[mirror_ubuntu-zesty-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)

#define VSS_VER_COUNT 1
static const int vss_versions[] = {
	VSS_VERSION
};

#define FW_VER_COUNT 1
static const int fw_versions[] = {
	UTIL_FW_VERSION
};

/*
 * 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;
	int vss_srv_version;

	struct icmsg_hdr *icmsghdrp;

	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) {
			if (vmbus_prep_negotiate_resp(icmsghdrp,
				 recv_buffer, fw_versions, FW_VER_COUNT,
				 vss_versions, VSS_VER_COUNT,
				 NULL, &vss_srv_version)) {

				pr_info("VSS IC version %d.%d\n",
					vss_srv_version >> 16,
					vss_srv_version & 0xFFFF);
			}
		} 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
06b734ab AN	34	#define VSS_VER_COUNT 1
	35	static const int vss_versions[] = {
	36	VSS_VERSION
	37	};
	38
	39	#define FW_VER_COUNT 1
	40	static const int fw_versions[] = {
	41	UTIL_FW_VERSION
	42	};
	43
b357fd39 AN	44	/*
	45	* Timeout values are based on expecations from host
	46	*/
	47	#define VSS_FREEZE_TIMEOUT (15 * 60)
96dd86fa S	48
96dd86fa S	49	/*
086a6f68 VK	50	* Global state maintained for transaction that is being processed. For a class
	51	* of integration services, including the "VSS service", the specified protocol
	52	* is a "request/response" protocol which means that there can only be single
	53	* outstanding transaction from the host at any given point in time. We use
	54	* this to simplify memory management in this driver - we cache and process
	55	* only one message at a time.
96dd86fa	56	*
086a6f68 VK	57	* While the request/response protocol is guaranteed by the host, we further
	58	* ensure this by serializing packet processing in this driver - we do not
	59	* read additional packets from the VMBUs until the current packet is fully
	60	* handled.
96dd86fa S	61	*/
	62
	63	static struct {
086a6f68	64	int state; /* hvutil_device_state */
96dd86fa S	65	int recv_len; /* number of bytes received. */
	66	struct vmbus_channel recv_channel; / chn we got the request */
	67	u64 recv_req_id; /* request ID. */
	68	struct hv_vss_msg msg; / current message */
	69	} vss_transaction;
	70
	71
	72	static void vss_respond_to_host(int error);
	73
cd8dc054 VK	74	/*
	75	* This state maintains the version number registered by the daemon.
	76	*/
	77	static int dm_reg_value;
	78
6472f80a	79	static const char vss_devname[] = "vmbus/hv_vss";
96dd86fa	80	static __u8 *recv_buffer;
6472f80a	81	static struct hvutil_transport *hvt;
83ffa1b0	82	static struct completion release_event;
96dd86fa	83
64914207	84	static void vss_timeout_func(struct work_struct *dummy);
497af84b	85	static void vss_handle_request(struct work_struct *dummy);
64914207 VK	86
64914207 VK	87	static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
497af84b	88	static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
96dd86fa	89
3cace4a6 OH	90	static void vss_poll_wrapper(void *channel)
	91	{
	92	/* Transaction is finished, reset the state here to avoid races. */
	93	vss_transaction.state = HVUTIL_READY;
	94	hv_vss_onchannelcallback(channel);
	95	}
	96
96dd86fa S	97	/*
	98	* Callback when data is received from user mode.
	99	*/
	100
64914207 VK	101	static void vss_timeout_func(struct work_struct *dummy)
	102	{
	103	/*
	104	* Timeout waiting for userspace component to reply happened.
	105	*/
	106	pr_warn("VSS: timeout waiting for daemon to reply\n");
	107	vss_respond_to_host(HV_E_FAIL);
38c06c29	108
3cace4a6	109	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
64914207 VK	110	}
64914207 VK	111
e0fa3e5e VK	112	static void vss_register_done(void)
	113	{
	114	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
	115	pr_debug("VSS: userspace daemon registered\n");
	116	}
	117
cd8dc054 VK	118	static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
	119	{
	120	u32 our_ver = VSS_OP_REGISTER1;
	121
	122	switch (vss_msg->vss_hdr.operation) {
	123	case VSS_OP_REGISTER:
	124	/* Daemon doesn't expect us to reply */
	125	dm_reg_value = VSS_OP_REGISTER;
	126	break;
	127	case VSS_OP_REGISTER1:
e0fa3e5e VK	128	/* Daemon expects us to reply with our own version */
	129	if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
	130	vss_register_done))
cd8dc054 VK	131	return -EFAULT;
	132	dm_reg_value = VSS_OP_REGISTER1;
	133	break;
	134	default:
	135	return -EINVAL;
	136	}
