[deliverable/linux.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 */
	void *vss_context; /* for the channel callback */
} vss_transaction;


static void vss_respond_to_host(int error);

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);

/*
 * 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);

	/* Transaction is finished, reset the state. */
	if (vss_transaction.state > HVUTIL_READY)
		vss_transaction.state = HVUTIL_READY;

	hv_poll_channel(vss_transaction.vss_context,
			hv_vss_onchannelcallback);
}

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;

	/*
	 * Don't process registration messages if we're in the middle of
	 * a transaction processing.
	 */
	if (vss_transaction.state > HVUTIL_READY &&
	    vss_msg->vss_hdr.operation == VSS_OP_REGISTER)
		return -EINVAL;

	if (vss_transaction.state == HVUTIL_DEVICE_INIT &&
	    vss_msg->vss_hdr.operation == VSS_OP_REGISTER) {
		pr_info("VSS daemon registered\n");
		vss_transaction.state = HVUTIL_READY;
	} 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. */
			vss_transaction.state = HVUTIL_READY;
			hv_poll_channel(vss_transaction.vss_context,
					hv_vss_onchannelcallback);
		}
	} 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) {
		/*
		 * We will defer processing this callback once
		 * the current transaction is complete.
		 */
		vss_transaction.vss_context = context;
		return;
	}
	vss_transaction.vss_context = NULL;

	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_channel = channel;
			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)
{
	recv_buffer = srv->recv_buffer;

