linux-stable/drivers/hv/hv_util.c
Michael Kelley 31e5e64694 drivers: hv: Decouple Hyper-V clock/timer code from VMbus drivers
Hyper-V clock/timer code in hyperv_timer.c is mostly independent from
other VMbus drivers, but building for ARM64 without hyperv_timer.c
shows some remaining entanglements.  A default implementation of
hv_read_reference_counter can just read a Hyper-V synthetic register
and be independent of hyperv_timer.c, so move this code out and into
hv_common.c. Then it can be used by the timesync driver even if
hyperv_timer.c isn't built on a particular architecture.  If
hyperv_timer.c *is* built, it can override with a faster implementation.

Also provide stubs for stimer functions called by the VMbus driver when
hyperv_timer.c isn't built.

No functional changes.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1626220906-22629-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-07-19 09:24:28 +00:00

793 lines
20 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2010, 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/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/reboot.h>
#include <linux/hyperv.h>
#include <linux/clockchips.h>
#include <linux/ptp_clock_kernel.h>
#include <asm/mshyperv.h>
#include "hyperv_vmbus.h"
#define SD_MAJOR 3
#define SD_MINOR 0
#define SD_MINOR_1 1
#define SD_MINOR_2 2
#define SD_VERSION_3_1 (SD_MAJOR << 16 | SD_MINOR_1)
#define SD_VERSION_3_2 (SD_MAJOR << 16 | SD_MINOR_2)
#define SD_VERSION (SD_MAJOR << 16 | SD_MINOR)
#define SD_MAJOR_1 1
#define SD_VERSION_1 (SD_MAJOR_1 << 16 | SD_MINOR)
#define TS_MAJOR 4
#define TS_MINOR 0
#define TS_VERSION (TS_MAJOR << 16 | TS_MINOR)
#define TS_MAJOR_1 1
#define TS_VERSION_1 (TS_MAJOR_1 << 16 | TS_MINOR)
#define TS_MAJOR_3 3
#define TS_VERSION_3 (TS_MAJOR_3 << 16 | TS_MINOR)
#define HB_MAJOR 3
#define HB_MINOR 0
#define HB_VERSION (HB_MAJOR << 16 | HB_MINOR)
#define HB_MAJOR_1 1
#define HB_VERSION_1 (HB_MAJOR_1 << 16 | HB_MINOR)
static int sd_srv_version;
static int ts_srv_version;
static int hb_srv_version;
#define SD_VER_COUNT 4
static const int sd_versions[] = {
SD_VERSION_3_2,
SD_VERSION_3_1,
SD_VERSION,
SD_VERSION_1
};
#define TS_VER_COUNT 3
static const int ts_versions[] = {
TS_VERSION,
TS_VERSION_3,
TS_VERSION_1
};
#define HB_VER_COUNT 2
static const int hb_versions[] = {
HB_VERSION,
HB_VERSION_1
};
#define FW_VER_COUNT 2
static const int fw_versions[] = {
UTIL_FW_VERSION,
UTIL_WS2K8_FW_VERSION
};
/*
* Send the "hibernate" udev event in a thread context.
