/*
 * An implementation of key value pair (KVP) functionality for Linux.
 *
 *
 * Copyright (C) 2010, Novell, Inc.
 * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/net.h>
#include <linux/nls.h>
#include <linux/connector.h>
#include <linux/workqueue.h>
#include <linux/hyperv.h>
#include <asm/hyperv-tlfs.h>

#include "hyperv_vmbus.h"
#include "hv_utils_transport.h"

/*
 * Pre win8 version numbers used in ws2008 and ws 2008 r2 (win7)
 */
#define WS2008_SRV_MAJOR        1
#define WS2008_SRV_MINOR        0
#define WS2008_SRV_VERSION     (WS2008_SRV_MAJOR << 16 | WS2008_SRV_MINOR)

#define WIN7_SRV_MAJOR   3
#define WIN7_SRV_MINOR   0
#define WIN7_SRV_VERSION     (WIN7_SRV_MAJOR << 16 | WIN7_SRV_MINOR)

#define WIN8_SRV_MAJOR   4
#define WIN8_SRV_MINOR   0
#define WIN8_SRV_VERSION     (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)

#define KVP_VER_COUNT 3
static const int kvp_versions[] = {
        WIN8_SRV_VERSION,
        WIN7_SRV_VERSION,
        WS2008_SRV_VERSION
};

#define FW_VER_COUNT 2
static const int fw_versions[] = {
        UTIL_FW_VERSION,
        UTIL_WS2K8_FW_VERSION
};

/*
 * Global state maintained for transaction that is being processed. For a class
 * of integration services, including the "KVP service", the specified protocol
 * is a "request/response" protocol which means that there can only be single
 * outstanding transaction from the host at any given point in time. We use
 * this to simplify memory management in this driver - we cache and process
 * only one message at a time.
 *
 * While the request/response protocol is guaranteed by the host, we further
 * ensure this by serializing packet processing in this driver - we do not
 * read additional packets from the VMBUS until the current packet is fully
 * handled.
 */

static struct {
        int state;   /* hvutil_device_state */
        int recv_len; /* number of bytes received. */
        struct hv_kvp_msg  *kvp_msg; /* current message */
        struct vmbus_channel *recv_channel; /* chn we got the request */
        u64 recv_req_id; /* request ID. */
} kvp_transaction;

/*
 * This state maintains the version number registered by the daemon.
 */
static int dm_reg_value;

static void kvp_send_key(struct work_struct *dummy);


static void kvp_respond_to_host(struct hv_kvp_msg *msg, int error);
static void kvp_timeout_func(struct work_struct *dummy);
static void kvp_host_handshake_func(struct work_struct *dummy);
static void kvp_register(int);

static DECLARE_DELAYED_WORK(kvp_timeout_work, kvp_timeout_func);
static DECLARE_DELAYED_WORK(kvp_host_handshake_work, kvp_host_handshake_func);
static DECLARE_WORK(kvp_sendkey_work, kvp_send_key);

static const char kvp_devname[] = "vmbus/hv_kvp";
static u8 *recv_buffer;
static struct hvutil_transport *hvt;
/*
 * Register the kernel component with the user-level daemon.
 * As part of this registration, pass the LIC version number.
 * This number has no meaning, it satisfies the registration protocol.
 */
#define HV_DRV_VERSION           "3.1"

static void kvp_poll_wrapper(void *channel)
{
        /* Transaction is finished, reset the state here to avoid races. */
        kvp_transaction.state = HVUTIL_READY;
        tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event);
}

static void kvp_register_done(void)
{
        /*
         * If we're still negotiating with the host cancel the timeout
         * work to not poll the channel twice.
         */
        pr_debug("KVP: userspace daemon registered\n");
        cancel_delayed_work_sync(&kvp_host_handshake_work);
        hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
}

static void
kvp_register(int reg_value)
{

        struct hv_kvp_msg *kvp_msg;
        char *version;

        kvp_msg = kzalloc(sizeof(*kvp_msg), GFP_KERNEL);

        if (kvp_msg) {
                version = kvp_msg->body.kvp_register.version;
                kvp_msg->kvp_hdr.operation = reg_value;
                strcpy(version, HV_DRV_VERSION);

                hvutil_transport_send(hvt, kvp_msg, sizeof(*kvp_msg),
                                      kvp_register_done);
                kfree(kvp_msg);
        }
}

