[mirror_ubuntu-hirsute-kernel.git] / drivers / hv / connection.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/hyperv.h>
#include <linux/export.h>
#include <asm/mshyperv.h>

#include "hyperv_vmbus.h"


struct vmbus_connection vmbus_connection = {
	.conn_state		= DISCONNECTED,
	.next_gpadl_handle	= ATOMIC_INIT(0xE1E10),

	.ready_for_suspend_event= COMPLETION_INITIALIZER(
				  vmbus_connection.ready_for_suspend_event),
	.ready_for_resume_event	= COMPLETION_INITIALIZER(
				  vmbus_connection.ready_for_resume_event),
};
EXPORT_SYMBOL_GPL(vmbus_connection);

/*
 * Negotiated protocol version with the host.
 */
__u32 vmbus_proto_version;
EXPORT_SYMBOL_GPL(vmbus_proto_version);

/*
 * Table of VMBus versions listed from newest to oldest.
 */
static __u32 vmbus_versions[] = {
	VERSION_WIN10_V5_2,
	VERSION_WIN10_V5_1,
	VERSION_WIN10_V5,
	VERSION_WIN10_V4_1,
	VERSION_WIN10,
	VERSION_WIN8_1,
	VERSION_WIN8,
	VERSION_WIN7,
	VERSION_WS2008
};

/*
 * Maximal VMBus protocol version guests can negotiate.  Useful to cap the
 * VMBus version for testing and debugging purpose.
 */
static uint max_version = VERSION_WIN10_V5_2;

module_param(max_version, uint, S_IRUGO);
MODULE_PARM_DESC(max_version,
		 "Maximal VMBus protocol version which can be negotiated");

int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
{
	int ret = 0;
	unsigned int cur_cpu;
	struct vmbus_channel_initiate_contact *msg;
	unsigned long flags;

	init_completion(&msginfo->waitevent);

	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;

	memset(msg, 0, sizeof(*msg));
	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
	msg->vmbus_version_requested = version;

	/*
	 * VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
	 * use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
	 * and for subsequent messages, we must use the Message Connection ID
	 * field in the host-returned Version Response Message. And, with
	 * VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
	 * tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
	 * compatibility.
	 *
	 * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
	 */
	if (version >= VERSION_WIN10_V5) {
		msg->msg_sint = VMBUS_MESSAGE_SINT;
		vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
	} else {
		msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
		vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
	}

	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
	/*
	 * We want all channel messages to be delivered on CPU 0.
	 * This has been the behavior pre-win8. This is not
	 * perf issue and having all channel messages delivered on CPU 0
	 * would be ok.
	 * For post win8 hosts, we support receiving channel messagges on
	 * all the CPUs. This is needed for kexec to work correctly where
	 * the CPU attempting to connect may not be CPU 0.
	 */
	if (version >= VERSION_WIN8_1) {
		cur_cpu = get_cpu();
		msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
		vmbus_connection.connect_cpu = cur_cpu;
		put_cpu();
	} else {
		msg->target_vcpu = 0;
		vmbus_connection.connect_cpu = 0;
	}

	/*
	 * Add to list before we send the request since we may
	 * receive the response before returning from this routine
	 */
	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	list_add_tail(&msginfo->msglistentry,
		      &vmbus_connection.chn_msg_list);

	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);

	ret = vmbus_post_msg(msg,
			     sizeof(struct vmbus_channel_initiate_contact),
			     true);

	trace_vmbus_negotiate_version(msg, ret);

	if (ret != 0) {
		spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
		list_del(&msginfo->msglistentry);
		spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
					flags);
		return ret;
	}

	/* Wait for the connection response */
	wait_for_completion(&msginfo->waitevent);

	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	list_del(&msginfo->msglistentry);
	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);

