// 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/kernel.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/if_ether.h>
#include <linux/vmalloc.h>
#include <linux/rtnetlink.h>
#include <linux/prefetch.h>
#include <linux/filter.h>

#include <asm/sync_bitops.h>
#include <asm/mshyperv.h>

#include "hyperv_net.h"
#include "netvsc_trace.h"

/*
 * Switch the data path from the synthetic interface to the VF
 * interface.
 */
int netvsc_switch_datapath(struct net_device *ndev, bool vf)
{
        struct net_device_context *net_device_ctx = netdev_priv(ndev);
        struct hv_device *dev = net_device_ctx->device_ctx;
        struct netvsc_device *nv_dev = rtnl_dereference(net_device_ctx->nvdev);
        struct nvsp_message *init_pkt = &nv_dev->channel_init_pkt;
        int ret, retry = 0;

        /* Block sending traffic to VF if it's about to be gone */
        if (!vf)
                net_device_ctx->data_path_is_vf = vf;

        memset(init_pkt, 0, sizeof(struct nvsp_message));
        init_pkt->hdr.msg_type = NVSP_MSG4_TYPE_SWITCH_DATA_PATH;
        if (vf)
                init_pkt->msg.v4_msg.active_dp.active_datapath =
                        NVSP_DATAPATH_VF;
        else
                init_pkt->msg.v4_msg.active_dp.active_datapath =
                        NVSP_DATAPATH_SYNTHETIC;

again:
        trace_nvsp_send(ndev, init_pkt);

        ret = vmbus_sendpacket(dev->channel, init_pkt,
                               sizeof(struct nvsp_message),
                               (unsigned long)init_pkt, VM_PKT_DATA_INBAND,
                               VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

        /* If failed to switch to/from VF, let data_path_is_vf stay false,
         * so we use synthetic path to send data.
         */
        if (ret) {
                if (ret != -EAGAIN) {
                        netdev_err(ndev,
                                   "Unable to send sw datapath msg, err: %d\n",
                                   ret);
                        return ret;
                }

                if (retry++ < RETRY_MAX) {
                        usleep_range(RETRY_US_LO, RETRY_US_HI);
                        goto again;
                } else {
                        netdev_err(
                                ndev,
                                "Retry failed to send sw datapath msg, err: %d\n",
                                ret);
                        return ret;
                }
        }

        wait_for_completion(&nv_dev->channel_init_wait);
        net_device_ctx->data_path_is_vf = vf;

        return 0;
}

/* Worker to setup sub channels on initial setup
 * Initial hotplug event occurs in softirq context
 * and can't wait for channels.
 */
static void netvsc_subchan_work(struct work_struct *w)
{
        struct netvsc_device *nvdev =
                container_of(w, struct netvsc_device, subchan_work);
        struct rndis_device *rdev;
        int i, ret;

        /* Avoid deadlock with device removal already under RTNL */
        if (!rtnl_trylock()) {
                schedule_work(w);
                return;
        }

        rdev = nvdev->extension;
        if (rdev) {
                ret = rndis_set_subchannel(rdev->ndev, nvdev, NULL);
                if (ret == 0) {
                        netif_device_attach(rdev->ndev);
                } else {
                        /* fallback to only primary channel */
                        for (i = 1; i < nvdev->num_chn; i++)
                                netif_napi_del(&nvdev->chan_table[i].napi);

                        nvdev->max_chn = 1;
                        nvdev->num_chn = 1;
                }
        }

        rtnl_unlock();
}

static struct netvsc_device *alloc_net_device(void)
{
        struct netvsc_device *net_device;

        net_device = kzalloc_obj(struct netvsc_device);
        if (!net_device)
                return NULL;

        init_waitqueue_head(&net_device->wait_drain);
        net_device->destroy = false;
        net_device->tx_disable = true;

        net_device->max_pkt = RNDIS_MAX_PKT_DEFAULT;
        net_device->pkt_align = RNDIS_PKT_ALIGN_DEFAULT;

        init_completion(&net_device->channel_init_wait);
        init_waitqueue_head(&net_device->subchan_open);
        INIT_WORK(&net_device->subchan_work, netvsc_subchan_work);

        return net_device;
}

static void free_netvsc_device(struct rcu_head *head)
{
        struct netvsc_device *nvdev
                = container_of(head, struct netvsc_device, rcu);
        int i;

        kfree(nvdev->extension);

        if (!nvdev->recv_buf_gpadl_handle.decrypted)
                vfree(nvdev->recv_buf);
        if (!nvdev->send_buf_gpadl_handle.decrypted)
                vfree(nvdev->send_buf);
        bitmap_free(nvdev->send_section_map);

        for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
                xdp_rxq_info_unreg(&nvdev->chan_table[i].xdp_rxq);
                kfree(nvdev->chan_table[i].recv_buf);
                vfree(nvdev->chan_table[i].mrc.slots);
        }

        kfree(nvdev);
}

static void free_netvsc_device_rcu(struct netvsc_device *nvdev)
{
        call_rcu(&nvdev->rcu, free_netvsc_device);
}

static void netvsc_revoke_recv_buf(struct hv_device *device,
                                   struct netvsc_device *net_device,
                                   struct net_device *ndev)
{
        struct nvsp_message *revoke_packet;
        int ret;

        /*
         * If we got a section count, it means we received a
         * SendReceiveBufferComplete msg (ie sent
         * NvspMessage1TypeSendReceiveBuffer msg) therefore, we need
         * to send a revoke msg here
         */
        if (net_device->recv_section_cnt) {
                /* Send the revoke receive buffer */
                revoke_packet = &net_device->revoke_packet;
                memset(revoke_packet, 0, sizeof(struct nvsp_message));

                revoke_packet->hdr.msg_type =
                        NVSP_MSG1_TYPE_REVOKE_RECV_BUF;
                revoke_packet->msg.v1_msg.
                revoke_recv_buf.id = NETVSC_RECEIVE_BUFFER_ID;

                trace_nvsp_send(ndev, revoke_packet);

                ret = vmbus_sendpacket(device->channel,
                                       revoke_packet,
                                       sizeof(struct nvsp_message),
                                       VMBUS_RQST_ID_NO_RESPONSE,
                                       VM_PKT_DATA_INBAND, 0);
                /* If the failure is because the channel is rescinded;
                 * ignore the failure since we cannot send on a rescinded
                 * channel. This would allow us to properly cleanup
                 * even when the channel is rescinded.
                 */
                if (device->channel->rescind)
                        ret = 0;
                /*
                 * If we failed here, we might as well return and
                 * have a leak rather than continue and a bugchk
                 */
                if (ret != 0) {
                        netdev_err(ndev, "unable to send "
                                "revoke receive buffer to netvsp\n");
                        return;
                }
                net_device->recv_section_cnt = 0;
        }
}

static void netvsc_revoke_send_buf(struct hv_device *device,
                                   struct netvsc_device *net_device,
                                   struct net_device *ndev)
{
        struct nvsp_message *revoke_packet;
        int ret;

        /* Deal with the send buffer we may have setup.
         * If we got a  send section size, it means we received a
         * NVSP_MSG1_TYPE_SEND_SEND_BUF_COMPLETE msg (ie sent
         * NVSP_MSG1_TYPE_SEND_SEND_BUF msg) therefore, we need
         * to send a revoke msg here
         */
        if (net_device->send_section_cnt) {
                /* Send the revoke receive buffer */
                revoke_packet = &net_device->revoke_packet;
                memset(revoke_packet, 0, sizeof(struct nvsp_message));

                revoke_packet->hdr.msg_type =
                        NVSP_MSG1_TYPE_REVOKE_SEND_BUF;
                revoke_packet->msg.v1_msg.revoke_send_buf.id =
                        NETVSC_SEND_BUFFER_ID;

                trace_nvsp_send(ndev, revoke_packet);

                ret = vmbus_sendpacket(device->channel,
                                       revoke_packet,
                                       sizeof(struct nvsp_message),
                                       VMBUS_RQST_ID_NO_RESPONSE,
                                       VM_PKT_DATA_INBAND, 0);

                /* If the failure is because the channel is rescinded;
                 * ignore the failure since we cannot send on a rescinded
                 * channel. This would allow us to properly cleanup
                 * even when the channel is rescinded.
                 */
                if (device->channel->rescind)
                        ret = 0;

