drivers/hv/hv_util.c - kernel/lockdown - Git at Google

 /*
  * Copyright (c) 2010, Microsoft Corporation.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
  * version 2, as published by the Free Software Foundation.
  *
  * This program is distributed in the hope it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  * Place - Suite 330, Boston, MA 02111-1307 USA.
  *
  * Authors:
  *   Haiyang Zhang <haiyangz@microsoft.com>
  *   Hank Janssen  <hjanssen@microsoft.com>
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sysctl.h>
 #include <linux/reboot.h>
 #include <linux/hyperv.h>


 #define SD_MAJOR	3
 #define SD_MINOR	0
 #define SD_VERSION	(SD_MAJOR << 16 | SD_MINOR)

 #define SD_WS2008_MAJOR		1
 #define SD_WS2008_VERSION	(SD_WS2008_MAJOR << 16 | SD_MINOR)

 #define TS_MAJOR	3
 #define TS_MINOR	0
 #define TS_VERSION	(TS_MAJOR << 16 | TS_MINOR)

 #define TS_WS2008_MAJOR		1
 #define TS_WS2008_VERSION	(TS_WS2008_MAJOR << 16 | TS_MINOR)

 #define HB_MAJOR	3
 #define HB_MINOR 0
 #define HB_VERSION	(HB_MAJOR << 16 | HB_MINOR)

 #define HB_WS2008_MAJOR	1
 #define HB_WS2008_VERSION	(HB_WS2008_MAJOR << 16 | HB_MINOR)

 static int sd_srv_version;
 static int ts_srv_version;
 static int hb_srv_version;
 static int util_fw_version;

 static void shutdown_onchannelcallback(void *context);
 static struct hv_util_service util_shutdown = {
 	.util_cb = shutdown_onchannelcallback,
 };

 static void timesync_onchannelcallback(void *context);
 static struct hv_util_service util_timesynch = {
 	.util_cb = timesync_onchannelcallback,
 };

 static void heartbeat_onchannelcallback(void *context);
 static struct hv_util_service util_heartbeat = {
 	.util_cb = heartbeat_onchannelcallback,
 };

 static struct hv_util_service util_kvp = {
 	.util_cb = hv_kvp_onchannelcallback,
 	.util_init = hv_kvp_init,
 	.util_deinit = hv_kvp_deinit,
 };

 static struct hv_util_service util_vss = {
 	.util_cb = hv_vss_onchannelcallback,
 	.util_init = hv_vss_init,
 	.util_deinit = hv_vss_deinit,
 };

 static void perform_shutdown(struct work_struct *dummy)
 {
 	orderly_poweroff(true);
 }

 /*
  * Perform the shutdown operation in a thread context.
  */
 static DECLARE_WORK(shutdown_work, perform_shutdown);

 static void shutdown_onchannelcallback(void *context)
 {
 	struct vmbus_channel *channel = context;
 	u32 recvlen;
 	u64 requestid;
 	bool execute_shutdown = false;
 	u8  *shut_txf_buf = util_shutdown.recv_buffer;

 	struct shutdown_msg_data *shutdown_msg;

 	struct icmsg_hdr *icmsghdrp;
 	struct icmsg_negotiate *negop = NULL;

 	vmbus_recvpacket(channel, shut_txf_buf,
 			 PAGE_SIZE, &recvlen, &requestid);

 	if (recvlen > 0) {
 		icmsghdrp = (struct icmsg_hdr *)&shut_txf_buf[
 			sizeof(struct vmbuspipe_hdr)];

 		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 			vmbus_prep_negotiate_resp(icmsghdrp, negop,
 					shut_txf_buf, util_fw_version,
 					sd_srv_version);
 		} else {
 			shutdown_msg =
 				(struct shutdown_msg_data *)&shut_txf_buf[
 					sizeof(struct vmbuspipe_hdr) +
 					sizeof(struct icmsg_hdr)];

 			switch (shutdown_msg->flags) {
 			case 0:
 			case 1:
 				icmsghdrp->status = HV_S_OK;
 				execute_shutdown = true;

 				pr_info("Shutdown request received -"
 					    " graceful shutdown initiated\n");
 				break;
 			default:
 				icmsghdrp->status = HV_E_FAIL;
 				execute_shutdown = false;

 				pr_info("Shutdown request received -"
 					    " Invalid request\n");
 				break;
 			}
 		}

