[linux.git] / drivers / hv / connection.c

/*
 *
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Haiyang Zhang <[email protected]>
 *   Hank Janssen  <[email protected]>
 *
 */
#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/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),
};
EXPORT_SYMBOL_GPL(vmbus_connection);

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

static __u32 vmbus_get_next_version(__u32 current_version)
{
	switch (current_version) {
	case (VERSION_WIN7):
		return VERSION_WS2008;

	case (VERSION_WIN8):
		return VERSION_WIN7;

	case (VERSION_WIN8_1):
		return VERSION_WIN8;

	case (VERSION_WIN10):
		return VERSION_WIN8_1;

	case (VERSION_WIN10_V5):
		return VERSION_WIN10;

	case (VERSION_WS2008):
	default:
		return VERSION_INVAL;
	}
}

static 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) requires 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, 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)
{
	int ret = 0;
	struct vmbus_channel_msginfo *msginfo = NULL;
	__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;
	}

	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.
	 */

	version = VERSION_CURRENT;

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

		if (vmbus_connection.conn_state == CONNECTED)
			break;

		version = vmbus_get_next_version(version);
	} while (version != VERSION_INVAL);

	if (version == VERSION_INVAL)
		goto cleanup;

	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.work_queue) {
		drain_workqueue(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
			 * requires 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
3e7ee490 HJ	1	/*
	2	*
	3	* Copyright (c) 2009, Microsoft Corporation.
	4	*
	5	* This program is free software; you can redistribute it and/or modify it
	6	* under the terms and conditions of the GNU General Public License,
	7	* version 2, as published by the Free Software Foundation.
	8	*
	9	* This program is distributed in the hope it will be useful, but WITHOUT
	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	12	* more details.
	13	*
	14	* You should have received a copy of the GNU General Public License along with
	15	* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
	16	* Place - Suite 330, Boston, MA 02111-1307 USA.
	17	*
	18	* Authors:
	19	* Haiyang Zhang <[email protected]>
	20	* Hank Janssen <[email protected]>
	21	*
	22	*/
0a46618d HJ	23	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0a46618d HJ	24
a0086dc5	25	#include <linux/kernel.h>
0c3b7b2f S	26	#include <linux/sched.h>
0c3b7b2f S	27	#include <linux/wait.h>
5289d3d1	28	#include <linux/delay.h>
a0086dc5	29	#include <linux/mm.h>
5a0e3ad6	30	#include <linux/slab.h>
a0086dc5	31	#include <linux/vmalloc.h>
46a97191	32	#include <linux/hyperv.h>
37f7278b	33	#include <linux/export.h>
fc53662f VK	34	#include <asm/mshyperv.h>
fc53662f VK	35
0f2a6619	36	#include "hyperv_vmbus.h"
3e7ee490	37
3e7ee490	38
da9fcb72 HZ	39	struct vmbus_connection vmbus_connection = {
	40	.conn_state = DISCONNECTED,
	41	.next_gpadl_handle = ATOMIC_INIT(0xE1E10),
3e7ee490	42	};
95096f2f	43	EXPORT_SYMBOL_GPL(vmbus_connection);
3e7ee490	44
37f7278b S	45	/*
	46	* Negotiated protocol version with the host.
	47	*/
	48	__u32 vmbus_proto_version;
	49	EXPORT_SYMBOL_GPL(vmbus_proto_version);
	50
610071c3 S	51	static __u32 vmbus_get_next_version(__u32 current_version)
	52	{
	53	switch (current_version) {
	54	case (VERSION_WIN7):
	55	return VERSION_WS2008;
	56
	57	case (VERSION_WIN8):