*/
struct hibernate_work_context {
struct work_struct work;
struct hv_device *dev;
};
static struct hibernate_work_context hibernate_context;
static bool hibernation_supported;
static void send_hibernate_uevent(struct work_struct *work)
{
char *uevent_env[2] = { "EVENT=hibernate", NULL };
struct hibernate_work_context *ctx;
ctx = container_of(work, struct hibernate_work_context, work);
kobject_uevent_env(&ctx->dev->device.kobj, KOBJ_CHANGE, uevent_env);
pr_info("Sent hibernation uevent\n");
}
static int hv_shutdown_init(struct hv_util_service *srv)
{
struct vmbus_channel *channel = srv->channel;
INIT_WORK(&hibernate_context.work, send_hibernate_uevent);
hibernate_context.dev = channel->device_obj;
hibernation_supported = hv_is_hibernation_supported();
return 0;
}
static void shutdown_onchannelcallback(void *context);
static struct hv_util_service util_shutdown = {
.util_cb = shutdown_onchannelcallback,
.util_init = hv_shutdown_init,
};
static int hv_timesync_init(struct hv_util_service *srv);
static int hv_timesync_pre_suspend(void);
static void hv_timesync_deinit(void);
static void timesync_onchannelcallback(void *context);
static struct hv_util_service util_timesynch = {
.util_cb = timesync_onchannelcallback,
.util_init = hv_timesync_init,
.util_pre_suspend = hv_timesync_pre_suspend,
.util_deinit = hv_timesync_deinit,
};
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_pre_suspend = hv_kvp_pre_suspend,
.util_pre_resume = hv_kvp_pre_resume,
.util_deinit = hv_kvp_deinit,
};
static struct hv_util_service util_vss = {
.util_cb = hv_vss_onchannelcallback,
.util_init = hv_vss_init,
.util_pre_suspend = hv_vss_pre_suspend,
.util_pre_resume = hv_vss_pre_resume,
.util_deinit = hv_vss_deinit,
};
static struct hv_util_service util_fcopy = {
.util_cb = hv_fcopy_onchannelcallback,
.util_init = hv_fcopy_init,
.util_pre_suspend = hv_fcopy_pre_suspend,
.util_pre_resume = hv_fcopy_pre_resume,
.util_deinit = hv_fcopy_deinit,
};
static void perform_shutdown(struct work_struct *dummy)
{
orderly_poweroff(true);
}
static void perform_restart(struct work_struct *dummy)
{
orderly_reboot();
}
/*
* Perform the shutdown operation in a thread context.
*/
static DECLARE_WORK(shutdown_work, perform_shutdown);
/*
* Perform the restart operation in a thread context.
*/
static DECLARE_WORK(restart_work, perform_restart);
static void shutdown_onchannelcallback(void *context)
{
struct vmbus_channel *channel = context;
struct work_struct *work = NULL;
u32 recvlen;
u64 requestid;
u8 *shut_txf_buf = util_shutdown.recv_buffer;
struct shutdown_msg_data *shutdown_msg;
struct icmsg_hdr *icmsghdrp;
if (vmbus_recvpacket(channel, shut_txf_buf, HV_HYP_PAGE_SIZE, &recvlen, &requestid)) {
pr_err_ratelimited("Shutdown request received. Could not read into shut txf buf\n");
return;
}
if (!recvlen)
return;
/* Ensure recvlen is big enough to read header data */
if (recvlen < ICMSG_HDR) {
pr_err_ratelimited("Shutdown request received. Packet length too small: %d\n",
recvlen);
return;
}
icmsghdrp = (struct icmsg_hdr *)&shut_txf_buf[sizeof(struct vmbuspipe_hdr)];
if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
if (vmbus_prep_negotiate_resp(icmsghdrp,
shut_txf_buf, recvlen,
fw_versions, FW_VER_COUNT,
sd_versions, SD_VER_COUNT,
NULL, &sd_srv_version)) {
pr_info("Shutdown IC version %d.%d\n",
sd_srv_version >> 16,
sd_srv_version & 0xFFFF);
}
} else if (icmsghdrp->icmsgtype == ICMSGTYPE_SHUTDOWN) {
/* Ensure recvlen is big enough to contain shutdown_msg_data struct */
if (recvlen < ICMSG_HDR + sizeof(struct shutdown_msg_data)) {
pr_err_ratelimited("Invalid shutdown msg data. Packet length too small: %u\n",
recvlen);
return;
}
shutdown_msg = (struct shutdown_msg_data *)&shut_txf_buf[ICMSG_HDR];
/*
* shutdown_msg->flags can be 0(shut down), 2(reboot),
* or 4(hibernate). It may bitwise-OR 1, which means
* performing the request by force. Linux always tries
* to perform the request by force.
*/
switch (shutdown_msg->flags) {
case 0:
case 1:
icmsghdrp->status = HV_S_OK;
work = &shutdown_work;
pr_info("Shutdown request received - graceful shutdown initiated\n");
break;
case 2:
case 3:
icmsghdrp->status = HV_S_OK;
work = &restart_work;
pr_info("Restart request received - graceful restart initiated\n");
break;
case 4:
case 5:
pr_info("Hibernation request received\n");
icmsghdrp->status = hibernation_supported ?