 		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 			| ICMSGHDRFLAG_RESPONSE;

 		vmbus_sendpacket(channel, shut_txf_buf,
 				       recvlen, requestid,
 				       VM_PKT_DATA_INBAND, 0);
 	}

 	if (execute_shutdown == true)
 		schedule_work(&shutdown_work);
 }

 /*
  * Set guest time to host UTC time.
  */
 static inline void do_adj_guesttime(u64 hosttime)
 {
 	s64 host_tns;
 	struct timespec host_ts;

 	host_tns = (hosttime - WLTIMEDELTA) * 100;
 	host_ts = ns_to_timespec(host_tns);

 	do_settimeofday(&host_ts);
 }

 /*
  * Set the host time in a process context.
  */

 struct adj_time_work {
 	struct work_struct work;
 	u64	host_time;
 };

 static void hv_set_host_time(struct work_struct *work)
 {
 	struct adj_time_work	*wrk;

 	wrk = container_of(work, struct adj_time_work, work);
 	do_adj_guesttime(wrk->host_time);
 	kfree(wrk);
 }

 /*
  * Synchronize time with host after reboot, restore, etc.
  *
  * ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.
  * After reboot the flag ICTIMESYNCFLAG_SYNC is included in the first time
  * message after the timesync channel is opened. Since the hv_utils module is
  * loaded after hv_vmbus, the first message is usually missed. The other
  * thing is, systime is automatically set to emulated hardware clock which may
  * not be UTC time or in the same time zone. So, to override these effects, we
  * use the first 50 time samples for initial system time setting.
  */
 static inline void adj_guesttime(u64 hosttime, u8 flags)
 {
 	struct adj_time_work    *wrk;
 	static s32 scnt = 50;

 	wrk = kmalloc(sizeof(struct adj_time_work), GFP_ATOMIC);
 	if (wrk == NULL)
 		return;

 	wrk->host_time = hosttime;
 	if ((flags & ICTIMESYNCFLAG_SYNC) != 0) {
 		INIT_WORK(&wrk->work, hv_set_host_time);
 		schedule_work(&wrk->work);
 		return;
 	}

 	if ((flags & ICTIMESYNCFLAG_SAMPLE) != 0 && scnt > 0) {
 		scnt--;
 		INIT_WORK(&wrk->work, hv_set_host_time);
 		schedule_work(&wrk->work);
 	} else
 		kfree(wrk);
 }

 /*
  * Time Sync Channel message handler.
  */
 static void timesync_onchannelcallback(void *context)
 {
 	struct vmbus_channel *channel = context;
 	u32 recvlen;
 	u64 requestid;
 	struct icmsg_hdr *icmsghdrp;
 	struct ictimesync_data *timedatap;
 	u8 *time_txf_buf = util_timesynch.recv_buffer;
 	struct icmsg_negotiate *negop = NULL;

 	vmbus_recvpacket(channel, time_txf_buf,
 			 PAGE_SIZE, &recvlen, &requestid);

 	if (recvlen > 0) {
 		icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
 				sizeof(struct vmbuspipe_hdr)];

 		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 			vmbus_prep_negotiate_resp(icmsghdrp, negop,
 						time_txf_buf,
 						util_fw_version,
 						ts_srv_version);
 		} else {
 			timedatap = (struct ictimesync_data *)&time_txf_buf[
 				sizeof(struct vmbuspipe_hdr) +
 				sizeof(struct icmsg_hdr)];
 			adj_guesttime(timedatap->parenttime, timedatap->flags);
 		}

 		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 			| ICMSGHDRFLAG_RESPONSE;

 		vmbus_sendpacket(channel, time_txf_buf,
 				recvlen, requestid,
 				VM_PKT_DATA_INBAND, 0);
 	}
 }

 /*
  * Heartbeat functionality.
  * Every two seconds, Hyper-V send us a heartbeat request message.
  * we respond to this message, and Hyper-V knows we are alive.
  */
 static void heartbeat_onchannelcallback(void *context)
 {
 	struct vmbus_channel *channel = context;
 	u32 recvlen;
 	u64 requestid;
 	struct icmsg_hdr *icmsghdrp;
 	struct heartbeat_msg_data *heartbeat_msg;
 	u8 *hbeat_txf_buf = util_heartbeat.recv_buffer;
 	struct icmsg_negotiate *negop = NULL;

 	vmbus_recvpacket(channel, hbeat_txf_buf,
 			 PAGE_SIZE, &recvlen, &requestid);

 	if (recvlen > 0) {
 		icmsghdrp = (struct icmsg_hdr *)&hbeat_txf_buf[
 				sizeof(struct vmbuspipe_hdr)];

