[mirror_ubuntu-zesty-kernel.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 <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/slab.h>
#include <linux/vmalloc.h>
#include <linux/hyperv.h>
#include <linux/export.h>
#include <asm/hyperv.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_WS2008):
	default:
		return VERSION_INVAL;
	}
}

static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
					__u32 version)
{
	int ret = 0;
	struct vmbus_channel_initiate_contact *msg;
	unsigned long flags;

	init_completion(&msginfo->waitevent);

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

	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
	msg->vmbus_version_requested = version;
	msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
	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) {
		msg->target_vcpu = hv_context.vp_index[get_cpu()];
		put_cpu();
	} else {
		msg->target_vcpu = 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);
	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;
	} 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("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
		    host_info_eax, host_info_ebx >> 16,
		    host_info_ebx & 0xFFFF, host_info_ecx,
		    host_info_edx >> 24, host_info_edx & 0xFFFFFF,
		    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;
}

/*
 * Map the given relid to the corresponding channel based on the
 * per-cpu list of channels that have been affinitized to this CPU.
 * This will be used in the channel callback path as we can do this
 * mapping in a lock-free fashion.
 */
static struct vmbus_channel *pcpu_relid2channel(u32 relid)
{
	struct vmbus_channel *channel;
	struct vmbus_channel *found_channel  = NULL;
	int cpu = smp_processor_id();
	struct list_head *pcpu_head = &hv_context.percpu_list[cpu];

	list_for_each_entry(channel, pcpu_head, percpu_list) {
		if (channel->offermsg.child_relid == relid) {
			found_channel = channel;
			break;
		}
	}

	return found_channel;
}

/*
 * 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;
}

/*
 * process_chn_event - Process a channel event notification
 */
static void process_chn_event(u32 relid)
{
	struct vmbus_channel *channel;
	void *arg;
	bool read_state;
	u32 bytes_to_read;

	/*
	 * Find the channel based on this relid and invokes the
	 * channel callback to process the event
	 */
	channel = pcpu_relid2channel(relid);

	if (!channel)
		return;

	/*
	 * A channel once created is persistent even when there
	 * is no driver handling the device. An unloading driver
	 * sets the onchannel_callback to NULL on the same CPU
	 * as where this interrupt is handled (in an interrupt context).
	 * Thus, checking and invoking the driver specific callback takes
	 * care of orderly unloading of the driver.
	 */

	if (channel->onchannel_callback != NULL) {
		arg = channel->channel_callback_context;
		read_state = channel->batched_reading;
		/*
		 * This callback reads the messages sent by the host.
		 * We can 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.
		 */

		do {
			if (read_state)
				hv_begin_read(&channel->inbound);
			channel->onchannel_callback(arg);
			if (read_state)
				bytes_to_read = hv_end_read(&channel->inbound);
			else
				bytes_to_read = 0;
		} while (read_state && (bytes_to_read != 0));
	}
}

/*
 * vmbus_on_event - Handler for events
 */
void vmbus_on_event(unsigned long data)
{
	u32 dword;
	u32 maxdword;
	int bit;
	u32 relid;
	u32 *recv_int_page = NULL;
	void *page_addr;
	int cpu = smp_processor_id();
	union hv_synic_event_flags *event;

	if (vmbus_proto_version < VERSION_WIN8) {
		maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
		recv_int_page = vmbus_connection.recv_int_page;
	} else {
		/*
		 * When the host is win8 and beyond, the event page
		 * can be directly checked to get the id of the channel
		 * that has the interrupt pending.
		 */
		maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
		page_addr = hv_context.synic_event_page[cpu];
		event = (union hv_synic_event_flags *)page_addr +
						 VMBUS_MESSAGE_SINT;
		recv_int_page = event->flags32;
	}


	/* Check events */
	if (!recv_int_page)
		return;
	for (dword = 0; dword < maxdword; dword++) {
		if (!recv_int_page[dword])
			continue;
		for (bit = 0; bit < 32; bit++) {
			if (sync_test_and_clear_bit(bit,
				(unsigned long *)&recv_int_page[dword])) {
				relid = (dword << 5) + bit;

				if (relid == 0)
					/*
					 * Special case - vmbus
					 * channel protocol msg
					 */
					continue;

