[mirror_ubuntu-bionic-kernel.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)

/*
 * Timeout values are based on expecations from host
 */
#define VSS_FREEZE_TIMEOUT (15 * 60)

/*
 * 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 struct completion release_event;

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

static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
static DECLARE_WORK(vss_handle_request_work, vss_handle_request);

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 void vss_register_done(void)
{
	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
	pr_debug("VSS: userspace daemon registered\n");
}

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),
					  vss_register_done))
			return -EFAULT;
		dm_reg_value = VSS_OP_REGISTER1;
		break;
	default:
		return -EINVAL;
	}
	pr_info("VSS: userspace daemon ver. %d connected\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)) {
		pr_debug("VSS: Message size does not match length\n");
		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) {
			pr_debug("VSS: Got unexpected registration request\n");
			return -EINVAL;
		}

		return vss_handle_handshake(vss_msg);
	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
		vss_transaction.state = HVUTIL_USERSPACE_RECV;

		if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
			vss_transaction.msg->vss_cf.flags =
				VSS_HBU_NO_AUTO_RECOVERY;

		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_debug("VSS: Transaction not active\n");
		return -EINVAL;
	}
	return 0;
}

static void vss_send_op(void)
{
	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) {
		pr_debug("VSS: Unexpected attempt to send to daemon\n");
		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;

	schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
			VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ);

	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
	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;
}

static void vss_handle_request(struct work_struct *dummy)
{
	switch (vss_transaction.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_THAW:
	case VSS_OP_FREEZE:
	case VSS_OP_HOT_BACKUP:
		if (vss_transaction.state < HVUTIL_READY) {
			/* Userspace is not registered yet */
			pr_debug("VSS: Not ready for request.\n");
			vss_respond_to_host(HV_E_FAIL);
			return;
		}

		pr_debug("VSS: Received request for op code: %d\n",
			vss_transaction.msg->vss_hdr.operation);
		vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
		vss_send_op();
		return;
	case VSS_OP_GET_DM_INFO:
		vss_transaction.msg->dm_info.flags = 0;
		break;
	default:
		break;
	}

	vss_respond_to_host(0);
	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
}

/*
 * 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;

			schedule_work(&vss_handle_request_work);
			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;
	complete(&release_event);
}

