[linux-2.6-block.git] / drivers / hv / hv_snapshot.c

/*
 * An implementation of host initiated guest snapshot.
 *
 *
 * Copyright (C) 2013, Microsoft, Inc.
 * Author : K. Y. Srinivasan <kys@microsoft.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.
 *
 */
#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 "hyperv_vmbus.h"
#include "hv_utils_transport.h"

#define VSS_MAJOR  5
#define VSS_MINOR  0
#define VSS_VERSION    (VSS_MAJOR << 16 | VSS_MINOR)

#define VSS_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000))

/*
 * Global state maintained for transaction that is being processed. For a class
 * of integration services, including the "VSS 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 vmbus_channel *recv_channel; /* chn we got the request */
	u64 recv_req_id; /* request ID. */
	struct hv_vss_msg  *msg; /* current message */
} vss_transaction;


static void vss_respond_to_host(int error);

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

static const char vss_devname[] = "vmbus/hv_vss";
static __u8 *recv_buffer;
static struct hvutil_transport *hvt;

static void vss_send_op(struct work_struct *dummy);
static void vss_timeout_func(struct work_struct *dummy);

static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
static DECLARE_WORK(vss_send_op_work, vss_send_op);

static void vss_poll_wrapper(void *channel)
{
	/* Transaction is finished, reset the state here to avoid races. */
	vss_transaction.state = HVUTIL_READY;
	hv_vss_onchannelcallback(channel);
}

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

static void vss_timeout_func(struct work_struct *dummy)
{
	/*
	 * Timeout waiting for userspace component to reply happened.
	 */
	pr_warn("VSS: timeout waiting for daemon to reply\n");
	vss_respond_to_host(HV_E_FAIL);

	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
}

static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
{
	u32 our_ver = VSS_OP_REGISTER1;

	switch (vss_msg->vss_hdr.operation) {
	case VSS_OP_REGISTER:
		/* Daemon doesn't expect us to reply */
		dm_reg_value = VSS_OP_REGISTER;
		break;
	case VSS_OP_REGISTER1:
		/* Daemon expects us to reply with our own version*/
		if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver)))
			return -EFAULT;
		dm_reg_value = VSS_OP_REGISTER1;
		break;
	default:
		return -EINVAL;
	}
	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
	pr_debug("VSS: userspace daemon ver. %d registered\n", dm_reg_value);
	return 0;
}

static int vss_on_msg(void *msg, int len)
{
	struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;

	if (len != sizeof(*vss_msg))
		return -EINVAL;

	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
	    vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
		/*
		 * Don't process registration messages if we're in the middle
		 * of a transaction processing.
		 */
		if (vss_transaction.state > HVUTIL_READY)
			return -EINVAL;
		return vss_handle_handshake(vss_msg);
	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
		vss_transaction.state = HVUTIL_USERSPACE_RECV;
		if (cancel_delayed_work_sync(&vss_timeout_work)) {
			vss_respond_to_host(vss_msg->error);
			/* Transaction is finished, reset the state. */
			hv_poll_channel(vss_transaction.recv_channel,
					vss_poll_wrapper);
		}
	} else {
		/* This is a spurious call! */
		pr_warn("VSS: Transaction not active\n");
		return -EINVAL;
	}
	return 0;
}


static void vss_send_op(struct work_struct *dummy)
{
	int op = vss_transaction.msg->vss_hdr.operation;
	int rc;
	struct hv_vss_msg *vss_msg;

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

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

	vss_msg->vss_hdr.operation = op;

	vss_transaction.state = HVUTIL_USERSPACE_REQ;
	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg));
	if (rc) {
		pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
		if (cancel_delayed_work_sync(&vss_timeout_work)) {
			vss_respond_to_host(HV_E_FAIL);
			vss_transaction.state = HVUTIL_READY;
		}
	}

	kfree(vss_msg);

	return;
}

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

static void
vss_respond_to_host(int error)
{
	struct icmsg_hdr *icmsghdrp;
	u32	buf_len;
	struct vmbus_channel *channel;
	u64	req_id;

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

	buf_len = vss_transaction.recv_len;
	channel = vss_transaction.recv_channel;
	req_id = vss_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;

