// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * 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/ethtool.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/pci.h>
#include <linux/skbuff.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <linux/rtnetlink.h>
#include <linux/netpoll.h>
#include <linux/bpf.h>

#include <net/arp.h>
#include <net/route.h>
#include <net/sock.h>
#include <net/pkt_sched.h>
#include <net/checksum.h>
#include <net/ip6_checksum.h>

#include "hyperv_net.h"

#define RING_SIZE_MIN   64

#define LINKCHANGE_INT (2 * HZ)
#define VF_TAKEOVER_INT (HZ / 10)

static unsigned int ring_size __ro_after_init = 128;
module_param(ring_size, uint, 0444);
MODULE_PARM_DESC(ring_size, "Ring buffer size (# of pages)");
unsigned int netvsc_ring_bytes __ro_after_init;

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, 0444);
MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");

static LIST_HEAD(netvsc_dev_list);

static void netvsc_change_rx_flags(struct net_device *net, int change)
{
        struct net_device_context *ndev_ctx = netdev_priv(net);
        struct net_device *vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
        int inc;

        if (!vf_netdev)
                return;

        if (change & IFF_PROMISC) {
                inc = (net->flags & IFF_PROMISC) ? 1 : -1;
                dev_set_promiscuity(vf_netdev, inc);
        }

        if (change & IFF_ALLMULTI) {
                inc = (net->flags & IFF_ALLMULTI) ? 1 : -1;
                dev_set_allmulti(vf_netdev, inc);
        }
}

static void netvsc_set_rx_mode(struct net_device *net)
{
        struct net_device_context *ndev_ctx = netdev_priv(net);
        struct net_device *vf_netdev;
        struct netvsc_device *nvdev;

        rcu_read_lock();
        vf_netdev = rcu_dereference(ndev_ctx->vf_netdev);
        if (vf_netdev) {
                dev_uc_sync(vf_netdev, net);
                dev_mc_sync(vf_netdev, net);
        }

        nvdev = rcu_dereference(ndev_ctx->nvdev);
        if (nvdev)
                rndis_filter_update(nvdev);
        rcu_read_unlock();
}

static void netvsc_tx_enable(struct netvsc_device *nvscdev,
                             struct net_device *ndev)
{
        nvscdev->tx_disable = false;
        virt_wmb(); /* ensure queue wake up mechanism is on */

        netif_tx_wake_all_queues(ndev);
}

static int netvsc_open(struct net_device *net)
{
        struct net_device_context *ndev_ctx = netdev_priv(net);
        struct net_device *vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
        struct netvsc_device *nvdev = rtnl_dereference(ndev_ctx->nvdev);
        struct rndis_device *rdev;
        int ret = 0;

        netif_carrier_off(net);

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

        rdev = nvdev->extension;
        if (!rdev->link_state) {
                netif_carrier_on(net);
                netvsc_tx_enable(nvdev, net);
        }

        if (vf_netdev) {
                /* Setting synthetic device up transparently sets
                 * slave as up. If open fails, then slave will be
                 * still be offline (and not used).
                 */
                ret = dev_open(vf_netdev, NULL);
                if (ret)
                        netdev_warn(net,
                                    "unable to open slave: %s: %d\n",
                                    vf_netdev->name, ret);
        }
        return 0;
}

static int netvsc_wait_until_empty(struct netvsc_device *nvdev)
{
        unsigned int retry = 0;
        int i;

        /* Ensure pending bytes in ring are read */
        for (;;) {
                u32 aread = 0;

                for (i = 0; i < nvdev->num_chn; i++) {
                        struct vmbus_channel *chn
                                = nvdev->chan_table[i].channel;

                        if (!chn)
                                continue;

                        /* make sure receive not running now */
                        napi_synchronize(&nvdev->chan_table[i].napi);

                        aread = hv_get_bytes_to_read(&chn->inbound);
                        if (aread)
                                break;

                        aread = hv_get_bytes_to_read(&chn->outbound);
                        if (aread)
                                break;
                }

                if (aread == 0)
                        return 0;

                if (++retry > RETRY_MAX)
                        return -ETIMEDOUT;

                usleep_range(RETRY_US_LO, RETRY_US_HI);
        }
}

static void netvsc_tx_disable(struct netvsc_device *nvscdev,
                              struct net_device *ndev)
{
        if (nvscdev) {
                nvscdev->tx_disable = true;
                virt_wmb(); /* ensure txq will not wake up after stop */
        }

        netif_tx_disable(ndev);
}

static int netvsc_close(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct net_device *vf_netdev
                = rtnl_dereference(net_device_ctx->vf_netdev);
        struct netvsc_device *nvdev = rtnl_dereference(net_device_ctx->nvdev);
        int ret;

        netvsc_tx_disable(nvdev, net);

        /* No need to close rndis filter if it is removed already */
        if (!nvdev)
                return 0;

        ret = rndis_filter_close(nvdev);
        if (ret != 0) {
                netdev_err(net, "unable to close device (ret %d).\n", ret);
                return ret;
        }

        ret = netvsc_wait_until_empty(nvdev);
        if (ret)
                netdev_err(net, "Ring buffer not empty after closing rndis\n");

        if (vf_netdev)
                dev_close(vf_netdev);

        return ret;
}

static inline void *init_ppi_data(struct rndis_message *msg,
                                  u32 ppi_size, u32 pkt_type)
{
        struct rndis_packet *rndis_pkt = &msg->msg.pkt;
        struct rndis_per_packet_info *ppi;

        rndis_pkt->data_offset += ppi_size;
        ppi = (void *)rndis_pkt + rndis_pkt->per_pkt_info_offset
                + rndis_pkt->per_pkt_info_len;

        ppi->size = ppi_size;
        ppi->type = pkt_type;
        ppi->internal = 0;
        ppi->ppi_offset = sizeof(struct rndis_per_packet_info);

        rndis_pkt->per_pkt_info_len += ppi_size;

        return ppi + 1;
}

/* Azure hosts don't support non-TCP port numbers in hashing for fragmented
 * packets. We can use ethtool to change UDP hash level when necessary.
 */
static inline u32 netvsc_get_hash(
        struct sk_buff *skb,
        const struct net_device_context *ndc)
{
        struct flow_keys flow;
        u32 hash, pkt_proto = 0;
        static u32 hashrnd __read_mostly;

        net_get_random_once(&hashrnd, sizeof(hashrnd));

        if (!skb_flow_dissect_flow_keys(skb, &flow, 0))
                return 0;

        switch (flow.basic.ip_proto) {
        case IPPROTO_TCP:
                if (flow.basic.n_proto == htons(ETH_P_IP))
                        pkt_proto = HV_TCP4_L4HASH;
                else if (flow.basic.n_proto == htons(ETH_P_IPV6))
                        pkt_proto = HV_TCP6_L4HASH;

                break;

        case IPPROTO_UDP:
                if (flow.basic.n_proto == htons(ETH_P_IP))
                        pkt_proto = HV_UDP4_L4HASH;
                else if (flow.basic.n_proto == htons(ETH_P_IPV6))
                        pkt_proto = HV_UDP6_L4HASH;

                break;
        }

        if (pkt_proto & ndc->l4_hash) {
                return skb_get_hash(skb);
        } else {
                if (flow.basic.n_proto == htons(ETH_P_IP))
                        hash = jhash2((u32 *)&flow.addrs.v4addrs, 2, hashrnd);
                else if (flow.basic.n_proto == htons(ETH_P_IPV6))
                        hash = jhash2((u32 *)&flow.addrs.v6addrs, 8, hashrnd);
                else
                        return 0;

                __skb_set_sw_hash(skb, hash, false);
        }

        return hash;
}

static inline int netvsc_get_tx_queue(struct net_device *ndev,
                                      struct sk_buff *skb, int old_idx)
{
        const struct net_device_context *ndc = netdev_priv(ndev);
        struct sock *sk = skb->sk;
        int q_idx;

        q_idx = ndc->tx_table[netvsc_get_hash(skb, ndc) &
                              (VRSS_SEND_TAB_SIZE - 1)];

        /* If queue index changed record the new value */
        if (q_idx != old_idx &&
            sk && sk_fullsock(sk) && rcu_access_pointer(sk->sk_dst_cache))
                sk_tx_queue_set(sk, q_idx);

        return q_idx;
}

/*
 * Select queue for transmit.
 *
 * If a valid queue has already been assigned, then use that.
 * Otherwise compute tx queue based on hash and the send table.
 *
 * This is basically similar to default (netdev_pick_tx) with the added step
 * of using the host send_table when no other queue has been assigned.
 *
 * TODO support XPS - but get_xps_queue not exported
 */
static u16 netvsc_pick_tx(struct net_device *ndev, struct sk_buff *skb)
{
        int q_idx = sk_tx_queue_get(skb->sk);

        if (q_idx < 0 || skb->ooo_okay || q_idx >= ndev->real_num_tx_queues) {
                /* If forwarding a packet, we use the recorded queue when
                 * available for better cache locality.
                 */
                if (skb_rx_queue_recorded(skb))
                        q_idx = skb_get_rx_queue(skb);
                else
                        q_idx = netvsc_get_tx_queue(ndev, skb, q_idx);
        }

        return q_idx;
}

static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb,
                               struct net_device *sb_dev)
{
        struct net_device_context *ndc = netdev_priv(ndev);
        struct net_device *vf_netdev;
        u16 txq;

        rcu_read_lock();
        vf_netdev = rcu_dereference(ndc->vf_netdev);
        if (vf_netdev) {
                const struct net_device_ops *vf_ops = vf_netdev->netdev_ops;

                if (vf_ops->ndo_select_queue)
                        txq = vf_ops->ndo_select_queue(vf_netdev, skb, sb_dev);
                else
                        txq = netdev_pick_tx(vf_netdev, skb, NULL);

