[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)

#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 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);
}

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;
}

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) {
		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);
}
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
a1656454 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;
96dd86fa	82
64914207	83	static void vss_timeout_func(struct work_struct *dummy);
497af84b	84	static void vss_handle_request(struct work_struct *dummy);
64914207 VK	85
64914207 VK	86	static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
497af84b	87	static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
96dd86fa	88
3cace4a6 OH	89	static void vss_poll_wrapper(void *channel)
	90	{
	91	/* Transaction is finished, reset the state here to avoid races. */
	92	vss_transaction.state = HVUTIL_READY;
	93	hv_vss_onchannelcallback(channel);
	94	}
	95
96dd86fa S	96	/*
	97	* Callback when data is received from user mode.
	98	*/
	99
64914207 VK	100	static void vss_timeout_func(struct work_struct *dummy)
	101	{
	102	/*
	103	* Timeout waiting for userspace component to reply happened.
	104	*/
	105	pr_warn("VSS: timeout waiting for daemon to reply\n");
	106	vss_respond_to_host(HV_E_FAIL);
38c06c29	107
3cace4a6	108	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
64914207 VK	109	}
64914207 VK	110
e0fa3e5e VK	111	static void vss_register_done(void)
	112	{
	113	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
	114	pr_debug("VSS: userspace daemon registered\n");
	115	}
	116
cd8dc054 VK	117	static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
	118	{
	119	u32 our_ver = VSS_OP_REGISTER1;
	120
	121	switch (vss_msg->vss_hdr.operation) {
	122	case VSS_OP_REGISTER:
	123	/* Daemon doesn't expect us to reply */
	124	dm_reg_value = VSS_OP_REGISTER;
	125	break;
	126	case VSS_OP_REGISTER1:
e0fa3e5e VK	127	/* Daemon expects us to reply with our own version */
	128	if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
	129	vss_register_done))
cd8dc054 VK	130	return -EFAULT;
	131	dm_reg_value = VSS_OP_REGISTER1;
	132	break;
	133	default:
	134	return -EINVAL;
	135	}
23d2cc0c	136	pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
cd8dc054 VK	137	return 0;
	138	}
	139
6472f80a	140	static int vss_on_msg(void *msg, int len)
96dd86fa	141	{
6472f80a	142	struct hv_vss_msg vss_msg = (struct hv_vss_msg )msg;
96dd86fa	143
23d2cc0c AN	144	if (len != sizeof(*vss_msg)) {
23d2cc0c AN	145	pr_debug("VSS: Message size does not match length\n");
6472f80a	146	return -EINVAL;
23d2cc0c	147	}
96dd86fa	148
cd8dc054 VK	149	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER \|\|
	150	vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
	151	/*
	152	* Don't process registration messages if we're in the middle
	153	* of a transaction processing.
	154	*/
23d2cc0c AN	155	if (vss_transaction.state > HVUTIL_READY) {
23d2cc0c AN	156	pr_debug("VSS: Got unexpected registration request\n");
cd8dc054	157	return -EINVAL;
23d2cc0c AN	158	}
23d2cc0c AN	159
cd8dc054	160	return vss_handle_handshake(vss_msg);
086a6f68 VK	161	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
086a6f68 VK	162	vss_transaction.state = HVUTIL_USERSPACE_RECV;
db886e4d AN	163
	164	if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
	165	vss_transaction.msg->vss_cf.flags =
	166	VSS_HBU_NO_AUTO_RECOVERY;
	167
086a6f68 VK	168	if (cancel_delayed_work_sync(&vss_timeout_work)) {
	169	vss_respond_to_host(vss_msg->error);
	170	/* Transaction is finished, reset the state. */
3cace4a6 OH	171	hv_poll_channel(vss_transaction.recv_channel,
3cace4a6 OH	172	vss_poll_wrapper);
086a6f68 VK	173	}
	174	} else {