int
hv_vss_init(struct hv_util_service *srv)
{
	init_completion(&release_event);
	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) {
		pr_warn("VSS: Failed to initialize transport\n");
		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_handle_request_work);
	hvutil_transport_destroy(hvt);
	wait_for_completion(&release_event);
}
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
b357fd39 AN	34	/*
	35	* Timeout values are based on expecations from host
	36	*/
	37	#define VSS_FREEZE_TIMEOUT (15 * 60)
96dd86fa S	38
96dd86fa S	39	/*
086a6f68 VK	40	* Global state maintained for transaction that is being processed. For a class
	41	* of integration services, including the "VSS service", the specified protocol
	42	* is a "request/response" protocol which means that there can only be single
	43	* outstanding transaction from the host at any given point in time. We use
	44	* this to simplify memory management in this driver - we cache and process
	45	* only one message at a time.
96dd86fa	46	*
086a6f68 VK	47	* While the request/response protocol is guaranteed by the host, we further
	48	* ensure this by serializing packet processing in this driver - we do not
	49	* read additional packets from the VMBUs until the current packet is fully
	50	* handled.
96dd86fa S	51	*/
	52
	53	static struct {
086a6f68	54	int state; /* hvutil_device_state */
96dd86fa S	55	int recv_len; /* number of bytes received. */
	56	struct vmbus_channel recv_channel; / chn we got the request */
	57	u64 recv_req_id; /* request ID. */
	58	struct hv_vss_msg msg; / current message */
	59	} vss_transaction;
	60
	61
	62	static void vss_respond_to_host(int error);
	63
cd8dc054 VK	64	/*
	65	* This state maintains the version number registered by the daemon.
	66	*/
	67	static int dm_reg_value;
	68
6472f80a	69	static const char vss_devname[] = "vmbus/hv_vss";
96dd86fa	70	static __u8 *recv_buffer;
6472f80a	71	static struct hvutil_transport *hvt;
d77044d1	72	static struct completion release_event;
96dd86fa	73
64914207	74	static void vss_timeout_func(struct work_struct *dummy);
497af84b	75	static void vss_handle_request(struct work_struct *dummy);
64914207 VK	76
64914207 VK	77	static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
497af84b	78	static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
96dd86fa	79
3cace4a6 OH	80	static void vss_poll_wrapper(void *channel)
	81	{
	82	/* Transaction is finished, reset the state here to avoid races. */
	83	vss_transaction.state = HVUTIL_READY;
	84	hv_vss_onchannelcallback(channel);
	85	}
	86
96dd86fa S	87	/*
	88	* Callback when data is received from user mode.
	89	*/
	90
64914207 VK	91	static void vss_timeout_func(struct work_struct *dummy)
	92	{
	93	/*
	94	* Timeout waiting for userspace component to reply happened.
	95	*/
	96	pr_warn("VSS: timeout waiting for daemon to reply\n");
	97	vss_respond_to_host(HV_E_FAIL);
38c06c29	98
3cace4a6	99	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
64914207 VK	100	}
64914207 VK	101
e0fa3e5e VK	102	static void vss_register_done(void)
	103	{
	104	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
	105	pr_debug("VSS: userspace daemon registered\n");
	106	}
	107
cd8dc054 VK	108	static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
	109	{
	110	u32 our_ver = VSS_OP_REGISTER1;
	111
	112	switch (vss_msg->vss_hdr.operation) {
	113	case VSS_OP_REGISTER:
	114	/* Daemon doesn't expect us to reply */
	115	dm_reg_value = VSS_OP_REGISTER;
	116	break;
	117	case VSS_OP_REGISTER1:
e0fa3e5e VK	118	/* Daemon expects us to reply with our own version */
	119	if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
	120	vss_register_done))
cd8dc054 VK	121	return -EFAULT;
	122	dm_reg_value = VSS_OP_REGISTER1;
	123	break;
	124	default:
	125	return -EINVAL;
	126	}
23d2cc0c	127	pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
cd8dc054 VK	128	return 0;
	129	}
	130
6472f80a	131	static int vss_on_msg(void *msg, int len)
96dd86fa	132	{
6472f80a	133	struct hv_vss_msg vss_msg = (struct hv_vss_msg )msg;
96dd86fa	134
23d2cc0c AN	135	if (len != sizeof(*vss_msg)) {