23d2cc0c	137	pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
cd8dc054 VK	138	return 0;
	139	}
	140
6472f80a	141	static int vss_on_msg(void *msg, int len)
96dd86fa	142	{
6472f80a	143	struct hv_vss_msg vss_msg = (struct hv_vss_msg )msg;
96dd86fa	144
23d2cc0c AN	145	if (len != sizeof(*vss_msg)) {
23d2cc0c AN	146	pr_debug("VSS: Message size does not match length\n");
6472f80a	147	return -EINVAL;
23d2cc0c	148	}
96dd86fa	149
cd8dc054 VK	150	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER \|\|
	151	vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
	152	/*
	153	* Don't process registration messages if we're in the middle
	154	* of a transaction processing.
	155	*/
23d2cc0c AN	156	if (vss_transaction.state > HVUTIL_READY) {
23d2cc0c AN	157	pr_debug("VSS: Got unexpected registration request\n");
cd8dc054	158	return -EINVAL;
23d2cc0c AN	159	}
23d2cc0c AN	160
cd8dc054	161	return vss_handle_handshake(vss_msg);
086a6f68 VK	162	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
086a6f68 VK	163	vss_transaction.state = HVUTIL_USERSPACE_RECV;
db886e4d AN	164
	165	if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
	166	vss_transaction.msg->vss_cf.flags =
	167	VSS_HBU_NO_AUTO_RECOVERY;
	168
086a6f68 VK	169	if (cancel_delayed_work_sync(&vss_timeout_work)) {
	170	vss_respond_to_host(vss_msg->error);
	171	/* Transaction is finished, reset the state. */
3cace4a6 OH	172	hv_poll_channel(vss_transaction.recv_channel,
3cace4a6 OH	173	vss_poll_wrapper);
086a6f68 VK	174	}
	175	} else {
	176	/* This is a spurious call! */
23d2cc0c	177	pr_debug("VSS: Transaction not active\n");
6472f80a	178	return -EINVAL;
96dd86fa	179	}
6472f80a	180	return 0;
96dd86fa S	181	}
96dd86fa S	182
497af84b	183	static void vss_send_op(void)
96dd86fa S	184	{
96dd86fa S	185	int op = vss_transaction.msg->vss_hdr.operation;
8d9560eb	186	int rc;
96dd86fa S	187	struct hv_vss_msg *vss_msg;
96dd86fa S	188
086a6f68	189	/* The transaction state is wrong. */
23d2cc0c AN	190	if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) {
23d2cc0c AN	191	pr_debug("VSS: Unexpected attempt to send to daemon\n");
086a6f68	192	return;
23d2cc0c	193	}
086a6f68	194
6472f80a VK	195	vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
6472f80a VK	196	if (!vss_msg)
96dd86fa S	197	return;
96dd86fa S	198
96dd86fa	199	vss_msg->vss_hdr.operation = op;
96dd86fa	200
086a6f68	201	vss_transaction.state = HVUTIL_USERSPACE_REQ;
497af84b	202
b357fd39 AN	203	schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
b357fd39 AN	204	VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ);
497af84b	205
e0fa3e5e	206	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
8d9560eb VK	207	if (rc) {
8d9560eb VK	208	pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
086a6f68	209	if (cancel_delayed_work_sync(&vss_timeout_work)) {
8d9560eb	210	vss_respond_to_host(HV_E_FAIL);
086a6f68 VK	211	vss_transaction.state = HVUTIL_READY;
086a6f68 VK	212	}
8d9560eb	213	}
086a6f68	214
6472f80a	215	kfree(vss_msg);
96dd86fa S	216
	217	return;
	218	}
	219
497af84b AN	220	static void vss_handle_request(struct work_struct *dummy)
	221	{
	222	switch (vss_transaction.msg->vss_hdr.operation) {
	223	/*
	224	* Initiate a "freeze/thaw" operation in the guest.
	225	* We respond to the host once the operation is complete.
	226	*
	227	* We send the message to the user space daemon and the operation is
	228	* performed in the daemon.
	229	*/
	230	case VSS_OP_THAW:
	231	case VSS_OP_FREEZE:
db886e4d	232	case VSS_OP_HOT_BACKUP:
497af84b AN	233	if (vss_transaction.state < HVUTIL_READY) {
497af84b AN	234	/* Userspace is not registered yet */
23d2cc0c	235	pr_debug("VSS: Not ready for request.\n");
497af84b AN	236	vss_respond_to_host(HV_E_FAIL);
	237	return;
	238	}
23d2cc0c AN	239
	240	pr_debug("VSS: Received request for op code: %d\n",
	241	vss_transaction.msg->vss_hdr.operation);
497af84b AN	242	vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
	243	vss_send_op();
	244	return;
497af84b AN	245	case VSS_OP_GET_DM_INFO:
	246	vss_transaction.msg->dm_info.flags = 0;
	247	break;
	248	default:
	249	break;
	250	}
	251
	252	vss_respond_to_host(0);
	253	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
	254	}
	255
96dd86fa S	256	/*
	257	* Send a response back to the host.
	258	*/
	259
	260	static void
	261	vss_respond_to_host(int error)
	262	{
	263	struct icmsg_hdr *icmsghdrp;
	264	u32 buf_len;