static void kvp_timeout_func(struct work_struct *dummy)
{
        /*
         * If the timer fires, the user-mode component has not responded;
         * process the pending transaction.
         */
        kvp_respond_to_host(NULL, HV_E_FAIL);

        hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
}

static void kvp_host_handshake_func(struct work_struct *dummy)
{
        tasklet_schedule(&kvp_transaction.recv_channel->callback_event);
}

static int kvp_handle_handshake(struct hv_kvp_msg *msg)
{
        switch (msg->kvp_hdr.operation) {
        case KVP_OP_REGISTER:
                dm_reg_value = KVP_OP_REGISTER;
                pr_info("KVP: IP injection functionality not available\n");
                pr_info("KVP: Upgrade the KVP daemon\n");
                break;
        case KVP_OP_REGISTER1:
                dm_reg_value = KVP_OP_REGISTER1;
                break;
        default:
                pr_info("KVP: incompatible daemon\n");
                pr_info("KVP: KVP version: %d, Daemon version: %d\n",
                        KVP_OP_REGISTER1, msg->kvp_hdr.operation);
                return -EINVAL;
        }

        /*
         * We have a compatible daemon; complete the handshake.
         */
        pr_debug("KVP: userspace daemon ver. %d connected\n",
                 msg->kvp_hdr.operation);
        kvp_register(dm_reg_value);

        return 0;
}


/*
 * Callback when data is received from user mode.
 */

static int kvp_on_msg(void *msg, int len)
{
        struct hv_kvp_msg *message = (struct hv_kvp_msg *)msg;
        struct hv_kvp_msg_enumerate *data;
        int     error = 0;

        if (len < sizeof(*message))
                return -EINVAL;

        /*
         * If we are negotiating the version information
         * with the daemon; handle that first.
         */

        if (kvp_transaction.state < HVUTIL_READY) {
                return kvp_handle_handshake(message);
        }

        /* We didn't send anything to userspace so the reply is spurious */
        if (kvp_transaction.state < HVUTIL_USERSPACE_REQ)
                return -EINVAL;

        kvp_transaction.state = HVUTIL_USERSPACE_RECV;

        /*
         * Based on the version of the daemon, we propagate errors from the
         * daemon differently.
         */

        data = &message->body.kvp_enum_data;

        switch (dm_reg_value) {
        case KVP_OP_REGISTER:
                /*
                 * Null string is used to pass back error condition.
                 */
                if (data->data.key[0] == 0)
                        error = HV_S_CONT;
                break;

        case KVP_OP_REGISTER1:
                /*
                 * We use the message header information from
                 * the user level daemon to transmit errors.
                 */
                error = message->error;
                break;
        }

        /*
         * Complete the transaction by forwarding the key value
         * to the host. But first, cancel the timeout.
         */
        if (cancel_delayed_work_sync(&kvp_timeout_work)) {
                kvp_respond_to_host(message, error);
                hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
        }

        return 0;
}


static int process_ob_ipinfo(void *in_msg, void *out_msg, int op)
{
        struct hv_kvp_msg *in = in_msg;
        struct hv_kvp_ip_msg *out = out_msg;
        int len;

        switch (op) {
        case KVP_OP_GET_IP_INFO:
                /*
                 * Transform all parameters into utf16 encoding.
                 */
                len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.ip_addr,
                                strlen((char *)in->body.kvp_ip_val.ip_addr),
                                UTF16_HOST_ENDIAN,
                                (wchar_t *)out->kvp_ip_val.ip_addr,
                                MAX_IP_ADDR_SIZE);
                if (len < 0)
                        return len;

                len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.sub_net,
                                strlen((char *)in->body.kvp_ip_val.sub_net),
                                UTF16_HOST_ENDIAN,
                                (wchar_t *)out->kvp_ip_val.sub_net,
                                MAX_IP_ADDR_SIZE);
                if (len < 0)
                        return len;

                len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.gate_way,
                                strlen((char *)in->body.kvp_ip_val.gate_way),
                                UTF16_HOST_ENDIAN,
                                (wchar_t *)out->kvp_ip_val.gate_way,
                                MAX_GATEWAY_SIZE);
                if (len < 0)
                        return len;

                len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.dns_addr,
                                strlen((char *)in->body.kvp_ip_val.dns_addr),
                                UTF16_HOST_ENDIAN,
                                (wchar_t *)out->kvp_ip_val.dns_addr,
                                MAX_IP_ADDR_SIZE);
                if (len < 0)
                        return len;