				process_chn_event(relid);
			}
		}
	}
}

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

	conn_id.asu32 = 0;
	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_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:
			/*
			 * We could get this if we send messages too
			 * frequently.
			 */
			ret = -EAGAIN;
			break;
		case HV_STATUS_INSUFFICIENT_MEMORY:
		case HV_STATUS_INSUFFICIENT_BUFFERS:
			ret = -ENOMEM;
			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 (usec < 256000)
			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) {
		/* Each u32 represents 32 channels */
		sync_set_bit(child_relid & 31,
			(unsigned long *)vmbus_connection.send_int_page +
			(child_relid >> 5));
	}

	hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
}
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 <haiyangz@microsoft.com>
	20	* Hank Janssen <hjanssen@microsoft.com>
	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>
407dd164	34	#include <asm/hyperv.h>
0f2a6619	35	#include "hyperv_vmbus.h"
3e7ee490	36
3e7ee490	37
da9fcb72 HZ	38	struct vmbus_connection vmbus_connection = {
	39	.conn_state = DISCONNECTED,
	40	.next_gpadl_handle = ATOMIC_INIT(0xE1E10),
3e7ee490	41	};
95096f2f	42	EXPORT_SYMBOL_GPL(vmbus_connection);
3e7ee490	43
37f7278b S	44	/*
	45	* Negotiated protocol version with the host.
	46	*/
	47	__u32 vmbus_proto_version;
	48	EXPORT_SYMBOL_GPL(vmbus_proto_version);
	49
610071c3 S	50	static __u32 vmbus_get_next_version(__u32 current_version)
	51	{
	52	switch (current_version) {
	53	case (VERSION_WIN7):
	54	return VERSION_WS2008;
	55
	56	case (VERSION_WIN8):
	57	return VERSION_WIN7;
	58
03367ef5 S	59	case (VERSION_WIN8_1):
	60	return VERSION_WIN8;
	61
6c4e5f9c KM	62	case (VERSION_WIN10):
	63	return VERSION_WIN8_1;
	64
610071c3 S	65	case (VERSION_WS2008):
	66	default:
	67	return VERSION_INVAL;
	68	}
	69	}
	70
	71	static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
	72	__u32 version)
	73	{
	74	int ret = 0;
	75	struct vmbus_channel_initiate_contact *msg;
	76	unsigned long flags;
610071c3 S	77
	78	init_completion(&msginfo->waitevent);
	79
	80	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
	81
	82	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
	83	msg->vmbus_version_requested = version;
	84	msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
8681db44 GKH	85	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
8681db44 GKH	86	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
b282e4c0 S	87	/*
	88	* We want all channel messages to be delivered on CPU 0.
	89	* This has been the behavior pre-win8. This is not
	90	* perf issue and having all channel messages delivered on CPU 0
	91	* would be ok.
72686447 AN	92	* For post win8 hosts, we support receiving channel messagges on
	93	* all the CPUs. This is needed for kexec to work correctly where
	94	* the CPU attempting to connect may not be CPU 0.
b282e4c0	95	*/
72686447 AN	96	if (version >= VERSION_WIN8_1) {
	97	msg->target_vcpu = hv_context.vp_index[get_cpu()];
	98	put_cpu();
	99	} else {
	100	msg->target_vcpu = 0;
	101	}
610071c3 S	102
	103	/*
	104	* Add to list before we send the request since we may
	105	* receive the response before returning from this routine
	106	*/
	107	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	108	list_add_tail(&msginfo->msglistentry,
	109	&vmbus_connection.chn_msg_list);
	110
	111	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	112
	113	ret = vmbus_post_msg(msg,
816725f6 VK	114	sizeof(struct vmbus_channel_initiate_contact),
816725f6 VK	115	true);
610071c3 S	116	if (ret != 0) {
	117	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	118	list_del(&msginfo->msglistentry);
	119	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
	120	flags);
	121	return ret;
	122	}
	123
	124	/* Wait for the connection response */
269f9794	125	wait_for_completion(&msginfo->waitevent);