	/*
	 * 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 */
38c06c29	56	void vss_context; / for the channel callback */
96dd86fa S	57	} vss_transaction;
	58
	59
	60	static void vss_respond_to_host(int error);
	61
6472f80a	62	static const char vss_devname[] = "vmbus/hv_vss";
96dd86fa	63	static __u8 *recv_buffer;
6472f80a	64	static struct hvutil_transport *hvt;
96dd86fa S	65
96dd86fa S	66	static void vss_send_op(struct work_struct *dummy);
64914207 VK	67	static void vss_timeout_func(struct work_struct *dummy);
	68
	69	static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
96dd86fa S	70	static DECLARE_WORK(vss_send_op_work, vss_send_op);
	71
	72	/*
	73	* Callback when data is received from user mode.
	74	*/
	75
64914207 VK	76	static void vss_timeout_func(struct work_struct *dummy)
	77	{
	78	/*
	79	* Timeout waiting for userspace component to reply happened.
	80	*/
	81	pr_warn("VSS: timeout waiting for daemon to reply\n");
	82	vss_respond_to_host(HV_E_FAIL);
38c06c29	83
086a6f68 VK	84	/* Transaction is finished, reset the state. */
	85	if (vss_transaction.state > HVUTIL_READY)
	86	vss_transaction.state = HVUTIL_READY;
	87
38c06c29 VK	88	hv_poll_channel(vss_transaction.vss_context,
38c06c29 VK	89	hv_vss_onchannelcallback);
64914207 VK	90	}
64914207 VK	91
6472f80a	92	static int vss_on_msg(void *msg, int len)
96dd86fa	93	{
6472f80a	94	struct hv_vss_msg vss_msg = (struct hv_vss_msg )msg;
96dd86fa	95
6472f80a VK	96	if (len != sizeof(*vss_msg))
6472f80a VK	97	return -EINVAL;
96dd86fa	98
086a6f68 VK	99	/*
	100	* Don't process registration messages if we're in the middle of
	101	* a transaction processing.
	102	*/
	103	if (vss_transaction.state > HVUTIL_READY &&
	104	vss_msg->vss_hdr.operation == VSS_OP_REGISTER)
6472f80a	105	return -EINVAL;
086a6f68 VK	106
	107	if (vss_transaction.state == HVUTIL_DEVICE_INIT &&
	108	vss_msg->vss_hdr.operation == VSS_OP_REGISTER) {
96dd86fa	109	pr_info("VSS daemon registered\n");
086a6f68 VK	110	vss_transaction.state = HVUTIL_READY;
	111	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
	112	vss_transaction.state = HVUTIL_USERSPACE_RECV;
	113	if (cancel_delayed_work_sync(&vss_timeout_work)) {
	114	vss_respond_to_host(vss_msg->error);
	115	/* Transaction is finished, reset the state. */
	116	vss_transaction.state = HVUTIL_READY;
	117	hv_poll_channel(vss_transaction.vss_context,
	118	hv_vss_onchannelcallback);
	119	}
	120	} else {
	121	/* This is a spurious call! */
	122	pr_warn("VSS: Transaction not active\n");
6472f80a	123	return -EINVAL;
96dd86fa	124	}
6472f80a	125	return 0;
96dd86fa S	126	}
	127
	128
	129	static void vss_send_op(struct work_struct *dummy)
	130	{
	131	int op = vss_transaction.msg->vss_hdr.operation;
8d9560eb	132	int rc;
96dd86fa S	133	struct hv_vss_msg *vss_msg;
96dd86fa S	134
086a6f68 VK	135	/* The transaction state is wrong. */
	136	if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED)
	137	return;
	138
6472f80a VK	139	vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
6472f80a VK	140	if (!vss_msg)
96dd86fa S	141	return;
96dd86fa S	142
96dd86fa	143	vss_msg->vss_hdr.operation = op;
96dd86fa	144
086a6f68	145	vss_transaction.state = HVUTIL_USERSPACE_REQ;
6472f80a	146	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg));
8d9560eb VK	147	if (rc) {
8d9560eb VK	148	pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
086a6f68	149	if (cancel_delayed_work_sync(&vss_timeout_work)) {
8d9560eb	150	vss_respond_to_host(HV_E_FAIL);
086a6f68 VK	151	vss_transaction.state = HVUTIL_READY;
086a6f68 VK	152	}
8d9560eb	153	}
086a6f68	154
6472f80a	155	kfree(vss_msg);
96dd86fa S	156
	157	return;
	158	}
	159
	160	/*
	161	* Send a response back to the host.
	162	*/
	163
	164	static void
	165	vss_respond_to_host(int error)
	166	{
	167	struct icmsg_hdr *icmsghdrp;
	168	u32 buf_len;
	169	struct vmbus_channel *channel;
	170	u64 req_id;
	171
96dd86fa S	172	/*
	173	* Copy the global state for completing the transaction. Note that
	174	* only one transaction can be active at a time.
	175	*/
	176
	177	buf_len = vss_transaction.recv_len;
	178	channel = vss_transaction.recv_channel;
	179	req_id = vss_transaction.recv_req_id;
96dd86fa S	180
	181	icmsghdrp = (struct icmsg_hdr *)
	182	&recv_buffer[sizeof(struct vmbuspipe_hdr)];
	183
	184	if (channel->onchannel_callback == NULL)
	185	/*
	186	* We have raced with util driver being unloaded;