                len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.adapter_id,
                                strlen((char *)in->body.kvp_ip_val.adapter_id),
                                UTF16_HOST_ENDIAN,
                                (wchar_t *)out->kvp_ip_val.adapter_id,
                                MAX_ADAPTER_ID_SIZE);
                if (len < 0)
                        return len;

                out->kvp_ip_val.dhcp_enabled =
                        in->body.kvp_ip_val.dhcp_enabled;
                out->kvp_ip_val.addr_family =
                        in->body.kvp_ip_val.addr_family;
        }

        return 0;
}

static void process_ib_ipinfo(void *in_msg, void *out_msg, int op)
{
        struct hv_kvp_ip_msg *in = in_msg;
        struct hv_kvp_msg *out = out_msg;

        switch (op) {
        case KVP_OP_SET_IP_INFO:
                /*
                 * Transform all parameters into utf8 encoding.
                 */
                utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.ip_addr,
                                MAX_IP_ADDR_SIZE,
                                UTF16_LITTLE_ENDIAN,
                                (__u8 *)out->body.kvp_ip_val.ip_addr,
                                MAX_IP_ADDR_SIZE);

                utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.sub_net,
                                MAX_IP_ADDR_SIZE,
                                UTF16_LITTLE_ENDIAN,
                                (__u8 *)out->body.kvp_ip_val.sub_net,
                                MAX_IP_ADDR_SIZE);

                utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.gate_way,
                                MAX_GATEWAY_SIZE,
                                UTF16_LITTLE_ENDIAN,
                                (__u8 *)out->body.kvp_ip_val.gate_way,
                                MAX_GATEWAY_SIZE);

                utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.dns_addr,
                                MAX_IP_ADDR_SIZE,
                                UTF16_LITTLE_ENDIAN,
                                (__u8 *)out->body.kvp_ip_val.dns_addr,
                                MAX_IP_ADDR_SIZE);

                out->body.kvp_ip_val.dhcp_enabled = in->kvp_ip_val.dhcp_enabled;

                fallthrough;

        case KVP_OP_GET_IP_INFO:
                utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
                                MAX_ADAPTER_ID_SIZE,
                                UTF16_LITTLE_ENDIAN,
                                (__u8 *)out->body.kvp_ip_val.adapter_id,
                                MAX_ADAPTER_ID_SIZE);

                out->body.kvp_ip_val.addr_family = in->kvp_ip_val.addr_family;
        }
}




static void
kvp_send_key(struct work_struct *dummy)
{
        struct hv_kvp_msg *message;
        struct hv_kvp_msg *in_msg;
        __u8 operation = kvp_transaction.kvp_msg->kvp_hdr.operation;
        __u8 pool = kvp_transaction.kvp_msg->kvp_hdr.pool;
        __u32 val32;
        __u64 val64;
        int rc;

        /* The transaction state is wrong. */
        if (kvp_transaction.state != HVUTIL_HOSTMSG_RECEIVED)
                return;

        message = kzalloc(sizeof(*message), GFP_KERNEL);
        if (!message)
                return;

        message->kvp_hdr.operation = operation;
        message->kvp_hdr.pool = pool;
        in_msg = kvp_transaction.kvp_msg;

        /*
         * The key/value strings sent from the host are encoded in
         * in utf16; convert it to utf8 strings.
         * The host assures us that the utf16 strings will not exceed
         * the max lengths specified. We will however, reserve room
         * for the string terminating character - in the utf16s_utf8s()
         * function we limit the size of the buffer where the converted
         * string is placed to HV_KVP_EXCHANGE_MAX_*_SIZE -1 to guarantee
         * that the strings can be properly terminated!
         */

        switch (message->kvp_hdr.operation) {
        case KVP_OP_SET_IP_INFO:
                process_ib_ipinfo(in_msg, message, KVP_OP_SET_IP_INFO);
                break;
        case KVP_OP_GET_IP_INFO:
                /*
                 * We only need to pass on the info of operation, adapter_id
                 * and addr_family to the userland kvp daemon.
                 */
                process_ib_ipinfo(in_msg, message, KVP_OP_GET_IP_INFO);
                break;
        case KVP_OP_SET:
                switch (in_msg->body.kvp_set.data.value_type) {
                case REG_SZ:
                        /*
                         * The value is a string - utf16 encoding.
                         */
                        message->body.kvp_set.data.value_size =
                                utf16s_to_utf8s(
                                (wchar_t *)in_msg->body.kvp_set.data.value,
                                in_msg->body.kvp_set.data.value_size,
                                UTF16_LITTLE_ENDIAN,
                                message->body.kvp_set.data.value,
                                HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1) + 1;
                        break;