	/* Check if successful */
	if (msginfo->response.version_response.version_supported) {
		vmbus_connection.conn_state = CONNECTED;

		if (version >= VERSION_WIN10_V5)
			vmbus_connection.msg_conn_id =
				msginfo->response.version_response.msg_conn_id;
	} else {
		return -ECONNREFUSED;
	}

	return ret;
}

/*
 * vmbus_connect - Sends a connect request on the partition service connection
 */
int vmbus_connect(void)
{
	struct vmbus_channel_msginfo *msginfo = NULL;
	int i, ret = 0;
	__u32 version;

	/* Initialize the vmbus connection */
	vmbus_connection.conn_state = CONNECTING;
	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
	if (!vmbus_connection.work_queue) {
		ret = -ENOMEM;
		goto cleanup;
	}

	vmbus_connection.handle_primary_chan_wq =
		create_workqueue("hv_pri_chan");
	if (!vmbus_connection.handle_primary_chan_wq) {
		ret = -ENOMEM;
		goto cleanup;
	}

	vmbus_connection.handle_sub_chan_wq =
		create_workqueue("hv_sub_chan");
	if (!vmbus_connection.handle_sub_chan_wq) {
		ret = -ENOMEM;
		goto cleanup;
	}

	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
	spin_lock_init(&vmbus_connection.channelmsg_lock);

	INIT_LIST_HEAD(&vmbus_connection.chn_list);
	mutex_init(&vmbus_connection.channel_mutex);

	/*
	 * Setup the vmbus event connection for channel interrupt
	 * abstraction stuff
	 */
	vmbus_connection.int_page =
	(void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
	if (vmbus_connection.int_page == NULL) {
		ret = -ENOMEM;
		goto cleanup;
	}

	vmbus_connection.recv_int_page = vmbus_connection.int_page;
	vmbus_connection.send_int_page =
		(void *)((unsigned long)vmbus_connection.int_page +
			(PAGE_SIZE >> 1));

	/*
	 * Setup the monitor notification facility. The 1st page for
	 * parent->child and the 2nd page for child->parent
	 */
	vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
	vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
	if ((vmbus_connection.monitor_pages[0] == NULL) ||
	    (vmbus_connection.monitor_pages[1] == NULL)) {
		ret = -ENOMEM;
		goto cleanup;
	}

	msginfo = kzalloc(sizeof(*msginfo) +
			  sizeof(struct vmbus_channel_initiate_contact),
			  GFP_KERNEL);
	if (msginfo == NULL) {
		ret = -ENOMEM;
		goto cleanup;
	}

	/*
	 * Negotiate a compatible VMBUS version number with the
	 * host. We start with the highest number we can support
	 * and work our way down until we negotiate a compatible
	 * version.
	 */

	for (i = 0; ; i++) {
		if (i == ARRAY_SIZE(vmbus_versions))
			goto cleanup;

		version = vmbus_versions[i];
		if (version > max_version)
			continue;

		ret = vmbus_negotiate_version(msginfo, version);
		if (ret == -ETIMEDOUT)
			goto cleanup;

		if (vmbus_connection.conn_state == CONNECTED)
			break;
	}

	vmbus_proto_version = version;
	pr_info("Vmbus version:%d.%d\n",
		version >> 16, version & 0xFFFF);

	kfree(msginfo);
	return 0;

cleanup:
	pr_err("Unable to connect to host\n");

	vmbus_connection.conn_state = DISCONNECTED;
	vmbus_disconnect();

	kfree(msginfo);

	return ret;
}

void vmbus_disconnect(void)
{
	/*
	 * First send the unload request to the host.
	 */
	vmbus_initiate_unload(false);

	if (vmbus_connection.handle_sub_chan_wq)
		destroy_workqueue(vmbus_connection.handle_sub_chan_wq);

	if (vmbus_connection.handle_primary_chan_wq)
		destroy_workqueue(vmbus_connection.handle_primary_chan_wq);

	if (vmbus_connection.work_queue)
		destroy_workqueue(vmbus_connection.work_queue);

	if (vmbus_connection.int_page) {
		free_pages((unsigned long)vmbus_connection.int_page, 0);
		vmbus_connection.int_page = NULL;
	}

	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
	vmbus_connection.monitor_pages[0] = NULL;
	vmbus_connection.monitor_pages[1] = NULL;
}