23d2cc0c AN	136	pr_debug("VSS: Message size does not match length\n");
6472f80a	137	return -EINVAL;
23d2cc0c	138	}
96dd86fa	139
cd8dc054 VK	140	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER \|\|
	141	vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
	142	/*
	143	* Don't process registration messages if we're in the middle
	144	* of a transaction processing.
	145	*/
23d2cc0c AN	146	if (vss_transaction.state > HVUTIL_READY) {
23d2cc0c AN	147	pr_debug("VSS: Got unexpected registration request\n");
cd8dc054	148	return -EINVAL;
23d2cc0c AN	149	}
23d2cc0c AN	150
cd8dc054	151	return vss_handle_handshake(vss_msg);
086a6f68 VK	152	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
086a6f68 VK	153	vss_transaction.state = HVUTIL_USERSPACE_RECV;
db886e4d AN	154
	155	if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
	156	vss_transaction.msg->vss_cf.flags =
	157	VSS_HBU_NO_AUTO_RECOVERY;
	158
086a6f68 VK	159	if (cancel_delayed_work_sync(&vss_timeout_work)) {
	160	vss_respond_to_host(vss_msg->error);
	161	/* Transaction is finished, reset the state. */
3cace4a6 OH	162	hv_poll_channel(vss_transaction.recv_channel,
3cace4a6 OH	163	vss_poll_wrapper);
086a6f68 VK	164	}
	165	} else {
	166	/* This is a spurious call! */
23d2cc0c	167	pr_debug("VSS: Transaction not active\n");
6472f80a	168	return -EINVAL;
96dd86fa	169	}
6472f80a	170	return 0;
96dd86fa S	171	}
96dd86fa S	172
497af84b	173	static void vss_send_op(void)
96dd86fa S	174	{
96dd86fa S	175	int op = vss_transaction.msg->vss_hdr.operation;
8d9560eb	176	int rc;
96dd86fa S	177	struct hv_vss_msg *vss_msg;
96dd86fa S	178
086a6f68	179	/* The transaction state is wrong. */
23d2cc0c AN	180	if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) {
23d2cc0c AN	181	pr_debug("VSS: Unexpected attempt to send to daemon\n");
086a6f68	182	return;
23d2cc0c	183	}
086a6f68	184
6472f80a VK	185	vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
6472f80a VK	186	if (!vss_msg)
96dd86fa S	187	return;
96dd86fa S	188
96dd86fa	189	vss_msg->vss_hdr.operation = op;
96dd86fa	190
086a6f68	191	vss_transaction.state = HVUTIL_USERSPACE_REQ;
497af84b	192
b357fd39 AN	193	schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
b357fd39 AN	194	VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ);
497af84b	195
e0fa3e5e	196	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
8d9560eb VK	197	if (rc) {
8d9560eb VK	198	pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
086a6f68	199	if (cancel_delayed_work_sync(&vss_timeout_work)) {
8d9560eb	200	vss_respond_to_host(HV_E_FAIL);
086a6f68 VK	201	vss_transaction.state = HVUTIL_READY;
086a6f68 VK	202	}
8d9560eb	203	}
086a6f68	204
6472f80a	205	kfree(vss_msg);
96dd86fa S	206
	207	return;
	208	}
	209
497af84b AN	210	static void vss_handle_request(struct work_struct *dummy)
	211	{
	212	switch (vss_transaction.msg->vss_hdr.operation) {
	213	/*
	214	* Initiate a "freeze/thaw" operation in the guest.
	215	* We respond to the host once the operation is complete.
	216	*
	217	* We send the message to the user space daemon and the operation is
	218	* performed in the daemon.
	219	*/
	220	case VSS_OP_THAW:
	221	case VSS_OP_FREEZE:
db886e4d	222	case VSS_OP_HOT_BACKUP:
497af84b AN	223	if (vss_transaction.state < HVUTIL_READY) {
497af84b AN	224	/* Userspace is not registered yet */
23d2cc0c	225	pr_debug("VSS: Not ready for request.\n");
497af84b AN	226	vss_respond_to_host(HV_E_FAIL);
	227	return;
	228	}
23d2cc0c AN	229
	230	pr_debug("VSS: Received request for op code: %d\n",
	231	vss_transaction.msg->vss_hdr.operation);
497af84b AN	232	vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
	233	vss_send_op();
	234	return;
497af84b AN	235	case VSS_OP_GET_DM_INFO:
	236	vss_transaction.msg->dm_info.flags = 0;
	237	break;
	238	default:
	239	break;
	240	}
	241
	242	vss_respond_to_host(0);
	243	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
	244	}
	245
96dd86fa S	246	/*
	247	* Send a response back to the host.
	248	*/
	249
	250	static void
	251	vss_respond_to_host(int error)
	252	{
	253	struct icmsg_hdr *icmsghdrp;
	254	u32 buf_len;
	255	struct vmbus_channel *channel;
	256	u64 req_id;