                case REG_U32:
                        /*
                         * The value is a 32 bit scalar.
                         * We save this as a utf8 string.
                         */
                        val32 = in_msg->body.kvp_set.data.value_u32;
                        message->body.kvp_set.data.value_size =
                                sprintf(message->body.kvp_set.data.value,
                                        "%u", val32) + 1;
                        break;

                case REG_U64:
                        /*
                         * The value is a 64 bit scalar.
                         * We save this as a utf8 string.
                         */
                        val64 = in_msg->body.kvp_set.data.value_u64;
                        message->body.kvp_set.data.value_size =
                                sprintf(message->body.kvp_set.data.value,
                                        "%llu", val64) + 1;
                        break;

                }

                /*
                 * The key is always a string - utf16 encoding.
                 */
                message->body.kvp_set.data.key_size =
                        utf16s_to_utf8s(
                        (wchar_t *)in_msg->body.kvp_set.data.key,
                        in_msg->body.kvp_set.data.key_size,
                        UTF16_LITTLE_ENDIAN,
                        message->body.kvp_set.data.key,
                        HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;

                break;

        case KVP_OP_GET:
                message->body.kvp_get.data.key_size =
                        utf16s_to_utf8s(
                        (wchar_t *)in_msg->body.kvp_get.data.key,
                        in_msg->body.kvp_get.data.key_size,
                        UTF16_LITTLE_ENDIAN,
                        message->body.kvp_get.data.key,
                        HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
                break;

        case KVP_OP_DELETE:
                message->body.kvp_delete.key_size =
                        utf16s_to_utf8s(
                        (wchar_t *)in_msg->body.kvp_delete.key,
                        in_msg->body.kvp_delete.key_size,
                        UTF16_LITTLE_ENDIAN,
                        message->body.kvp_delete.key,
                        HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
                break;

        case KVP_OP_ENUMERATE:
                message->body.kvp_enum_data.index =
                        in_msg->body.kvp_enum_data.index;
                break;
        }

        kvp_transaction.state = HVUTIL_USERSPACE_REQ;
        rc = hvutil_transport_send(hvt, message, sizeof(*message), NULL);
        if (rc) {
                pr_debug("KVP: failed to communicate to the daemon: %d\n", rc);
                if (cancel_delayed_work_sync(&kvp_timeout_work)) {
                        kvp_respond_to_host(message, HV_E_FAIL);
                        kvp_transaction.state = HVUTIL_READY;
                }
        }

        kfree(message);
}

/*
 * Send a response back to the host.
 */

static void
kvp_respond_to_host(struct hv_kvp_msg *msg_to_host, int error)
{
        struct hv_kvp_msg  *kvp_msg;
        struct hv_kvp_exchg_msg_value  *kvp_data;
        char    *key_name;
        char    *value;
        struct icmsg_hdr *icmsghdrp;
        int     keylen = 0;
        int     valuelen = 0;
        u32     buf_len;
        struct vmbus_channel *channel;
        u64     req_id;
        int ret;

        /*
         * Copy the global state for completing the transaction. Note that
         * only one transaction can be active at a time.
         */

        buf_len = kvp_transaction.recv_len;
        channel = kvp_transaction.recv_channel;
        req_id = kvp_transaction.recv_req_id;

        icmsghdrp = (struct icmsg_hdr *)
                        &recv_buffer[sizeof(struct vmbuspipe_hdr)];

        if (channel->onchannel_callback == NULL)
                /*
                 * We have raced with util driver being unloaded;
                 * silently return.
                 */
                return;

        icmsghdrp->status = error;