                /* Record the queue selected by VF so that it can be
                 * used for common case where VF has more queues than
                 * the synthetic device.
                 */
                qdisc_skb_cb(skb)->slave_dev_queue_mapping = txq;
        } else {
                txq = netvsc_pick_tx(ndev, skb);
        }
        rcu_read_unlock();

        while (txq >= ndev->real_num_tx_queues)
                txq -= ndev->real_num_tx_queues;

        return txq;
}

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

        hvpfn += offset >> HV_HYP_PAGE_SHIFT;
        offset = offset & ~HV_HYP_PAGE_MASK;

        while (len > 0) {
                unsigned long bytes;

                bytes = HV_HYP_PAGE_SIZE - offset;
                if (bytes > len)
                        bytes = len;
                pb[j].pfn = hvpfn;
                pb[j].offset = offset;
                pb[j].len = bytes;

                offset += bytes;
                len -= bytes;

                if (offset == HV_HYP_PAGE_SIZE && len) {
                        hvpfn++;
                        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 *pb)
{
        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
         */
        slots_used += fill_pg_buf(virt_to_hvpfn(hdr),
                                  offset_in_hvpage(hdr),
                                  len,
                                  &pb[slots_used]);

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

        slots_used += fill_pg_buf(virt_to_hvpfn(data),
                                  offset_in_hvpage(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(page_to_hvpfn(skb_frag_page(frag)),
                                          skb_frag_off(frag),
                                          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 = skb_frag_off(frag);

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

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

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

static u32 net_checksum_info(struct sk_buff *skb)
{
        if (skb->protocol == htons(ETH_P_IP)) {
                struct iphdr *ip = ip_hdr(skb);

                if (ip->protocol == IPPROTO_TCP)
                        return TRANSPORT_INFO_IPV4_TCP;
                else if (ip->protocol == IPPROTO_UDP)
                        return TRANSPORT_INFO_IPV4_UDP;
        } else {
                struct ipv6hdr *ip6 = ipv6_hdr(skb);

                if (ip6->nexthdr == IPPROTO_TCP)
                        return TRANSPORT_INFO_IPV6_TCP;
                else if (ip6->nexthdr == IPPROTO_UDP)
                        return TRANSPORT_INFO_IPV6_UDP;
        }

        return TRANSPORT_INFO_NOT_IP;
}

/* Send skb on the slave VF device. */
static int netvsc_vf_xmit(struct net_device *net, struct net_device *vf_netdev,
                          struct sk_buff *skb)
{
        struct net_device_context *ndev_ctx = netdev_priv(net);
        unsigned int len = skb->len;
        int rc;

        skb->dev = vf_netdev;
        skb_record_rx_queue(skb, qdisc_skb_cb(skb)->slave_dev_queue_mapping);

        rc = dev_queue_xmit(skb);
        if (likely(rc == NET_XMIT_SUCCESS || rc == NET_XMIT_CN)) {
                struct netvsc_vf_pcpu_stats *pcpu_stats
                        = this_cpu_ptr(ndev_ctx->vf_stats);

                u64_stats_update_begin(&pcpu_stats->syncp);
                pcpu_stats->tx_packets++;
                pcpu_stats->tx_bytes += len;
                u64_stats_update_end(&pcpu_stats->syncp);
        } else {
                this_cpu_inc(ndev_ctx->vf_stats->tx_dropped);
        }

        return rc;
}

static int netvsc_xmit(struct sk_buff *skb, struct net_device *net, bool xdp_tx)
{
        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 net_device *vf_netdev;
        u32 rndis_msg_size;
        u32 hash;
        struct hv_page_buffer pb[MAX_PAGE_BUFFER_COUNT];

        /* If VF is present and up then redirect packets to it.
         * Skip the VF if it is marked down or has no carrier.
         * If netpoll is in uses, then VF can not be used either.
         */
        vf_netdev = rcu_dereference_bh(net_device_ctx->vf_netdev);
        if (vf_netdev && netif_running(vf_netdev) &&
            netif_carrier_ok(vf_netdev) && !netpoll_tx_running(net) &&
            net_device_ctx->data_path_is_vf)
                return netvsc_vf_xmit(net, vf_netdev, skb);

        /* 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.
         */

        num_data_pgs = netvsc_get_slots(skb) + 2;

        if (unlikely(num_data_pgs > MAX_PAGE_BUFFER_COUNT)) {
                ++net_device_ctx->eth_stats.tx_scattered;

                if (skb_linearize(skb))
                        goto no_memory;

                num_data_pgs = netvsc_get_slots(skb) + 2;
                if (num_data_pgs > MAX_PAGE_BUFFER_COUNT) {
                        ++net_device_ctx->eth_stats.tx_too_big;
                        goto drop;
                }
        }

        /*
         * 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)
                goto no_memory;

        /* Use the skb control buffer for building up the packet */
        BUILD_BUG_ON(sizeof(struct hv_netvsc_packet) >
                        sizeof_field(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;
        packet->total_bytes = skb->len;
        packet->total_packets = 1;

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

        /* Add the rndis header */
        rndis_msg->ndis_msg_type = RNDIS_MSG_PACKET;
        rndis_msg->msg_len = packet->total_data_buflen;

        rndis_msg->msg.pkt = (struct rndis_packet) {
                .data_offset = sizeof(struct rndis_packet),
                .data_len = packet->total_data_buflen,
                .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) {
                u32 *hash_info;

                rndis_msg_size += NDIS_HASH_PPI_SIZE;
                hash_info = init_ppi_data(rndis_msg, NDIS_HASH_PPI_SIZE,
                                          NBL_HASH_VALUE);
                *hash_info = hash;
        }

        /* When using AF_PACKET we need to drop VLAN header from
         * the frame and update the SKB to allow the HOST OS
         * to transmit the 802.1Q packet
         */
        if (skb->protocol == htons(ETH_P_8021Q)) {
                u16 vlan_tci;

                skb_reset_mac_header(skb);
                if (eth_type_vlan(eth_hdr(skb)->h_proto)) {
                        if (unlikely(__skb_vlan_pop(skb, &vlan_tci) != 0)) {
                                ++net_device_ctx->eth_stats.vlan_error;
                                goto drop;
                        }

                        __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vlan_tci);
                        /* Update the NDIS header pkt lengths */
                        packet->total_data_buflen -= VLAN_HLEN;
                        packet->total_bytes -= VLAN_HLEN;
                        rndis_msg->msg_len = packet->total_data_buflen;
                        rndis_msg->msg.pkt.data_len = packet->total_data_buflen;
                }
        }

        if (skb_vlan_tag_present(skb)) {
                struct ndis_pkt_8021q_info *vlan;

                rndis_msg_size += NDIS_VLAN_PPI_SIZE;
                vlan = init_ppi_data(rndis_msg, NDIS_VLAN_PPI_SIZE,
                                     IEEE_8021Q_INFO);

                vlan->value = 0;
                vlan->vlanid = skb_vlan_tag_get_id(skb);
                vlan->cfi = skb_vlan_tag_get_cfi(skb);
                vlan->pri = skb_vlan_tag_get_prio(skb);
        }

        if (skb_is_gso(skb)) {
                struct ndis_tcp_lso_info *lso_info;

                rndis_msg_size += NDIS_LSO_PPI_SIZE;
                lso_info = init_ppi_data(rndis_msg, NDIS_LSO_PPI_SIZE,
                                         TCP_LARGESEND_PKTINFO);

                lso_info->value = 0;
                lso_info->lso_v2_transmit.type = NDIS_TCP_LARGE_SEND_OFFLOAD_V2_TYPE;
                if (skb->protocol == htons(ETH_P_IP)) {
                        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;
                        tcp_v6_gso_csum_prep(skb);
                }
                lso_info->lso_v2_transmit.tcp_header_offset = skb_transport_offset(skb);
                lso_info->lso_v2_transmit.mss = skb_shinfo(skb)->gso_size;
        } else if (skb->ip_summed == CHECKSUM_PARTIAL) {
                if (net_checksum_info(skb) & net_device_ctx->tx_checksum_mask) {
                        struct ndis_tcp_ip_checksum_info *csum_info;

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

                        csum_info->value = 0;
                        csum_info->transmit.tcp_header_offset = skb_transport_offset(skb);

                        if (skb->protocol == htons(ETH_P_IP)) {
                                csum_info->transmit.is_ipv4 = 1;

                                if (ip_hdr(skb)->protocol == IPPROTO_TCP)
                                        csum_info->transmit.tcp_checksum = 1;
                                else
                                        csum_info->transmit.udp_checksum = 1;
                        } else {
                                csum_info->transmit.is_ipv6 = 1;

                                if (ipv6_hdr(skb)->nexthdr == IPPROTO_TCP)
                                        csum_info->transmit.tcp_checksum = 1;
                                else
                                        csum_info->transmit.udp_checksum = 1;
                        }
                } else {
                        /* Can't do offload of this type of checksum */
                        if (skb_checksum_help(skb))
                                goto drop;
                }
        }

        /* 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, packet, rndis_msg, pb, skb, xdp_tx);
        if (likely(ret == 0))
                return NETDEV_TX_OK;

        if (ret == -EAGAIN) {
                ++net_device_ctx->eth_stats.tx_busy;
                return NETDEV_TX_BUSY;
        }

        if (ret == -ENOSPC)
                ++net_device_ctx->eth_stats.tx_no_space;

drop:
        dev_kfree_skb_any(skb);
        net->stats.tx_dropped++;

        return NETDEV_TX_OK;

no_memory:
        ++net_device_ctx->eth_stats.tx_no_memory;
        goto drop;
}

static netdev_tx_t netvsc_start_xmit(struct sk_buff *skb,
                                     struct net_device *ndev)
{
        return netvsc_xmit(skb, ndev, false);
}

/*
 * netvsc_linkstatus_callback - Link up/down notification
 */
void netvsc_linkstatus_callback(struct net_device *net,
                                struct rndis_message *resp,
                                void *data, u32 data_buflen)
{
        struct rndis_indicate_status *indicate = &resp->msg.indicate_status;
        struct net_device_context *ndev_ctx = netdev_priv(net);
        struct netvsc_reconfig *event;
        unsigned long flags;

        /* Ensure the packet is big enough to access its fields */
        if (resp->msg_len - RNDIS_HEADER_SIZE < sizeof(struct rndis_indicate_status)) {
                netdev_err(net, "invalid rndis_indicate_status packet, len: %u\n",
                           resp->msg_len);
                return;
        }

        /* Copy the RNDIS indicate status into nvchan->recv_buf */
        memcpy(indicate, data + RNDIS_HEADER_SIZE, sizeof(*indicate));

        /* Update the physical link speed when changing to another vSwitch */
        if (indicate->status == RNDIS_STATUS_LINK_SPEED_CHANGE) {
                u32 speed;

