;
}

static int netvsc_set_mac_addr(struct net_device *ndev, void *p)
{
        struct net_device_context *ndevctx = netdev_priv(ndev);
        struct hv_device *hdev =  ndevctx->device_ctx;
        struct sockaddr *addr = p;
        char save_adr[ETH_ALEN];
        unsigned char save_aatype;
        int err;

        memcpy(save_adr, ndev->dev_addr, ETH_ALEN);
        save_aatype = ndev->addr_assign_type;

        err = eth_mac_addr(ndev, p);
        if (err != 0)
                return err;

        err = rndis_filter_set_device_mac(hdev, addr->sa_data);
        if (err != 0) {
                /* roll back to saved MAC */
                memcpy(ndev->dev_addr, save_adr, ETH_ALEN);
                ndev->addr_assign_type = save_aatype;
        }

        return err;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
static void netvsc_poll_controller(struct net_device *net)
{
        /* As netvsc_start_xmit() works synchronous we don't have to
         * trigger anything here.
         */
}
#endif

static const struct ethtool_ops ethtool_ops = {
        .get_drvinfo    = netvsc_get_drvinfo,
        .get_link       = ethtool_op_get_link,
        .get_channels   = netvsc_get_channels,
        .set_channels   = netvsc_set_channels,
        .get_ts_info    = ethtool_op_get_ts_info,
        .get_settings   = netvsc_get_settings,
        .set_settings   = netvsc_set_settings,
};

static const struct net_device_ops device_ops = {
        .ndo_open =                     netvsc_open,
        .ndo_stop =                     netvsc_close,
        .ndo_start_xmit =               netvsc_start_xmit,
        .ndo_set_rx_mode =              netvsc_set_multicast_list,
        .ndo_change_mtu =               netvsc_change_mtu,
        .ndo_validate_addr =            eth_validate_addr,
        .ndo_set_mac_address =          netvsc_set_mac_addr,
        .ndo_select_queue =             netvsc_select_queue,
        .ndo_get_stats64 =              netvsc_get_stats64,
#ifdef CONFIG_NET_POLL_CONTROLLER
        .ndo_poll_controller =          netvsc_poll_controller,
#endif
};

/*

 * Handle link status changes. For RNDIS_STATUS_NETWORK_CHANGE emulate link
 * down/up sequence. In case of RNDIS_STATUS_MEDIA_CONNECT when carrier is
 * present send GARP packet to network peers with netif_notify_peers().
 */
static void netvsc_link_change(struct work_struct *w)
{
        struct net_device_context *ndev_ctx;
        struct net_device *net;
        struct netvsc_device *net_device;
        struct rndis_device *rdev;
        struct netvsc_reconfig *event = NULL;
        bool notify = false, reschedule = false;
        unsigned long flags, next_reconfig, delay;

        ndev_ctx = container_of(w, struct net_device_context, dwork.work);
        net_device = hv_get_drvdata(ndev_ctx->device_ctx);
        rdev = net_device->extension;
        net = net_device->ndev;

        next_reconfig = ndev_ctx->last_reconfig + LINKCHANGE_INT;
        if (time_is_after_jiffies(next_reconfig)) {
                /* link_watch only sends one notification with current state
                 * per second, avoid doing reconfig more frequently. Handle
                 * wrap around.
                 */
                delay = next_reconfig - jiffies;
                delay = delay < LINKCHANGE_INT ? delay : LINKCHANGE_INT;
                schedule_delayed_work(&ndev_ctx->dwork, delay);
                return;
        }
        ndev_ctx->last_reconfig = jiffies;

        spin_lock_irqsave(&ndev_ctx->lock, flags);
        if (!list_empty(&ndev_ctx->reconfig_events)) {
                event = list_first_entry(&ndev_ctx->reconfig_events,
                                         struct netvsc_reconfig, list);
                list_del(&event->list);
                reschedule = !list_empty(&ndev_ctx->reconfig_events);
        }
        spin_unlock_irqrestore(&ndev_ctx->lock, flags);

        if (!event)
                return;

        rtnl_lock();

        switch (event->event) {
                /* Only the following events are possible due to the check in
                 * netvsc_linkstatus_callback()
                 */
        case RNDIS_STATUS_MEDIA_CONNECT:
                if (rdev->link_state) {
                        rdev->link_state = false;
                        netif_carrier_on(net);
                        netif_tx_wake_all_queues(net);
                } else {
                        notify = true;
                }
                kfree(event);
                break;
        case RNDIS_STATUS_MEDIA_DISCONNECT:
                if (!rdev->link_state) {
                        rdev->link_state = true;
                        netif_carrier_off(net);
                        netif_tx_stop_all_queues(net);
                }
                kfree(event);
                break;
        case RNDIS_STATUS_NETWORK_CHANGE:
                /* Only makes sense if carrier is present */
                if (!rdev->link_state) {
                        rdev->link_state = true;
                        netif_carrier_off(net);
                        netif_tx_stop_all_queues(net);
                        event->event = RNDIS_STATUS_MEDIA_CONNECT;
                        spin_lock_irqsave(&ndev_ctx->lock, flags);
                        list_add_tail(&event->list, &ndev_ctx->reconfig_events);
                        spin_unlock_irqrestore(&ndev_ctx->lock, flags);
                        reschedule = true;
                }
                break;
        }

        rtnl_unlock();

        if (notify)
                netdev_notify_peers(net);