/*
 * relid2channel - Get the channel object given its
 * child relative id (ie channel id)
 */
struct vmbus_channel *relid2channel(u32 relid)
{
	struct vmbus_channel *channel;
	struct vmbus_channel *found_channel  = NULL;
	struct list_head *cur, *tmp;
	struct vmbus_channel *cur_sc;

	BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));

	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
		if (channel->offermsg.child_relid == relid) {
			found_channel = channel;
			break;
		} else if (!list_empty(&channel->sc_list)) {
			/*
			 * Deal with sub-channels.
			 */
			list_for_each_safe(cur, tmp, &channel->sc_list) {
				cur_sc = list_entry(cur, struct vmbus_channel,
							sc_list);
				if (cur_sc->offermsg.child_relid == relid) {
					found_channel = cur_sc;
					break;
				}
			}
		}
	}

	return found_channel;
}

/*
 * vmbus_on_event - Process a channel event notification
 *
 * For batched channels (default) optimize host to guest signaling
 * by ensuring:
 * 1. While reading the channel, we disable interrupts from host.
 * 2. Ensure that we process all posted messages from the host
 *    before returning from this callback.
 * 3. Once we return, enable signaling from the host. Once this
 *    state is set we check to see if additional packets are
 *    available to read. In this case we repeat the process.
 *    If this tasklet has been running for a long time
 *    then reschedule ourselves.
 */
void vmbus_on_event(unsigned long data)
{
	struct vmbus_channel *channel = (void *) data;
	unsigned long time_limit = jiffies + 2;

	trace_vmbus_on_event(channel);

	do {
		void (*callback_fn)(void *);

		/* A channel once created is persistent even when
		 * there is no driver handling the device. An
		 * unloading driver sets the onchannel_callback to NULL.
		 */
		callback_fn = READ_ONCE(channel->onchannel_callback);
		if (unlikely(callback_fn == NULL))
			return;

		(*callback_fn)(channel->channel_callback_context);

		if (channel->callback_mode != HV_CALL_BATCHED)
			return;

		if (likely(hv_end_read(&channel->inbound) == 0))
			return;

		hv_begin_read(&channel->inbound);
	} while (likely(time_before(jiffies, time_limit)));

	/* The time limit (2 jiffies) has been reached */
	tasklet_schedule(&channel->callback_event);
}

/*
 * vmbus_post_msg - Send a msg on the vmbus's message connection
 */
int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
{
	struct vmbus_channel_message_header *hdr;
	union hv_connection_id conn_id;
	int ret = 0;
	int retries = 0;
	u32 usec = 1;

	conn_id.asu32 = 0;
	conn_id.u.id = vmbus_connection.msg_conn_id;

	/*
	 * hv_post_message() can have transient failures because of
	 * insufficient resources. Retry the operation a couple of
	 * times before giving up.
	 */
	while (retries < 100) {
		ret = hv_post_message(conn_id, 1, buffer, buflen);

		switch (ret) {
		case HV_STATUS_INVALID_CONNECTION_ID:
			/*
			 * See vmbus_negotiate_version(): VMBus protocol 5.0
			 * and higher require that we must use
			 * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
			 * Contact message, but on old hosts that only
			 * support VMBus protocol 4.0 or lower, here we get
			 * HV_STATUS_INVALID_CONNECTION_ID and we should
			 * return an error immediately without retrying.
			 */
			hdr = buffer;
			if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
				return -EINVAL;
			/*
			 * We could get this if we send messages too
			 * frequently.
			 */
			ret = -EAGAIN;
			break;
		case HV_STATUS_INSUFFICIENT_MEMORY:
		case HV_STATUS_INSUFFICIENT_BUFFERS:
			ret = -ENOBUFS;
			break;
		case HV_STATUS_SUCCESS:
			return ret;
		default:
			pr_err("hv_post_msg() failed; error code:%d\n", ret);
			return -EINVAL;
		}

		retries++;
		if (can_sleep && usec > 1000)
			msleep(usec / 1000);
		else if (usec < MAX_UDELAY_MS * 1000)
			udelay(usec);
		else
			mdelay(usec / 1000);

		if (retries < 22)
			usec *= 2;
	}
	return ret;
}

/*
 * vmbus_set_event - Send an event notification to the parent
 */
void vmbus_set_event(struct vmbus_channel *channel)
{
	u32 child_relid = channel->offermsg.child_relid;

	if (!channel->is_dedicated_interrupt)
		vmbus_send_interrupt(child_relid);