                /* If we failed here, we might as well return and
                 * have a leak rather than continue and a bugchk
                 */
                if (ret != 0) {
                        netdev_err(ndev, "unable to send "
                                   "revoke send buffer to netvsp\n");
                        return;
                }
                net_device->send_section_cnt = 0;
        }
}

static void netvsc_teardown_recv_gpadl(struct hv_device *device,
                                       struct netvsc_device *net_device,
                                       struct net_device *ndev)
{
        int ret;

        if (net_device->recv_buf_gpadl_handle.gpadl_handle) {
                ret = vmbus_teardown_gpadl(device->channel,
                                           &net_device->recv_buf_gpadl_handle);

                /* If we failed here, we might as well return and have a leak
                 * rather than continue and a bugchk
                 */
                if (ret != 0) {
                        netdev_err(ndev,
                                   "unable to teardown receive buffer's gpadl\n");
                        return;
                }
        }
}

static void netvsc_teardown_send_gpadl(struct hv_device *device,
                                       struct netvsc_device *net_device,
                                       struct net_device *ndev)
{
        int ret;

        if (net_device->send_buf_gpadl_handle.gpadl_handle) {
                ret = vmbus_teardown_gpadl(device->channel,
                                           &net_device->send_buf_gpadl_handle);

                /* If we failed here, we might as well return and have a leak
                 * rather than continue and a bugchk
                 */
                if (ret != 0) {
                        netdev_err(ndev,
                                   "unable to teardown send buffer's gpadl\n");
                        return;
                }
        }
}

int netvsc_alloc_recv_comp_ring(struct netvsc_device *net_device, u32 q_idx)
{
        struct netvsc_channel *nvchan = &net_device->chan_table[q_idx];
        int node = cpu_to_node(nvchan->channel->target_cpu);
        size_t size;

        size = net_device->recv_completion_cnt * sizeof(struct recv_comp_data);
        nvchan->mrc.slots = vzalloc_node(size, node);
        if (!nvchan->mrc.slots)
                nvchan->mrc.slots = vzalloc(size);

        return nvchan->mrc.slots ? 0 : -ENOMEM;
}

static int netvsc_init_buf(struct hv_device *device,
                           struct netvsc_device *net_device,
                           const struct netvsc_device_info *device_info)
{
        struct nvsp_1_message_send_receive_buffer_complete *resp;
        struct net_device *ndev = hv_get_drvdata(device);
        struct nvsp_message *init_packet;
        unsigned int buf_size;
        int i, ret = 0;

        /* Get receive buffer area. */
        buf_size = device_info->recv_sections * device_info->recv_section_size;
        buf_size = roundup(buf_size, PAGE_SIZE);

        /* Legacy hosts only allow smaller receive buffer */
        if (net_device->nvsp_version <= NVSP_PROTOCOL_VERSION_2)
                buf_size = min_t(unsigned int, buf_size,
                                 NETVSC_RECEIVE_BUFFER_SIZE_LEGACY);

        net_device->recv_buf = vzalloc(buf_size);
        if (!net_device->recv_buf) {
                netdev_err(ndev,
                           "unable to allocate receive buffer of size %u\n",
                           buf_size);
                ret = -ENOMEM;
                goto cleanup;
        }

        net_device->recv_buf_size = buf_size;

        /*
         * Establish the gpadl handle for this buffer on this
         * channel.  Note: This call uses the vmbus connection rather
         * than the channel to establish the gpadl handle.
         */
        ret = vmbus_establish_gpadl(device->channel, net_device->recv_buf,
                                    buf_size,
                                    &net_device->recv_buf_gpadl_handle);
        if (ret != 0) {
                netdev_err(ndev,
                        "unable to establish receive buffer's gpadl\n");
                goto cleanup;
        }

        /* Notify the NetVsp of the gpadl handle */
        init_packet = &net_device->channel_init_pkt;
        memset(init_packet, 0, sizeof(struct nvsp_message));
        init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_RECV_BUF;
        init_packet->msg.v1_msg.send_recv_buf.
                gpadl_handle = net_device->recv_buf_gpadl_handle.gpadl_handle;
        init_packet->msg.v1_msg.
                send_recv_buf.id = NETVSC_RECEIVE_BUFFER_ID;

        trace_nvsp_send(ndev, init_packet);

        /* Send the gpadl notification request */
        ret = vmbus_sendpacket(device->channel, init_packet,
                               sizeof(struct nvsp_message),
                               (unsigned long)init_packet,
                               VM_PKT_DATA_INBAND,
                               VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
        if (ret != 0) {
                netdev_err(ndev,
                        "unable to send receive buffer's gpadl to netvsp\n");
                goto cleanup;
        }

        wait_for_completion(&net_device->channel_init_wait);

        /* Check the response */
        resp = &init_packet->msg.v1_msg.send_recv_buf_complete;
        if (resp->status != NVSP_STAT_SUCCESS) {
                netdev_err(ndev,
                           "Unable to complete receive buffer initialization with NetVsp - status %d\n",
                           resp->status);
                ret = -EINVAL;
                goto cleanup;
        }

        /* Parse the response */
        netdev_dbg(ndev, "Receive sections: %u sub_allocs: size %u count: %u\n",
                   resp->num_sections, resp->sections[0].sub_alloc_size,
                   resp->sections[0].num_sub_allocs);

        /* There should only be one section for the entire receive buffer */
        if (resp->num_sections != 1 || resp->sections[0].offset != 0) {
                ret = -EINVAL;
                goto cleanup;
        }

        net_device->recv_section_size = resp->sections[0].sub_alloc_size;
        net_device->recv_section_cnt = resp->sections[0].num_sub_allocs;

        /* Ensure buffer will not overflow */
        if (net_device->recv_section_size < NETVSC_MTU_MIN || (u64)net_device->recv_section_size *
            (u64)net_device->recv_section_cnt > (u64)buf_size) {
                netdev_err(ndev, "invalid recv_section_size %u\n",
                           net_device->recv_section_size);
                ret = -EINVAL;
                goto cleanup;
        }

        for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
                struct netvsc_channel *nvchan = &net_device->chan_table[i];

                nvchan->recv_buf = kzalloc(net_device->recv_section_size, GFP_KERNEL);
                if (nvchan->recv_buf == NULL) {
                        ret = -ENOMEM;
                        goto cleanup;
                }
        }

        /* Setup receive completion ring.
         * Add 1 to the recv_section_cnt because at least one entry in a
         * ring buffer has to be empty.
         */
        net_device->recv_completion_cnt = net_device->recv_section_cnt + 1;
        ret = netvsc_alloc_recv_comp_ring(net_device, 0);
        if (ret)
                goto cleanup;

        /* Now setup the send buffer. */
        buf_size = device_info->send_sections * device_info->send_section_size;
        buf_size = round_up(buf_size, PAGE_SIZE);

        net_device->send_buf = vzalloc(buf_size);
        if (!net_device->send_buf) {
                netdev_err(ndev, "unable to allocate send buffer of size %u\n",
                           buf_size);
                ret = -ENOMEM;
                goto cleanup;
        }
        net_device->send_buf_size = buf_size;

        /* Establish the gpadl handle for this buffer on this
         * channel.  Note: This call uses the vmbus connection rather
         * than the channel to establish the gpadl handle.
         */
        ret = vmbus_establish_gpadl(device->channel, net_device->send_buf,
                                    buf_size,
                                    &net_device->send_buf_gpadl_handle);
        if (ret != 0) {
                netdev_err(ndev,
                           "unable to establish send buffer's gpadl\n");
                goto cleanup;
        }

        /* Notify the NetVsp of the gpadl handle */
        init_packet = &net_device->channel_init_pkt;
        memset(init_packet, 0, sizeof(struct nvsp_message));
        init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_SEND_BUF;
        init_packet->msg.v1_msg.send_send_buf.gpadl_handle =
                net_device->send_buf_gpadl_handle.gpadl_handle;
        init_packet->msg.v1_msg.send_send_buf.id = NETVSC_SEND_BUFFER_ID;

        trace_nvsp_send(ndev, init_packet);