 		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 			vmbus_prep_negotiate_resp(icmsghdrp, negop,
 				hbeat_txf_buf, util_fw_version,
 				hb_srv_version);
 		} else {
 			heartbeat_msg =
 				(struct heartbeat_msg_data *)&hbeat_txf_buf[
 					sizeof(struct vmbuspipe_hdr) +
 					sizeof(struct icmsg_hdr)];

 			heartbeat_msg->seq_num += 1;
 		}

 		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 			| ICMSGHDRFLAG_RESPONSE;

 		vmbus_sendpacket(channel, hbeat_txf_buf,
 				       recvlen, requestid,
 				       VM_PKT_DATA_INBAND, 0);
 	}
 }

 static int util_probe(struct hv_device *dev,
 			const struct hv_vmbus_device_id *dev_id)
 {
 	struct hv_util_service *srv =
 		(struct hv_util_service *)dev_id->driver_data;
 	int ret;

 	srv->recv_buffer = kmalloc(PAGE_SIZE * 4, GFP_KERNEL);
 	if (!srv->recv_buffer)
 		return -ENOMEM;
 	if (srv->util_init) {
 		ret = srv->util_init(srv);
 		if (ret) {
 			ret = -ENODEV;
 			goto error1;
 		}
 	}

 	/*
 	 * The set of services managed by the util driver are not performance
 	 * critical and do not need batched reading. Furthermore, some services
 	 * such as KVP can only handle one message from the host at a time.
 	 * Turn off batched reading for all util drivers before we open the
 	 * channel.
 	 */

 	set_channel_read_state(dev->channel, false);

 	ret = vmbus_open(dev->channel, 4 * PAGE_SIZE, 4 * PAGE_SIZE, NULL, 0,
 			srv->util_cb, dev->channel);
 	if (ret)
 		goto error;

 	hv_set_drvdata(dev, srv);
 	/*
 	 * Based on the host; initialize the framework and
 	 * service version numbers we will negotiate.
 	 */
 	switch (vmbus_proto_version) {
 	case (VERSION_WS2008):
 		util_fw_version = UTIL_WS2K8_FW_VERSION;
 		sd_srv_version = SD_WS2008_VERSION;
 		ts_srv_version = TS_WS2008_VERSION;
 		hb_srv_version = HB_WS2008_VERSION;
 		break;

 	default:
 		util_fw_version = UTIL_FW_VERSION;
 		sd_srv_version = SD_VERSION;
 		ts_srv_version = TS_VERSION;
 		hb_srv_version = HB_VERSION;
 	}

 	return 0;

 error:
 	if (srv->util_deinit)
 		srv->util_deinit();
 error1:
 	kfree(srv->recv_buffer);
 	return ret;
 }

 static int util_remove(struct hv_device *dev)
 {
 	struct hv_util_service *srv = hv_get_drvdata(dev);

 	vmbus_close(dev->channel);
 	if (srv->util_deinit)
 		srv->util_deinit();
 	kfree(srv->recv_buffer);

 	return 0;
 }

 static const struct hv_vmbus_device_id id_table[] = {
 	/* Shutdown guid */
 	{ HV_SHUTDOWN_GUID,
 	  .driver_data = (unsigned long)&util_shutdown
 	},
 	/* Time synch guid */
 	{ HV_TS_GUID,
 	  .driver_data = (unsigned long)&util_timesynch
 	},
 	/* Heartbeat guid */
 	{ HV_HEART_BEAT_GUID,
 	  .driver_data = (unsigned long)&util_heartbeat
 	},
 	/* KVP guid */
 	{ HV_KVP_GUID,
 	  .driver_data = (unsigned long)&util_kvp
 	},
 	/* VSS GUID */
 	{ HV_VSS_GUID,
 	  .driver_data = (unsigned long)&util_vss
 	},
 	{ },
 };

 MODULE_DEVICE_TABLE(vmbus, id_table);

 /* The one and only one */
 static  struct hv_driver util_drv = {
 	.name = "hv_util",
 	.id_table = id_table,
 	.probe =  util_probe,
 	.remove =  util_remove,
 };

 static int __init init_hyperv_utils(void)
 {
 	pr_info("Registering HyperV Utility Driver\n");

 	return vmbus_driver_register(&util_drv);
 }

 static void exit_hyperv_utils(void)
 {
 	pr_info("De-Registered HyperV Utility Driver\n");

 	vmbus_driver_unregister(&util_drv);
 }

 module_init(init_hyperv_utils);
 module_exit(exit_hyperv_utils);