	175	/* This is a spurious call! */
23d2cc0c	176	pr_debug("VSS: Transaction not active\n");
6472f80a	177	return -EINVAL;
96dd86fa	178	}
6472f80a	179	return 0;
96dd86fa S	180	}
96dd86fa S	181
497af84b	182	static void vss_send_op(void)
96dd86fa S	183	{
96dd86fa S	184	int op = vss_transaction.msg->vss_hdr.operation;
8d9560eb	185	int rc;
96dd86fa S	186	struct hv_vss_msg *vss_msg;
96dd86fa S	187
086a6f68	188	/* The transaction state is wrong. */
23d2cc0c AN	189	if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) {
23d2cc0c AN	190	pr_debug("VSS: Unexpected attempt to send to daemon\n");
086a6f68	191	return;
23d2cc0c	192	}
086a6f68	193
6472f80a VK	194	vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
6472f80a VK	195	if (!vss_msg)
96dd86fa S	196	return;
96dd86fa S	197
96dd86fa	198	vss_msg->vss_hdr.operation = op;
96dd86fa	199
086a6f68	200	vss_transaction.state = HVUTIL_USERSPACE_REQ;
497af84b	201
b357fd39 AN	202	schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
b357fd39 AN	203	VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ);
497af84b	204
e0fa3e5e	205	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
8d9560eb VK	206	if (rc) {
8d9560eb VK	207	pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
086a6f68	208	if (cancel_delayed_work_sync(&vss_timeout_work)) {
8d9560eb	209	vss_respond_to_host(HV_E_FAIL);
086a6f68 VK	210	vss_transaction.state = HVUTIL_READY;
086a6f68 VK	211	}
8d9560eb	212	}
086a6f68	213
6472f80a	214	kfree(vss_msg);
96dd86fa S	215	}
96dd86fa S	216
497af84b AN	217	static void vss_handle_request(struct work_struct *dummy)
	218	{
	219	switch (vss_transaction.msg->vss_hdr.operation) {
	220	/*
	221	* Initiate a "freeze/thaw" operation in the guest.
	222	* We respond to the host once the operation is complete.
	223	*
	224	* We send the message to the user space daemon and the operation is
	225	* performed in the daemon.
	226	*/
	227	case VSS_OP_THAW:
	228	case VSS_OP_FREEZE:
db886e4d	229	case VSS_OP_HOT_BACKUP:
497af84b AN	230	if (vss_transaction.state < HVUTIL_READY) {
497af84b AN	231	/* Userspace is not registered yet */
23d2cc0c	232	pr_debug("VSS: Not ready for request.\n");
497af84b AN	233	vss_respond_to_host(HV_E_FAIL);
	234	return;
	235	}
23d2cc0c AN	236
	237	pr_debug("VSS: Received request for op code: %d\n",
	238	vss_transaction.msg->vss_hdr.operation);
497af84b AN	239	vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
	240	vss_send_op();
	241	return;
497af84b AN	242	case VSS_OP_GET_DM_INFO:
	243	vss_transaction.msg->dm_info.flags = 0;
	244	break;
	245	default:
	246	break;
	247	}
	248
	249	vss_respond_to_host(0);
	250	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
	251	}
	252
96dd86fa S	253	/*
	254	* Send a response back to the host.
	255	*/
	256
	257	static void
	258	vss_respond_to_host(int error)
	259	{
	260	struct icmsg_hdr *icmsghdrp;
	261	u32 buf_len;
	262	struct vmbus_channel *channel;
	263	u64 req_id;
	264
96dd86fa S	265	/*
	266	* Copy the global state for completing the transaction. Note that
	267	* only one transaction can be active at a time.
	268	*/
	269
	270	buf_len = vss_transaction.recv_len;
	271	channel = vss_transaction.recv_channel;
	272	req_id = vss_transaction.recv_req_id;
96dd86fa S	273
	274	icmsghdrp = (struct icmsg_hdr *)
	275	&recv_buffer[sizeof(struct vmbuspipe_hdr)];
	276
	277	if (channel->onchannel_callback == NULL)
	278	/*
	279	* We have raced with util driver being unloaded;
	280	* silently return.
	281	*/
	282	return;
	283
	284	icmsghdrp->status = error;
	285
	286	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION \| ICMSGHDRFLAG_RESPONSE;
	287
	288	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
	289	VM_PKT_DATA_INBAND, 0);
	290
	291	}
	292
	293	/*
	294	* This callback is invoked when we get a VSS message from the host.