        /* Send the gpadl notification request */
        ret = vmbus_sendpacket(device->channel, init_packet,
                               sizeof(struct nvsp_message),
                               (unsigned long)init_packet,
                               VM_PKT_DATA_INBAND,
                               VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
        if (ret != 0) {
                netdev_err(ndev,
                           "unable to send send buffer's gpadl to netvsp\n");
                goto cleanup;
        }

        wait_for_completion(&net_device->channel_init_wait);

        /* Check the response */
        if (init_packet->msg.v1_msg.
            send_send_buf_complete.status != NVSP_STAT_SUCCESS) {
                netdev_err(ndev, "Unable to complete send buffer "
                           "initialization with NetVsp - status %d\n",
                           init_packet->msg.v1_msg.
                           send_send_buf_complete.status);
                ret = -EINVAL;
                goto cleanup;
        }

        /* Parse the response */
        net_device->send_section_size = init_packet->msg.
                                v1_msg.send_send_buf_complete.section_size;
        if (net_device->send_section_size < NETVSC_MTU_MIN) {
                netdev_err(ndev, "invalid send_section_size %u\n",
                           net_device->send_section_size);
                ret = -EINVAL;
                goto cleanup;
        }

        /* Section count is simply the size divided by the section size. */
        net_device->send_section_cnt = buf_size / net_device->send_section_size;

        netdev_dbg(ndev, "Send section size: %d, Section count:%d\n",
                   net_device->send_section_size, net_device->send_section_cnt);

        /* Setup state for managing the send buffer. */
        net_device->send_section_map = bitmap_zalloc(net_device->send_section_cnt,
                                                     GFP_KERNEL);
        if (!net_device->send_section_map) {
                ret = -ENOMEM;
                goto cleanup;
        }

        goto exit;

cleanup:
        netvsc_revoke_recv_buf(device, net_device, ndev);
        netvsc_revoke_send_buf(device, net_device, ndev);
        netvsc_teardown_recv_gpadl(device, net_device, ndev);
        netvsc_teardown_send_gpadl(device, net_device, ndev);

exit:
        return ret;
}

/* Negotiate NVSP protocol version */
static int negotiate_nvsp_ver(struct hv_device *device,
                              struct netvsc_device *net_device,
                              struct nvsp_message *init_packet,
                              u32 nvsp_ver)
{
        struct net_device *ndev = hv_get_drvdata(device);
        int ret;

        memset(init_packet, 0, sizeof(struct nvsp_message));
        init_packet->hdr.msg_type = NVSP_MSG_TYPE_INIT;
        init_packet->msg.init_msg.init.min_protocol_ver = nvsp_ver;
        init_packet->msg.init_msg.init.max_protocol_ver = nvsp_ver;
        trace_nvsp_send(ndev, init_packet);

        /* Send the init request */
        ret = vmbus_sendpacket(device->channel, init_packet,
                               sizeof(struct nvsp_message),
                               (unsigned long)init_packet,
                               VM_PKT_DATA_INBAND,
                               VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

        if (ret != 0)
                return ret;

        wait_for_completion(&net_device->channel_init_wait);

        if (init_packet->msg.init_msg.init_complete.status !=
            NVSP_STAT_SUCCESS)
                return -EINVAL;

        if (nvsp_ver == NVSP_PROTOCOL_VERSION_1)
                return 0;

        /* NVSPv2 or later: Send NDIS config */
        memset(init_packet, 0, sizeof(struct nvsp_message));
        init_packet->hdr.msg_type = NVSP_MSG2_TYPE_SEND_NDIS_CONFIG;
        init_packet->msg.v2_msg.send_ndis_config.mtu = ndev->mtu + ETH_HLEN;
        init_packet->msg.v2_msg.send_ndis_config.capability.ieee8021q = 1;

        if (nvsp_ver >= NVSP_PROTOCOL_VERSION_5) {
                if (hv_is_isolation_supported())
                        netdev_info(ndev, "SR-IOV not advertised by guests on the host supporting isolation\n");
                else
                        init_packet->msg.v2_msg.send_ndis_config.capability.sriov = 1;

                /* Teaming bit is needed to receive link speed updates */
                init_packet->msg.v2_msg.send_ndis_config.capability.teaming = 1;
        }

        if (nvsp_ver >= NVSP_PROTOCOL_VERSION_61)
                init_packet->msg.v2_msg.send_ndis_config.capability.rsc = 1;

        trace_nvsp_send(ndev, init_packet);

        ret = vmbus_sendpacket(device->channel, init_packet,
                                sizeof(struct nvsp_message),
                                VMBUS_RQST_ID_NO_RESPONSE,
                                VM_PKT_DATA_INBAND, 0);

        return ret;
}

static int netvsc_connect_vsp(struct hv_device *device,
                              struct netvsc_device *net_device,
                              const struct netvsc_device_info *device_info)
{
        struct net_device *ndev = hv_get_drvdata(device);
        static const u32 ver_list[] = {
                NVSP_PROTOCOL_VERSION_1, NVSP_PROTOCOL_VERSION_2,
                NVSP_PROTOCOL_VERSION_4, NVSP_PROTOCOL_VERSION_5,
                NVSP_PROTOCOL_VERSION_6, NVSP_PROTOCOL_VERSION_61
        };
        struct nvsp_message *init_packet;
        int ndis_version, i, ret;

        init_packet = &net_device->channel_init_pkt;

        /* Negotiate the latest NVSP protocol supported */
        for (i = ARRAY_SIZE(ver_list) - 1; i >= 0; i--)
                if (negotiate_nvsp_ver(device, net_device, init_packet,
                                       ver_list[i])  == 0) {
                        net_device->nvsp_version = ver_list[i];
                        break;
                }

        if (i < 0) {
                ret = -EPROTO;
                goto cleanup;
        }

        if (hv_is_isolation_supported() && net_device->nvsp_version < NVSP_PROTOCOL_VERSION_61) {
                netdev_err(ndev, "Invalid NVSP version 0x%x (expected >= 0x%x) from the host supporting isolation\n",
                           net_device->nvsp_version, NVSP_PROTOCOL_VERSION_61);
                ret = -EPROTO;
                goto cleanup;
        }

        pr_debug("Negotiated NVSP version:%x\n", net_device->nvsp_version);

        /* Send the ndis version */
        memset(init_packet, 0, sizeof(struct nvsp_message));

        if (net_device->nvsp_version <= NVSP_PROTOCOL_VERSION_4)
                ndis_version = 0x00060001;
        else
                ndis_version = 0x0006001e;

        init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_NDIS_VER;
        init_packet->msg.v1_msg.
                send_ndis_ver.ndis_major_ver =
                                (ndis_version & 0xFFFF0000) >> 16;
        init_packet->msg.v1_msg.
                send_ndis_ver.ndis_minor_ver =
                                ndis_version & 0xFFFF;

        trace_nvsp_send(ndev, init_packet);

        /* Send the init request */
        ret = vmbus_sendpacket(device->channel, init_packet,
                                sizeof(struct nvsp_message),
                                VMBUS_RQST_ID_NO_RESPONSE,
                                VM_PKT_DATA_INBAND, 0);
        if (ret != 0)
                goto cleanup;


        ret = netvsc_init_buf(device, net_device, device_info);

cleanup:
        return ret;
}

/*
 * netvsc_device_remove - Callback when the root bus device is removed
 */
void netvsc_device_remove(struct hv_device *device)
{
        struct net_device *ndev = hv_get_drvdata(device);
        struct net_device_context *net_device_ctx = netdev_priv(ndev);
        struct netvsc_device *net_device
                = rtnl_dereference(net_device_ctx->nvdev);
        int i;

        /*
         * Revoke receive buffer. If host is pre-Win2016 then tear down
         * receive buffer GPADL. Do the same for send buffer.
         */
        netvsc_revoke_recv_buf(device, net_device, ndev);
        if (vmbus_proto_version < VERSION_WIN10)
                netvsc_teardown_recv_gpadl(device, net_device, ndev);

        netvsc_revoke_send_buf(device, net_device, ndev);
        if (vmbus_proto_version < VERSION_WIN10)
                netvsc_teardown_send_gpadl(device, net_device, ndev);

        RCU_INIT_POINTER(net_device_ctx->nvdev, NULL);