                /* Validate status_buf_offset and status_buflen.
                 *
                 * Certain (pre-Fe) implementations of Hyper-V's vSwitch didn't account
                 * for the status buffer field in resp->msg_len; perform the validation
                 * using data_buflen (>= resp->msg_len).
                 */
                if (indicate->status_buflen < sizeof(speed) ||
                    indicate->status_buf_offset < sizeof(*indicate) ||
                    data_buflen - RNDIS_HEADER_SIZE < indicate->status_buf_offset ||
                    data_buflen - RNDIS_HEADER_SIZE - indicate->status_buf_offset
                                < indicate->status_buflen) {
                        netdev_err(net, "invalid rndis_indicate_status packet\n");
                        return;
                }

                speed = *(u32 *)(data + RNDIS_HEADER_SIZE + indicate->status_buf_offset) / 10000;
                ndev_ctx->speed = speed;
                return;
        }

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

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

        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);
}

static void netvsc_xdp_xmit(struct sk_buff *skb, struct net_device *ndev)
{
        int rc;

        skb->queue_mapping = skb_get_rx_queue(skb);
        __skb_push(skb, ETH_HLEN);

        rc = netvsc_xmit(skb, ndev, true);

        if (dev_xmit_complete(rc))
                return;

        dev_kfree_skb_any(skb);
        ndev->stats.tx_dropped++;
}

static void netvsc_comp_ipcsum(struct sk_buff *skb)
{
        struct iphdr *iph = (struct iphdr *)skb->data;

        iph->check = 0;
        iph->check = ip_fast_csum(iph, iph->ihl);
}

static struct sk_buff *netvsc_alloc_recv_skb(struct net_device *net,
                                             struct netvsc_channel *nvchan,
                                             struct xdp_buff *xdp)
{
        struct napi_struct *napi = &nvchan->napi;
        const struct ndis_pkt_8021q_info *vlan = &nvchan->rsc.vlan;
        const struct ndis_tcp_ip_checksum_info *csum_info =
                                                &nvchan->rsc.csum_info;
        const u32 *hash_info = &nvchan->rsc.hash_info;
        u8 ppi_flags = nvchan->rsc.ppi_flags;
        struct sk_buff *skb;
        void *xbuf = xdp->data_hard_start;
        int i;

        if (xbuf) {
                unsigned int hdroom = xdp->data - xdp->data_hard_start;
                unsigned int xlen = xdp->data_end - xdp->data;
                unsigned int frag_size = xdp->frame_sz;

                skb = build_skb(xbuf, frag_size);

                if (!skb) {
                        __free_page(virt_to_page(xbuf));
                        return NULL;
                }

                skb_reserve(skb, hdroom);
                skb_put(skb, xlen);
                skb->dev = napi->dev;
        } else {
                skb = napi_alloc_skb(napi, nvchan->rsc.pktlen);

                if (!skb)
                        return NULL;

                /* Copy to skb. This copy is needed here since the memory
                 * pointed by hv_netvsc_packet cannot be deallocated.
                 */
                for (i = 0; i < nvchan->rsc.cnt; i++)
                        skb_put_data(skb, nvchan->rsc.data[i],
                                     nvchan->rsc.len[i]);
        }

        skb->protocol = eth_type_trans(skb, net);

        /* skb is already created with CHECKSUM_NONE */
        skb_checksum_none_assert(skb);

        /* Incoming packets may have IP header checksum verified by the host.
         * They may not have IP header checksum computed after coalescing.
         * We compute it here if the flags are set, because on Linux, the IP
         * checksum is always checked.
         */
        if ((ppi_flags & NVSC_RSC_CSUM_INFO) && csum_info->receive.ip_checksum_value_invalid &&
            csum_info->receive.ip_checksum_succeeded &&
            skb->protocol == htons(ETH_P_IP)) {
                /* Check that there is enough space to hold the IP header. */
                if (skb_headlen(skb) < sizeof(struct iphdr)) {
                        kfree_skb(skb);
                        return NULL;
                }
                netvsc_comp_ipcsum(skb);
        }

        /* Do L4 checksum offload if enabled and present. */
        if ((ppi_flags & NVSC_RSC_CSUM_INFO) && (net->features & NETIF_F_RXCSUM)) {
                if (csum_info->receive.tcp_checksum_succeeded ||
                    csum_info->receive.udp_checksum_succeeded)
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
        }

        if ((ppi_flags & NVSC_RSC_HASH_INFO) && (net->features & NETIF_F_RXHASH))
                skb_set_hash(skb, *hash_info, PKT_HASH_TYPE_L4);

        if (ppi_flags & NVSC_RSC_VLAN) {
                u16 vlan_tci = vlan->vlanid | (vlan->pri << VLAN_PRIO_SHIFT) |
                        (vlan->cfi ? VLAN_CFI_MASK : 0);

                __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
                                       vlan_tci);
        }

        return skb;
}

/*
 * netvsc_recv_callback -  Callback when we receive a packet from the
 * "wire" on the specified device.
 */
int netvsc_recv_callback(struct net_device *net,
                         struct netvsc_device *net_device,
                         struct netvsc_channel *nvchan)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct vmbus_channel *channel = nvchan->channel;
        u16 q_idx = channel->offermsg.offer.sub_channel_index;
        struct sk_buff *skb;
        struct netvsc_stats *rx_stats = &nvchan->rx_stats;
        struct xdp_buff xdp;
        u32 act;

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

        act = netvsc_run_xdp(net, nvchan, &xdp);

        if (act != XDP_PASS && act != XDP_TX) {
                u64_stats_update_begin(&rx_stats->syncp);
                rx_stats->xdp_drop++;
                u64_stats_update_end(&rx_stats->syncp);

                return NVSP_STAT_SUCCESS; /* consumed by XDP */
        }

        /* Allocate a skb - TODO direct I/O to pages? */
        skb = netvsc_alloc_recv_skb(net, nvchan, &xdp);

        if (unlikely(!skb)) {
                ++net_device_ctx->eth_stats.rx_no_memory;
                return NVSP_STAT_FAIL;
        }

        skb_record_rx_queue(skb, q_idx);

        /*
         * Even if injecting the packet, record the statistics
         * on the synthetic device because modifying the VF device
         * statistics will not work correctly.
         */
        u64_stats_update_begin(&rx_stats->syncp);
        rx_stats->packets++;
        rx_stats->bytes += nvchan->rsc.pktlen;

        if (skb->pkt_type == PACKET_BROADCAST)
                ++rx_stats->broadcast;
        else if (skb->pkt_type == PACKET_MULTICAST)
                ++rx_stats->multicast;
        u64_stats_update_end(&rx_stats->syncp);

        if (act == XDP_TX) {
                netvsc_xdp_xmit(skb, net);
                return NVSP_STAT_SUCCESS;
        }

        napi_gro_receive(&nvchan->napi, skb);
        return NVSP_STAT_SUCCESS;
}

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 netvsc_device *nvdev = rtnl_dereference(net_device_ctx->nvdev);

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

/* Alloc struct netvsc_device_info, and initialize it from either existing
 * struct netvsc_device, or from default values.
 */
static

struct netvsc_device_info *netvsc_devinfo_get(struct netvsc_device *nvdev)
{
        struct netvsc_device_info *dev_info;
        struct bpf_prog *prog;

        dev_info = kzalloc(sizeof(*dev_info), GFP_ATOMIC);

        if (!dev_info)
                return NULL;

        if (nvdev) {
                ASSERT_RTNL();

                dev_info->num_chn = nvdev->num_chn;
                dev_info->send_sections = nvdev->send_section_cnt;
                dev_info->send_section_size = nvdev->send_section_size;
                dev_info->recv_sections = nvdev->recv_section_cnt;
                dev_info->recv_section_size = nvdev->recv_section_size;

                memcpy(dev_info->rss_key, nvdev->extension->rss_key,
                       NETVSC_HASH_KEYLEN);

                prog = netvsc_xdp_get(nvdev);
                if (prog) {
                        bpf_prog_inc(prog);
                        dev_info->bprog = prog;
                }
        } else {
                dev_info->num_chn = VRSS_CHANNEL_DEFAULT;
                dev_info->send_sections = NETVSC_DEFAULT_TX;
                dev_info->send_section_size = NETVSC_SEND_SECTION_SIZE;
                dev_info->recv_sections = NETVSC_DEFAULT_RX;
                dev_info->recv_section_size = NETVSC_RECV_SECTION_SIZE;
        }

        return dev_info;
}

/* Free struct netvsc_device_info */
static void netvsc_devinfo_put(struct netvsc_device_info *dev_info)
{
        if (dev_info->bprog) {
                ASSERT_RTNL();
                bpf_prog_put(dev_info->bprog);
        }

        kfree(dev_info);
}

static int netvsc_detach(struct net_device *ndev,
                         struct netvsc_device *nvdev)
{
        struct net_device_context *ndev_ctx = netdev_priv(ndev);
        struct hv_device *hdev = ndev_ctx->device_ctx;
        int ret;

        /* Don't try continuing to try and setup sub channels */
        if (cancel_work_sync(&nvdev->subchan_work))
                nvdev->num_chn = 1;

        netvsc_xdp_set(ndev, NULL, NULL, nvdev);

        /* If device was up (receiving) then shutdown */
        if (netif_running(ndev)) {
                netvsc_tx_disable(nvdev, ndev);

                ret = rndis_filter_close(nvdev);
                if (ret) {
                        netdev_err(ndev,
                                   "unable to close device (ret %d).\n", ret);
                        return ret;
                }

                ret = netvsc_wait_until_empty(nvdev);
                if (ret) {
                        netdev_err(ndev,
                                   "Ring buffer not empty after closing rndis\n");
                        return ret;
                }
        }

        netif_device_detach(ndev);

        rndis_filter_device_remove(hdev, nvdev);

        return 0;
}

static int netvsc_attach(struct net_device *ndev,
                         struct netvsc_device_info *dev_info)
{
        struct net_device_context *ndev_ctx = netdev_priv(ndev);
        struct hv_device *hdev = ndev_ctx->device_ctx;
        struct netvsc_device *nvdev;
        struct rndis_device *rdev;
        struct bpf_prog *prog;
        int ret = 0;

        nvdev = rndis_filter_device_add(hdev, dev_info);
        if (IS_ERR(nvdev))
                return PTR_ERR(nvdev);

        if (nvdev->num_chn > 1) {
                ret = rndis_set_subchannel(ndev, nvdev, dev_info);