HV_S_OK : HV_E_FAIL;
if (hibernation_supported)
work = &hibernate_context.work;
break;
default:
icmsghdrp->status = HV_E_FAIL;
pr_info("Shutdown request received - Invalid request\n");
break;
}
} else {
icmsghdrp->status = HV_E_FAIL;
pr_err_ratelimited("Shutdown request received. Invalid msg type: %d\n",
icmsghdrp->icmsgtype);
}
icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
| ICMSGHDRFLAG_RESPONSE;
vmbus_sendpacket(channel, shut_txf_buf,
recvlen, requestid,
VM_PKT_DATA_INBAND, 0);
if (work)
schedule_work(work);
}
/*
* Set the host time in a process context.
*/
static struct work_struct adj_time_work;
/*
* The last time sample, received from the host. PTP device responds to
* requests by using this data and the current partition-wide time reference
* count.
*/
static struct {
u64 host_time;
u64 ref_time;
spinlock_t lock;
} host_ts;
static inline u64 reftime_to_ns(u64 reftime)
{
return (reftime - WLTIMEDELTA) * 100;
}
/*
* Hard coded threshold for host timesync delay: 600 seconds
*/
static const u64 HOST_TIMESYNC_DELAY_THRESH = 600 * (u64)NSEC_PER_SEC;
static int hv_get_adj_host_time(struct timespec64 *ts)
{
u64 newtime, reftime, timediff_adj;
unsigned long flags;
int ret = 0;
spin_lock_irqsave(&host_ts.lock, flags);
reftime = hv_read_reference_counter();
/*
* We need to let the caller know that last update from host
* is older than the max allowable threshold. clock_gettime()
* and PTP ioctl do not have a documented error that we could
* return for this specific case. Use ESTALE to report this.
*/
timediff_adj = reftime - host_ts.ref_time;
if (timediff_adj * 100 > HOST_TIMESYNC_DELAY_THRESH) {
pr_warn_once("TIMESYNC IC: Stale time stamp, %llu nsecs old\n",
(timediff_adj * 100));
ret = -ESTALE;
}
newtime = host_ts.host_time + timediff_adj;
*ts = ns_to_timespec64(reftime_to_ns(newtime));
spin_unlock_irqrestore(&host_ts.lock, flags);
return ret;
}
static void hv_set_host_time(struct work_struct *work)
{
struct timespec64 ts;
if (!hv_get_adj_host_time(&ts))
do_settimeofday64(&ts);
}
/*
* 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. This bit is
* considered a hard request to discipline the clock.
*
* ICTIMESYNCFLAG_SAMPLE bit indicates a time sample from host. This is
* typically used as a hint to the guest. The guest is under no obligation
* to discipline the clock.
*/
static inline void adj_guesttime(u64 hosttime, u64 reftime, u8 adj_flags)
{
unsigned long flags;
u64 cur_reftime;
/*
* Save the adjusted time sample from the host and the snapshot
* of the current system time.
*/
spin_lock_irqsave(&host_ts.lock, flags);
cur_reftime = hv_read_reference_counter();
host_ts.host_time = hosttime;
host_ts.ref_time = cur_reftime;
/*
* TimeSync v4 messages contain reference time (guest's Hyper-V
* clocksource read when the time sample was generated), we can
* improve the precision by adding the delta between now and the
* time of generation. For older protocols we set
* reftime == cur_reftime on call.