	58	return VERSION_WIN7;
	59
03367ef5 S	60	case (VERSION_WIN8_1):
	61	return VERSION_WIN8;
	62
6c4e5f9c KM	63	case (VERSION_WIN10):
	64	return VERSION_WIN8_1;
	65
ae20b254 DC	66	case (VERSION_WIN10_V5):
	67	return VERSION_WIN10;
	68
610071c3 S	69	case (VERSION_WS2008):
	70	default:
	71	return VERSION_INVAL;
	72	}
	73	}
	74
	75	static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
	76	__u32 version)
	77	{
	78	int ret = 0;
41e270f6	79	unsigned int cur_cpu;
610071c3 S	80	struct vmbus_channel_initiate_contact *msg;
610071c3 S	81	unsigned long flags;
610071c3 S	82
	83	init_completion(&msginfo->waitevent);
	84
	85	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
	86
ae20b254	87	memset(msg, 0, sizeof(*msg));
610071c3 S	88	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
610071c3 S	89	msg->vmbus_version_requested = version;
ae20b254 DC	90
	91	/*
	92	* VMBus protocol 5.0 (VERSION_WIN10_V5) requires that we must use
	93	* VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
	94	* and for subsequent messages, we must use the Message Connection ID
	95	* field in the host-returned Version Response Message. And, with
	96	* VERSION_WIN10_V5, we don't use msg->interrupt_page, but we tell
	97	* the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
	98	* compatibility.
	99	*
	100	* On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
	101	*/
	102	if (version >= VERSION_WIN10_V5) {
	103	msg->msg_sint = VMBUS_MESSAGE_SINT;
	104	vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
	105	} else {
	106	msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
	107	vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
	108	}
	109
8681db44 GKH	110	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
8681db44 GKH	111	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
b282e4c0 S	112	/*
	113	* We want all channel messages to be delivered on CPU 0.
	114	* This has been the behavior pre-win8. This is not
	115	* perf issue and having all channel messages delivered on CPU 0
	116	* would be ok.
72686447 AN	117	* For post win8 hosts, we support receiving channel messagges on
	118	* all the CPUs. This is needed for kexec to work correctly where
	119	* the CPU attempting to connect may not be CPU 0.
b282e4c0	120	*/
54a66265	121	if (version >= VERSION_WIN8_1) {
41e270f6 DC	122	cur_cpu = get_cpu();
	123	msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
	124	vmbus_connection.connect_cpu = cur_cpu;
	125	put_cpu();
54a66265	126	} else {
72686447	127	msg->target_vcpu = 0;
54a66265 S	128	vmbus_connection.connect_cpu = 0;
54a66265 S	129	}
610071c3 S	130
	131	/*
	132	* Add to list before we send the request since we may
	133	* receive the response before returning from this routine
	134	*/
	135	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	136	list_add_tail(&msginfo->msglistentry,
	137	&vmbus_connection.chn_msg_list);
	138
	139	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	140
	141	ret = vmbus_post_msg(msg,
c0bb0392 VK	142	sizeof(struct vmbus_channel_initiate_contact),
c0bb0392 VK	143	true);
034ebf55 VK	144
	145	trace_vmbus_negotiate_version(msg, ret);
	146
610071c3 S	147	if (ret != 0) {
	148	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	149	list_del(&msginfo->msglistentry);
	150	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
	151	flags);
	152	return ret;
	153	}
	154
	155	/* Wait for the connection response */
269f9794	156	wait_for_completion(&msginfo->waitevent);
610071c3 S	157