                /* if unavailable, just proceed with one queue */
                if (ret) {
                        nvdev->max_chn = 1;
                        nvdev->num_chn = 1;
                }
        }

        prog = dev_info->bprog;
        if (prog) {
                bpf_prog_inc(prog);
                ret = netvsc_xdp_set(ndev, prog, NULL, nvdev);
                if (ret) {
                        bpf_prog_put(prog);
                        goto err1;
                }
        }

        /* In any case device is now ready */
        nvdev->tx_disable = false;
        netif_device_attach(ndev);

        /* Note: enable and attach happen when sub-channels setup */
        netif_carrier_off(ndev);

        if (netif_running(ndev)) {
                ret = rndis_filter_open(nvdev);
                if (ret)
                        goto err2;

                rdev = nvdev->extension;
                if (!rdev->link_state)
                        netif_carrier_on(ndev);
        }

        return 0;

err2:
        netif_device_detach(ndev);

err1:
        rndis_filter_device_remove(hdev, nvdev);

        return ret;
}

static int netvsc_set_channels(struct net_device *net,
                               struct ethtool_channels *channels)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct netvsc_device *nvdev = rtnl_dereference(net_device_ctx->nvdev);
        unsigned int orig, count = channels->combined_count;
        struct netvsc_device_info *device_info;
        int ret;

        /* We do not support separate count for rx, tx, or other */
        if (count == 0 ||
            channels->rx_count || channels->tx_count || channels->other_count)
                return -EINVAL;

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

        if (nvdev->nvsp_version < NVSP_PROTOCOL_VERSION_5)
                return -EINVAL;

        if (count > nvdev->max_chn)
                return -EINVAL;

        orig = nvdev->num_chn;

        device_info = netvsc_devinfo_get(nvdev);

        if (!device_info)
                return -ENOMEM;

        device_info->num_chn = count;

        ret = netvsc_detach(net, nvdev);
        if (ret)
                goto out;

        ret = netvsc_attach(net, device_info);
        if (ret) {
                device_info->num_chn = orig;
                if (netvsc_attach(net, device_info))
                        netdev_err(net, "restoring channel setting failed\n");
        }

out:
        netvsc_devinfo_put(device_info);
        return ret;
}

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

        ndc->l4_hash = HV_DEFAULT_L4HASH;

        ndc->speed = SPEED_UNKNOWN;
        ndc->duplex = DUPLEX_FULL;

        dev->features = NETIF_F_LRO;
}

static int netvsc_get_link_ksettings(struct net_device *dev,
                                     struct ethtool_link_ksettings *cmd)
{
        struct net_device_context *ndc = netdev_priv(dev);
        struct net_device *vf_netdev;

        vf_netdev = rtnl_dereference(ndc->vf_netdev);

        if (vf_netdev)
                return __ethtool_get_link_ksettings(vf_netdev, cmd);

        cmd->base.speed = ndc->speed;
        cmd->base.duplex = ndc->duplex;
        cmd->base.port = PORT_OTHER;

        return 0;
}

static int netvsc_set_link_ksettings(struct net_device *dev,
                                     const struct ethtool_link_ksettings *cmd)
{
        struct net_device_context *ndc = netdev_priv(dev);
        struct net_device *vf_netdev = rtnl_dereference(ndc->vf_netdev);

        if (vf_netdev) {
                if (!vf_netdev->ethtool_ops->set_link_ksettings)
                        return -EOPNOTSUPP;

                return vf_netdev->ethtool_ops->set_link_ksettings(vf_netdev,
                                                                  cmd);
        }

        return ethtool_virtdev_set_link_ksettings(dev, cmd,
                                                  &ndc->speed, &ndc->duplex);
}

static int netvsc_change_mtu(struct net_device *ndev, int mtu)
{
        struct net_device_context *ndevctx = netdev_priv(ndev);
        struct net_device *vf_netdev = rtnl_dereference(ndevctx->vf_netdev);
        struct netvsc_device *nvdev = rtnl_dereference(ndevctx->nvdev);
        int orig_mtu = ndev->mtu;
        struct netvsc_device_info *device_info;
        int ret = 0;

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

        device_info = netvsc_devinfo_get(nvdev);

        if (!device_info)
                return -ENOMEM;

        /* Change MTU of underlying VF netdev first. */
        if (vf_netdev) {
                ret = dev_set_mtu(vf_netdev, mtu);
                if (ret)
                        goto out;
        }

        ret = netvsc_detach(ndev, nvdev);
        if (ret)
                goto rollback_vf;

        ndev->mtu = mtu;

        ret = netvsc_attach(ndev, device_info);
        if (!ret)
                goto out;

        /* Attempt rollback to original MTU */
        ndev->mtu = orig_mtu;

        if (netvsc_attach(ndev, device_info))
                netdev_err(ndev, "restoring mtu failed\n");
rollback_vf:
        if (vf_netdev)
                dev_set_mtu(vf_netdev, orig_mtu);

out:
        netvsc_devinfo_put(device_info);
        return ret;
}

static void netvsc_get_vf_stats(struct net_device *net,
                                struct netvsc_vf_pcpu_stats *tot)
{
        struct net_device_context *ndev_ctx = netdev_priv(net);
        int i;

        memset(tot, 0, sizeof(*tot));

        for_each_possible_cpu(i) {
                const struct netvsc_vf_pcpu_stats *stats
                        = per_cpu_ptr(ndev_ctx->vf_stats, i);
                u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
                unsigned int start;

                do {
                        start = u64_stats_fetch_begin_irq(&stats->syncp);
                        rx_packets = stats->rx_packets;
                        tx_packets = stats->tx_packets;
                        rx_bytes = stats->rx_bytes;
                        tx_bytes = stats->tx_bytes;
                } while (u64_stats_fetch_retry_irq(&stats->syncp, start));

                tot->rx_packets += rx_packets;
                tot->tx_packets += tx_packets;
                tot->rx_bytes   += rx_bytes;
                tot->tx_bytes   += tx_bytes;
                tot->tx_dropped += stats->tx_dropped;
        }
}

static void netvsc_get_pcpu_stats(struct net_device *net,
                                  struct netvsc_ethtool_pcpu_stats *pcpu_tot)
{
        struct net_device_context *ndev_ctx = netdev_priv(net);
        struct netvsc_device *nvdev = rcu_dereference_rtnl(ndev_ctx->nvdev);
        int i;

        /* fetch percpu stats of vf */
        for_each_possible_cpu(i) {
                const struct netvsc_vf_pcpu_stats *stats =
                        per_cpu_ptr(ndev_ctx->vf_stats, i);
                struct netvsc_ethtool_pcpu_stats *this_tot = &pcpu_tot[i];
                unsigned int start;

                do {
                        start = u64_stats_fetch_begin_irq(&stats->syncp);
                        this_tot->vf_rx_packets = stats->rx_packets;
                        this_tot->vf_tx_packets = stats->tx_packets;
                        this_tot->vf_rx_bytes = stats->rx_bytes;
                        this_tot->vf_tx_bytes = stats->tx_bytes;
                } while (u64_stats_fetch_retry_irq(&stats->syncp, start));
                this_tot->rx_packets = this_tot->vf_rx_packets;
                this_tot->tx_packets = this_tot->vf_tx_packets;
                this_tot->rx_bytes   = this_tot->vf_rx_bytes;
                this_tot->tx_bytes   = this_tot->vf_tx_bytes;
        }

        /* fetch percpu stats of netvsc */
        for (i = 0; i < nvdev->num_chn; i++) {
                const struct netvsc_channel *nvchan = &nvdev->chan_table[i];
                const struct netvsc_stats *stats;
                struct netvsc_ethtool_pcpu_stats *this_tot =
                        &pcpu_tot[nvchan->channel->target_cpu];
                u64 packets, bytes;
                unsigned int start;

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

                this_tot->tx_bytes      += bytes;
                this_tot->tx_packets    += packets;

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

                this_tot->rx_bytes      += bytes;
                this_tot->rx_packets    += packets;
        }
}

static void netvsc_get_stats64(struct net_device *net,
                               struct rtnl_link_stats64 *t)
{
        struct net_device_context *ndev_ctx = netdev_priv(net);
        struct netvsc_device *nvdev;
        struct netvsc_vf_pcpu_stats vf_tot;
        int i;

        rcu_read_lock();

        nvdev = rcu_dereference(ndev_ctx->nvdev);
        if (!nvdev)
                goto out;

        netdev_stats_to_stats64(t, &net->stats);

        netvsc_get_vf_stats(net, &vf_tot);
        t->rx_packets += vf_tot.rx_packets;
        t->tx_packets += vf_tot.tx_packets;
        t->rx_bytes   += vf_tot.rx_bytes;
        t->tx_bytes   += vf_tot.tx_bytes;
        t->tx_dropped += vf_tot.tx_dropped;

        for (i = 0; i < nvdev->num_chn; i++) {
                const struct netvsc_channel *nvchan = &nvdev->chan_table[i];
                const struct netvsc_stats *stats;
                u64 packets, bytes, multicast;
                unsigned int start;