        /* Disable NAPI and disassociate its context from the device. */
        for (i = 0; i < net_device->num_chn; i++) {
                /* See also vmbus_reset_channel_cb(). */
                /* only disable enabled NAPI channel */
                if (i < ndev->real_num_rx_queues) {
                        netif_queue_set_napi(ndev, i, NETDEV_QUEUE_TYPE_TX,
                                             NULL);
                        netif_queue_set_napi(ndev, i, NETDEV_QUEUE_TYPE_RX,
                                             NULL);
                        napi_disable(&net_device->chan_table[i].napi);
                }

                netif_napi_del(&net_device->chan_table[i].napi);
        }

        /*
         * At this point, no one should be accessing net_device
         * except in here
         */
        netdev_dbg(ndev, "net device safe to remove\n");

        /* Now, we can close the channel safely */
        vmbus_close(device->channel);

        /*
         * If host is Win2016 or higher then we do the GPADL tear down
         * here after VMBus is closed.
        */
        if (vmbus_proto_version >= VERSION_WIN10) {
                netvsc_teardown_recv_gpadl(device, net_device, ndev);
                netvsc_teardown_send_gpadl(device, net_device, ndev);
        }

        /* Release all resources */
        free_netvsc_device_rcu(net_device);
}

#define RING_AVAIL_PERCENT_HIWATER 20
#define RING_AVAIL_PERCENT_LOWATER 10

static inline void netvsc_free_send_slot(struct netvsc_device *net_device,
                                         u32 index)
{
        sync_change_bit(index, net_device->send_section_map);
}

static void netvsc_send_tx_complete(struct net_device *ndev,
                                    struct netvsc_device *net_device,
                                    struct vmbus_channel *channel,
                                    const struct vmpacket_descriptor *desc,
                                    int budget)
{
        struct net_device_context *ndev_ctx = netdev_priv(ndev);
        struct sk_buff *skb;
        u16 q_idx = 0;
        int queue_sends;
        u64 cmd_rqst;

        cmd_rqst = channel->request_addr_callback(channel, desc->trans_id);
        if (cmd_rqst == VMBUS_RQST_ERROR) {
                netdev_err(ndev, "Invalid transaction ID %llx\n", desc->trans_id);
                return;
        }

        skb = (struct sk_buff *)(unsigned long)cmd_rqst;

        /* Notify the layer above us */
        if (likely(skb)) {
                struct hv_netvsc_packet *packet
                        = (struct hv_netvsc_packet *)skb->cb;
                u32 send_index = packet->send_buf_index;
                struct netvsc_stats_tx *tx_stats;

                if (send_index != NETVSC_INVALID_INDEX)
                        netvsc_free_send_slot(net_device, send_index);
                q_idx = packet->q_idx;

                tx_stats = &net_device->chan_table[q_idx].tx_stats;

                u64_stats_update_begin(&tx_stats->syncp);
                tx_stats->packets += packet->total_packets;
                tx_stats->bytes += packet->total_bytes;
                u64_stats_update_end(&tx_stats->syncp);

                netvsc_dma_unmap(ndev_ctx->device_ctx, packet);
                napi_consume_skb(skb, budget);
        }

        queue_sends =
                atomic_dec_return(&net_device->chan_table[q_idx].queue_sends);

        if (unlikely(net_device->destroy)) {
                if (queue_sends == 0)
                        wake_up(&net_device->wait_drain);
        } else {
                struct netdev_queue *txq = netdev_get_tx_queue(ndev, q_idx);

                if (netif_tx_queue_stopped(txq) && !net_device->tx_disable &&
                    (hv_get_avail_to_write_percent(&channel->outbound) >
                     RING_AVAIL_PERCENT_HIWATER || queue_sends < 1)) {
                        netif_tx_wake_queue(txq);
                        ndev_ctx->eth_stats.wake_queue++;
                }
        }
}

static void netvsc_send_completion(struct net_device *ndev,
                                   struct netvsc_device *net_device,
                                   struct vmbus_channel *incoming_channel,
                                   const struct vmpacket_descriptor *desc,
                                   int budget)
{
        const struct nvsp_message *nvsp_packet;
        u32 msglen = hv_pkt_datalen(desc);
        struct nvsp_message *pkt_rqst;
        u64 cmd_rqst;
        u32 status;

        /* First check if this is a VMBUS completion without data payload */
        if (!msglen) {
                cmd_rqst = incoming_channel->request_addr_callback(incoming_channel,
                                                                   desc->trans_id);
                if (cmd_rqst == VMBUS_RQST_ERROR) {
                        netdev_err(ndev, "Invalid transaction ID %llx\n", desc->trans_id);
                        return;
                }

                pkt_rqst = (struct nvsp_message *)(uintptr_t)cmd_rqst;
                switch (pkt_rqst->hdr.msg_type) {
                case NVSP_MSG4_TYPE_SWITCH_DATA_PATH:
                        complete(&net_device->channel_init_wait);
                        break;

                default:
                        netdev_err(ndev, "Unexpected VMBUS completion!!\n");
                }
                return;
        }

        /* Ensure packet is big enough to read header fields */
        if (msglen < sizeof(struct nvsp_message_header)) {
                netdev_err(ndev, "nvsp_message length too small: %u\n", msglen);
                return;
        }

        nvsp_packet = hv_pkt_data(desc);
        switch (nvsp_packet->hdr.msg_type) {
        case NVSP_MSG_TYPE_INIT_COMPLETE:
                if (msglen < sizeof(struct nvsp_message_header) +
                                sizeof(struct nvsp_message_init_complete)) {
                        netdev_err(ndev, "nvsp_msg length too small: %u\n",
                                   msglen);
                        return;
                }
                break;

        case NVSP_MSG1_TYPE_SEND_RECV_BUF_COMPLETE:
                if (msglen < sizeof(struct nvsp_message_header) +
                                struct_size_t(struct nvsp_1_message_send_receive_buffer_complete,
                                              sections, 1)) {
                        netdev_err(ndev, "nvsp_msg1 length too small: %u\n",
                                   msglen);
                        return;
                }
                break;

        case NVSP_MSG1_TYPE_SEND_SEND_BUF_COMPLETE:
                if (msglen < sizeof(struct nvsp_message_header) +
                                sizeof(struct nvsp_1_message_send_send_buffer_complete)) {
                        netdev_err(ndev, "nvsp_msg1 length too small: %u\n",
                                   msglen);
                        return;
                }
                break;

        case NVSP_MSG5_TYPE_SUBCHANNEL:
                if (msglen < sizeof(struct nvsp_message_header) +
                                sizeof(struct nvsp_5_subchannel_complete)) {
                        netdev_err(ndev, "nvsp_msg5 length too small: %u\n",
                                   msglen);
                        return;
                }
                break;

        case NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE:
                if (msglen < sizeof(struct nvsp_message_header) +
                    sizeof(struct nvsp_1_message_send_rndis_packet_complete)) {
                        if (net_ratelimit())
                                netdev_err(ndev, "nvsp_rndis_pkt_complete length too small: %u\n",
                                           msglen);
                        return;
                }

                /* If status indicates an error, output a message so we know
                 * there's a problem. But process the completion anyway so the
                 * resources are released.
                 */
                status = nvsp_packet->msg.v1_msg.send_rndis_pkt_complete.status;
                if (status != NVSP_STAT_SUCCESS && net_ratelimit())
                        netdev_err(ndev, "nvsp_rndis_pkt_complete error status: %x\n",
                                   status);

                netvsc_send_tx_complete(ndev, net_device, incoming_channel,
                                        desc, budget);
                return;

        default:
                netdev_err(ndev,
                           "Unknown send completion type %d received!!\n",
                           nvsp_packet->hdr.msg_type);
                return;
        }

        /* Copy the response back */
        memcpy(&net_device->channel_init_pkt, nvsp_packet,
               sizeof(struct nvsp_message));
        complete(&net_device->channel_init_wait);
}

static u32 netvsc_get_next_send_section(struct netvsc_device *net_device)
{
        unsigned long *map_addr = net_device->send_section_map;
        unsigned int i;

        for_each_clear_bit(i, map_addr, net_device->send_section_cnt) {
                if (sync_test_and_set_bit(i, map_addr) == 0)
                        return i;
        }

        return NETVSC_INVALID_INDEX;
}

static void netvsc_copy_to_send_buf(struct netvsc_device *net_device,
                                    unsigned int section_index,
                                    u32 pend_size,
                                    struct hv_netvsc_packet *packet,
                                    struct rndis_message *rndis_msg,
                                    struct hv_page_buffer *pb,
                                    bool xmit_more)
{
        char *start = net_device->send_buf;
        char *dest = start + (section_index * net_device->send_section_size)
                     + pend_size;
        int i;
        u32 padding = 0;
        u32 page_count = packet->cp_partial ? 1 : packet->page_buf_cnt;
        u32 remain;