	187	* silently return.
	188	*/
	189	return;
	190
	191	icmsghdrp->status = error;
	192
	193	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION \| ICMSGHDRFLAG_RESPONSE;
	194
	195	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
	196	VM_PKT_DATA_INBAND, 0);
	197
	198	}
	199
	200	/*
	201	* This callback is invoked when we get a VSS message from the host.
	202	* The host ensures that only one VSS transaction can be active at a time.
	203	*/
	204
	205	void hv_vss_onchannelcallback(void *context)
	206	{
	207	struct vmbus_channel *channel = context;
	208	u32 recvlen;
	209	u64 requestid;
	210	struct hv_vss_msg *vss_msg;
	211
	212
	213	struct icmsg_hdr *icmsghdrp;
	214	struct icmsg_negotiate *negop = NULL;
	215
086a6f68	216	if (vss_transaction.state > HVUTIL_READY) {
96dd86fa S	217	/*
	218	* We will defer processing this callback once
	219	* the current transaction is complete.
	220	*/
38c06c29	221	vss_transaction.vss_context = context;
96dd86fa S	222	return;
96dd86fa S	223	}
38c06c29	224	vss_transaction.vss_context = NULL;
96dd86fa S	225
	226	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
	227	&requestid);
	228
	229	if (recvlen > 0) {
	230	icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
	231	sizeof(struct vmbuspipe_hdr)];
	232
	233	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
	234	vmbus_prep_negotiate_resp(icmsghdrp, negop,
3a491605 S	235	recv_buffer, UTIL_FW_VERSION,
3a491605 S	236	VSS_VERSION);
96dd86fa S	237	} else {
	238	vss_msg = (struct hv_vss_msg *)&recv_buffer[
	239	sizeof(struct vmbuspipe_hdr) +
	240	sizeof(struct icmsg_hdr)];
	241
	242	/*
	243	* Stash away this global state for completing the
	244	* transaction; note transactions are serialized.
	245	*/
	246
	247	vss_transaction.recv_len = recvlen;
	248	vss_transaction.recv_channel = channel;
	249	vss_transaction.recv_req_id = requestid;
96dd86fa S	250	vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
	251
	252	switch (vss_msg->vss_hdr.operation) {
	253	/*
	254	* Initiate a "freeze/thaw"
	255	* operation in the guest.
	256	* We respond to the host once
	257	* the operation is complete.
	258	*
	259	* We send the message to the
	260	* user space daemon and the
	261	* operation is performed in
	262	* the daemon.
	263	*/
	264	case VSS_OP_FREEZE:
	265	case VSS_OP_THAW:
086a6f68 VK	266	if (vss_transaction.state < HVUTIL_READY) {
	267	/* Userspace is not registered yet */
	268	vss_respond_to_host(HV_E_FAIL);
	269	return;
	270	}
	271	vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
96dd86fa	272	schedule_work(&vss_send_op_work);
64914207 VK	273	schedule_delayed_work(&vss_timeout_work,
64914207 VK	274	VSS_USERSPACE_TIMEOUT);
96dd86fa S	275	return;
	276
	277	case VSS_OP_HOT_BACKUP:
	278	vss_msg->vss_cf.flags =
	279	VSS_HBU_NO_AUTO_RECOVERY;
	280	vss_respond_to_host(0);
	281	return;
	282
	283	case VSS_OP_GET_DM_INFO:
	284	vss_msg->dm_info.flags = 0;
	285	vss_respond_to_host(0);
	286	return;
	287
	288	default:
	289	vss_respond_to_host(0);
	290	return;
	291
	292	}
	293
	294	}
	295
	296	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
	297	\| ICMSGHDRFLAG_RESPONSE;
	298
	299	vmbus_sendpacket(channel, recv_buffer,
	300	recvlen, requestid,
	301	VM_PKT_DATA_INBAND, 0);
	302	}
	303
	304	}
	305
6472f80a VK	306	static void vss_on_reset(void)
	307	{
	308	if (cancel_delayed_work_sync(&vss_timeout_work))
	309	vss_respond_to_host(HV_E_FAIL);
	310	vss_transaction.state = HVUTIL_DEVICE_INIT;
	311	}
	312
96dd86fa S	313	int
	314	hv_vss_init(struct hv_util_service *srv)
	315	{
96dd86fa S	316	recv_buffer = srv->recv_buffer;
	317
	318	/*
	319	* When this driver loads, the user level daemon that
	320	* processes the host requests may not yet be running.
	321	* Defer processing channel callbacks until the daemon
	322	* has registered.
	323	*/
086a6f68 VK	324	vss_transaction.state = HVUTIL_DEVICE_INIT;
086a6f68 VK	325
6472f80a VK	326	hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
	327	vss_on_msg, vss_on_reset);
	328	if (!hvt)
	329	return -EFAULT;
	330
96dd86fa S	331	return 0;
	332	}
	333
	334	void hv_vss_deinit(void)
	335	{
086a6f68	336	vss_transaction.state = HVUTIL_DEVICE_DYING;
64914207	337	cancel_delayed_work_sync(&vss_timeout_work);
96dd86fa	338	cancel_work_sync(&vss_send_op_work);
6472f80a	339	hvutil_transport_destroy(hvt);
96dd86fa	340	}