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

                t->tx_bytes     += bytes;
                t->tx_packets   += packets;

                stats = &nvchan->rx_stats;
                do {
                        start = u64_stats_fetch_begin_irq(&stats->syncp);
                        packets = stats->packets;
                        bytes = stats->bytes;
                        multicast = stats->multicast + stats->broadcast;
                } while (u64_stats_fetch_retry_irq(&stats->syncp, start));

                t->rx_bytes     += bytes;
                t->rx_packets   += packets;
                t->multicast    += multicast;
        }
out:
        rcu_read_unlock();
}

static int netvsc_set_mac_addr(struct net_device *ndev, void *p)
{
        struct net_device_context *ndc = netdev_priv(ndev);
        struct net_device *vf_netdev = rtnl_dereference(ndc->vf_netdev);
        struct netvsc_device *nvdev = rtnl_dereference(ndc->nvdev);
        struct sockaddr *addr = p;
        int err;

        err = eth_prepare_mac_addr_change(ndev, p);
        if (err)
                return err;

        if (!nvdev)
                return -ENODEV;

        if (vf_netdev) {
                err = dev_set_mac_address(vf_netdev, addr, NULL);
                if (err)
                        return err;
        }

        err = rndis_filter_set_device_mac(nvdev, addr->sa_data);
        if (!err) {
                eth_commit_mac_addr_change(ndev, p);
        } else if (vf_netdev) {
                /* rollback change on VF */
                memcpy(addr->sa_data, ndev->dev_addr, ETH_ALEN);
                dev_set_mac_address(vf_netdev, addr, NULL);
        }

        return err;
}

static const struct {
        char name[ETH_GSTRING_LEN];
        u16 offset;
} netvsc_stats[] = {
        { "tx_scattered", offsetof(struct netvsc_ethtool_stats, tx_scattered) },
        { "tx_no_memory", offsetof(struct netvsc_ethtool_stats, tx_no_memory) },
        { "tx_no_space",  offsetof(struct netvsc_ethtool_stats, tx_no_space) },
        { "tx_too_big",   offsetof(struct netvsc_ethtool_stats, tx_too_big) },
        { "tx_busy",      offsetof(struct netvsc_ethtool_stats, tx_busy) },
        { "tx_send_full", offsetof(struct netvsc_ethtool_stats, tx_send_full) },
        { "rx_comp_busy", offsetof(struct netvsc_ethtool_stats, rx_comp_busy) },
        { "rx_no_memory", offsetof(struct netvsc_ethtool_stats, rx_no_memory) },
        { "stop_queue", offsetof(struct netvsc_ethtool_stats, stop_queue) },
        { "wake_queue", offsetof(struct netvsc_ethtool_stats, wake_queue) },
        { "vlan_error", offsetof(struct netvsc_ethtool_stats, vlan_error) },
}, pcpu_stats[] = {
        { "cpu%u_rx_packets",
                offsetof(struct netvsc_ethtool_pcpu_stats, rx_packets) },
        { "cpu%u_rx_bytes",
                offsetof(struct netvsc_ethtool_pcpu_stats, rx_bytes) },
        { "cpu%u_tx_packets",
                offsetof(struct netvsc_ethtool_pcpu_stats, tx_packets) },
        { "cpu%u_tx_bytes",
                offsetof(struct netvsc_ethtool_pcpu_stats, tx_bytes) },
        { "cpu%u_vf_rx_packets",
                offsetof(struct netvsc_ethtool_pcpu_stats, vf_rx_packets) },
        { "cpu%u_vf_rx_bytes",
                offsetof(struct netvsc_ethtool_pcpu_stats, vf_rx_bytes) },
        { "cpu%u_vf_tx_packets",
                offsetof(struct netvsc_ethtool_pcpu_stats, vf_tx_packets) },
        { "cpu%u_vf_tx_bytes",
                offsetof(struct netvsc_ethtool_pcpu_stats, vf_tx_bytes) },
}, vf_stats[] = {
        { "vf_rx_packets", offsetof(struct netvsc_vf_pcpu_stats, rx_packets) },
        { "vf_rx_bytes",   offsetof(struct netvsc_vf_pcpu_stats, rx_bytes) },
        { "vf_tx_packets", offsetof(struct netvsc_vf_pcpu_stats, tx_packets) },
        { "vf_tx_bytes",   offsetof(struct netvsc_vf_pcpu_stats, tx_bytes) },
        { "vf_tx_dropped", offsetof(struct netvsc_vf_pcpu_stats, tx_dropped) },
};

#define NETVSC_GLOBAL_STATS_LEN ARRAY_SIZE(netvsc_stats)
#define NETVSC_VF_STATS_LEN     ARRAY_SIZE(vf_stats)

/* statistics per queue (rx/tx packets/bytes) */
#define NETVSC_PCPU_STATS_LEN (num_present_cpus() * ARRAY_SIZE(pcpu_stats))

/* 5 statistics per queue (rx/tx packets/bytes, rx xdp_drop) */
#define NETVSC_QUEUE_STATS_LEN(dev) ((dev)->num_chn * 5)

static int netvsc_get_sset_count(struct net_device *dev, int string_set)
{
        struct net_device_context *ndc = netdev_priv(dev);
        struct netvsc_device *nvdev = rtnl_dereference(ndc->nvdev);

        if (!nvdev)
                return -ENODEV;

        switch (string_set) {
        case ETH_SS_STATS:
                return NETVSC_GLOBAL_STATS_LEN
                        + NETVSC_VF_STATS_LEN
                        + NETVSC_QUEUE_STATS_LEN(nvdev)
                        + NETVSC_PCPU_STATS_LEN;
        default:
                return -EINVAL;
        }
}

static void netvsc_get_ethtool_stats(struct net_device *dev,
                                     struct ethtool_stats *stats, u64 *data)
{
        struct net_device_context *ndc = netdev_priv(dev);
        struct netvsc_device *nvdev = rtnl_dereference(ndc->nvdev);
        const void *nds = &ndc->eth_stats;
        const struct netvsc_stats *qstats;
        struct netvsc_vf_pcpu_stats sum;
        struct netvsc_ethtool_pcpu_stats *pcpu_sum;
        unsigned int start;
        u64 packets, bytes;
        u64 xdp_drop;
        int i, j, cpu;

        if (!nvdev)
                return;

        for (i = 0; i < NETVSC_GLOBAL_STATS_LEN; i++)
                data[i] = *(unsigned long *)(nds + netvsc_stats[i].offset);

        netvsc_get_vf_stats(dev, &sum);
        for (j = 0; j < NETVSC_VF_STATS_LEN; j++)
                data[i++] = *(u64 *)((void *)&sum + vf_stats[j].offset);

        for (j = 0; j < nvdev->num_chn; j++) {
                qstats = &nvdev->chan_table[j].tx_stats;

                do {
                        start = u64_stats_fetch_begin_irq(&qstats->syncp);
                        packets = qstats->packets;
                        bytes = qstats->bytes;
                } while (u64_stats_fetch_retry_irq(&qstats->syncp, start));
                data[i++] = packets;
                data[i++] = bytes;

                qstats = &nvdev->chan_table[j].rx_stats;
                do {
                        start = u64_stats_fetch_begin_irq(&qstats->syncp);
                        packets = qstats->packets;
                        bytes = qstats->bytes;
                        xdp_drop = qstats->xdp_drop;
                } while (u64_stats_fetch_retry_irq(&qstats->syncp, start));
                data[i++] = packets;
                data[i++] = bytes;
                data[i++] = xdp_drop;
        }

        pcpu_sum = kvmalloc_array(num_possible_cpus(),
                                  sizeof(struct netvsc_ethtool_pcpu_stats),
                                  GFP_KERNEL);
        netvsc_get_pcpu_stats(dev, pcpu_sum);
        for_each_present_cpu(cpu) {
                struct netvsc_ethtool_pcpu_stats *this_sum = &pcpu_sum[cpu];

                for (j = 0; j < ARRAY_SIZE(pcpu_stats); j++)
                        data[i++] = *(u64 *)((void *)this_sum
                                             + pcpu_stats[j].offset);
        }
        kvfree(pcpu_sum);
}

static void netvsc_get_strings(struct net_device *dev, u32 stringset, u8 *data)
{
        struct net_device_context *ndc = netdev_priv(dev);
        struct netvsc_device *nvdev = rtnl_dereference(ndc->nvdev);
        u8 *p = data;
        int i, cpu;

        if (!nvdev)
                return;

        switch (stringset) {
        case ETH_SS_STATS:
                for (i = 0; i < ARRAY_SIZE(netvsc_stats); i++)
                        ethtool_sprintf(&p, netvsc_stats[i].name);

                for (i = 0; i < ARRAY_SIZE(vf_stats); i++)
                        ethtool_sprintf(&p, vf_stats[i].name);

                for (i = 0; i < nvdev->num_chn; i++) {
                        ethtool_sprintf(&p, "tx_queue_%u_packets", i);
                        ethtool_sprintf(&p, "tx_queue_%u_bytes", i);
                        ethtool_sprintf(&p, "rx_queue_%u_packets", i);
                        ethtool_sprintf(&p, "rx_queue_%u_bytes", i);
                        ethtool_sprintf(&p, "rx_queue_%u_xdp_drop", i);
                }

                for_each_present_cpu(cpu) {
                        for (i = 0; i < ARRAY_SIZE(pcpu_stats); i++)
                                ethtool_sprintf(&p, pcpu_stats[i].name, cpu);
                }

                break;
        }
}

static int
netvsc_get_rss_hash_opts(struct net_device_context *ndc,
                         struct ethtool_rxnfc *info)
{
        const u32 l4_flag = RXH_L4_B_0_1 | RXH_L4_B_2_3;

        info->data = RXH_IP_SRC | RXH_IP_DST;

        switch (info->flow_type) {
        case TCP_V4_FLOW:
                if (ndc->l4_hash & HV_TCP4_L4HASH)
                        info->data |= l4_flag;

                break;

        case TCP_V6_FLOW:
                if (ndc->l4_hash & HV_TCP6_L4HASH)
                        info->data |= l4_flag;

                break;

        case UDP_V4_FLOW:
                if (ndc->l4_hash & HV_UDP4_L4HASH)
                        info->data |= l4_flag;

                break;

        case UDP_V6_FLOW:
                if (ndc->l4_hash & HV_UDP6_L4HASH)
                        info->data |= l4_flag;

                break;

        case IPV4_FLOW:
        case IPV6_FLOW:
                break;
        default:
                info->data = 0;
                break;
        }

        return 0;
}

static int
netvsc_get_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info,
                 u32 *rules)
{
        struct net_device_context *ndc = netdev_priv(dev);
        struct netvsc_device *nvdev = rtnl_dereference(ndc->nvdev);

        if (!nvdev)
                return -ENODEV;

        switch (info->cmd) {
        case ETHTOOL_GRXRINGS:
                info->data = nvdev->num_chn;
                return 0;

        case ETHTOOL_GRXFH:
                return netvsc_get_rss_hash_opts(ndc, info);
        }
        return -EOPNOTSUPP;
}

static int netvsc_set_rss_hash_opts(struct net_device_context *ndc,
                                    struct ethtool_rxnfc *info)
{
        if (info->data == (RXH_IP_SRC | RXH_IP_DST |
                           RXH_L4_B_0_1 | RXH_L4_B_2_3)) {
                switch (info->flow_type) {
                case TCP_V4_FLOW:
                        ndc->l4_hash |= HV_TCP4_L4HASH;
                        break;

                case TCP_V6_FLOW:
                        ndc->l4_hash |= HV_TCP6_L4HASH;
                        break;

                case UDP_V4_FLOW:
                        ndc->l4_hash |= HV_UDP4_L4HASH;
                        break;