	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 VSS message from the host.
 * The host ensures that only one VSS transaction can be active at a time.
 */

void hv_vss_onchannelcallback(void *context)
{
	struct vmbus_channel *channel = context;
	u32 recvlen;
	u64 requestid;
	struct hv_vss_msg *vss_msg;


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

	if (vss_transaction.state > HVUTIL_READY)
		return;

	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
			 &requestid);

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

		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
			vmbus_prep_negotiate_resp(icmsghdrp, negop,
				 recv_buffer, UTIL_FW_VERSION,
				 VSS_VERSION);
		} else {
			vss_msg = (struct hv_vss_msg *)&recv_buffer[
				sizeof(struct vmbuspipe_hdr) +
				sizeof(struct icmsg_hdr)];

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

			vss_transaction.recv_len = recvlen;
			vss_transaction.recv_req_id = requestid;
			vss_transaction.msg = (struct hv_vss_msg *)vss_msg;

			switch (vss_msg->vss_hdr.operation) {
				/*
				 * Initiate a "freeze/thaw"
				 * operation in the guest.
				 * We respond to the host once
				 * the operation is complete.
				 *
				 * We send the message to the
				 * user space daemon and the
				 * operation is performed in
				 * the daemon.
				 */
			case VSS_OP_FREEZE:
			case VSS_OP_THAW:
				if (vss_transaction.state < HVUTIL_READY) {
					/* Userspace is not registered yet */
					vss_respond_to_host(HV_E_FAIL);
					return;
				}
				vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
				schedule_work(&vss_send_op_work);
				schedule_delayed_work(&vss_timeout_work,
						      VSS_USERSPACE_TIMEOUT);
				return;

			case VSS_OP_HOT_BACKUP:
				vss_msg->vss_cf.flags =
					 VSS_HBU_NO_AUTO_RECOVERY;
				vss_respond_to_host(0);
				return;

			case VSS_OP_GET_DM_INFO:
				vss_msg->dm_info.flags = 0;
				vss_respond_to_host(0);
				return;

			default:
				vss_respond_to_host(0);
				return;

			}

		}

		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
			| ICMSGHDRFLAG_RESPONSE;

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

}

static void vss_on_reset(void)
{
	if (cancel_delayed_work_sync(&vss_timeout_work))
		vss_respond_to_host(HV_E_FAIL);
	vss_transaction.state = HVUTIL_DEVICE_INIT;
}

int
hv_vss_init(struct hv_util_service *srv)
{
	if (vmbus_proto_version < VERSION_WIN8_1) {
		pr_warn("Integration service 'Backup (volume snapshot)'"
			" not supported on this host version.\n");
		return -ENOTSUPP;
	}
	recv_buffer = srv->recv_buffer;
	vss_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.
	 */
	vss_transaction.state = HVUTIL_DEVICE_INIT;

	hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
				    vss_on_msg, vss_on_reset);
	if (!hvt)
		return -EFAULT;