*/
host_ts.host_time += (cur_reftime - reftime);
spin_unlock_irqrestore(&host_ts.lock, flags);
/* Schedule work to do do_settimeofday64() */
if (adj_flags & ICTIMESYNCFLAG_SYNC)
schedule_work(&adj_time_work);
}
/*
* 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;
struct ictimesync_ref_data *refdata;
u8 *time_txf_buf = util_timesynch.recv_buffer;
/*
* Drain the ring buffer and use the last packet to update
* host_ts
*/
while (1) {
int ret = vmbus_recvpacket(channel, time_txf_buf,
HV_HYP_PAGE_SIZE, &recvlen,
&requestid);
if (ret) {
pr_err_ratelimited("TimeSync IC pkt recv failed (Err: %d)\n",
ret);
break;
}
if (!recvlen)
break;
/* Ensure recvlen is big enough to read header data */
if (recvlen < ICMSG_HDR) {
pr_err_ratelimited("Timesync request received. Packet length too small: %d\n",
recvlen);
break;
}
icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
sizeof(struct vmbuspipe_hdr)];
if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
if (vmbus_prep_negotiate_resp(icmsghdrp,
time_txf_buf, recvlen,
fw_versions, FW_VER_COUNT,
ts_versions, TS_VER_COUNT,
NULL, &ts_srv_version)) {
pr_info("TimeSync IC version %d.%d\n",
ts_srv_version >> 16,
ts_srv_version & 0xFFFF);
}
} else if (icmsghdrp->icmsgtype == ICMSGTYPE_TIMESYNC) {
if (ts_srv_version > TS_VERSION_3) {
/* Ensure recvlen is big enough to read ictimesync_ref_data */
if (recvlen < ICMSG_HDR + sizeof(struct ictimesync_ref_data)) {
pr_err_ratelimited("Invalid ictimesync ref data. Length too small: %u\n",
recvlen);
break;
}
refdata = (struct ictimesync_ref_data *)&time_txf_buf[ICMSG_HDR];
adj_guesttime(refdata->parenttime,
refdata->vmreferencetime,
refdata->flags);
} else {
/* Ensure recvlen is big enough to read ictimesync_data */
if (recvlen < ICMSG_HDR + sizeof(struct ictimesync_data)) {
pr_err_ratelimited("Invalid ictimesync data. Length too small: %u\n",
recvlen);
break;
}
timedatap = (struct ictimesync_data *)&time_txf_buf[ICMSG_HDR];
adj_guesttime(timedatap->parenttime,
hv_read_reference_counter(),
timedatap->flags);
}
} else {
icmsghdrp->status = HV_E_FAIL;
pr_err_ratelimited("Timesync request received. Invalid msg type: %d\n",
icmsghdrp->icmsgtype);
}
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;
while (1) {
if (vmbus_recvpacket(channel, hbeat_txf_buf, HV_HYP_PAGE_SIZE,
&recvlen, &requestid)) {
pr_err_ratelimited("Heartbeat request received. Could not read into hbeat txf buf\n");
return;
}
if (!recvlen)
break;
/* Ensure recvlen is big enough to read header data */
if (recvlen < ICMSG_HDR) {
pr_err_ratelimited("Heartbeat request received. Packet length too small: %d\n",
recvlen);
break;
}
icmsghdrp = (struct icmsg_hdr *)&hbeat_txf_buf[
sizeof(struct vmbuspipe_hdr)];
if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
if (vmbus_prep_negotiate_resp(icmsghdrp,
hbeat_txf_buf, recvlen,
fw_versions, FW_VER_COUNT,
hb_versions, HB_VER_COUNT,
NULL, &hb_srv_version)) {
pr_info("Heartbeat IC version %d.%d\n",
hb_srv_version >> 16,
hb_srv_version & 0xFFFF);
}
} else if (icmsghdrp->icmsgtype == ICMSGTYPE_HEARTBEAT) {
/*
* Ensure recvlen is big enough to read seq_num. Reserved area is not
* included in the check as the host may not fill it up entirely
*/
if (recvlen < ICMSG_HDR + sizeof(u64)) {
pr_err_ratelimited("Invalid heartbeat msg data. Length too small: %u\n",
recvlen);
break;
}
heartbeat_msg = (struct heartbeat_msg_data *)&hbeat_txf_buf[ICMSG_HDR];
heartbeat_msg->seq_num += 1;
} else {
icmsghdrp->status = HV_E_FAIL;
pr_err_ratelimited("Heartbeat request received. Invalid msg type: %d\n",
icmsghdrp->icmsgtype);
}
icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
| ICMSGHDRFLAG_RESPONSE;
vmbus_sendpacket(channel, hbeat_txf_buf,
recvlen, requestid,
VM_PKT_DATA_INBAND, 0);
}
}
#define HV_UTIL_RING_SEND_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)
#define HV_UTIL_RING_RECV_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)
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(HV_HYP_PAGE_SIZE * 4, GFP_KERNEL);
if (!srv->recv_buffer)
return -ENOMEM;
srv->channel = dev->channel;
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_mode(dev->channel, HV_CALL_DIRECT);
hv_set_drvdata(dev, srv);
ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
dev->channel);
if (ret)
goto error;
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);
if (srv->util_deinit)
srv->util_deinit();
vmbus_close(dev->channel);
kfree(srv->recv_buffer);
return 0;
}
/*
* When we're in util_suspend(), all the userspace processes have been frozen
* (refer to hibernate() -> freeze_processes()). The userspace is thawed only
* after the whole resume procedure, including util_resume(), finishes.