 MODULE_DESCRIPTION("Hyper-V Utilities");
 MODULE_LICENSE("GPL");
	/*
	* Copyright (c) 2010, Microsoft Corporation.
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms and conditions of the GNU General Public License,
	* version 2, as published by the Free Software Foundation.
	*
	* This program is distributed in the hope it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*
	* You should have received a copy of the GNU General Public License along with
	* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
	* Place - Suite 330, Boston, MA 02111-1307 USA.
	*
	* Authors:
	* Haiyang Zhang <haiyangz@microsoft.com>
	* Hank Janssen <hjanssen@microsoft.com>
	*/
	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/sysctl.h>
	#include <linux/reboot.h>
	#include <linux/hyperv.h>


	#define SD_MAJOR 3
	#define SD_MINOR 0
	#define SD_VERSION (SD_MAJOR << 16 \| SD_MINOR)

	#define SD_WS2008_MAJOR 1
	#define SD_WS2008_VERSION (SD_WS2008_MAJOR << 16 \| SD_MINOR)

	#define TS_MAJOR 3
	#define TS_MINOR 0
	#define TS_VERSION (TS_MAJOR << 16 \| TS_MINOR)

	#define TS_WS2008_MAJOR 1
	#define TS_WS2008_VERSION (TS_WS2008_MAJOR << 16 \| TS_MINOR)

	#define HB_MAJOR 3
	#define HB_MINOR 0
	#define HB_VERSION (HB_MAJOR << 16 \| HB_MINOR)

	#define HB_WS2008_MAJOR 1
	#define HB_WS2008_VERSION (HB_WS2008_MAJOR << 16 \| HB_MINOR)

	static int sd_srv_version;
	static int ts_srv_version;
	static int hb_srv_version;
	static int util_fw_version;

	static void shutdown_onchannelcallback(void *context);
	static struct hv_util_service util_shutdown = {
	.util_cb = shutdown_onchannelcallback,
	};

	static void timesync_onchannelcallback(void *context);
	static struct hv_util_service util_timesynch = {
	.util_cb = timesync_onchannelcallback,
	};

	static void heartbeat_onchannelcallback(void *context);
	static struct hv_util_service util_heartbeat = {
	.util_cb = heartbeat_onchannelcallback,
	};

	static struct hv_util_service util_kvp = {
	.util_cb = hv_kvp_onchannelcallback,
	.util_init = hv_kvp_init,
	.util_deinit = hv_kvp_deinit,
	};

	static struct hv_util_service util_vss = {
	.util_cb = hv_vss_onchannelcallback,
	.util_init = hv_vss_init,
	.util_deinit = hv_vss_deinit,
	};

	static void perform_shutdown(struct work_struct *dummy)
	{
	orderly_poweroff(true);
	}

	/*
	* Perform the shutdown operation in a thread context.
	*/
	static DECLARE_WORK(shutdown_work, perform_shutdown);

	static void shutdown_onchannelcallback(void *context)
	{
	struct vmbus_channel *channel = context;
	u32 recvlen;
	u64 requestid;
	bool execute_shutdown = false;
	u8 *shut_txf_buf = util_shutdown.recv_buffer;

	struct shutdown_msg_data *shutdown_msg;

	struct icmsg_hdr *icmsghdrp;
	struct icmsg_negotiate *negop = NULL;

	vmbus_recvpacket(channel, shut_txf_buf,
	PAGE_SIZE, &recvlen, &requestid);

	if (recvlen > 0) {
	icmsghdrp = (struct icmsg_hdr *)&shut_txf_buf[
	sizeof(struct vmbuspipe_hdr)];

	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
	vmbus_prep_negotiate_resp(icmsghdrp, negop,
	shut_txf_buf, util_fw_version,
	sd_srv_version);
	} else {
	shutdown_msg =
	(struct shutdown_msg_data *)&shut_txf_buf[
	sizeof(struct vmbuspipe_hdr) +
	sizeof(struct icmsg_hdr)];

	switch (shutdown_msg->flags) {
	case 0:
	case 1:
	icmsghdrp->status = HV_S_OK;
	execute_shutdown = true;

	pr_info("Shutdown request received -"
	" graceful shutdown initiated\n");
	break;
	default:
	icmsghdrp->status = HV_E_FAIL;
	execute_shutdown = false;