	158	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	159	list_del(&msginfo->msglistentry);
	160	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	161
	162	/* Check if successful */
	163	if (msginfo->response.version_response.version_supported) {
	164	vmbus_connection.conn_state = CONNECTED;
ae20b254 DC	165
	166	if (version >= VERSION_WIN10_V5)
	167	vmbus_connection.msg_conn_id =
	168	msginfo->response.version_response.msg_conn_id;
610071c3	169	} else {
610071c3 S	170	return -ECONNREFUSED;
	171	}
	172
	173	return ret;
	174	}
	175
3e189519	176	/*
c6977677	177	* vmbus_connect - Sends a connect request on the partition service connection
fd8b85ea	178	*/
c6977677	179	int vmbus_connect(void)
3e7ee490	180	{
fd8b85ea	181	int ret = 0;
15b2f647	182	struct vmbus_channel_msginfo *msginfo = NULL;
610071c3	183	__u32 version;
3e7ee490	184
454f18a9	185	/* Initialize the vmbus connection */
da9fcb72 HZ	186	vmbus_connection.conn_state = CONNECTING;
	187	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
	188	if (!vmbus_connection.work_queue) {
3a7546d9	189	ret = -ENOMEM;
b0043863	190	goto cleanup;
de65a384	191	}
3e7ee490	192
da9fcb72	193	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
15b2f647	194	spin_lock_init(&vmbus_connection.channelmsg_lock);
3e7ee490	195
da9fcb72	196	INIT_LIST_HEAD(&vmbus_connection.chn_list);
d6f591e3	197	mutex_init(&vmbus_connection.channel_mutex);
3e7ee490	198
454f18a9 BP	199	/*
	200	* Setup the vmbus event connection for channel interrupt
	201	* abstraction stuff
	202	*/
df3493e0 S	203	vmbus_connection.int_page =
df3493e0 S	204	(void *)__get_free_pages(GFP_KERNEL\|__GFP_ZERO, 0);
da9fcb72	205	if (vmbus_connection.int_page == NULL) {
3a7546d9	206	ret = -ENOMEM;
b0043863	207	goto cleanup;
3e7ee490 HJ	208	}
3e7ee490 HJ	209
da9fcb72 HZ	210	vmbus_connection.recv_int_page = vmbus_connection.int_page;
	211	vmbus_connection.send_int_page =
	212	(void *)((unsigned long)vmbus_connection.int_page +
fd8b85ea	213	(PAGE_SIZE >> 1));
3e7ee490	214
fd8b85ea GKH	215	/*
	216	* Setup the monitor notification facility. The 1st page for
	217	* parent->child and the 2nd page for child->parent
454f18a9	218	*/
8681db44 GKH	219	vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	220	vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	221	if ((vmbus_connection.monitor_pages[0] == NULL) \|\|
	222	(vmbus_connection.monitor_pages[1] == NULL)) {
3a7546d9	223	ret = -ENOMEM;
b0043863	224	goto cleanup;
3e7ee490 HJ	225	}
3e7ee490 HJ	226
15b2f647	227	msginfo = kzalloc(sizeof(*msginfo) +
fd8b85ea GKH	228	sizeof(struct vmbus_channel_initiate_contact),
fd8b85ea GKH	229	GFP_KERNEL);
15b2f647	230	if (msginfo == NULL) {
8cad0af9	231	ret = -ENOMEM;
b0043863	232	goto cleanup;
3e7ee490 HJ	233	}
3e7ee490 HJ	234
454f18a9	235	/*
610071c3 S	236	* Negotiate a compatible VMBUS version number with the
	237	* host. We start with the highest number we can support
	238	* and work our way down until we negotiate a compatible
	239	* version.
454f18a9	240	*/
3e7ee490	241
2a5c43a8	242	version = VERSION_CURRENT;
3e7ee490	243
610071c3 S	244	do {
610071c3 S	245	ret = vmbus_negotiate_version(msginfo, version);
8bbf9f44	246	if (ret == -ETIMEDOUT)
666b9adc S	247	goto cleanup;
	248
	249	if (vmbus_connection.conn_state == CONNECTED)
610071c3	250	break;
3e7ee490	251
610071c3 S	252	version = vmbus_get_next_version(version);
610071c3 S	253	} while (version != VERSION_INVAL);
3e7ee490	254
610071c3	255	if (version == VERSION_INVAL)
b0043863	256	goto cleanup;
3e7ee490	257