                case UDP_V6_FLOW:
                        ndc->l4_hash |= HV_UDP6_L4HASH;
                        break;

                default:
                        return -EOPNOTSUPP;
                }

                return 0;
        }

        if (info->data == (RXH_IP_SRC | RXH_IP_DST)) {
                switch (info->flow_type) {
                case TCP_V4_FLOW:
                        ndc->l4_hash &= ~HV_TCP4_L4HASH;
                        break;

                case TCP_V6_FLOW:
                        ndc->l4_hash &= ~HV_TCP6_L4HASH;
                        break;

                case UDP_V4_FLOW:
                        ndc->l4_hash &= ~HV_UDP4_L4HASH;
                        break;

                case UDP_V6_FLOW:
                        ndc->l4_hash &= ~HV_UDP6_L4HASH;
                        break;

                default:
                        return -EOPNOTSUPP;
                }

                return 0;
        }

        return -EOPNOTSUPP;
}

static int
netvsc_set_rxnfc(struct net_device *ndev, struct ethtool_rxnfc *info)
{
        struct net_device_context *ndc = netdev_priv(ndev);

        if (info->cmd == ETHTOOL_SRXFH)
                return netvsc_set_rss_hash_opts(ndc, info);

        return -EOPNOTSUPP;
}

static u32 netvsc_get_rxfh_key_size(struct net_device *dev)
{
        return NETVSC_HASH_KEYLEN;
}

static u32 netvsc_rss_indir_size(struct net_device *dev)
{
        return ITAB_NUM;
}

static int netvsc_get_rxfh(struct net_device *dev, u32 *indir, u8 *key,
                           u8 *hfunc)
{
        struct net_device_context *ndc = netdev_priv(dev);
        struct netvsc_device *ndev = rtnl_dereference(ndc->nvdev);
        struct rndis_device *rndis_dev;
        int i;

        if (!ndev)
                return -ENODEV;

        if (hfunc)
                *hfunc = ETH_RSS_HASH_TOP;      /* Toeplitz */

        rndis_dev = ndev->extension;
        if (indir) {
                for (i = 0; i < ITAB_NUM; i++)
                        indir[i] = ndc->rx_table[i];
        }

        if (key)
                memcpy(key, rndis_dev->rss_key, NETVSC_HASH_KEYLEN);

        return 0;
}

static int netvsc_set_rxfh(struct net_device *dev, const u32 *indir,
                           const u8 *key, const u8 hfunc)
{
        struct net_device_context *ndc = netdev_priv(dev);
        struct netvsc_device *ndev = rtnl_dereference(ndc->nvdev);
        struct rndis_device *rndis_dev;
        int i;

        if (!ndev)
                return -ENODEV;

        if (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP)
                return -EOPNOTSUPP;

        rndis_dev = ndev->extension;
        if (indir) {
                for (i = 0; i < ITAB_NUM; i++)
                        if (indir[i] >= ndev->num_chn)
                                return -EINVAL;

                for (i = 0; i < ITAB_NUM; i++)
                        ndc->rx_table[i] = indir[i];
        }

        if (!key) {
                if (!indir)
                        return 0;

                key = rndis_dev->rss_key;
        }

        return rndis_filter_set_rss_param(rndis_dev, key);
}

/* Hyper-V RNDIS protocol does not have ring in the HW sense.
 * It does have pre-allocated receive area which is divided into sections.
 */
static void __netvsc_get_ringparam(struct netvsc_device *nvdev,
                                   struct ethtool_ringparam *ring)
{
        u32 max_buf_size;

        ring->rx_pending = nvdev->recv_section_cnt;
        ring->tx_pending = nvdev->send_section_cnt;

        if (nvdev->nvsp_version <= NVSP_PROTOCOL_VERSION_2)
                max_buf_size = NETVSC_RECEIVE_BUFFER_SIZE_LEGACY;
        else
                max_buf_size = NETVSC_RECEIVE_BUFFER_SIZE;

        ring->rx_max_pending = max_buf_size / nvdev->recv_section_size;
        ring->tx_max_pending = NETVSC_SEND_BUFFER_SIZE
                / nvdev->send_section_size;
}

static void netvsc_get_ringparam(struct net_device *ndev,
                                 struct ethtool_ringparam *ring)
{
        struct net_device_context *ndevctx = netdev_priv(ndev);
        struct netvsc_device *nvdev = rtnl_dereference(ndevctx->nvdev);

        if (!nvdev)
                return;

        __netvsc_get_ringparam(nvdev, ring);
}

static int netvsc_set_ringparam(struct net_device *ndev,
                                struct ethtool_ringparam *ring)
{
        struct net_device_context *ndevctx = netdev_priv(ndev);
        struct netvsc_device *nvdev = rtnl_dereference(ndevctx->nvdev);
        struct netvsc_device_info *device_info;
        struct ethtool_ringparam orig;
        u32 new_tx, new_rx;
        int ret = 0;

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

        memset(&orig, 0, sizeof(orig));
        __netvsc_get_ringparam(nvdev, &orig);

        new_tx = clamp_t(u32, ring->tx_pending,
                         NETVSC_MIN_TX_SECTIONS, orig.tx_max_pending);
        new_rx = clamp_t(u32, ring->rx_pending,
                         NETVSC_MIN_RX_SECTIONS, orig.rx_max_pending);

        if (new_tx == orig.tx_pending &&
            new_rx == orig.rx_pending)
                return 0;        /* no change */

        device_info = netvsc_devinfo_get(nvdev);

        if (!device_info)
                return -ENOMEM;

        device_info->send_sections = new_tx;
        device_info->recv_sections = new_rx;

        ret = netvsc_detach(ndev, nvdev);
        if (ret)
                goto out;

        ret = netvsc_attach(ndev, device_info);
        if (ret) {
                device_info->send_sections = orig.tx_pending;
                device_info->recv_sections = orig.rx_pending;

                if (netvsc_attach(ndev, device_info))
                        netdev_err(ndev, "restoring ringparam failed");
        }

out:
        netvsc_devinfo_put(device_info);
        return ret;
}

static netdev_features_t netvsc_fix_features(struct net_device *ndev,
                                             netdev_features_t features)
{
        struct net_device_context *ndevctx = netdev_priv(ndev);
        struct netvsc_device *nvdev = rtnl_dereference(ndevctx->nvdev);

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

        if ((features & NETIF_F_LRO) && netvsc_xdp_get(nvdev)) {
                features ^= NETIF_F_LRO;
                netdev_info(ndev, "Skip LRO - unsupported with XDP\n");
        }

        return features;
}

static int netvsc_set_features(struct net_device *ndev,
                               netdev_features_t features)
{
        netdev_features_t change = features ^ ndev->features;
        struct net_device_context *ndevctx = netdev_priv(ndev);
        struct netvsc_device *nvdev = rtnl_dereference(ndevctx->nvdev);
        struct net_device *vf_netdev = rtnl_dereference(ndevctx->vf_netdev);
        struct ndis_offload_params offloads;
        int ret = 0;

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

        if (!(change & NETIF_F_LRO))
                goto syncvf;

        memset(&offloads, 0, sizeof(struct ndis_offload_params));

        if (features & NETIF_F_LRO) {
                offloads.rsc_ip_v4 = NDIS_OFFLOAD_PARAMETERS_RSC_ENABLED;
                offloads.rsc_ip_v6 = NDIS_OFFLOAD_PARAMETERS_RSC_ENABLED;
        } else {
                offloads.rsc_ip_v4 = NDIS_OFFLOAD_PARAMETERS_RSC_DISABLED;
                offloads.rsc_ip_v6 = NDIS_OFFLOAD_PARAMETERS_RSC_DISABLED;
        }

        ret = rndis_filter_set_offload_params(ndev, nvdev, &offloads);

        if (ret) {
                features ^= NETIF_F_LRO;
                ndev->features = features;
        }

syncvf:
        if (!vf_netdev)
                return ret;

        vf_netdev->wanted_features = features;
        netdev_update_features(vf_netdev);

        return ret;
}

static int netvsc_get_regs_len(struct net_device *netdev)
{
        return VRSS_SEND_TAB_SIZE * sizeof(u32);
}

static void netvsc_get_regs(struct net_device *netdev,
                            struct ethtool_regs *regs, void *p)
{
        struct net_device_context *ndc = netdev_priv(netdev);
        u32 *regs_buff = p;

        /* increase the version, if buffer format is changed. */
        regs->version = 1;

        memcpy(regs_buff, ndc->tx_table, VRSS_SEND_TAB_SIZE * sizeof(u32));
}

static u32 netvsc_get_msglevel(struct net_device *ndev)
{

        struct net_device_context *ndev_ctx = netdev_priv(ndev);

        return ndev_ctx->msg_enable;
}

static void netvsc_set_msglevel(struct net_device *ndev, u32 val)
{
        struct net_device_context *ndev_ctx = netdev_priv(ndev);

        ndev_ctx->msg_enable = val;
}

static const struct ethtool_ops ethtool_ops = {
        .get_drvinfo    = netvsc_get_drvinfo,
        .get_regs_len   = netvsc_get_regs_len,
        .get_regs       = netvsc_get_regs,
        .get_msglevel   = netvsc_get_msglevel,
        .set_msglevel   = netvsc_set_msglevel,
        .get_link       = ethtool_op_get_link,
        .get_ethtool_stats = netvsc_get_ethtool_stats,
        .get_sset_count = netvsc_get_sset_count,
        .get_strings    = netvsc_get_strings,
        .get_channels   = netvsc_get_channels,
        .set_channels   = netvsc_set_channels,
        .get_ts_info    = ethtool_op_get_ts_info,
        .get_rxnfc      = netvsc_get_rxnfc,
        .set_rxnfc      = netvsc_set_rxnfc,
        .get_rxfh_key_size = netvsc_get_rxfh_key_size,
        .get_rxfh_indir_size = netvsc_rss_indir_size,
        .get_rxfh       = netvsc_get_rxfh,
        .set_rxfh       = netvsc_set_rxfh,
        .get_link_ksettings = netvsc_get_link_ksettings,
        .set_link_ksettings = netvsc_set_link_ksettings,
        .get_ringparam  = netvsc_get_ringparam,
        .set_ringparam  = netvsc_set_ringparam,
};

static const struct net_device_ops device_ops = {
        .ndo_open =                     netvsc_open,
        .ndo_stop =                     netvsc_close,
        .ndo_start_xmit =               netvsc_start_xmit,
        .ndo_change_rx_flags =          netvsc_change_rx_flags,
        .ndo_set_rx_mode =              netvsc_set_rx_mode,
        .ndo_fix_features =             netvsc_fix_features,
        .ndo_set_features =             netvsc_set_features,
        .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,
        .ndo_bpf =                      netvsc_bpf,
};