        /*
         * If the error parameter is set, terminate the host's enumeration
         * on this pool.
         */
        if (error) {
                /*
                 * Something failed or we have timed out;
                 * terminate the current host-side iteration.
                 */
                goto response_done;
        }

        kvp_msg = (struct hv_kvp_msg *)
                        &recv_buffer[sizeof(struct vmbuspipe_hdr) +
                        sizeof(struct icmsg_hdr)];

        switch (kvp_transaction.kvp_msg->kvp_hdr.operation) {
        case KVP_OP_GET_IP_INFO:
                ret = process_ob_ipinfo(msg_to_host,
                                 (struct hv_kvp_ip_msg *)kvp_msg,
                                 KVP_OP_GET_IP_INFO);
                if (ret < 0)
                        icmsghdrp->status = HV_E_FAIL;

                goto response_done;
        case KVP_OP_SET_IP_INFO:
                goto response_done;
        case KVP_OP_GET:
                kvp_data = &kvp_msg->body.kvp_get.data;
                goto copy_value;

        case KVP_OP_SET:
        case KVP_OP_DELETE:
                goto response_done;

        default:
                break;
        }

        kvp_data = &kvp_msg->body.kvp_enum_data.data;
        key_name = msg_to_host->body.kvp_enum_data.data.key;

        /*
         * The windows host expects the key/value pair to be encoded
         * in utf16. Ensure that the key/value size reported to the host
         * will be less than or equal to the MAX size (including the
         * terminating character).
         */
        keylen = utf8s_to_utf16s(key_name, strlen(key_name), UTF16_HOST_ENDIAN,
                                (wchar_t *) kvp_data->key,
                                (HV_KVP_EXCHANGE_MAX_KEY_SIZE / 2) - 2);
        kvp_data->key_size = 2*(keylen + 1); /* utf16 encoding */

copy_value:
        value = msg_to_host->body.kvp_enum_data.data.value;
        valuelen = utf8s_to_utf16s(value, strlen(value), UTF16_HOST_ENDIAN,
                                (wchar_t *) kvp_data->value,
                                (HV_KVP_EXCHANGE_MAX_VALUE_SIZE / 2) - 2);
        kvp_data->value_size = 2*(valuelen + 1); /* utf16 encoding */

        /*
         * If the utf8s to utf16s conversion failed; notify host
         * of the error.
         */
        if ((keylen < 0) || (valuelen < 0))
                icmsghdrp->status = HV_E_FAIL;

        kvp_data->value_type = REG_SZ; /* all our values are strings */

response_done:
        icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;

        vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
                                VM_PKT_DATA_INBAND, 0);
}

/*
 * This callback is invoked when we get a KVP message from the host.
 * The host ensures that only one KVP transaction can be active at a time.
 * KVP implementation in Linux needs to forward the key to a user-mde
 * component to retrieve the corresponding value. Consequently, we cannot
 * respond to the host in the context of this callback. Since the host
 * guarantees that at most only one transaction can be active at a time,
 * we stash away the transaction state in a set of global variables.
 */

void hv_kvp_onchannelcallback(void *context)
{
        struct vmbus_channel *channel = context;
        u32 recvlen;
        u64 requestid;

        struct hv_kvp_msg *kvp_msg;

        struct icmsg_hdr *icmsghdrp;
        int kvp_srv_version;
        static enum {NEGO_NOT_STARTED,
                     NEGO_IN_PROGRESS,
                     NEGO_FINISHED} host_negotiatied = NEGO_NOT_STARTED;

        if (kvp_transaction.state < HVUTIL_READY) {
                /*
                 * If userspace daemon is not connected and host is asking
                 * us to negotiate we need to delay to not lose messages.
                 * This is important for Failover IP setting.
                 */
                if (host_negotiatied == NEGO_NOT_STARTED) {
                        host_negotiatied = NEGO_IN_PROGRESS;
                        schedule_delayed_work(&kvp_host_handshake_work,
                                      HV_UTIL_NEGO_TIMEOUT * HZ);
                }
                return;
        }
        if (kvp_transaction.state > HVUTIL_READY)
                return;

        if (vmbus_recvpacket(channel, recv_buffer, HV_HYP_PAGE_SIZE * 4, &recvlen, &requestid)) {
                pr_err_ratelimited("KVP request received. Could not read into recv buf\n");
                return;
        }

        if (!recvlen)
                return;