	257
96dd86fa S	258	/*
	259	* Copy the global state for completing the transaction. Note that
	260	* only one transaction can be active at a time.
	261	*/
	262
	263	buf_len = vss_transaction.recv_len;
	264	channel = vss_transaction.recv_channel;
	265	req_id = vss_transaction.recv_req_id;
96dd86fa S	266
	267	icmsghdrp = (struct icmsg_hdr *)
	268	&recv_buffer[sizeof(struct vmbuspipe_hdr)];
	269
	270	if (channel->onchannel_callback == NULL)
	271	/*
	272	* We have raced with util driver being unloaded;
	273	* silently return.
	274	*/
	275	return;
	276
	277	icmsghdrp->status = error;
	278
	279	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION \| ICMSGHDRFLAG_RESPONSE;
	280
	281	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
	282	VM_PKT_DATA_INBAND, 0);
	283
	284	}
	285
	286	/*
	287	* This callback is invoked when we get a VSS message from the host.
	288	* The host ensures that only one VSS transaction can be active at a time.
	289	*/
	290
	291	void hv_vss_onchannelcallback(void *context)
	292	{
	293	struct vmbus_channel *channel = context;
	294	u32 recvlen;
	295	u64 requestid;
	296	struct hv_vss_msg *vss_msg;
	297
	298
	299	struct icmsg_hdr *icmsghdrp;
	300	struct icmsg_negotiate *negop = NULL;
	301
3cace4a6	302	if (vss_transaction.state > HVUTIL_READY)
96dd86fa	303	return;
96dd86fa S	304
	305	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
	306	&requestid);
	307
	308	if (recvlen > 0) {
	309	icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
	310	sizeof(struct vmbuspipe_hdr)];
	311
	312	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
	313	vmbus_prep_negotiate_resp(icmsghdrp, negop,
3a491605 S	314	recv_buffer, UTIL_FW_VERSION,
3a491605 S	315	VSS_VERSION);
96dd86fa S	316	} else {
	317	vss_msg = (struct hv_vss_msg *)&recv_buffer[
	318	sizeof(struct vmbuspipe_hdr) +
	319	sizeof(struct icmsg_hdr)];
	320
	321	/*
	322	* Stash away this global state for completing the
	323	* transaction; note transactions are serialized.
	324	*/
	325
	326	vss_transaction.recv_len = recvlen;
96dd86fa	327	vss_transaction.recv_req_id = requestid;
96dd86fa S	328	vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
96dd86fa S	329
497af84b AN	330	schedule_work(&vss_handle_request_work);
497af84b AN	331	return;
96dd86fa S	332	}
	333
	334	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
	335	\| ICMSGHDRFLAG_RESPONSE;
	336
	337	vmbus_sendpacket(channel, recv_buffer,
	338	recvlen, requestid,
	339	VM_PKT_DATA_INBAND, 0);
	340	}
	341
	342	}
	343
6472f80a VK	344	static void vss_on_reset(void)
	345	{
	346	if (cancel_delayed_work_sync(&vss_timeout_work))
	347	vss_respond_to_host(HV_E_FAIL);
	348	vss_transaction.state = HVUTIL_DEVICE_INIT;
d77044d1	349	complete(&release_event);
6472f80a VK	350	}
6472f80a VK	351
96dd86fa S	352	int
	353	hv_vss_init(struct hv_util_service *srv)
	354	{
d77044d1	355	init_completion(&release_event);
ed9ba608 OH	356	if (vmbus_proto_version < VERSION_WIN8_1) {
	357	pr_warn("Integration service 'Backup (volume snapshot)'"
	358	" not supported on this host version.\n");
	359	return -ENOTSUPP;
	360	}
96dd86fa	361	recv_buffer = srv->recv_buffer;
b9830d12	362	vss_transaction.recv_channel = srv->channel;
96dd86fa S	363
	364	/*
	365	* When this driver loads, the user level daemon that
	366	* processes the host requests may not yet be running.
	367	* Defer processing channel callbacks until the daemon
	368	* has registered.
	369	*/
086a6f68 VK	370	vss_transaction.state = HVUTIL_DEVICE_INIT;
086a6f68 VK	371
6472f80a VK	372	hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
6472f80a VK	373	vss_on_msg, vss_on_reset);
23d2cc0c AN	374	if (!hvt) {
23d2cc0c AN	375	pr_warn("VSS: Failed to initialize transport\n");
6472f80a	376	return -EFAULT;
23d2cc0c	377	}
6472f80a	378
96dd86fa S	379	return 0;
	380	}
	381
	382	void hv_vss_deinit(void)
	383	{
086a6f68	384	vss_transaction.state = HVUTIL_DEVICE_DYING;
64914207	385	cancel_delayed_work_sync(&vss_timeout_work);
497af84b	386	cancel_work_sync(&vss_handle_request_work);
6472f80a	387	hvutil_transport_destroy(hvt);
d77044d1	388	wait_for_completion(&release_event);
96dd86fa	389	}