/*
 * 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 =
                container_of(w, struct net_device_context, dwork.work);
        struct hv_device *device_obj = ndev_ctx->device_ctx;
        struct net_device *net = hv_get_drvdata(device_obj);
        unsigned long flags, next_reconfig, delay;
        struct netvsc_reconfig *event = NULL;
        struct netvsc_device *net_device;
        struct rndis_device *rdev;
        bool reschedule = false;

        /* if changes are happening, comeback later */
        if (!rtnl_trylock()) {
                schedule_delayed_work(&ndev_ctx->dwork, LINKCHANGE_INT);
                return;
        }

        net_device = rtnl_dereference(ndev_ctx->nvdev);
        if (!net_device)
                goto out_unlock;

        rdev = net_device->extension;

        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);
                goto out_unlock;
        }
        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)
                goto out_unlock;

        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);
                        netvsc_tx_enable(net_device, net);
                } else {
                        __netdev_notify_peers(net);
                }
                kfree(event);
                break;
        case RNDIS_STATUS_MEDIA_DISCONNECT:
                if (!rdev->link_state) {
                        rdev->link_state = true;
                        netif_carrier_off(net);
                        netvsc_tx_disable(net_device, 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);
                        netvsc_tx_disable(net_device, net);
                        event->event = RNDIS_STATUS_MEDIA_CONNECT;
                        spin_lock_irqsave(&ndev_ctx->lock, flags);
                        list_add(&event->list, &ndev_ctx->reconfig_events);
                        spin_unlock_irqrestore(&ndev_ctx->lock, flags);
                        reschedule = true;
                }
                break;
        }

        rtnl_unlock();

        /* 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);

        return;

out_unlock:
        rtnl_unlock();
}

static struct net_device *get_netvsc_byref(struct net_device *vf_netdev)
{
        struct net_device_context *net_device_ctx;
        struct net_device *dev;

        dev = netdev_master_upper_dev_get(vf_netdev);
        if (!dev || dev->netdev_ops != &device_ops)
                return NULL;    /* not a netvsc device */

        net_device_ctx = netdev_priv(dev);
        if (!rtnl_dereference(net_device_ctx->nvdev))
                return NULL;    /* device is removed */

        return dev;
}

/* Called when VF is injecting data into network stack.
 * Change the associated network device from VF to netvsc.
 * note: already called with rcu_read_lock
 */
static rx_handler_result_t netvsc_vf_handle_frame(struct sk_buff **pskb)
{
        struct sk_buff *skb = *pskb;
        struct net_device *ndev = rcu_dereference(skb->dev->rx_handler_data);
        struct net_device_context *ndev_ctx = netdev_priv(ndev);
        struct netvsc_vf_pcpu_stats *pcpu_stats
                 = this_cpu_ptr(ndev_ctx->vf_stats);

        skb = skb_share_check(skb, GFP_ATOMIC);
        if (unlikely(!skb))
                return RX_HANDLER_CONSUMED;

        *pskb = skb;

        skb->dev = ndev;

        u64_stats_update_begin(&pcpu_stats->syncp);
        pcpu_stats->rx_packets++;
        pcpu_stats->rx_bytes += skb->len;
        u64_stats_update_end(&pcpu_stats->syncp);

        return RX_HANDLER_ANOTHER;
}

static int netvsc_vf_join(struct net_device *vf_netdev,
                          struct net_device *ndev)
{
        struct net_device_context *ndev_ctx = netdev_priv(ndev);
        int ret;

        ret = netdev_rx_handler_register(vf_netdev,
                                         netvsc_vf_handle_frame, ndev);
        if (ret != 0) {
                netdev_err(vf_netdev,
                           "can not register netvsc VF receive handler (err = %d)\n",
                           ret);
                goto rx_handler_failed;
        }

        ret = netdev_master_upper_dev_link(vf_netdev, ndev,
                                           NULL, NULL, NULL);
        if (ret != 0) {
                netdev_err(vf_netdev,
                           "can not set master device %s (err = %d)\n",
                           ndev->name, ret);
                goto upper_link_failed;
        }

        /* set slave flag before open to prevent IPv6 addrconf */
        vf_netdev->flags |= IFF_SLAVE;

        schedule_delayed_work(&ndev_ctx->vf_takeover, VF_TAKEOVER_INT);

        call_netdevice_notifiers(NETDEV_JOIN, vf_netdev);

        netdev_info(vf_netdev, "joined to %s\n", ndev->name);
        return 0;

upper_link_failed:
        netdev_rx_handler_unregister(vf_netdev);
rx_handler_failed:
        return ret;
}

static void __netvsc_vf_setup(struct net_device *ndev,
                              struct net_device *vf_netdev)
{
        int ret;

        /* Align MTU of VF with master */
        ret = dev_set_mtu(vf_netdev, ndev->mtu);
        if (ret)
                netdev_warn(vf_netdev,
                            "unable to change mtu to %u\n", ndev->mtu);

        /* set multicast etc flags on VF */
        dev_change_flags(vf_netdev, ndev->flags | IFF_SLAVE, NULL);

        /* sync address list from ndev to VF */
        netif_addr_lock_bh(ndev);
        dev_uc_sync(vf_netdev, ndev);
        dev_mc_sync(vf_netdev, ndev);
        netif_addr_unlock_bh(ndev);

        if (netif_running(ndev)) {
                ret = dev_open(vf_netdev, NULL);
                if (ret)
                        netdev_warn(vf_netdev,
                                    "unable to open: %d\n", ret);
        }
}

/* Setup VF as slave of the synthetic device.
 * Runs in workqueue to avoid recursion in netlink callbacks.
 */
static void netvsc_vf_setup(struct work_struct *w)
{
        struct net_device_context *ndev_ctx
                = container_of(w, struct net_device_context, vf_takeover.work);
        struct net_device *ndev = hv_get_drvdata(ndev_ctx->device_ctx);
        struct net_device *vf_netdev;

        if (!rtnl_trylock()) {
                schedule_delayed_work(&ndev_ctx->vf_takeover, 0);
                return;
        }

        vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
        if (vf_netdev)
                __netvsc_vf_setup(ndev, vf_netdev);

        rtnl_unlock();
}

/* Find netvsc by VF serial number.
 * The PCI hyperv controller records the serial number as the slot kobj name.
 */
static struct net_device *get_netvsc_byslot(const struct net_device *vf_netdev)
{
        struct device *parent = vf_netdev->dev.parent;
        struct net_device_context *ndev_ctx;
        struct net_device *ndev;
        struct pci_dev *pdev;
        u32 serial;

        if (!parent || !dev_is_pci(parent))
                return NULL; /* not a PCI device */

        pdev = to_pci_dev(parent);
        if (!pdev->slot) {
                netdev_notice(vf_netdev, "no PCI slot information\n");
                return NULL;
        }

        if (kstrtou32(pci_slot_name(pdev->slot), 10, &serial)) {
                netdev_notice(vf_netdev, "Invalid vf serial:%s\n",
                              pci_slot_name(pdev->slot));
                return NULL;
        }

        list_for_each_entry(ndev_ctx, &netvsc_dev_list, list) {
                if (!ndev_ctx->vf_alloc)
                        continue;

                if (ndev_ctx->vf_serial != serial)
                        continue;

                ndev = hv_get_drvdata(ndev_ctx->device_ctx);
                if (ndev->addr_len != vf_netdev->addr_len ||
                    memcmp(ndev->perm_addr, vf_netdev->perm_addr,
                           ndev->addr_len) != 0)
                        continue;

                return ndev;

        }

        netdev_notice(vf_netdev,
                      "no netdev found for vf serial:%u\n", serial);
        return NULL;
}

static int netvsc_register_vf(struct net_device *vf_netdev)
{
        struct net_device_context *net_device_ctx;
        struct netvsc_device *netvsc_dev;
        struct bpf_prog *prog;
        struct net_device *ndev;
        int ret;

        if (vf_netdev->addr_len != ETH_ALEN)
                return NOTIFY_DONE;

        ndev = get_netvsc_byslot(vf_netdev);
        if (!ndev)
                return NOTIFY_DONE;

        net_device_ctx = netdev_priv(ndev);
        netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
        if (!netvsc_dev || rtnl_dereference(net_device_ctx->vf_netdev))
                return NOTIFY_DONE;

        /* if synthetic interface is a different namespace,
         * then move the VF to that namespace; join will be
         * done again in that context.
         */
        if (!net_eq(dev_net(ndev), dev_net(vf_netdev))) {
                ret = dev_change_net_namespace(vf_netdev,
                                               dev_net(ndev), "eth%d");
                if (ret)
                        netdev_err(vf_netdev,
                                   "could not move to same namespace as %s: %d\n",
                                   ndev->name, ret);
                else
                        netdev_info(vf_netdev,
                                    "VF moved to namespace with: %s\n",
                                    ndev->name);
                return NOTIFY_DONE;
        }

        netdev_info(ndev, "VF registering: %s\n", vf_netdev->name);

        if (netvsc_vf_join(vf_netdev, ndev) != 0)
                return NOTIFY_DONE;

        dev_hold(vf_netdev);
        rcu_assign_pointer(net_device_ctx->vf_netdev, vf_netdev);

        if (ndev->needed_headroom < vf_netdev->needed_headroom)
                ndev->needed_headroom = vf_netdev->needed_headroom;

        vf_netdev->wanted_features = ndev->features;
        netdev_update_features(vf_netdev);

        prog = netvsc_xdp_get(netvsc_dev);
        netvsc_vf_setxdp(vf_netdev, prog);

        return NOTIFY_OK;
}

/* Change the data path when VF UP/DOWN/CHANGE are detected.
 *
 * Typically a UP or DOWN event is followed by a CHANGE event, so
 * net_device_ctx->data_path_is_vf is used to cache the current data path
 * to avoid the duplicate call of netvsc_switch_datapath() and the duplicate
 * message.
 *
 * During hibernation, if a VF NIC driver (e.g. mlx5) preserves the network
 * interface, there is only the CHANGE event and no UP or DOWN event.
 */
static int netvsc_vf_changed(struct net_device *vf_netdev, unsigned long event)
{
        struct net_device_context *net_device_ctx;
        struct netvsc_device *netvsc_dev;
        struct net_device *ndev;
        bool vf_is_up = false;
        int ret;