	pr_info("Shutdown request received -"
	" Invalid request\n");
	break;
	}
	}

	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
	\| ICMSGHDRFLAG_RESPONSE;

	vmbus_sendpacket(channel, shut_txf_buf,
	recvlen, requestid,
	VM_PKT_DATA_INBAND, 0);
	}

	if (execute_shutdown == true)
	schedule_work(&shutdown_work);
	}

	/*
	* Set guest time to host UTC time.
	*/
	static inline void do_adj_guesttime(u64 hosttime)
	{
	s64 host_tns;
	struct timespec host_ts;

	host_tns = (hosttime - WLTIMEDELTA) * 100;
	host_ts = ns_to_timespec(host_tns);

	do_settimeofday(&host_ts);
	}

	/*
	* Set the host time in a process context.
	*/

	struct adj_time_work {
	struct work_struct work;
	u64 host_time;
	};

	static void hv_set_host_time(struct work_struct *work)
	{
	struct adj_time_work *wrk;

	wrk = container_of(work, struct adj_time_work, work);
	do_adj_guesttime(wrk->host_time);
	kfree(wrk);
	}

	/*
	* Synchronize time with host after reboot, restore, etc.
	*
	* ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.
	* After reboot the flag ICTIMESYNCFLAG_SYNC is included in the first time
	* message after the timesync channel is opened. Since the hv_utils module is
	* loaded after hv_vmbus, the first message is usually missed. The other
	* thing is, systime is automatically set to emulated hardware clock which may
	* not be UTC time or in the same time zone. So, to override these effects, we
	* use the first 50 time samples for initial system time setting.
	*/
	static inline void adj_guesttime(u64 hosttime, u8 flags)
	{
	struct adj_time_work *wrk;
	static s32 scnt = 50;

	wrk = kmalloc(sizeof(struct adj_time_work), GFP_ATOMIC);
	if (wrk == NULL)
	return;

	wrk->host_time = hosttime;
	if ((flags & ICTIMESYNCFLAG_SYNC) != 0) {
	INIT_WORK(&wrk->work, hv_set_host_time);
	schedule_work(&wrk->work);
	return;
	}

	if ((flags & ICTIMESYNCFLAG_SAMPLE) != 0 && scnt > 0) {
	scnt--;
	INIT_WORK(&wrk->work, hv_set_host_time);
	schedule_work(&wrk->work);
	} else
	kfree(wrk);
	}

	/*
	* Time Sync Channel message handler.
	*/
	static void timesync_onchannelcallback(void *context)
	{
	struct vmbus_channel *channel = context;
	u32 recvlen;
	u64 requestid;
	struct icmsg_hdr *icmsghdrp;
	struct ictimesync_data *timedatap;
	u8 *time_txf_buf = util_timesynch.recv_buffer;
	struct icmsg_negotiate *negop = NULL;

	vmbus_recvpacket(channel, time_txf_buf,
	PAGE_SIZE, &recvlen, &requestid);

	if (recvlen > 0) {
	icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
	sizeof(struct vmbuspipe_hdr)];

	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
	vmbus_prep_negotiate_resp(icmsghdrp, negop,
	time_txf_buf,
	util_fw_version,
	ts_srv_version);
	} else {
	timedatap = (struct ictimesync_data *)&time_txf_buf[
	sizeof(struct vmbuspipe_hdr) +
	sizeof(struct icmsg_hdr)];
	adj_guesttime(timedatap->parenttime, timedatap->flags);
	}

	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
	\| ICMSGHDRFLAG_RESPONSE;

	vmbus_sendpacket(channel, time_txf_buf,
	recvlen, requestid,
	VM_PKT_DATA_INBAND, 0);
	}
	}

	/*
	* Heartbeat functionality.
	* Every two seconds, Hyper-V send us a heartbeat request message.
	* we respond to this message, and Hyper-V knows we are alive.
	*/
	static void heartbeat_onchannelcallback(void *context)
	{
	struct vmbus_channel *channel = context;
	u32 recvlen;
	u64 requestid;
	struct icmsg_hdr *icmsghdrp;
	struct heartbeat_msg_data *heartbeat_msg;
	u8 *hbeat_txf_buf = util_heartbeat.recv_buffer;
	struct icmsg_negotiate *negop = NULL;

	vmbus_recvpacket(channel, hbeat_txf_buf,
	PAGE_SIZE, &recvlen, &requestid);

	if (recvlen > 0) {
	icmsghdrp = (struct icmsg_hdr *)&hbeat_txf_buf[
	sizeof(struct vmbuspipe_hdr)];