        /* link_watch only sends one notification with current state per
         * second, handle next reconfig event in 2 seconds.
         */
        if (reschedule)
                schedule_delayed_work(&ndev_ctx->dwork, LINKCHANGE_INT);
}

static void netvsc_free_netdev(struct net_device *netdev)
{
        struct net_device_context *net_device_ctx = netdev_priv(netdev);

        free_percpu(net_device_ctx->tx_stats);
        free_percpu(net_device_ctx->rx_stats);
        free_netdev(netdev);
}

static int netvsc_probe(struct hv_device *dev,
                        const struct hv_vmbus_device_id *dev_id)
{
        struct net_device *net = NULL;
        struct net_device_context *net_device_ctx;
        struct netvsc_device_info device_info;
        struct netvsc_device *nvdev;
        int ret;

        net = alloc_etherdev_mq(sizeof(struct net_device_context),
                                num_online_cpus());
        if (!net)
                return -ENOMEM;

        netif_carrier_off(net);

        net_device_ctx = netdev_priv(net);
        net_device_ctx->device_ctx = dev;
        net_device_ctx->msg_enable = netif_msg_init(debug, default_msg);
        if (netif_msg_probe(net_device_ctx))
                netdev_dbg(net, "netvsc msg_enable: %d\n",
                           net_device_ctx->msg_enable);

        net_device_ctx->tx_stats = netdev_alloc_pcpu_stats(struct netvsc_stats);
        if (!net_device_ctx->tx_stats) {
                free_netdev(net);
                return -ENOMEM;
        }
        net_device_ctx->rx_stats = netdev_alloc_pcpu_stats(struct netvsc_stats);
        if (!net_device_ctx->rx_stats) {
                free_percpu(net_device_ctx->tx_stats);
                free_netdev(net);
                return -ENOMEM;
        }

        hv_set_drvdata(dev, net);
        INIT_DELAYED_WORK(&net_device_ctx->dwork, netvsc_link_change);
        INIT_WORK(&net_device_ctx->work, do_set_multicast);

        spin_lock_init(&net_device_ctx->lock);
        INIT_LIST_HEAD(&net_device_ctx->reconfig_events);

        net->netdev_ops = &device_ops;

        net->hw_features = NETVSC_HW_FEATURES;
        net->features = NETVSC_HW_FEATURES | NETIF_F_HW_VLAN_CTAG_TX;

        net->ethtool_ops = &ethtool_ops;
        SET_NETDEV_DEV(net, &dev->device);

        /* We always need headroom for rndis header */
        net->needed_headroom = RNDIS_AND_PPI_SIZE;

        /* Notify the netvsc driver of the new device */
        memset(&device_info, 0, sizeof(device_info));
        device_info.ring_size = ring_size;
        device_info.max_num_vrss_chns = max_num_vrss_chns;
        ret = rndis_filter_device_add(dev, &device_info);
        if (ret != 0) {
                netdev_err(net, "unable to add netvsc device (ret %d)\n", ret);
                netvsc_free_netdev(net);
                hv_set_drvdata(dev, NULL);
                return ret;
        }
        memcpy(net->dev_addr, device_info.mac_adr, ETH_ALEN);

        nvdev = hv_get_drvdata(dev);
        netif_set_real_num_tx_queues(net, nvdev->num_chn);
        netif_set_real_num_rx_queues(net, nvdev->num_chn);

        netvsc_init_settings(net);

        ret = register_netdev(net);
        if (ret != 0) {
                pr_err("Unable to register netdev.\n");
                rndis_filter_device_remove(dev);
                netvsc_free_netdev(net);
        }

        return ret;
}

static int netvsc_remove(struct hv_device *dev)
{
        struct net_device *net;
        struct net_device_context *ndev_ctx;
        struct netvsc_device *net_device;

        net_device = hv_get_drvdata(dev);
        net = net_device->ndev;

        if (net == NULL) {
                dev_err(&dev->device, "No net device to remove\n");
                return 0;
        }

        net_device->start_remove = true;

        ndev_ctx = netdev_priv(net);
        cancel_delayed_work_sync(&ndev_ctx->dwork);
        cancel_work_sync(&ndev_ctx->work);

        /* Stop outbound asap */
        netif_tx_disable(net);

        unregister_netdev(net);

        /*
         * Call to the vsc driver to let it know that the device is being
         * removed
         */
        rndis_filter_device_remove(dev);

        netvsc_free_netdev(net);
        return 0;
}

static const struct hv_vmbus_device_id id_table[] = {
        /* Network guid */
        { HV_NIC_GUID, },
        { },
};

MODULE_DEVICE_TABLE(vmbus, id_table);

/* The one and only one */
static struct  hv_driver netvsc_drv = {
        .name = KBUILD_MODNAME,
        .id_table = id_table,
        .probe = netvsc_probe,
        .remove = netvsc_remove,
};

static void __exit netvsc_drv_exit(void)
{
        vmbus_driver_unregister(&netvsc_drv);
}

static int __init netvsc_drv_init(void)
{
        if (ring_size < RING_SIZE_MIN) {
                ring_size = RING_SIZE_MIN;
                pr_info("Increased ring_size to %d (min allowed)\n",
                        ring_size);
        }
        return vmbus_driver_register(&netvsc_drv);
}

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Microsoft Hyper-V network driver");

module_init(netvsc_drv_init);
module_exit(netvsc_drv_exit);