	return 0;
}

void hv_vss_deinit(void)
{
	vss_transaction.state = HVUTIL_DEVICE_DYING;
	cancel_delayed_work_sync(&vss_timeout_work);
	cancel_work_sync(&vss_send_op_work);
	hvutil_transport_destroy(hvt);
}
Commit	Line	Data
96dd86fa S	1	/*
	2	* An implementation of host initiated guest snapshot.
	3	*
	4	*
	5	* Copyright (C) 2013, Microsoft, Inc.
	6	* Author : K. Y. Srinivasan <kys@microsoft.com>
	7	*
	8	* This program is free software; you can redistribute it and/or modify it
	9	* under the terms of the GNU General Public License version 2 as published
	10	* by the Free Software Foundation.
	11	*
	12	* This program is distributed in the hope that it will be useful, but
	13	* WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	15	* NON INFRINGEMENT. See the GNU General Public License for more
	16	* details.
	17	*
	18	*/
	19	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	20
	21	#include <linux/net.h>
	22	#include <linux/nls.h>
	23	#include <linux/connector.h>
	24	#include <linux/workqueue.h>
	25	#include <linux/hyperv.h>
	26
3647a83d	27	#include "hyperv_vmbus.h"
6472f80a	28	#include "hv_utils_transport.h"
3647a83d	29
6741335b S	30	#define VSS_MAJOR 5
6741335b S	31	#define VSS_MINOR 0
3a491605	32	#define VSS_VERSION (VSS_MAJOR << 16 \| VSS_MINOR)
6741335b	33
64914207	34	#define VSS_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000))
96dd86fa S	35
96dd86fa S	36	/*
086a6f68 VK	37	* Global state maintained for transaction that is being processed. For a class
	38	* of integration services, including the "VSS service", the specified protocol
	39	* is a "request/response" protocol which means that there can only be single
	40	* outstanding transaction from the host at any given point in time. We use
	41	* this to simplify memory management in this driver - we cache and process
	42	* only one message at a time.
96dd86fa	43	*
086a6f68 VK	44	* While the request/response protocol is guaranteed by the host, we further
	45	* ensure this by serializing packet processing in this driver - we do not
	46	* read additional packets from the VMBUs until the current packet is fully
	47	* handled.
96dd86fa S	48	*/
	49
	50	static struct {
086a6f68	51	int state; /* hvutil_device_state */
96dd86fa S	52	int recv_len; /* number of bytes received. */
	53	struct vmbus_channel recv_channel; / chn we got the request */
	54	u64 recv_req_id; /* request ID. */
	55	struct hv_vss_msg msg; / current message */
	56	} vss_transaction;
	57
	58
	59	static void vss_respond_to_host(int error);
	60
cd8dc054 VK	61	/*
	62	* This state maintains the version number registered by the daemon.
	63	*/
	64	static int dm_reg_value;
	65
6472f80a	66	static const char vss_devname[] = "vmbus/hv_vss";
96dd86fa	67	static __u8 *recv_buffer;
6472f80a	68	static struct hvutil_transport *hvt;
96dd86fa S	69
96dd86fa S	70	static void vss_send_op(struct work_struct *dummy);
64914207 VK	71	static void vss_timeout_func(struct work_struct *dummy);
	72
	73	static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
96dd86fa S	74	static DECLARE_WORK(vss_send_op_work, vss_send_op);
96dd86fa S	75
3cace4a6 OH	76	static void vss_poll_wrapper(void *channel)
	77	{
	78	/* Transaction is finished, reset the state here to avoid races. */
	79	vss_transaction.state = HVUTIL_READY;
	80	hv_vss_onchannelcallback(channel);
	81	}
	82
96dd86fa S	83	/*
	84	* Callback when data is received from user mode.
	85	*/
	86
64914207 VK	87	static void vss_timeout_func(struct work_struct *dummy)
	88	{
	89	/*
	90	* Timeout waiting for userspace component to reply happened.
	91	*/
	92	pr_warn("VSS: timeout waiting for daemon to reply\n");
	93	vss_respond_to_host(HV_E_FAIL);
38c06c29	94
3cace4a6	95	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
64914207 VK	96	}
64914207 VK	97
cd8dc054 VK	98	static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
	99	{
	100	u32 our_ver = VSS_OP_REGISTER1;
	101
	102	switch (vss_msg->vss_hdr.operation) {