	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
	vmbus_prep_negotiate_resp(icmsghdrp, negop,
	hbeat_txf_buf, util_fw_version,
	hb_srv_version);
	} else {
	heartbeat_msg =
	(struct heartbeat_msg_data *)&hbeat_txf_buf[
	sizeof(struct vmbuspipe_hdr) +
	sizeof(struct icmsg_hdr)];

	heartbeat_msg->seq_num += 1;
	}

	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
	\| ICMSGHDRFLAG_RESPONSE;

	vmbus_sendpacket(channel, hbeat_txf_buf,
	recvlen, requestid,
	VM_PKT_DATA_INBAND, 0);
	}
	}

	static int util_probe(struct hv_device *dev,
	const struct hv_vmbus_device_id *dev_id)
	{
	struct hv_util_service *srv =
	(struct hv_util_service *)dev_id->driver_data;
	int ret;

	srv->recv_buffer = kmalloc(PAGE_SIZE * 4, GFP_KERNEL);
	if (!srv->recv_buffer)
	return -ENOMEM;
	if (srv->util_init) {
	ret = srv->util_init(srv);
	if (ret) {
	ret = -ENODEV;
	goto error1;
	}
	}

	/*
	* The set of services managed by the util driver are not performance
	* critical and do not need batched reading. Furthermore, some services
	* such as KVP can only handle one message from the host at a time.
	* Turn off batched reading for all util drivers before we open the
	* channel.
	*/

	set_channel_read_state(dev->channel, false);

	ret = vmbus_open(dev->channel, 4 * PAGE_SIZE, 4 * PAGE_SIZE, NULL, 0,
	srv->util_cb, dev->channel);
	if (ret)
	goto error;

	hv_set_drvdata(dev, srv);
	/*
	* Based on the host; initialize the framework and
	* service version numbers we will negotiate.
	*/
	switch (vmbus_proto_version) {
	case (VERSION_WS2008):
	util_fw_version = UTIL_WS2K8_FW_VERSION;
	sd_srv_version = SD_WS2008_VERSION;
	ts_srv_version = TS_WS2008_VERSION;
	hb_srv_version = HB_WS2008_VERSION;
	break;

	default:
	util_fw_version = UTIL_FW_VERSION;
	sd_srv_version = SD_VERSION;
	ts_srv_version = TS_VERSION;
	hb_srv_version = HB_VERSION;
	}

	return 0;

	error:
	if (srv->util_deinit)
	srv->util_deinit();
	error1:
	kfree(srv->recv_buffer);
	return ret;
	}

	static int util_remove(struct hv_device *dev)
	{
	struct hv_util_service *srv = hv_get_drvdata(dev);

	vmbus_close(dev->channel);
	if (srv->util_deinit)
	srv->util_deinit();
	kfree(srv->recv_buffer);

	return 0;
	}

	static const struct hv_vmbus_device_id id_table[] = {
	/* Shutdown guid */
	{ HV_SHUTDOWN_GUID,
	.driver_data = (unsigned long)&util_shutdown
	},
	/* Time synch guid */
	{ HV_TS_GUID,
	.driver_data = (unsigned long)&util_timesynch
	},
	/* Heartbeat guid */
	{ HV_HEART_BEAT_GUID,
	.driver_data = (unsigned long)&util_heartbeat
	},
	/* KVP guid */
	{ HV_KVP_GUID,
	.driver_data = (unsigned long)&util_kvp
	},
	/* VSS GUID */
	{ HV_VSS_GUID,
	.driver_data = (unsigned long)&util_vss
	},
	{ },
	};

	MODULE_DEVICE_TABLE(vmbus, id_table);

	/* The one and only one */
	static struct hv_driver util_drv = {
	.name = "hv_util",
	.id_table = id_table,
	.probe = util_probe,
	.remove = util_remove,
	};

	static int __init init_hyperv_utils(void)
	{
	pr_info("Registering HyperV Utility Driver\n");

	return vmbus_driver_register(&util_drv);
	}

	static void exit_hyperv_utils(void)
	{
	pr_info("De-Registered HyperV Utility Driver\n");

	vmbus_driver_unregister(&util_drv);
	}

	module_init(init_hyperv_utils);
	module_exit(exit_hyperv_utils);

	MODULE_DESCRIPTION("Hyper-V Utilities");
	MODULE_LICENSE("GPL");