*/
static int util_suspend(struct hv_device *dev)
{
struct hv_util_service *srv = hv_get_drvdata(dev);
int ret = 0;
if (srv->util_pre_suspend) {
ret = srv->util_pre_suspend();
if (ret)
return ret;
}
vmbus_close(dev->channel);
return 0;
}
static int util_resume(struct hv_device *dev)
{
struct hv_util_service *srv = hv_get_drvdata(dev);
int ret = 0;
if (srv->util_pre_resume) {
ret = srv->util_pre_resume();
if (ret)
return ret;
}
ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
dev->channel);
return ret;
}
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
},
/* File copy GUID */
{ HV_FCOPY_GUID,
.driver_data = (unsigned long)&util_fcopy
},
{ },
};
MODULE_DEVICE_TABLE(vmbus, id_table);
/* The one and only one */
static struct hv_driver util_drv = {
.name = "hv_utils",
.id_table = id_table,
.probe = util_probe,
.remove = util_remove,
.suspend = util_suspend,
.resume = util_resume,
.driver = {
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
};
static int hv_ptp_enable(struct ptp_clock_info *info,
struct ptp_clock_request *request, int on)
{
return -EOPNOTSUPP;
}
static int hv_ptp_settime(struct ptp_clock_info *p, const struct timespec64 *ts)
{
return -EOPNOTSUPP;
}
static int hv_ptp_adjfreq(struct ptp_clock_info *ptp, s32 delta)
{
return -EOPNOTSUPP;
}
static int hv_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
return -EOPNOTSUPP;
}
static int hv_ptp_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
{
return hv_get_adj_host_time(ts);
}
static struct ptp_clock_info ptp_hyperv_info = {
.name = "hyperv",
.enable = hv_ptp_enable,
.adjtime = hv_ptp_adjtime,
.adjfreq = hv_ptp_adjfreq,
.gettime64 = hv_ptp_gettime,
.settime64 = hv_ptp_settime,
.owner = THIS_MODULE,
};
static struct ptp_clock *hv_ptp_clock;
static int hv_timesync_init(struct hv_util_service *srv)
{
spin_lock_init(&host_ts.lock);
INIT_WORK(&adj_time_work, hv_set_host_time);
/*
* ptp_clock_register() returns NULL when CONFIG_PTP_1588_CLOCK is
* disabled but the driver is still useful without the PTP device
* as it still handles the ICTIMESYNCFLAG_SYNC case.
*/
hv_ptp_clock = ptp_clock_register(&ptp_hyperv_info, NULL);
if (IS_ERR_OR_NULL(hv_ptp_clock)) {
pr_err("cannot register PTP clock: %d\n",
PTR_ERR_OR_ZERO(hv_ptp_clock));
hv_ptp_clock = NULL;
}
return 0;
}
static void hv_timesync_cancel_work(void)
{
cancel_work_sync(&adj_time_work);
}
static int hv_timesync_pre_suspend(void)
{
hv_timesync_cancel_work();
return 0;
}
static void hv_timesync_deinit(void)
{
if (hv_ptp_clock)
ptp_clock_unregister(hv_ptp_clock);
hv_timesync_cancel_work();
}
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");