37f7278b	258	vmbus_proto_version = version;
8de8af7e S	259	pr_info("Vmbus version:%d.%d\n",
8de8af7e S	260	version >> 16, version & 0xFFFF);
3bacaf0c	261
15b2f647	262	kfree(msginfo);
3e7ee490 HJ	263	return 0;
3e7ee490 HJ	264
b0043863	265	cleanup:
3bacaf0c	266	pr_err("Unable to connect to host\n");
09a19628	267
da9fcb72	268	vmbus_connection.conn_state = DISCONNECTED;
09a19628 VK	269	vmbus_disconnect();
	270
	271	kfree(msginfo);
	272
	273	return ret;
	274	}
3e7ee490	275
09a19628 VK	276	void vmbus_disconnect(void)
09a19628 VK	277	{
2db84eff S	278	/*
	279	* First send the unload request to the host.
	280	*/
75ff3a8a	281	vmbus_initiate_unload(false);
2db84eff	282
09a19628 VK	283	if (vmbus_connection.work_queue) {
09a19628 VK	284	drain_workqueue(vmbus_connection.work_queue);
da9fcb72	285	destroy_workqueue(vmbus_connection.work_queue);
09a19628	286	}
3e7ee490	287
da9fcb72	288	if (vmbus_connection.int_page) {
df3493e0	289	free_pages((unsigned long)vmbus_connection.int_page, 0);
da9fcb72	290	vmbus_connection.int_page = NULL;
3e7ee490 HJ	291	}
3e7ee490 HJ	292
a100d88d RK	293	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
a100d88d RK	294	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
8681db44 GKH	295	vmbus_connection.monitor_pages[0] = NULL;
8681db44 GKH	296	vmbus_connection.monitor_pages[1] = NULL;
3e7ee490 HJ	297	}
3e7ee490 HJ	298
3e189519	299	/*
c6977677 HZ	300	* relid2channel - Get the channel object given its
c6977677 HZ	301	* child relative id (ie channel id)
fd8b85ea	302	*/
d43e2fe7	303	struct vmbus_channel *relid2channel(u32 relid)
3e7ee490	304	{
aded7165	305	struct vmbus_channel *channel;
15b2f647	306	struct vmbus_channel *found_channel = NULL;
e68d2971 S	307	struct list_head cur, tmp;
e68d2971 S	308	struct vmbus_channel *cur_sc;
3e7ee490	309
85d9aa70 DC	310	BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
85d9aa70 DC	311
da9fcb72	312	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
15b2f647 HZ	313	if (channel->offermsg.child_relid == relid) {
15b2f647 HZ	314	found_channel = channel;
3e7ee490	315	break;
e68d2971 S	316	} else if (!list_empty(&channel->sc_list)) {
	317	/*
	318	* Deal with sub-channels.
	319	*/
	320	list_for_each_safe(cur, tmp, &channel->sc_list) {
	321	cur_sc = list_entry(cur, struct vmbus_channel,
	322	sc_list);
	323	if (cur_sc->offermsg.child_relid == relid) {
	324	found_channel = cur_sc;
	325	break;
	326	}
	327	}
3e7ee490 HJ	328	}
3e7ee490 HJ	329	}
3e7ee490	330
15b2f647	331	return found_channel;
3e7ee490 HJ	332	}
3e7ee490 HJ	333
3e189519	334	/*
631e63a9	335	* vmbus_on_event - Process a channel event notification
ada6eb11 SH	336	*
	337	* For batched channels (default) optimize host to guest signaling
	338	* by ensuring:
	339	* 1. While reading the channel, we disable interrupts from host.
	340	* 2. Ensure that we process all posted messages from the host
	341	* before returning from this callback.
	342	* 3. Once we return, enable signaling from the host. Once this
	343	* state is set we check to see if additional packets are
	344	* available to read. In this case we repeat the process.
	345	* If this tasklet has been running for a long time
	346	* then reschedule ourselves.
fd8b85ea	347	*/
631e63a9	348	void vmbus_on_event(unsigned long data)
3e7ee490	349	{
631e63a9	350	struct vmbus_channel channel = (void ) data;
ada6eb11	351	unsigned long time_limit = jiffies + 2;
3e7ee490	352
991f8f1c VK	353	trace_vmbus_on_event(channel);
991f8f1c VK	354
ada6eb11 SH	355	do {
	356	void (callback_fn)(void );
	357