	103	case VSS_OP_REGISTER:
	104	/* Daemon doesn't expect us to reply */
	105	dm_reg_value = VSS_OP_REGISTER;
	106	break;
	107	case VSS_OP_REGISTER1:
	108	/* Daemon expects us to reply with our own version*/
	109	if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver)))
	110	return -EFAULT;
	111	dm_reg_value = VSS_OP_REGISTER1;
	112	break;
	113	default:
	114	return -EINVAL;
	115	}
2d0c3b5a	116	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
7c959127	117	pr_debug("VSS: userspace daemon ver. %d registered\n", dm_reg_value);
cd8dc054 VK	118	return 0;
	119	}
	120
6472f80a	121	static int vss_on_msg(void *msg, int len)
96dd86fa	122	{
6472f80a	123	struct hv_vss_msg vss_msg = (struct hv_vss_msg )msg;
96dd86fa	124
6472f80a VK	125	if (len != sizeof(*vss_msg))
6472f80a VK	126	return -EINVAL;
96dd86fa	127
cd8dc054 VK	128	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER \|\|
	129	vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
	130	/*
	131	* Don't process registration messages if we're in the middle
	132	* of a transaction processing.
	133	*/
	134	if (vss_transaction.state > HVUTIL_READY)
	135	return -EINVAL;
	136	return vss_handle_handshake(vss_msg);
086a6f68 VK	137	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
	138	vss_transaction.state = HVUTIL_USERSPACE_RECV;
	139	if (cancel_delayed_work_sync(&vss_timeout_work)) {
	140	vss_respond_to_host(vss_msg->error);
	141	/* Transaction is finished, reset the state. */
3cace4a6 OH	142	hv_poll_channel(vss_transaction.recv_channel,
3cace4a6 OH	143	vss_poll_wrapper);
086a6f68 VK	144	}
	145	} else {
	146	/* This is a spurious call! */
	147	pr_warn("VSS: Transaction not active\n");
6472f80a	148	return -EINVAL;
96dd86fa	149	}
6472f80a	150	return 0;
96dd86fa S	151	}
	152
	153
	154	static void vss_send_op(struct work_struct *dummy)
	155	{
	156	int op = vss_transaction.msg->vss_hdr.operation;
8d9560eb	157	int rc;
96dd86fa S	158	struct hv_vss_msg *vss_msg;
96dd86fa S	159
086a6f68 VK	160	/* The transaction state is wrong. */
	161	if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED)
	162	return;
	163
6472f80a VK	164	vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
6472f80a VK	165	if (!vss_msg)
96dd86fa S	166	return;
96dd86fa S	167
96dd86fa	168	vss_msg->vss_hdr.operation = op;
96dd86fa	169
086a6f68	170	vss_transaction.state = HVUTIL_USERSPACE_REQ;
6472f80a	171	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg));
8d9560eb VK	172	if (rc) {
8d9560eb VK	173	pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
086a6f68	174	if (cancel_delayed_work_sync(&vss_timeout_work)) {
8d9560eb	175	vss_respond_to_host(HV_E_FAIL);
086a6f68 VK	176	vss_transaction.state = HVUTIL_READY;
086a6f68 VK	177	}
8d9560eb	178	}
086a6f68	179
6472f80a	180	kfree(vss_msg);
96dd86fa S	181
	182	return;
	183	}
	184
	185	/*
	186	* Send a response back to the host.
	187	*/
	188
	189	static void
	190	vss_respond_to_host(int error)
	191	{
	192	struct icmsg_hdr *icmsghdrp;
	193	u32 buf_len;
	194	struct vmbus_channel *channel;
	195	u64 req_id;
	196
96dd86fa S	197	/*
	198	* Copy the global state for completing the transaction. Note that
	199	* only one transaction can be active at a time.
	200	*/
	201
	202	buf_len = vss_transaction.recv_len;
	203	channel = vss_transaction.recv_channel;
	204	req_id = vss_transaction.recv_req_id;
96dd86fa S	205
	206	icmsghdrp = (struct icmsg_hdr *)
	207	&recv_buffer[sizeof(struct vmbuspipe_hdr)];
	208
	209	if (channel->onchannel_callback == NULL)
	210	/*
	211	* We have raced with util driver being unloaded;
	212	* silently return.
	213	*/
	214	return;
	215
	216	icmsghdrp->status = error;
	217
	218	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION \| ICMSGHDRFLAG_RESPONSE;
	219
	220	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
	221	VM_PKT_DATA_INBAND, 0);
	222
	223	}
	224
	225	/*
	226	* This callback is invoked when we get a VSS message from the host.
