drivers/hv/hv_snapshot.c - kernel/msm-4.19 - Gitiles

 /*
  * 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"

 #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 struct cb_id vss_id = { CN_VSS_IDX, CN_VSS_VAL };
 static const char vss_name[] = "vss_kernel_module";
 static __u8 *recv_buffer;

 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 void
 vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
 {
 	struct hv_vss_msg *vss_msg;

 	vss_msg = (struct hv_vss_msg *)msg->data;

 	/*
 	 * 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;

 	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;
 	}
 }


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

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

 	msg = kzalloc(sizeof(*msg) + sizeof(*vss_msg), GFP_ATOMIC);
 	if (!msg)
 		return;

 	vss_msg = (struct hv_vss_msg *)msg->data;

 	msg->id.idx =  CN_VSS_IDX;
 	msg->id.val = CN_VSS_VAL;

 	vss_msg->vss_hdr.operation = op;
 	msg->len = sizeof(struct hv_vss_msg);

 	vss_transaction.state = HVUTIL_USERSPACE_REQ;
 	rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
 	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(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);
 	}

 }

 int
 hv_vss_init(struct hv_util_service *srv)
 {
 	int err;

 	err = cn_add_callback(&vss_id, vss_name, vss_cn_callback);
 	if (err)
 		return err;
 	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;

 	return 0;
 }

 void hv_vss_deinit(void)
 {
 	vss_transaction.state = HVUTIL_DEVICE_DYING;
 	cn_del_callback(&vss_id);
 	cancel_delayed_work_sync(&vss_timeout_work);
 	cancel_work_sync(&vss_send_op_work);
 }
	/*
	* 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"

	#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 struct cb_id vss_id = { CN_VSS_IDX, CN_VSS_VAL };
	static const char vss_name[] = "vss_kernel_module";
	static __u8 *recv_buffer;

	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 void
	vss_cn_callback(struct cn_msg msg, struct netlink_skb_parms nsp)
	{
	struct hv_vss_msg *vss_msg;

	vss_msg = (struct hv_vss_msg *)msg->data;

	/*
	* 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;

	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;
	}
	}


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

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

	msg = kzalloc(sizeof(msg) + sizeof(vss_msg), GFP_ATOMIC);
	if (!msg)
	return;

	vss_msg = (struct hv_vss_msg *)msg->data;

	msg->id.idx = CN_VSS_IDX;
	msg->id.val = CN_VSS_VAL;

	vss_msg->vss_hdr.operation = op;
	msg->len = sizeof(struct hv_vss_msg);

	vss_transaction.state = HVUTIL_USERSPACE_REQ;
	rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
	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(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);
	}

	}

	int
	hv_vss_init(struct hv_util_service *srv)
	{
	int err;

	err = cn_add_callback(&vss_id, vss_name, vss_cn_callback);
	if (err)
	return err;
	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;

	return 0;
	}

	void hv_vss_deinit(void)
	{
	vss_transaction.state = HVUTIL_DEVICE_DYING;
	cn_del_callback(&vss_id);
	cancel_delayed_work_sync(&vss_timeout_work);
	cancel_work_sync(&vss_send_op_work);
	}