610071c3 S	126
	127	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	128	list_del(&msginfo->msglistentry);
	129	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	130
	131	/* Check if successful */
	132	if (msginfo->response.version_response.version_supported) {
	133	vmbus_connection.conn_state = CONNECTED;
	134	} else {
610071c3 S	135	return -ECONNREFUSED;
	136	}
	137
	138	return ret;
	139	}
	140
3e189519	141	/*
c6977677	142	* vmbus_connect - Sends a connect request on the partition service connection
fd8b85ea	143	*/
c6977677	144	int vmbus_connect(void)
3e7ee490	145	{
fd8b85ea	146	int ret = 0;
15b2f647	147	struct vmbus_channel_msginfo *msginfo = NULL;
610071c3	148	__u32 version;
3e7ee490	149
454f18a9	150	/* Initialize the vmbus connection */
da9fcb72 HZ	151	vmbus_connection.conn_state = CONNECTING;
	152	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
	153	if (!vmbus_connection.work_queue) {
3a7546d9	154	ret = -ENOMEM;
b0043863	155	goto cleanup;
de65a384	156	}
3e7ee490	157
da9fcb72	158	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
15b2f647	159	spin_lock_init(&vmbus_connection.channelmsg_lock);
3e7ee490	160
da9fcb72	161	INIT_LIST_HEAD(&vmbus_connection.chn_list);
d6f591e3	162	mutex_init(&vmbus_connection.channel_mutex);
3e7ee490	163
454f18a9 BP	164	/*
	165	* Setup the vmbus event connection for channel interrupt
	166	* abstraction stuff
	167	*/
df3493e0 S	168	vmbus_connection.int_page =
df3493e0 S	169	(void *)__get_free_pages(GFP_KERNEL\|__GFP_ZERO, 0);
da9fcb72	170	if (vmbus_connection.int_page == NULL) {
3a7546d9	171	ret = -ENOMEM;
b0043863	172	goto cleanup;
3e7ee490 HJ	173	}
3e7ee490 HJ	174
da9fcb72 HZ	175	vmbus_connection.recv_int_page = vmbus_connection.int_page;
	176	vmbus_connection.send_int_page =
	177	(void *)((unsigned long)vmbus_connection.int_page +
fd8b85ea	178	(PAGE_SIZE >> 1));
3e7ee490	179
fd8b85ea GKH	180	/*
	181	* Setup the monitor notification facility. The 1st page for
	182	* parent->child and the 2nd page for child->parent
454f18a9	183	*/
8681db44 GKH	184	vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	185	vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	186	if ((vmbus_connection.monitor_pages[0] == NULL) \|\|
	187	(vmbus_connection.monitor_pages[1] == NULL)) {
3a7546d9	188	ret = -ENOMEM;
b0043863	189	goto cleanup;
3e7ee490 HJ	190	}
3e7ee490 HJ	191
15b2f647	192	msginfo = kzalloc(sizeof(*msginfo) +
fd8b85ea GKH	193	sizeof(struct vmbus_channel_initiate_contact),
fd8b85ea GKH	194	GFP_KERNEL);
15b2f647	195	if (msginfo == NULL) {
8cad0af9	196	ret = -ENOMEM;
b0043863	197	goto cleanup;
3e7ee490 HJ	198	}
3e7ee490 HJ	199
454f18a9	200	/*
610071c3 S	201	* Negotiate a compatible VMBUS version number with the
	202	* host. We start with the highest number we can support
	203	* and work our way down until we negotiate a compatible
	204	* version.
454f18a9	205	*/
3e7ee490	206
2a5c43a8	207	version = VERSION_CURRENT;
3e7ee490	208
610071c3 S	209	do {
610071c3 S	210	ret = vmbus_negotiate_version(msginfo, version);
8bbf9f44	211	if (ret == -ETIMEDOUT)
666b9adc S	212	goto cleanup;
	213
	214	if (vmbus_connection.conn_state == CONNECTED)
610071c3	215	break;
3e7ee490	216
610071c3 S	217	version = vmbus_get_next_version(version);
610071c3 S	218	} while (version != VERSION_INVAL);
3e7ee490	219
610071c3	220	if (version == VERSION_INVAL)
b0043863	221	goto cleanup;
3e7ee490	222
37f7278b	223	vmbus_proto_version = version;
3bacaf0c S	224	pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
	225	host_info_eax, host_info_ebx >> 16,
	226	host_info_ebx & 0xFFFF, host_info_ecx,
	227	host_info_edx >> 24, host_info_edx & 0xFFFFFF,
	228	version >> 16, version & 0xFFFF);
	229
15b2f647	230	kfree(msginfo);
3e7ee490 HJ	231	return 0;
3e7ee490 HJ	232
b0043863	233	cleanup:
3bacaf0c	234	pr_err("Unable to connect to host\n");
09a19628	235
da9fcb72	236	vmbus_connection.conn_state = DISCONNECTED;