	++channel->sig_events;

	hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
}
EXPORT_SYMBOL_GPL(vmbus_set_event);
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-only
	2	/*
	3	*
	4	* Copyright (c) 2009, Microsoft Corporation.
	5	*
	6	* Authors:
	7	* Haiyang Zhang <haiyangz@microsoft.com>
	8	* Hank Janssen <hjanssen@microsoft.com>
	9	*/
	10	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	11
	12	#include <linux/kernel.h>
	13	#include <linux/sched.h>
	14	#include <linux/wait.h>
	15	#include <linux/delay.h>
	16	#include <linux/mm.h>
	17	#include <linux/module.h>
	18	#include <linux/slab.h>
	19	#include <linux/vmalloc.h>
	20	#include <linux/hyperv.h>
	21	#include <linux/export.h>
	22	#include <asm/mshyperv.h>
	23
	24	#include "hyperv_vmbus.h"
	25
	26
	27	struct vmbus_connection vmbus_connection = {
	28	.conn_state = DISCONNECTED,
	29	.next_gpadl_handle = ATOMIC_INIT(0xE1E10),
	30
	31	.ready_for_suspend_event= COMPLETION_INITIALIZER(
	32	vmbus_connection.ready_for_suspend_event),
	33	.ready_for_resume_event = COMPLETION_INITIALIZER(
	34	vmbus_connection.ready_for_resume_event),
	35	};
	36	EXPORT_SYMBOL_GPL(vmbus_connection);
	37
	38	/*
	39	* Negotiated protocol version with the host.
	40	*/
	41	__u32 vmbus_proto_version;
	42	EXPORT_SYMBOL_GPL(vmbus_proto_version);
	43
	44	/*
	45	* Table of VMBus versions listed from newest to oldest.
	46	*/
	47	static __u32 vmbus_versions[] = {
	48	VERSION_WIN10_V5_2,
	49	VERSION_WIN10_V5_1,
	50	VERSION_WIN10_V5,
	51	VERSION_WIN10_V4_1,
	52	VERSION_WIN10,
	53	VERSION_WIN8_1,
	54	VERSION_WIN8,
	55	VERSION_WIN7,
	56	VERSION_WS2008
	57	};
	58
	59	/*
	60	* Maximal VMBus protocol version guests can negotiate. Useful to cap the
	61	* VMBus version for testing and debugging purpose.
	62	*/
	63	static uint max_version = VERSION_WIN10_V5_2;
	64
	65	module_param(max_version, uint, S_IRUGO);
	66	MODULE_PARM_DESC(max_version,
	67	"Maximal VMBus protocol version which can be negotiated");
	68
	69	int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
	70	{
	71	int ret = 0;
	72	unsigned int cur_cpu;
	73	struct vmbus_channel_initiate_contact *msg;
	74	unsigned long flags;
	75
	76	init_completion(&msginfo->waitevent);
	77
	78	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
	79
	80	memset(msg, 0, sizeof(*msg));
	81	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
	82	msg->vmbus_version_requested = version;
	83
	84	/*
	85	* VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
	86	* use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
	87	* and for subsequent messages, we must use the Message Connection ID
	88	* field in the host-returned Version Response Message. And, with
	89	* VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
	90	* tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
	91	* compatibility.
	92	*
	93	* On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
	94	*/
	95	if (version >= VERSION_WIN10_V5) {
	96	msg->msg_sint = VMBUS_MESSAGE_SINT;
	97	vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
	98	} else {
	99	msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
	100	vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
	101	}
	102
	103	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
	104	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
	105	/*
	106	* We want all channel messages to be delivered on CPU 0.
	107	* This has been the behavior pre-win8. This is not
	108	* perf issue and having all channel messages delivered on CPU 0
	109	* would be ok.