        /* Add padding */
        remain = packet->total_data_buflen & (net_device->pkt_align - 1);
        if (xmit_more && remain) {
                padding = net_device->pkt_align - remain;
                rndis_msg->msg_len += padding;
                packet->total_data_buflen += padding;
        }

        for (i = 0; i < page_count; i++) {
                phys_addr_t paddr = (pb[i].pfn << HV_HYP_PAGE_SHIFT) +
                                    pb[i].offset;
                u32 len = pb[i].len;

                while (len) {
                        struct page *page = phys_to_page(paddr);
                        u32 off = offset_in_page(paddr);
                        u32 chunk = min_t(u32, len, PAGE_SIZE - off);
                        char *src = kmap_local_page(page);

                        memcpy(dest, src + off, chunk);
                        kunmap_local(src);
                        dest += chunk;
                        paddr += chunk;
                        len -= chunk;
                }
        }

        if (padding)
                memset(dest, 0, padding);
}

void netvsc_dma_unmap(struct hv_device *hv_dev,
                      struct hv_netvsc_packet *packet)
{
        int i;

        if (!hv_is_isolation_supported())
                return;

        if (!packet->dma_range)
                return;

        for (i = 0; i < packet->page_buf_cnt; i++)
                dma_unmap_single(&hv_dev->device, packet->dma_range[i].dma,
                                 packet->dma_range[i].mapping_size,
                                 DMA_TO_DEVICE);

        kfree(packet->dma_range);
}

/* netvsc_dma_map - Map swiotlb bounce buffer with data page of
 * packet sent by vmbus_sendpacket_pagebuffer() in the Isolation
 * VM.
 *
 * In isolation VM, netvsc send buffer has been marked visible to
 * host and so the data copied to send buffer doesn't need to use
 * bounce buffer. The data pages handled by vmbus_sendpacket_pagebuffer()
 * may not be copied to send buffer and so these pages need to be
 * mapped with swiotlb bounce buffer. netvsc_dma_map() is to do
 * that. The pfns in the struct hv_page_buffer need to be converted
 * to bounce buffer's pfn. The loop here is necessary because the
 * entries in the page buffer array are not necessarily full
 * pages of data.  Each entry in the array has a separate offset and
 * len that may be non-zero, even for entries in the middle of the
 * array.  And the entries are not physically contiguous.  So each
 * entry must be individually mapped rather than as a contiguous unit.
 * So not use dma_map_sg() here.
 */
static int netvsc_dma_map(struct hv_device *hv_dev,
                          struct hv_netvsc_packet *packet,
                          struct hv_page_buffer *pb)
{
        u32 page_count = packet->page_buf_cnt;
        dma_addr_t dma;
        int i;

        if (!hv_is_isolation_supported())
                return 0;

        packet->dma_range = kzalloc_objs(*packet->dma_range, page_count,
                                         GFP_ATOMIC);
        if (!packet->dma_range)
                return -ENOMEM;

        for (i = 0; i < page_count; i++) {
                char *src = phys_to_virt((pb[i].pfn << HV_HYP_PAGE_SHIFT)
                                         + pb[i].offset);
                u32 len = pb[i].len;

                dma = dma_map_single(&hv_dev->device, src, len,
                                     DMA_TO_DEVICE);
                if (dma_mapping_error(&hv_dev->device, dma)) {
                        kfree(packet->dma_range);
                        return -ENOMEM;
                }

                /* pb[].offset and pb[].len are not changed during dma mapping
                 * and so not reassign.
                 */
                packet->dma_range[i].dma = dma;
                packet->dma_range[i].mapping_size = len;
                pb[i].pfn = dma >> HV_HYP_PAGE_SHIFT;
        }

        return 0;
}

/* Build an "array" of mpb entries describing the data to be transferred
 * over VMBus. After the desc header fields, each "array" entry is variable
 * size, and each entry starts after the end of the previous entry. The
 * "offset" and "len" fields for each entry imply the size of the entry.
 *
 * The pfns are in HV_HYP_PAGE_SIZE, because all communication with Hyper-V
 * uses that granularity, even if the system page size of the guest is larger.
 * Each entry in the input "pb" array must describe a contiguous range of
 * guest physical memory so that the pfns are sequential if the range crosses
 * a page boundary. The offset field must be < HV_HYP_PAGE_SIZE.
 */
static inline void netvsc_build_mpb_array(struct hv_page_buffer *pb,
                                u32 page_buffer_count,
                                struct vmbus_packet_mpb_array *desc,
                                u32 *desc_size)
{
        struct hv_mpb_array *mpb_entry = &desc->range;
        int i, j;

        for (i = 0; i < page_buffer_count; i++) {
                u32 offset = pb[i].offset;
                u32 len = pb[i].len;

                mpb_entry->offset = offset;
                mpb_entry->len = len;

                for (j = 0; j < HVPFN_UP(offset + len); j++)
                        mpb_entry->pfn_array[j] = pb[i].pfn + j;

                mpb_entry = (struct hv_mpb_array *)&mpb_entry->pfn_array[j];
        }

        desc->rangecount = page_buffer_count;
        *desc_size = (char *)mpb_entry - (char *)desc;
}

static inline int netvsc_send_pkt(
        struct hv_device *device,
        struct hv_netvsc_packet *packet,
        struct netvsc_device *net_device,
        struct hv_page_buffer *pb,
        struct sk_buff *skb)
{
        struct nvsp_message nvmsg;
        struct nvsp_1_message_send_rndis_packet *rpkt =
                &nvmsg.msg.v1_msg.send_rndis_pkt;
        struct netvsc_channel * const nvchan =
                &net_device->chan_table[packet->q_idx];
        struct vmbus_channel *out_channel = nvchan->channel;
        struct net_device *ndev = hv_get_drvdata(device);
        struct net_device_context *ndev_ctx = netdev_priv(ndev);
        struct netdev_queue *txq = netdev_get_tx_queue(ndev, packet->q_idx);
        u64 req_id;
        int ret;
        u32 ring_avail = hv_get_avail_to_write_percent(&out_channel->outbound);

        memset(&nvmsg, 0, sizeof(struct nvsp_message));
        nvmsg.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT;
        if (skb)
                rpkt->channel_type = 0;         /* 0 is RMC_DATA */
        else
                rpkt->channel_type = 1;         /* 1 is RMC_CONTROL */

        rpkt->send_buf_section_index = packet->send_buf_index;
        if (packet->send_buf_index == NETVSC_INVALID_INDEX)
                rpkt->send_buf_section_size = 0;
        else
                rpkt->send_buf_section_size = packet->total_data_buflen;

        req_id = (ulong)skb;

        if (out_channel->rescind)
                return -ENODEV;

        trace_nvsp_send_pkt(ndev, out_channel, rpkt);

        packet->dma_range = NULL;
        if (packet->page_buf_cnt) {
                struct vmbus_channel_packet_page_buffer desc;
                u32 desc_size;

                if (packet->cp_partial)
                        pb++;

                ret = netvsc_dma_map(ndev_ctx->device_ctx, packet, pb);
                if (ret) {
                        ret = -EAGAIN;
                        goto exit;
                }

                netvsc_build_mpb_array(pb, packet->page_buf_cnt,
                                (struct vmbus_packet_mpb_array *)&desc,
                                 &desc_size);
                ret = vmbus_sendpacket_mpb_desc(out_channel,
                                (struct vmbus_packet_mpb_array *)&desc,
                                desc_size, &nvmsg, sizeof(nvmsg), req_id);
                if (ret)
                        netvsc_dma_unmap(ndev_ctx->device_ctx, packet);
        } else {
                ret = vmbus_sendpacket(out_channel,
                                       &nvmsg, sizeof(nvmsg),
                                       req_id, VM_PKT_DATA_INBAND,
                                       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
        }

exit:
        if (ret == 0) {
                atomic_inc_return(&nvchan->queue_sends);

                if (ring_avail < RING_AVAIL_PERCENT_LOWATER) {
                        netif_tx_stop_queue(txq);
                        ndev_ctx->eth_stats.stop_queue++;
                }
        } else if (ret == -EAGAIN) {
                netif_tx_stop_queue(txq);
                ndev_ctx->eth_stats.stop_queue++;
        } else {
                netdev_err(ndev,
                           "Unable to send packet pages %u len %u, ret %d\n",
                           packet->page_buf_cnt, packet->total_data_buflen,
                           ret);
        }

        if (netif_tx_queue_stopped(txq) &&
            atomic_read(&nvchan->queue_sends) < 1 &&
            !net_device->tx_disable) {
                netif_tx_wake_queue(txq);
                ndev_ctx->eth_stats.wake_queue++;
                if (ret == -EAGAIN)
                        ret = -ENOSPC;
        }

        return ret;
}

/* Move packet out of multi send data (msd), and clear msd */
static inline void move_pkt_msd(struct hv_netvsc_packet **msd_send,
                                struct sk_buff **msd_skb,
                                struct multi_send_data *msdp)
{
        *msd_skb = msdp->skb;
        *msd_send = msdp->pkt;
        msdp->skb = NULL;
        msdp->pkt = NULL;
        msdp->count = 0;
}