	295	* The host ensures that only one VSS transaction can be active at a time.
	296	*/
	297
	298	void hv_vss_onchannelcallback(void *context)
	299	{
	300	struct vmbus_channel *channel = context;
	301	u32 recvlen;
	302	u64 requestid;
	303	struct hv_vss_msg *vss_msg;
1274a690	304	int vss_srv_version;
96dd86fa S	305
96dd86fa S	306	struct icmsg_hdr *icmsghdrp;
96dd86fa	307
3cace4a6	308	if (vss_transaction.state > HVUTIL_READY)
96dd86fa	309	return;
96dd86fa S	310
	311	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
	312	&requestid);
	313
	314	if (recvlen > 0) {
	315	icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
	316	sizeof(struct vmbuspipe_hdr)];
	317
	318	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
1274a690	319	if (vmbus_prep_negotiate_resp(icmsghdrp,
a1656454 AN	320	recv_buffer, fw_versions, FW_VER_COUNT,
a1656454 AN	321	vss_versions, VSS_VER_COUNT,
1274a690 AN	322	NULL, &vss_srv_version)) {
	323
	324	pr_info("VSS IC version %d.%d\n",
	325	vss_srv_version >> 16,
	326	vss_srv_version & 0xFFFF);
	327	}
96dd86fa S	328	} else {
	329	vss_msg = (struct hv_vss_msg *)&recv_buffer[
	330	sizeof(struct vmbuspipe_hdr) +
	331	sizeof(struct icmsg_hdr)];
	332
	333	/*
	334	* Stash away this global state for completing the
	335	* transaction; note transactions are serialized.
	336	*/
	337
	338	vss_transaction.recv_len = recvlen;
96dd86fa	339	vss_transaction.recv_req_id = requestid;
96dd86fa S	340	vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
96dd86fa S	341
497af84b AN	342	schedule_work(&vss_handle_request_work);
497af84b AN	343	return;
96dd86fa S	344	}
	345
	346	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
	347	\| ICMSGHDRFLAG_RESPONSE;
	348
	349	vmbus_sendpacket(channel, recv_buffer,
	350	recvlen, requestid,
	351	VM_PKT_DATA_INBAND, 0);
	352	}
	353
	354	}
	355
6472f80a VK	356	static void vss_on_reset(void)
	357	{
	358	if (cancel_delayed_work_sync(&vss_timeout_work))
	359	vss_respond_to_host(HV_E_FAIL);
	360	vss_transaction.state = HVUTIL_DEVICE_INIT;
	361	}
	362
96dd86fa S	363	int
	364	hv_vss_init(struct hv_util_service *srv)
	365	{
ed9ba608 OH	366	if (vmbus_proto_version < VERSION_WIN8_1) {
	367	pr_warn("Integration service 'Backup (volume snapshot)'"
	368	" not supported on this host version.\n");
	369	return -ENOTSUPP;
	370	}
96dd86fa	371	recv_buffer = srv->recv_buffer;
b9830d12	372	vss_transaction.recv_channel = srv->channel;
96dd86fa S	373
	374	/*
	375	* When this driver loads, the user level daemon that
	376	* processes the host requests may not yet be running.
	377	* Defer processing channel callbacks until the daemon
	378	* has registered.
	379	*/
086a6f68 VK	380	vss_transaction.state = HVUTIL_DEVICE_INIT;
086a6f68 VK	381
6472f80a VK	382	hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
6472f80a VK	383	vss_on_msg, vss_on_reset);
23d2cc0c AN	384	if (!hvt) {
23d2cc0c AN	385	pr_warn("VSS: Failed to initialize transport\n");
6472f80a	386	return -EFAULT;
23d2cc0c	387	}
6472f80a	388
96dd86fa S	389	return 0;
	390	}
	391
	392	void hv_vss_deinit(void)
	393	{
086a6f68	394	vss_transaction.state = HVUTIL_DEVICE_DYING;
64914207	395	cancel_delayed_work_sync(&vss_timeout_work);
497af84b	396	cancel_work_sync(&vss_handle_request_work);
6472f80a	397	hvutil_transport_destroy(hvt);
96dd86fa	398	}