	110	* For post win8 hosts, we support receiving channel messagges on
	111	* all the CPUs. This is needed for kexec to work correctly where
	112	* the CPU attempting to connect may not be CPU 0.
	113	*/
	114	if (version >= VERSION_WIN8_1) {
	115	cur_cpu = get_cpu();
	116	msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
	117	vmbus_connection.connect_cpu = cur_cpu;
	118	put_cpu();
	119	} else {
	120	msg->target_vcpu = 0;
	121	vmbus_connection.connect_cpu = 0;
	122	}
	123
	124	/*
	125	* Add to list before we send the request since we may
	126	* receive the response before returning from this routine
	127	*/
	128	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	129	list_add_tail(&msginfo->msglistentry,
	130	&vmbus_connection.chn_msg_list);
	131
	132	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	133
	134	ret = vmbus_post_msg(msg,
	135	sizeof(struct vmbus_channel_initiate_contact),
	136	true);
	137
	138	trace_vmbus_negotiate_version(msg, ret);
	139
	140	if (ret != 0) {
	141	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	142	list_del(&msginfo->msglistentry);
	143	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
	144	flags);
	145	return ret;
	146	}
	147
	148	/* Wait for the connection response */
	149	wait_for_completion(&msginfo->waitevent);
	150
	151	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	152	list_del(&msginfo->msglistentry);
	153	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	154
	155	/* Check if successful */
	156	if (msginfo->response.version_response.version_supported) {
	157	vmbus_connection.conn_state = CONNECTED;
	158
	159	if (version >= VERSION_WIN10_V5)
	160	vmbus_connection.msg_conn_id =
	161	msginfo->response.version_response.msg_conn_id;
	162	} else {
	163	return -ECONNREFUSED;
	164	}
	165
	166	return ret;
	167	}
	168
	169	/*
	170	* vmbus_connect - Sends a connect request on the partition service connection
	171	*/
	172	int vmbus_connect(void)
	173	{
	174	struct vmbus_channel_msginfo *msginfo = NULL;
	175	int i, ret = 0;
	176	__u32 version;
	177
	178	/* Initialize the vmbus connection */
	179	vmbus_connection.conn_state = CONNECTING;
	180	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
	181	if (!vmbus_connection.work_queue) {
	182	ret = -ENOMEM;
	183	goto cleanup;
	184	}
	185
	186	vmbus_connection.handle_primary_chan_wq =
	187	create_workqueue("hv_pri_chan");
	188	if (!vmbus_connection.handle_primary_chan_wq) {
	189	ret = -ENOMEM;
	190	goto cleanup;
	191	}
	192
	193	vmbus_connection.handle_sub_chan_wq =
	194	create_workqueue("hv_sub_chan");
	195	if (!vmbus_connection.handle_sub_chan_wq) {
	196	ret = -ENOMEM;
	197	goto cleanup;
	198	}
	199
	200	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
	201	spin_lock_init(&vmbus_connection.channelmsg_lock);
	202
	203	INIT_LIST_HEAD(&vmbus_connection.chn_list);
	204	mutex_init(&vmbus_connection.channel_mutex);
	205
	206	/*
	207	* Setup the vmbus event connection for channel interrupt
	208	* abstraction stuff
	209	*/
	210	vmbus_connection.int_page =
	211	(void *)__get_free_pages(GFP_KERNEL\|__GFP_ZERO, 0);
	212	if (vmbus_connection.int_page == NULL) {
	213	ret = -ENOMEM;
	214	goto cleanup;
	215	}
	216
	217	vmbus_connection.recv_int_page = vmbus_connection.int_page;
	218	vmbus_connection.send_int_page =
	219	(void *)((unsigned long)vmbus_connection.int_page +
	220	(PAGE_SIZE >> 1));
	221
	222	/*
	223	* Setup the monitor notification facility. The 1st page for
	224	* parent->child and the 2nd page for child->parent
	225	*/