/* RCU already held by caller */
/* Batching/bouncing logic is designed to attempt to optimize
 * performance.
 *
 * For small, non-LSO packets we copy the packet to a send buffer
 * which is pre-registered with the Hyper-V side. This enables the
 * hypervisor to avoid remapping the aperture to access the packet
 * descriptor and data.
 *
 * If we already started using a buffer and the netdev is transmitting
 * a burst of packets, keep on copying into the buffer until it is
 * full or we are done collecting a burst. If there is an existing
 * buffer with space for the RNDIS descriptor but not the packet, copy
 * the RNDIS descriptor to the buffer, keeping the packet in place.
 *
 * If we do batching and send more than one packet using a single
 * NetVSC message, free the SKBs of the packets copied, except for the
 * last packet. This is done to streamline the handling of the case
 * where the last packet only had the RNDIS descriptor copied to the
 * send buffer, with the data pointers included in the NetVSC message.
 */
int netvsc_send(struct net_device *ndev,
                struct hv_netvsc_packet *packet,
                struct rndis_message *rndis_msg,
                struct hv_page_buffer *pb,
                struct sk_buff *skb,
                bool xdp_tx)
{
        struct net_device_context *ndev_ctx = netdev_priv(ndev);
        struct netvsc_device *net_device
                = rcu_dereference_bh(ndev_ctx->nvdev);
        struct hv_device *device = ndev_ctx->device_ctx;
        int ret = 0;
        struct netvsc_channel *nvchan;
        u32 pktlen = packet->total_data_buflen, msd_len = 0;
        unsigned int section_index = NETVSC_INVALID_INDEX;
        struct multi_send_data *msdp;
        struct hv_netvsc_packet *msd_send = NULL, *cur_send = NULL;
        struct sk_buff *msd_skb = NULL;
        bool try_batch, xmit_more;

        /* If device is rescinded, return error and packet will get dropped. */
        if (unlikely(!net_device || net_device->destroy))
                return -ENODEV;

        nvchan = &net_device->chan_table[packet->q_idx];
        packet->send_buf_index = NETVSC_INVALID_INDEX;
        packet->cp_partial = false;

        /* Send a control message or XDP packet directly without accessing
         * msd (Multi-Send Data) field which may be changed during data packet
         * processing.
         */
        if (!skb || xdp_tx)
                return netvsc_send_pkt(device, packet, net_device, pb, skb);

        /* batch packets in send buffer if possible */
        msdp = &nvchan->msd;
        if (msdp->pkt)
                msd_len = msdp->pkt->total_data_buflen;

        try_batch =  msd_len > 0 && msdp->count < net_device->max_pkt;
        if (try_batch && msd_len + pktlen + net_device->pkt_align <
            net_device->send_section_size) {
                section_index = msdp->pkt->send_buf_index;

        } else if (try_batch && msd_len + packet->rmsg_size <
                   net_device->send_section_size) {
                section_index = msdp->pkt->send_buf_index;
                packet->cp_partial = true;

        } else if (pktlen + net_device->pkt_align <
                   net_device->send_section_size) {
                section_index = netvsc_get_next_send_section(net_device);
                if (unlikely(section_index == NETVSC_INVALID_INDEX)) {
                        ++ndev_ctx->eth_stats.tx_send_full;
                } else {
                        move_pkt_msd(&msd_send, &msd_skb, msdp);
                        msd_len = 0;
                }
        }

        /* Keep aggregating only if stack says more data is coming
         * and not doing mixed modes send and not flow blocked
         */
        xmit_more = netdev_xmit_more() &&
                !packet->cp_partial &&
                !netif_xmit_stopped(netdev_get_tx_queue(ndev, packet->q_idx));

        if (section_index != NETVSC_INVALID_INDEX) {
                netvsc_copy_to_send_buf(net_device,
                                        section_index, msd_len,
                                        packet, rndis_msg, pb, xmit_more);

                packet->send_buf_index = section_index;

                if (packet->cp_partial) {
                        packet->page_buf_cnt--;
                        packet->total_data_buflen = msd_len + packet->rmsg_size;
                } else {
                        packet->page_buf_cnt = 0;
                        packet->total_data_buflen += msd_len;
                }

                if (msdp->pkt) {
                        packet->total_packets += msdp->pkt->total_packets;
                        packet->total_bytes += msdp->pkt->total_bytes;
                }

                if (msdp->skb)
                        dev_consume_skb_any(msdp->skb);

                if (xmit_more) {
                        msdp->skb = skb;
                        msdp->pkt = packet;
                        msdp->count++;
                } else {
                        cur_send = packet;
                        msdp->skb = NULL;
                        msdp->pkt = NULL;
                        msdp->count = 0;
                }
        } else {
                move_pkt_msd(&msd_send, &msd_skb, msdp);
                cur_send = packet;
        }

        if (msd_send) {
                int m_ret = netvsc_send_pkt(device, msd_send, net_device,
                                            NULL, msd_skb);

                if (m_ret != 0) {
                        netvsc_free_send_slot(net_device,
                                              msd_send->send_buf_index);
                        dev_kfree_skb_any(msd_skb);
                }
        }

        if (cur_send)
                ret = netvsc_send_pkt(device, cur_send, net_device, pb, skb);

        if (ret != 0 && section_index != NETVSC_INVALID_INDEX)
                netvsc_free_send_slot(net_device, section_index);

        return ret;
}

/* Send pending recv completions */
static int send_recv_completions(struct net_device *ndev,
                                 struct netvsc_device *nvdev,
                                 struct netvsc_channel *nvchan)
{
        struct multi_recv_comp *mrc = &nvchan->mrc;
        struct recv_comp_msg {
                struct nvsp_message_header hdr;
                u32 status;
        }  __packed;
        struct recv_comp_msg msg = {
                .hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE,
        };
        int ret;

        while (mrc->first != mrc->next) {
                const struct recv_comp_data *rcd
                        = mrc->slots + mrc->first;

                msg.status = rcd->status;
                ret = vmbus_sendpacket(nvchan->channel, &msg, sizeof(msg),
                                       rcd->tid, VM_PKT_COMP, 0);
                if (unlikely(ret)) {
                        struct net_device_context *ndev_ctx = netdev_priv(ndev);

                        ++ndev_ctx->eth_stats.rx_comp_busy;
                        return ret;
                }

                if (++mrc->first == nvdev->recv_completion_cnt)
                        mrc->first = 0;
        }

        /* receive completion ring has been emptied */
        if (unlikely(nvdev->destroy))
                wake_up(&nvdev->wait_drain);

        return 0;
}

/* Count how many receive completions are outstanding */
static void recv_comp_slot_avail(const struct netvsc_device *nvdev,
                                 const struct multi_recv_comp *mrc,
                                 u32 *filled, u32 *avail)
{
        u32 count = nvdev->recv_completion_cnt;

        if (mrc->next >= mrc->first)
                *filled = mrc->next - mrc->first;
        else
                *filled = (count - mrc->first) + mrc->next;