	265	struct vmbus_channel *channel;
	266	u64 req_id;
	267
96dd86fa S	268	/*
	269	* Copy the global state for completing the transaction. Note that
	270	* only one transaction can be active at a time.
	271	*/
	272
	273	buf_len = vss_transaction.recv_len;
	274	channel = vss_transaction.recv_channel;
	275	req_id = vss_transaction.recv_req_id;
96dd86fa S	276
	277	icmsghdrp = (struct icmsg_hdr *)
	278	&recv_buffer[sizeof(struct vmbuspipe_hdr)];
	279
	280	if (channel->onchannel_callback == NULL)
	281	/*
	282	* We have raced with util driver being unloaded;
	283	* silently return.
	284	*/
	285	return;
	286
	287	icmsghdrp->status = error;
	288
	289	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION \| ICMSGHDRFLAG_RESPONSE;
	290
	291	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
	292	VM_PKT_DATA_INBAND, 0);
	293
	294	}
	295
	296	/*
	297	* This callback is invoked when we get a VSS message from the host.
	298	* The host ensures that only one VSS transaction can be active at a time.
	299	*/
	300
	301	void hv_vss_onchannelcallback(void *context)
	302	{
	303	struct vmbus_channel *channel = context;
	304	u32 recvlen;
	305	u64 requestid;
	306	struct hv_vss_msg *vss_msg;
af5c6d33	307	int vss_srv_version;
96dd86fa S	308
96dd86fa S	309	struct icmsg_hdr *icmsghdrp;
96dd86fa	310
3cace4a6	311	if (vss_transaction.state > HVUTIL_READY)
96dd86fa	312	return;
96dd86fa S	313
	314	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
	315	&requestid);
	316
	317	if (recvlen > 0) {
	318	icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
	319	sizeof(struct vmbuspipe_hdr)];
	320
	321	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
af5c6d33	322	if (vmbus_prep_negotiate_resp(icmsghdrp,
06b734ab AN	323	recv_buffer, fw_versions, FW_VER_COUNT,
06b734ab AN	324	vss_versions, VSS_VER_COUNT,
af5c6d33 AN	325	NULL, &vss_srv_version)) {
	326
	327	pr_info("VSS IC version %d.%d\n",
	328	vss_srv_version >> 16,
	329	vss_srv_version & 0xFFFF);
	330	}
96dd86fa S	331	} else {
	332	vss_msg = (struct hv_vss_msg *)&recv_buffer[
	333	sizeof(struct vmbuspipe_hdr) +
	334	sizeof(struct icmsg_hdr)];
	335
	336	/*
	337	* Stash away this global state for completing the
	338	* transaction; note transactions are serialized.
	339	*/
	340
	341	vss_transaction.recv_len = recvlen;
96dd86fa	342	vss_transaction.recv_req_id = requestid;
96dd86fa S	343	vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
96dd86fa S	344
497af84b AN	345	schedule_work(&vss_handle_request_work);
497af84b AN	346	return;
96dd86fa S	347	}
	348
	349	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
	350	\| ICMSGHDRFLAG_RESPONSE;
	351
	352	vmbus_sendpacket(channel, recv_buffer,
	353	recvlen, requestid,
	354	VM_PKT_DATA_INBAND, 0);
	355	}
	356
	357	}
	358
6472f80a VK	359	static void vss_on_reset(void)
	360	{
	361	if (cancel_delayed_work_sync(&vss_timeout_work))
	362	vss_respond_to_host(HV_E_FAIL);
	363	vss_transaction.state = HVUTIL_DEVICE_INIT;
83ffa1b0	364	complete(&release_event);
6472f80a VK	365	}
6472f80a VK	366
96dd86fa S	367	int
	368	hv_vss_init(struct hv_util_service *srv)
	369	{
83ffa1b0	370	init_completion(&release_event);
ed9ba608 OH	371	if (vmbus_proto_version < VERSION_WIN8_1) {
	372	pr_warn("Integration service 'Backup (volume snapshot)'"
	373	" not supported on this host version.\n");
	374	return -ENOTSUPP;
	375	}
96dd86fa	376	recv_buffer = srv->recv_buffer;
b9830d12	377	vss_transaction.recv_channel = srv->channel;
96dd86fa S	378
	379	/*
	380	* When this driver loads, the user level daemon that
	381	* processes the host requests may not yet be running.
	382	* Defer processing channel callbacks until the daemon
	383	* has registered.
	384	*/
086a6f68 VK	385	vss_transaction.state = HVUTIL_DEVICE_INIT;
086a6f68 VK	386
6472f80a VK	387	hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
6472f80a VK	388	vss_on_msg, vss_on_reset);
23d2cc0c AN	389	if (!hvt) {
23d2cc0c AN	390	pr_warn("VSS: Failed to initialize transport\n");
6472f80a	391	return -EFAULT;
23d2cc0c	392	}
6472f80a	393
96dd86fa S	394	return 0;
	395	}
	396
	397	void hv_vss_deinit(void)
	398	{
086a6f68	399	vss_transaction.state = HVUTIL_DEVICE_DYING;
64914207	400	cancel_delayed_work_sync(&vss_timeout_work);
497af84b	401	cancel_work_sync(&vss_handle_request_work);
6472f80a	402	hvutil_transport_destroy(hvt);
83ffa1b0	403	wait_for_completion(&release_event);
96dd86fa	404	}