	226	vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	227	vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	228	if ((vmbus_connection.monitor_pages[0] == NULL) \|\|
	229	(vmbus_connection.monitor_pages[1] == NULL)) {
	230	ret = -ENOMEM;
	231	goto cleanup;
	232	}
	233
	234	msginfo = kzalloc(sizeof(*msginfo) +
	235	sizeof(struct vmbus_channel_initiate_contact),
	236	GFP_KERNEL);
	237	if (msginfo == NULL) {
	238	ret = -ENOMEM;
	239	goto cleanup;
	240	}
	241
	242	/*
	243	* Negotiate a compatible VMBUS version number with the
	244	* host. We start with the highest number we can support
	245	* and work our way down until we negotiate a compatible
	246	* version.
	247	*/
	248
	249	for (i = 0; ; i++) {
	250	if (i == ARRAY_SIZE(vmbus_versions))
	251	goto cleanup;
	252
	253	version = vmbus_versions[i];
	254	if (version > max_version)
	255	continue;
	256
	257	ret = vmbus_negotiate_version(msginfo, version);
	258	if (ret == -ETIMEDOUT)
	259	goto cleanup;
	260
	261	if (vmbus_connection.conn_state == CONNECTED)
	262	break;
	263	}
	264
	265	vmbus_proto_version = version;
	266	pr_info("Vmbus version:%d.%d\n",
	267	version >> 16, version & 0xFFFF);
	268
	269	kfree(msginfo);
	270	return 0;
	271
	272	cleanup:
	273	pr_err("Unable to connect to host\n");
	274
	275	vmbus_connection.conn_state = DISCONNECTED;
	276	vmbus_disconnect();
	277
	278	kfree(msginfo);
	279
	280	return ret;
	281	}
	282
	283	void vmbus_disconnect(void)
	284	{
	285	/*
	286	* First send the unload request to the host.
	287	*/
	288	vmbus_initiate_unload(false);
	289
	290	if (vmbus_connection.handle_sub_chan_wq)
	291	destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
	292
	293	if (vmbus_connection.handle_primary_chan_wq)
	294	destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
	295
	296	if (vmbus_connection.work_queue)
	297	destroy_workqueue(vmbus_connection.work_queue);
	298
	299	if (vmbus_connection.int_page) {
	300	free_pages((unsigned long)vmbus_connection.int_page, 0);
	301	vmbus_connection.int_page = NULL;
	302	}
	303
	304	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
	305	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
	306	vmbus_connection.monitor_pages[0] = NULL;
	307	vmbus_connection.monitor_pages[1] = NULL;
	308	}
	309
	310	/*
	311	* relid2channel - Get the channel object given its
	312	* child relative id (ie channel id)
	313	*/
	314	struct vmbus_channel *relid2channel(u32 relid)
	315	{
	316	struct vmbus_channel *channel;
	317	struct vmbus_channel *found_channel = NULL;
	318	struct list_head cur, tmp;
	319	struct vmbus_channel *cur_sc;
	320
	321	BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
	322
	323	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
	324	if (channel->offermsg.child_relid == relid) {
	325	found_channel = channel;
	326	break;
	327	} else if (!list_empty(&channel->sc_list)) {
	328	/*
	329	* Deal with sub-channels.
	330	*/
	331	list_for_each_safe(cur, tmp, &channel->sc_list) {
	332	cur_sc = list_entry(cur, struct vmbus_channel,
	333	sc_list);
	334	if (cur_sc->offermsg.child_relid == relid) {
	335	found_channel = cur_sc;
	336	break;
	337	}
	338	}
	339	}
	340	}
	341
	342	return found_channel;
	343	}
	344
	345	/*
	346	* vmbus_on_event - Process a channel event notification
	347	*
	348	* For batched channels (default) optimize host to guest signaling
	349	* by ensuring:
	350	* 1. While reading the channel, we disable interrupts from host.
	351	* 2. Ensure that we process all posted messages from the host
	352	* before returning from this callback.