	227	* The host ensures that only one VSS transaction can be active at a time.
	228	*/
	229
	230	void hv_vss_onchannelcallback(void *context)
	231	{
	232	struct vmbus_channel *channel = context;
	233	u32 recvlen;
	234	u64 requestid;
	235	struct hv_vss_msg *vss_msg;
	236
	237
	238	struct icmsg_hdr *icmsghdrp;
	239	struct icmsg_negotiate *negop = NULL;
	240
3cace4a6	241	if (vss_transaction.state > HVUTIL_READY)
96dd86fa	242	return;
96dd86fa S	243
	244	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
	245	&requestid);
	246
	247	if (recvlen > 0) {
	248	icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
	249	sizeof(struct vmbuspipe_hdr)];
	250
	251	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
	252	vmbus_prep_negotiate_resp(icmsghdrp, negop,
3a491605 S	253	recv_buffer, UTIL_FW_VERSION,
3a491605 S	254	VSS_VERSION);
96dd86fa S	255	} else {
	256	vss_msg = (struct hv_vss_msg *)&recv_buffer[
	257	sizeof(struct vmbuspipe_hdr) +
	258	sizeof(struct icmsg_hdr)];
	259
	260	/*
	261	* Stash away this global state for completing the
	262	* transaction; note transactions are serialized.
	263	*/
	264
	265	vss_transaction.recv_len = recvlen;
96dd86fa	266	vss_transaction.recv_req_id = requestid;
96dd86fa S	267	vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
	268
	269	switch (vss_msg->vss_hdr.operation) {
	270	/*
	271	* Initiate a "freeze/thaw"
	272	* operation in the guest.
	273	* We respond to the host once
	274	* the operation is complete.
	275	*
	276	* We send the message to the
	277	* user space daemon and the
	278	* operation is performed in
	279	* the daemon.
	280	*/
	281	case VSS_OP_FREEZE:
	282	case VSS_OP_THAW:
086a6f68 VK	283	if (vss_transaction.state < HVUTIL_READY) {
	284	/* Userspace is not registered yet */
	285	vss_respond_to_host(HV_E_FAIL);
	286	return;
	287	}
	288	vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
96dd86fa	289	schedule_work(&vss_send_op_work);
64914207 VK	290	schedule_delayed_work(&vss_timeout_work,
64914207 VK	291	VSS_USERSPACE_TIMEOUT);
96dd86fa S	292	return;
	293
	294	case VSS_OP_HOT_BACKUP:
	295	vss_msg->vss_cf.flags =
	296	VSS_HBU_NO_AUTO_RECOVERY;
	297	vss_respond_to_host(0);
	298	return;
	299
	300	case VSS_OP_GET_DM_INFO:
	301	vss_msg->dm_info.flags = 0;
	302	vss_respond_to_host(0);
	303	return;
	304
	305	default:
	306	vss_respond_to_host(0);
	307	return;
	308
	309	}
	310
	311	}
	312
	313	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
	314	\| ICMSGHDRFLAG_RESPONSE;
	315
	316	vmbus_sendpacket(channel, recv_buffer,
	317	recvlen, requestid,
	318	VM_PKT_DATA_INBAND, 0);
	319	}
	320
	321	}
	322
6472f80a VK	323	static void vss_on_reset(void)
	324	{
	325	if (cancel_delayed_work_sync(&vss_timeout_work))
	326	vss_respond_to_host(HV_E_FAIL);
	327	vss_transaction.state = HVUTIL_DEVICE_INIT;
	328	}
	329
96dd86fa S	330	int
	331	hv_vss_init(struct hv_util_service *srv)
	332	{
ed9ba608 OH	333	if (vmbus_proto_version < VERSION_WIN8_1) {
	334	pr_warn("Integration service 'Backup (volume snapshot)'"
	335	" not supported on this host version.\n");
	336	return -ENOTSUPP;
	337	}
96dd86fa	338	recv_buffer = srv->recv_buffer;
b9830d12	339	vss_transaction.recv_channel = srv->channel;
96dd86fa S	340
	341	/*
	342	* When this driver loads, the user level daemon that
	343	* processes the host requests may not yet be running.
	344	* Defer processing channel callbacks until the daemon
	345	* has registered.
	346	*/
086a6f68 VK	347	vss_transaction.state = HVUTIL_DEVICE_INIT;
086a6f68 VK	348
6472f80a VK	349	hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
	350	vss_on_msg, vss_on_reset);
	351	if (!hvt)
	352	return -EFAULT;
	353
96dd86fa S	354	return 0;
	355	}
	356
	357	void hv_vss_deinit(void)
	358	{
086a6f68	359	vss_transaction.state = HVUTIL_DEVICE_DYING;
64914207	360	cancel_delayed_work_sync(&vss_timeout_work);
96dd86fa	361	cancel_work_sync(&vss_send_op_work);
6472f80a	362	hvutil_transport_destroy(hvt);
96dd86fa	363	}