        if (event != NETDEV_GOING_DOWN)
                vf_is_up = netif_running(vf_netdev);

        ndev = get_netvsc_byref(vf_netdev);
        if (!ndev)
                return NOTIFY_DONE;

        net_device_ctx = netdev_priv(ndev);
        netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
        if (!netvsc_dev)
                return NOTIFY_DONE;

        if (net_device_ctx->data_path_is_vf == vf_is_up)
                return NOTIFY_OK;

        ret = netvsc_switch_datapath(ndev, vf_is_up);

        if (ret) {
                netdev_err(ndev,
                           "Data path failed to switch %s VF: %s, err: %d\n",
                           vf_is_up ? "to" : "from", vf_netdev->name, ret);
                return NOTIFY_DONE;
        } else {
                netdev_info(ndev, "Data path switched %s VF: %s\n",
                            vf_is_up ? "to" : "from", vf_netdev->name);
        }

        return NOTIFY_OK;
}

static int netvsc_unregister_vf(struct net_device *vf_netdev)
{
        struct net_device *ndev;
        struct net_device_context *net_device_ctx;

        ndev = get_netvsc_byref(vf_netdev);
        if (!ndev)
                return NOTIFY_DONE;

        net_device_ctx = netdev_priv(ndev);
        cancel_delayed_work_sync(&net_device_ctx->vf_takeover);

        netdev_info(ndev, "VF unregistering: %s\n", vf_netdev->name);

        netvsc_vf_setxdp(vf_netdev, NULL);

        netdev_rx_handler_unregister(vf_netdev);
        netdev_upper_dev_unlink(vf_netdev, ndev);
        RCU_INIT_POINTER(net_device_ctx->vf_netdev, NULL);
        dev_put(vf_netdev);

        ndev->needed_headroom = RNDIS_AND_PPI_SIZE;

        return NOTIFY_OK;
}

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 = NULL;
        struct netvsc_device *nvdev;
        int ret = -ENOMEM;

        net = alloc_etherdev_mq(sizeof(struct net_device_context),
                                VRSS_CHANNEL_MAX);
        if (!net)
                goto no_net;

        netif_carrier_off(net);

        netvsc_init_settings(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);

        hv_set_drvdata(dev, net);

        INIT_DELAYED_WORK(&net_device_ctx->dwork, netvsc_link_change);

        spin_lock_init(&net_device_ctx->lock);
        INIT_LIST_HEAD(&net_device_ctx->reconfig_events);
        INIT_DELAYED_WORK(&net_device_ctx->vf_takeover, netvsc_vf_setup);

        net_device_ctx->vf_stats
                = netdev_alloc_pcpu_stats(struct netvsc_vf_pcpu_stats);
        if (!net_device_ctx->vf_stats)
                goto no_stats;

        net->netdev_ops = &device_ops;
        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;

        /* Initialize the number of queues to be 1, we may change it if more
         * channels are offered later.
         */
        netif_set_real_num_tx_queues(net, 1);
        netif_set_real_num_rx_queues(net, 1);

        /* Notify the netvsc driver of the new device */
        device_info = netvsc_devinfo_get(NULL);

        if (!device_info) {
                ret = -ENOMEM;
                goto devinfo_failed;
        }

        nvdev = rndis_filter_device_add(dev, device_info);
        if (IS_ERR(nvdev)) {
                ret = PTR_ERR(nvdev);
                netdev_err(net, "unable to add netvsc device (ret %d)\n", ret);
                goto rndis_failed;
        }

        memcpy(net->dev_addr, device_info->mac_adr, ETH_ALEN);

        /* We must get rtnl lock before scheduling nvdev->subchan_work,
         * otherwise netvsc_subchan_work() can get rtnl lock first and wait
         * all subchannels to show up, but that may not happen because
         * netvsc_probe() can't get rtnl lock and as a result vmbus_onoffer()
         * -> ... -> device_add() -> ... -> __device_attach() can't get
         * the device lock, so all the subchannels can't be processed --
         * finally netvsc_subchan_work() hangs forever.
         */
        rtnl_lock();

        if (nvdev->num_chn > 1)
                schedule_work(&nvdev->subchan_work);

        /* hw_features computed in rndis_netdev_set_hwcaps() */
        net->features = net->hw_features |
                NETIF_F_HIGHDMA | NETIF_F_HW_VLAN_CTAG_TX |
                NETIF_F_HW_VLAN_CTAG_RX;
        net->vlan_features = net->features;

        netdev_lockdep_set_classes(net);

        /* MTU range: 68 - 1500 or 65521 */
        net->min_mtu = NETVSC_MTU_MIN;
        if (nvdev->nvsp_version >= NVSP_PROTOCOL_VERSION_2)
                net->max_mtu = NETVSC_MTU - ETH_HLEN;
        else
                net->max_mtu = ETH_DATA_LEN;

        nvdev->tx_disable = false;

        ret = register_netdevice(net);
        if (ret != 0) {
                pr_err("Unable to register netdev.\n");
                goto register_failed;
        }

        list_add(&net_device_ctx->list, &netvsc_dev_list);
        rtnl_unlock();

        netvsc_devinfo_put(device_info);
        return 0;

register_failed:
        rtnl_unlock();
        rndis_filter_device_remove(dev, nvdev);
rndis_failed:
        netvsc_devinfo_put(device_info);
devinfo_failed:
        free_percpu(net_device_ctx->vf_stats);
no_stats:
        hv_set_drvdata(dev, NULL);
        free_netdev(net);
no_net:
        return ret;
}

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

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

        ndev_ctx = netdev_priv(net);

        cancel_delayed_work_sync(&ndev_ctx->dwork);

        rtnl_lock();
        nvdev = rtnl_dereference(ndev_ctx->nvdev);
        if (nvdev) {
                cancel_work_sync(&nvdev->subchan_work);
                netvsc_xdp_set(net, NULL, NULL, nvdev);
        }

        /*
         * Call to the vsc driver to let it know that the device is being
         * removed. Also blocks mtu and channel changes.
         */
        vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
        if (vf_netdev)
                netvsc_unregister_vf(vf_netdev);

        if (nvdev)
                rndis_filter_device_remove(dev, nvdev);

        unregister_netdevice(net);
        list_del(&ndev_ctx->list);

        rtnl_unlock();

        hv_set_drvdata(dev, NULL);

        free_percpu(ndev_ctx->vf_stats);
        free_netdev(net);
        return 0;
}

static int netvsc_suspend(struct hv_device *dev)
{
        struct net_device_context *ndev_ctx;
        struct netvsc_device *nvdev;
        struct net_device *net;
        int ret;

        net = hv_get_drvdata(dev);

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

        rtnl_lock();

        nvdev = rtnl_dereference(ndev_ctx->nvdev);
        if (nvdev == NULL) {
                ret = -ENODEV;
                goto out;
        }

        /* Save the current config info */
        ndev_ctx->saved_netvsc_dev_info = netvsc_devinfo_get(nvdev);

        ret = netvsc_detach(net, nvdev);
out:
        rtnl_unlock();

        return ret;
}

static int netvsc_resume(struct hv_device *dev)
{
        struct net_device *net = hv_get_drvdata(dev);
        struct net_device_context *net_device_ctx;
        struct netvsc_device_info *device_info;
        int ret;

        rtnl_lock();

        net_device_ctx = netdev_priv(net);

        /* Reset the data path to the netvsc NIC before re-opening the vmbus
         * channel. Later netvsc_netdev_event() will switch the data path to
         * the VF upon the UP or CHANGE event.
         */
        net_device_ctx->data_path_is_vf = false;
        device_info = net_device_ctx->saved_netvsc_dev_info;

        ret = netvsc_attach(net, device_info);

        netvsc_devinfo_put(device_info);
        net_device_ctx->saved_netvsc_dev_info = NULL;

        rtnl_unlock();

        return ret;
}
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,
        .suspend = netvsc_suspend,
        .resume = netvsc_resume,
        .driver = {
                .probe_type = PROBE_FORCE_SYNCHRONOUS,
        },
};

/*
 * On Hyper-V, every VF interface is matched with a corresponding
 * synthetic interface. The synthetic interface is presented first
 * to the guest. When the corresponding VF instance is registered,
 * we will take care of switching the data path.
 */
static int netvsc_netdev_event(struct notifier_block *this,
                               unsigned long event, void *ptr)
{
        struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);

        /* Skip our own events */
        if (event_dev->netdev_ops == &device_ops)
                return NOTIFY_DONE;

        /* Avoid non-Ethernet type devices */
        if (event_dev->type != ARPHRD_ETHER)
                return NOTIFY_DONE;

        /* Avoid Vlan dev with same MAC registering as VF */
        if (is_vlan_dev(event_dev))
                return NOTIFY_DONE;

        /* Avoid Bonding master dev with same MAC registering as VF */
        if ((event_dev->priv_flags & IFF_BONDING) &&
            (event_dev->flags & IFF_MASTER))
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_REGISTER:
                return netvsc_register_vf(event_dev);
        case NETDEV_UNREGISTER:
                return netvsc_unregister_vf(event_dev);
        case NETDEV_UP:
        case NETDEV_DOWN:
        case NETDEV_CHANGE:
        case NETDEV_GOING_DOWN:
                return netvsc_vf_changed(event_dev, event);
        default:
                return NOTIFY_DONE;
        }
}

static struct notifier_block netvsc_netdev_notifier = {
        .notifier_call = netvsc_netdev_event,
};

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

static int __init netvsc_drv_init(void)
{
        int ret;

        if (ring_size < RING_SIZE_MIN) {
                ring_size = RING_SIZE_MIN;
                pr_info("Increased ring_size to %u (min allowed)\n",
                        ring_size);
        }
        netvsc_ring_bytes = ring_size * PAGE_SIZE;

        ret = vmbus_driver_register(&netvsc_drv);
        if (ret)
                return ret;

        register_netdevice_notifier(&netvsc_netdev_notifier);
        return 0;
}

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

module_init(netvsc_drv_init);
module_exit(netvsc_drv_exit);