	358	/* A channel once created is persistent even when
	359	* there is no driver handling the device. An
	360	* unloading driver sets the onchannel_callback to NULL.
f878f3d5	361	*/
ada6eb11 SH	362	callback_fn = READ_ONCE(channel->onchannel_callback);
	363	if (unlikely(callback_fn == NULL))
	364	return;
f878f3d5	365
ada6eb11 SH	366	(*callback_fn)(channel->channel_callback_context);
	367
	368	if (channel->callback_mode != HV_CALL_BATCHED)
	369	return;
	370
	371	if (likely(hv_end_read(&channel->inbound) == 0))
	372	return;
	373
	374	hv_begin_read(&channel->inbound);
	375	} while (likely(time_before(jiffies, time_limit)));
	376
	377	/* The time limit (2 jiffies) has been reached */
	378	tasklet_schedule(&channel->callback_event);
3e7ee490 HJ	379	}
3e7ee490 HJ	380
3e189519	381	/*
c6977677	382	* vmbus_post_msg - Send a msg on the vmbus's message connection
fd8b85ea	383	*/
c0bb0392	384	int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
3e7ee490	385	{
ae20b254	386	struct vmbus_channel_message_header *hdr;
15b2f647	387	union hv_connection_id conn_id;
5289d3d1 S	388	int ret = 0;
5289d3d1 S	389	int retries = 0;
8de0d7e9	390	u32 usec = 1;
3e7ee490	391
15b2f647	392	conn_id.asu32 = 0;
ae20b254	393	conn_id.u.id = vmbus_connection.msg_conn_id;
5289d3d1 S	394
	395	/*
	396	* hv_post_message() can have transient failures because of
	397	* insufficient resources. Retry the operation a couple of
	398	* times before giving up.
	399	*/
c0bb0392	400	while (retries < 100) {
fdeebcc6 S	401	ret = hv_post_message(conn_id, 1, buffer, buflen);
	402
	403	switch (ret) {
89f9f679	404	case HV_STATUS_INVALID_CONNECTION_ID:
ae20b254 DC	405	/*
	406	* See vmbus_negotiate_version(): VMBus protocol 5.0
	407	* requires that we must use
	408	* VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
	409	* Contact message, but on old hosts that only
	410	* support VMBus protocol 4.0 or lower, here we get
	411	* HV_STATUS_INVALID_CONNECTION_ID and we should
	412	* return an error immediately without retrying.
	413	*/
89760937	414	hdr = buffer;
ae20b254 DC	415	if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
ae20b254 DC	416	return -EINVAL;
89f9f679 DC	417	/*
	418	* We could get this if we send messages too
	419	* frequently.
	420	*/
	421	ret = -EAGAIN;
	422	break;
	423	case HV_STATUS_INSUFFICIENT_MEMORY:
fdeebcc6	424	case HV_STATUS_INSUFFICIENT_BUFFERS:
48f4ccdf	425	ret = -ENOBUFS;
fdeebcc6 S	426	break;
fdeebcc6 S	427	case HV_STATUS_SUCCESS:
5289d3d1	428	return ret;
fdeebcc6 S	429	default:
	430	pr_err("hv_post_msg() failed; error code:%d\n", ret);
	431	return -EINVAL;
	432	}
	433
5289d3d1	434	retries++;
c0bb0392 VK	435	if (can_sleep && usec > 1000)
	436	msleep(usec / 1000);
	437	else if (usec < MAX_UDELAY_MS * 1000)
	438	udelay(usec);
	439	else
	440	mdelay(usec / 1000);
	441
e917a5e2	442	if (retries < 22)
8de0d7e9	443	usec *= 2;
5289d3d1 S	444	}
5289d3d1 S	445	return ret;
3e7ee490 HJ	446	}
3e7ee490 HJ	447
3e189519	448	/*
c6977677	449	* vmbus_set_event - Send an event notification to the parent
fd8b85ea	450	*/
1b807e10	451	void vmbus_set_event(struct vmbus_channel *channel)
3e7ee490	452	{
21c3bef5	453	u32 child_relid = channel->offermsg.child_relid;
7c369f40	454
5c1bec61 SH	455	if (!channel->is_dedicated_interrupt)
5c1bec61 SH	456	vmbus_send_interrupt(child_relid);
3be77774	457
6981fbf3 SH	458	++channel->sig_events;
6981fbf3 SH	459
05784171	460	hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
3e7ee490	461	}
5cc47247	462	EXPORT_SYMBOL_GPL(vmbus_set_event);