        /* Ensure recvlen is big enough to read header data */
        if (recvlen < ICMSG_HDR) {
                pr_err_ratelimited("KVP request received. Packet length too small: %d\n",
                                   recvlen);
                return;
        }

        icmsghdrp = (struct icmsg_hdr *)&recv_buffer[sizeof(struct vmbuspipe_hdr)];

        if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
                if (vmbus_prep_negotiate_resp(icmsghdrp,
                                recv_buffer, recvlen,
                                fw_versions, FW_VER_COUNT,
                                kvp_versions, KVP_VER_COUNT,
                                NULL, &kvp_srv_version)) {
                        pr_info("KVP IC version %d.%d\n",
                                kvp_srv_version >> 16,
                                kvp_srv_version & 0xFFFF);
                }
        } else if (icmsghdrp->icmsgtype == ICMSGTYPE_KVPEXCHANGE) {
                /*
                 * recvlen is not checked against sizeof(struct kvp_msg) because kvp_msg contains
                 * a union of structs and the msg type received is not known. Code using this
                 * struct should provide validation when accessing its fields.
                 */
                kvp_msg = (struct hv_kvp_msg *)&recv_buffer[ICMSG_HDR];

                /*
                 * Stash away this global state for completing the
                 * transaction; note transactions are serialized.
                 */

                kvp_transaction.recv_len = recvlen;
                kvp_transaction.recv_req_id = requestid;
                kvp_transaction.kvp_msg = kvp_msg;

                if (kvp_transaction.state < HVUTIL_READY) {
                        /* Userspace is not registered yet */
                        kvp_respond_to_host(NULL, HV_E_FAIL);
                        return;
                }
                kvp_transaction.state = HVUTIL_HOSTMSG_RECEIVED;

                /*
                 * Get the information from the
                 * user-mode component.
                 * component. This transaction will be
                 * completed when we get the value from
                 * the user-mode component.
                 * Set a timeout to deal with
                 * user-mode not responding.
                 */
                schedule_work(&kvp_sendkey_work);
                schedule_delayed_work(&kvp_timeout_work,
                                        HV_UTIL_TIMEOUT * HZ);

                return;

        } else {
                pr_err_ratelimited("KVP request received. Invalid msg type: %d\n",
                                   icmsghdrp->icmsgtype);
                return;
        }

        icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
                | ICMSGHDRFLAG_RESPONSE;

        vmbus_sendpacket(channel, recv_buffer,
                         recvlen, requestid,
                         VM_PKT_DATA_INBAND, 0);

        host_negotiatied = NEGO_FINISHED;
        hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
}

static void kvp_on_reset(void)
{
        if (cancel_delayed_work_sync(&kvp_timeout_work))
                kvp_respond_to_host(NULL, HV_E_FAIL);
        kvp_transaction.state = HVUTIL_DEVICE_INIT;
}

int
hv_kvp_init(struct hv_util_service *srv)
{
        recv_buffer = srv->recv_buffer;
        kvp_transaction.recv_channel = srv->channel;

        /*
         * When this driver loads, the user level daemon that
         * processes the host requests may not yet be running.
         * Defer processing channel callbacks until the daemon
         * has registered.
         */
        kvp_transaction.state = HVUTIL_DEVICE_INIT;

        hvt = hvutil_transport_init(kvp_devname, CN_KVP_IDX, CN_KVP_VAL,
                                    kvp_on_msg, kvp_on_reset);
        if (!hvt)
                return -EFAULT;

        return 0;
}

static void hv_kvp_cancel_work(void)
{
        cancel_delayed_work_sync(&kvp_host_handshake_work);
        cancel_delayed_work_sync(&kvp_timeout_work);
        cancel_work_sync(&kvp_sendkey_work);
}

int hv_kvp_pre_suspend(void)
{
        struct vmbus_channel *channel = kvp_transaction.recv_channel;

        tasklet_disable(&channel->callback_event);

        /*
         * If there is a pending transtion, it's unnecessary to tell the host
         * that the transaction will fail, because that is implied when
         * util_suspend() calls vmbus_close() later.
         */
        hv_kvp_cancel_work();

        /*
         * Forece the state to READY to handle the ICMSGTYPE_NEGOTIATE message
         * later. The user space daemon may go out of order and its write()
         * may fail with EINVAL: this doesn't matter since the daemon will
         * reset the device by closing and re-opening it.
         */
        kvp_transaction.state = HVUTIL_READY;
        return 0;
}

int hv_kvp_pre_resume(void)
{
        struct vmbus_channel *channel = kvp_transaction.recv_channel;

        tasklet_enable(&channel->callback_event);

        return 0;
}

void hv_kvp_deinit(void)
{
        kvp_transaction.state = HVUTIL_DEVICE_DYING;

        hv_kvp_cancel_work();

        hvutil_transport_destroy(hvt);
}