        *avail = count - *filled - 1;
}

/* Add receive complete to ring to send to host. */
static void enq_receive_complete(struct net_device *ndev,
                                 struct netvsc_device *nvdev, u16 q_idx,
                                 u64 tid, u32 status)
{
        struct netvsc_channel *nvchan = &nvdev->chan_table[q_idx];
        struct multi_recv_comp *mrc = &nvchan->mrc;
        struct recv_comp_data *rcd;
        u32 filled, avail;

        recv_comp_slot_avail(nvdev, mrc, &filled, &avail);

        if (unlikely(filled > NAPI_POLL_WEIGHT)) {
                send_recv_completions(ndev, nvdev, nvchan);
                recv_comp_slot_avail(nvdev, mrc, &filled, &avail);
        }

        if (unlikely(!avail)) {
                netdev_err(ndev, "Recv_comp full buf q:%hd, tid:%llx\n",
                           q_idx, tid);
                return;
        }

        rcd = mrc->slots + mrc->next;
        rcd->tid = tid;
        rcd->status = status;

        if (++mrc->next == nvdev->recv_completion_cnt)
                mrc->next = 0;
}

static int netvsc_receive(struct net_device *ndev,
                          struct netvsc_device *net_device,
                          struct netvsc_channel *nvchan,
                          const struct vmpacket_descriptor *desc)
{
        struct net_device_context *net_device_ctx = netdev_priv(ndev);
        struct vmbus_channel *channel = nvchan->channel;
        const struct vmtransfer_page_packet_header *vmxferpage_packet
                = container_of(desc, const struct vmtransfer_page_packet_header, d);
        const struct nvsp_message *nvsp = hv_pkt_data(desc);
        u32 msglen = hv_pkt_datalen(desc);
        u16 q_idx = channel->offermsg.offer.sub_channel_index;
        char *recv_buf = net_device->recv_buf;
        u32 status = NVSP_STAT_SUCCESS;
        int i;
        int count = 0;

        /* Ensure packet is big enough to read header fields */
        if (msglen < sizeof(struct nvsp_message_header)) {
                netif_err(net_device_ctx, rx_err, ndev,
                          "invalid nvsp header, length too small: %u\n",
                          msglen);
                return 0;
        }

        /* Make sure this is a valid nvsp packet */
        if (unlikely(nvsp->hdr.msg_type != NVSP_MSG1_TYPE_SEND_RNDIS_PKT)) {
                netif_err(net_device_ctx, rx_err, ndev,
                          "Unknown nvsp packet type received %u\n",
                          nvsp->hdr.msg_type);
                return 0;
        }

        /* Validate xfer page pkt header */
        if ((desc->offset8 << 3) < sizeof(struct vmtransfer_page_packet_header)) {
                netif_err(net_device_ctx, rx_err, ndev,
                          "Invalid xfer page pkt, offset too small: %u\n",
                          desc->offset8 << 3);
                return 0;
        }

        if (unlikely(vmxferpage_packet->xfer_pageset_id != NETVSC_RECEIVE_BUFFER_ID)) {
                netif_err(net_device_ctx, rx_err, ndev,
                          "Invalid xfer page set id - expecting %x got %x\n",
                          NETVSC_RECEIVE_BUFFER_ID,
                          vmxferpage_packet->xfer_pageset_id);
                return 0;
        }

        count = vmxferpage_packet->range_cnt;

        /* Check count for a valid value */
        if (NETVSC_XFER_HEADER_SIZE(count) > desc->offset8 << 3) {
                netif_err(net_device_ctx, rx_err, ndev,
                          "Range count is not valid: %d\n",
                          count);
                return 0;
        }

        /* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
        for (i = 0; i < count; i++) {
                u32 offset = vmxferpage_packet->ranges[i].byte_offset;
                u32 buflen = vmxferpage_packet->ranges[i].byte_count;
                void *data;
                int ret;

                if (unlikely(offset > net_device->recv_buf_size ||
                             buflen > net_device->recv_buf_size - offset)) {
                        nvchan->rsc.cnt = 0;
                        status = NVSP_STAT_FAIL;
                        netif_err(net_device_ctx, rx_err, ndev,
                                  "Packet offset:%u + len:%u too big\n",
                                  offset, buflen);

                        continue;
                }

                /* We're going to copy (sections of) the packet into nvchan->recv_buf;
                 * make sure that nvchan->recv_buf is large enough to hold the packet.
                 */
                if (unlikely(buflen > net_device->recv_section_size)) {
                        nvchan->rsc.cnt = 0;
                        status = NVSP_STAT_FAIL;
                        netif_err(net_device_ctx, rx_err, ndev,
                                  "Packet too big: buflen=%u recv_section_size=%u\n",
                                  buflen, net_device->recv_section_size);

                        continue;
                }

                data = recv_buf + offset;

                nvchan->rsc.is_last = (i == count - 1);

                trace_rndis_recv(ndev, q_idx, data);

                /* Pass it to the upper layer */
                ret = rndis_filter_receive(ndev, net_device,
                                           nvchan, data, buflen);

                if (unlikely(ret != NVSP_STAT_SUCCESS)) {
                        /* Drop incomplete packet */
                        nvchan->rsc.cnt = 0;
                        status = NVSP_STAT_FAIL;
                }
        }

        enq_receive_complete(ndev, net_device, q_idx,
                             vmxferpage_packet->d.trans_id, status);

        return count;
}

static void netvsc_send_table(struct net_device *ndev,
                              struct netvsc_device *nvscdev,
                              const struct nvsp_message *nvmsg,
                              u32 msglen)
{
        struct net_device_context *net_device_ctx = netdev_priv(ndev);
        u32 count, offset, *tab;
        int i;

        /* Ensure packet is big enough to read send_table fields */
        if (msglen < sizeof(struct nvsp_message_header) +
                     sizeof(struct nvsp_5_send_indirect_table)) {
                netdev_err(ndev, "nvsp_v5_msg length too small: %u\n", msglen);
                return;
        }

        count = nvmsg->msg.v5_msg.send_table.count;
        offset = nvmsg->msg.v5_msg.send_table.offset;

        if (count != VRSS_SEND_TAB_SIZE) {
                netdev_err(ndev, "Received wrong send-table size:%u\n", count);
                return;
        }

        /* If negotiated version <= NVSP_PROTOCOL_VERSION_6, the offset may be
         * wrong due to a host bug. So fix the offset here.
         */
        if (nvscdev->nvsp_version <= NVSP_PROTOCOL_VERSION_6 &&
            msglen >= sizeof(struct nvsp_message_header) +
            sizeof(union nvsp_6_message_uber) + count * sizeof(u32))
                offset = sizeof(struct nvsp_message_header) +
                         sizeof(union nvsp_6_message_uber);

        /* Boundary check for all versions */
        if (msglen < count * sizeof(u32) || offset > msglen - count * sizeof(u32)) {
                netdev_err(ndev, "Received send-table offset too big:%u\n",
                           offset);
                return;
        }

        tab = (void *)nvmsg + offset;

        for (i = 0; i < count; i++)
                net_device_ctx->tx_table[i] = tab[i];
}

static void netvsc_send_vf(struct net_device *ndev,
                           const struct nvsp_message *nvmsg,
                           u32 msglen)
{
        struct net_device_context *net_device_ctx = netdev_priv(ndev);

        /* Ensure packet is big enough to read its fields */
        if (msglen < sizeof(struct nvsp_message_header) +
                     sizeof(struct nvsp_4_send_vf_association)) {
                netdev_err(ndev, "nvsp_v4_msg length too small: %u\n", msglen);
                return;
        }

        net_device_ctx->vf_alloc = nvmsg->msg.v4_msg.vf_assoc.allocated;
        net_device_ctx->vf_serial = nvmsg->msg.v4_msg.vf_assoc.serial;

        if (net_device_ctx->vf_alloc)
                complete(&net_device_ctx->vf_add);

        netdev_info(ndev, "VF slot %u %s\n",
                    net_device_ctx->vf_serial,
                    net_device_ctx->vf_alloc ? "added" : "removed");
}

static void netvsc_receive_inband(struct net_device *ndev,
                                  struct netvsc_device *nvscdev,
                                  const struct vmpacket_descriptor *desc)
{
        const struct nvsp_message *nvmsg = hv_pkt_data(desc);
        u32 msglen = hv_pkt_datalen(desc);