	353	* 3. Once we return, enable signaling from the host. Once this
	354	* state is set we check to see if additional packets are
	355	* available to read. In this case we repeat the process.
	356	* If this tasklet has been running for a long time
	357	* then reschedule ourselves.
	358	*/
	359	void vmbus_on_event(unsigned long data)
	360	{
	361	struct vmbus_channel channel = (void ) data;
	362	unsigned long time_limit = jiffies + 2;
	363
	364	trace_vmbus_on_event(channel);
	365
	366	do {
	367	void (callback_fn)(void );
	368
	369	/* A channel once created is persistent even when
	370	* there is no driver handling the device. An
	371	* unloading driver sets the onchannel_callback to NULL.
	372	*/
	373	callback_fn = READ_ONCE(channel->onchannel_callback);
	374	if (unlikely(callback_fn == NULL))
	375	return;
	376
	377	(*callback_fn)(channel->channel_callback_context);
	378
	379	if (channel->callback_mode != HV_CALL_BATCHED)
	380	return;
	381
	382	if (likely(hv_end_read(&channel->inbound) == 0))
	383	return;
	384
	385	hv_begin_read(&channel->inbound);
	386	} while (likely(time_before(jiffies, time_limit)));
	387
	388	/* The time limit (2 jiffies) has been reached */
	389	tasklet_schedule(&channel->callback_event);
	390	}
	391
	392	/*
	393	* vmbus_post_msg - Send a msg on the vmbus's message connection
	394	*/
	395	int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
	396	{
	397	struct vmbus_channel_message_header *hdr;
	398	union hv_connection_id conn_id;
	399	int ret = 0;
	400	int retries = 0;
	401	u32 usec = 1;
	402
	403	conn_id.asu32 = 0;
	404	conn_id.u.id = vmbus_connection.msg_conn_id;
	405
	406	/*
	407	* hv_post_message() can have transient failures because of
	408	* insufficient resources. Retry the operation a couple of
	409	* times before giving up.
	410	*/
	411	while (retries < 100) {
	412	ret = hv_post_message(conn_id, 1, buffer, buflen);
	413
	414	switch (ret) {
	415	case HV_STATUS_INVALID_CONNECTION_ID:
	416	/*
	417	* See vmbus_negotiate_version(): VMBus protocol 5.0
	418	* and higher require that we must use
	419	* VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
	420	* Contact message, but on old hosts that only
	421	* support VMBus protocol 4.0 or lower, here we get
	422	* HV_STATUS_INVALID_CONNECTION_ID and we should
	423	* return an error immediately without retrying.
	424	*/
	425	hdr = buffer;
	426	if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
	427	return -EINVAL;
	428	/*
	429	* We could get this if we send messages too
	430	* frequently.
	431	*/
	432	ret = -EAGAIN;
	433	break;
	434	case HV_STATUS_INSUFFICIENT_MEMORY:
	435	case HV_STATUS_INSUFFICIENT_BUFFERS:
	436	ret = -ENOBUFS;
	437	break;
	438	case HV_STATUS_SUCCESS:
	439	return ret;
	440	default:
	441	pr_err("hv_post_msg() failed; error code:%d\n", ret);
	442	return -EINVAL;
	443	}
	444
	445	retries++;
	446	if (can_sleep && usec > 1000)
	447	msleep(usec / 1000);
	448	else if (usec < MAX_UDELAY_MS * 1000)
	449	udelay(usec);
	450	else
	451	mdelay(usec / 1000);
	452
	453	if (retries < 22)
	454	usec *= 2;
	455	}
	456	return ret;
	457	}
	458
	459	/*
	460	* vmbus_set_event - Send an event notification to the parent
	461	*/
	462	void vmbus_set_event(struct vmbus_channel *channel)
	463	{
	464	u32 child_relid = channel->offermsg.child_relid;
	465
	466	if (!channel->is_dedicated_interrupt)
	467	vmbus_send_interrupt(child_relid);
	468
	469	++channel->sig_events;
	470
	471	hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
	472	}
	473	EXPORT_SYMBOL_GPL(vmbus_set_event);