        /* Ensure packet is big enough to read header fields */
        if (msglen < sizeof(struct nvsp_message_header)) {
                netdev_err(ndev, "inband nvsp_message length too small: %u\n", msglen);
                return;
        }

        switch (nvmsg->hdr.msg_type) {
        case NVSP_MSG5_TYPE_SEND_INDIRECTION_TABLE:
                netvsc_send_table(ndev, nvscdev, nvmsg, msglen);
                break;

        case NVSP_MSG4_TYPE_SEND_VF_ASSOCIATION:
                if (hv_is_isolation_supported())
                        netdev_err(ndev, "Ignore VF_ASSOCIATION msg from the host supporting isolation\n");
                else
                        netvsc_send_vf(ndev, nvmsg, msglen);
                break;
        }
}

static int netvsc_process_raw_pkt(struct hv_device *device,
                                  struct netvsc_channel *nvchan,
                                  struct netvsc_device *net_device,
                                  struct net_device *ndev,
                                  const struct vmpacket_descriptor *desc,
                                  int budget)
{
        struct vmbus_channel *channel = nvchan->channel;
        const struct nvsp_message *nvmsg = hv_pkt_data(desc);

        trace_nvsp_recv(ndev, channel, nvmsg);

        switch (desc->type) {
        case VM_PKT_COMP:
                netvsc_send_completion(ndev, net_device, channel, desc, budget);
                break;

        case VM_PKT_DATA_USING_XFER_PAGES:
                return netvsc_receive(ndev, net_device, nvchan, desc);

        case VM_PKT_DATA_INBAND:
                netvsc_receive_inband(ndev, net_device, desc);
                break;

        default:
                netdev_err(ndev, "unhandled packet type %d, tid %llx\n",
                           desc->type, desc->trans_id);
                break;
        }

        return 0;
}

static struct hv_device *netvsc_channel_to_device(struct vmbus_channel *channel)
{
        struct vmbus_channel *primary = channel->primary_channel;

        return primary ? primary->device_obj : channel->device_obj;
}

/* Network processing softirq
 * Process data in incoming ring buffer from host
 * Stops when ring is empty or budget is met or exceeded.
 */
int netvsc_poll(struct napi_struct *napi, int budget)
{
        struct netvsc_channel *nvchan
                = container_of(napi, struct netvsc_channel, napi);
        struct netvsc_device *net_device = nvchan->net_device;
        struct vmbus_channel *channel = nvchan->channel;
        struct hv_device *device = netvsc_channel_to_device(channel);
        struct net_device *ndev = hv_get_drvdata(device);
        int work_done = 0;
        int ret;

        /* If starting a new interval */
        if (!nvchan->desc)
                nvchan->desc = hv_pkt_iter_first(channel);

        nvchan->xdp_flush = false;

        while (nvchan->desc && work_done < budget) {
                work_done += netvsc_process_raw_pkt(device, nvchan, net_device,
                                                    ndev, nvchan->desc, budget);
                nvchan->desc = hv_pkt_iter_next(channel, nvchan->desc);
        }

        if (nvchan->xdp_flush)
                xdp_do_flush();

        /* Send any pending receive completions */
        ret = send_recv_completions(ndev, net_device, nvchan);

        /* If it did not exhaust NAPI budget this time
         *  and not doing busy poll
         * then re-enable host interrupts
         *  and reschedule if ring is not empty
         *   or sending receive completion failed.
         */
        if (work_done < budget &&
            napi_complete_done(napi, work_done) &&
            (ret || hv_end_read(&channel->inbound)) &&
            napi_schedule_prep(napi)) {
                hv_begin_read(&channel->inbound);
                __napi_schedule(napi);
        }

        /* Driver may overshoot since multiple packets per descriptor */
        return min(work_done, budget);
}

/* Call back when data is available in host ring buffer.
 * Processing is deferred until network softirq (NAPI)
 */
void netvsc_channel_cb(void *context)
{
        struct netvsc_channel *nvchan = context;
        struct vmbus_channel *channel = nvchan->channel;
        struct hv_ring_buffer_info *rbi = &channel->inbound;

        /* preload first vmpacket descriptor */
        prefetch(hv_get_ring_buffer(rbi) + rbi->priv_read_index);

        if (napi_schedule_prep(&nvchan->napi)) {
                /* disable interrupts from host */
                hv_begin_read(rbi);

                __napi_schedule_irqoff(&nvchan->napi);
        }
}

/*
 * netvsc_device_add - Callback when the device belonging to this
 * driver is added
 */
struct netvsc_device *netvsc_device_add(struct hv_device *device,
                                const struct netvsc_device_info *device_info)
{
        int i, ret = 0;
        struct netvsc_device *net_device;
        struct net_device *ndev = hv_get_drvdata(device);
        struct net_device_context *net_device_ctx = netdev_priv(ndev);

        net_device = alloc_net_device();
        if (!net_device)
                return ERR_PTR(-ENOMEM);

        for (i = 0; i < VRSS_SEND_TAB_SIZE; i++)
                net_device_ctx->tx_table[i] = 0;

        /* Because the device uses NAPI, all the interrupt batching and
         * control is done via Net softirq, not the channel handling
         */
        set_channel_read_mode(device->channel, HV_CALL_ISR);

        /* If we're reopening the device we may have multiple queues, fill the
         * chn_table with the default channel to use it before subchannels are
         * opened.
         * Initialize the channel state before we open;
         * we can be interrupted as soon as we open the channel.
         */

        for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
                struct netvsc_channel *nvchan = &net_device->chan_table[i];

                nvchan->channel = device->channel;
                nvchan->net_device = net_device;
                u64_stats_init(&nvchan->tx_stats.syncp);
                u64_stats_init(&nvchan->rx_stats.syncp);

                ret = xdp_rxq_info_reg(&nvchan->xdp_rxq, ndev, i, 0);

                if (ret) {
                        netdev_err(ndev, "xdp_rxq_info_reg fail: %d\n", ret);
                        goto cleanup2;
                }

                ret = xdp_rxq_info_reg_mem_model(&nvchan->xdp_rxq,
                                                 MEM_TYPE_PAGE_SHARED, NULL);

                if (ret) {
                        netdev_err(ndev, "xdp reg_mem_model fail: %d\n", ret);
                        goto cleanup2;
                }
        }

        /* Enable NAPI handler before init callbacks */
        netif_napi_add(ndev, &net_device->chan_table[0].napi, netvsc_poll);
        napi_enable(&net_device->chan_table[0].napi);
        netif_queue_set_napi(ndev, 0, NETDEV_QUEUE_TYPE_RX,
                             &net_device->chan_table[0].napi);
        netif_queue_set_napi(ndev, 0, NETDEV_QUEUE_TYPE_TX,
                             &net_device->chan_table[0].napi);

        /* Open the channel */
        device->channel->next_request_id_callback = vmbus_next_request_id;
        device->channel->request_addr_callback = vmbus_request_addr;
        device->channel->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
        device->channel->max_pkt_size = NETVSC_MAX_PKT_SIZE;

        ret = vmbus_open(device->channel, netvsc_ring_bytes,
                         netvsc_ring_bytes,  NULL, 0,
                         netvsc_channel_cb, net_device->chan_table);

        if (ret != 0) {
                netdev_err(ndev, "unable to open channel: %d\n", ret);
                goto cleanup;
        }

        /* Channel is opened */
        netdev_dbg(ndev, "hv_netvsc channel opened successfully\n");

        /* Connect with the NetVsp */
        ret = netvsc_connect_vsp(device, net_device, device_info);
        if (ret != 0) {
                netdev_err(ndev,
                        "unable to connect to NetVSP - %d\n", ret);
                goto close;
        }

        /* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is
         * populated.
         */
        rcu_assign_pointer(net_device_ctx->nvdev, net_device);

        return net_device;

close:
        RCU_INIT_POINTER(net_device_ctx->nvdev, NULL);

        /* Now, we can close the channel safely */
        vmbus_close(device->channel);

cleanup:
        netif_queue_set_napi(ndev, 0, NETDEV_QUEUE_TYPE_TX, NULL);
        netif_queue_set_napi(ndev, 0, NETDEV_QUEUE_TYPE_RX, NULL);
        napi_disable(&net_device->chan_table[0].napi);
        netif_napi_del(&net_device->chan_table[0].napi);

cleanup2:
        free_netvsc_device(&net_device->rcu);

        return ERR_PTR(ret);
}