09a19628 VK	237	vmbus_disconnect();
	238
	239	kfree(msginfo);
	240
	241	return ret;
	242	}
3e7ee490	243
09a19628 VK	244	void vmbus_disconnect(void)
09a19628 VK	245	{
2db84eff S	246	/*
	247	* First send the unload request to the host.
	248	*/
75ff3a8a	249	vmbus_initiate_unload(false);
2db84eff	250
09a19628 VK	251	if (vmbus_connection.work_queue) {
09a19628 VK	252	drain_workqueue(vmbus_connection.work_queue);
da9fcb72	253	destroy_workqueue(vmbus_connection.work_queue);
09a19628	254	}
3e7ee490	255
da9fcb72	256	if (vmbus_connection.int_page) {
df3493e0	257	free_pages((unsigned long)vmbus_connection.int_page, 0);
da9fcb72	258	vmbus_connection.int_page = NULL;
3e7ee490 HJ	259	}
3e7ee490 HJ	260
a100d88d RK	261	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
a100d88d RK	262	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
8681db44 GKH	263	vmbus_connection.monitor_pages[0] = NULL;
8681db44 GKH	264	vmbus_connection.monitor_pages[1] = NULL;
3e7ee490 HJ	265	}
3e7ee490 HJ	266
3a28fa35 S	267	/*
	268	* Map the given relid to the corresponding channel based on the
	269	* per-cpu list of channels that have been affinitized to this CPU.
	270	* This will be used in the channel callback path as we can do this
	271	* mapping in a lock-free fashion.
	272	*/
	273	static struct vmbus_channel *pcpu_relid2channel(u32 relid)
	274	{
	275	struct vmbus_channel *channel;
	276	struct vmbus_channel *found_channel = NULL;
	277	int cpu = smp_processor_id();
	278	struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
	279
	280	list_for_each_entry(channel, pcpu_head, percpu_list) {
	281	if (channel->offermsg.child_relid == relid) {
	282	found_channel = channel;
	283	break;
	284	}
	285	}
	286
	287	return found_channel;
	288	}
3e7ee490	289
3e189519	290	/*
c6977677 HZ	291	* relid2channel - Get the channel object given its
c6977677 HZ	292	* child relative id (ie channel id)
fd8b85ea	293	*/
d43e2fe7	294	struct vmbus_channel *relid2channel(u32 relid)
3e7ee490	295	{
aded7165	296	struct vmbus_channel *channel;
15b2f647	297	struct vmbus_channel *found_channel = NULL;
e68d2971 S	298	struct list_head cur, tmp;
e68d2971 S	299	struct vmbus_channel *cur_sc;
3e7ee490	300
85d9aa70 DC	301	BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
85d9aa70 DC	302
da9fcb72	303	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
15b2f647 HZ	304	if (channel->offermsg.child_relid == relid) {
15b2f647 HZ	305	found_channel = channel;
3e7ee490	306	break;
e68d2971 S	307	} else if (!list_empty(&channel->sc_list)) {
	308	/*
	309	* Deal with sub-channels.
	310	*/
	311	list_for_each_safe(cur, tmp, &channel->sc_list) {
	312	cur_sc = list_entry(cur, struct vmbus_channel,
	313	sc_list);
	314	if (cur_sc->offermsg.child_relid == relid) {
	315	found_channel = cur_sc;
	316	break;
	317	}
	318	}
3e7ee490 HJ	319	}
3e7ee490 HJ	320	}
3e7ee490	321
15b2f647	322	return found_channel;
3e7ee490 HJ	323	}
3e7ee490 HJ	324
3e189519	325	/*
c6977677	326	* process_chn_event - Process a channel event notification
fd8b85ea	327	*/
35436487	328	static void process_chn_event(u32 relid)
3e7ee490	329	{
aded7165	330	struct vmbus_channel *channel;
f878f3d5 S	331	void *arg;
	332	bool read_state;
	333	u32 bytes_to_read;
3e7ee490	334
454f18a9 BP	335	/*
	336	* Find the channel based on this relid and invokes the
	337	* channel callback to process the event
	338	*/
3a28fa35	339	channel = pcpu_relid2channel(relid);
3e7ee490	340
37f492ce	341	if (!channel)
24326039	342	return;
24326039 S	343
	344	/*
	345	* A channel once created is persistent even when there
	346	* is no driver handling the device. An unloading driver
d3ba720d S	347	* sets the onchannel_callback to NULL on the same CPU
	348	* as where this interrupt is handled (in an interrupt context).
	349	* Thus, checking and invoking the driver specific callback takes
	350	* care of orderly unloading of the driver.
24326039 S	351	*/
24326039 S	352
f878f3d5 S	353	if (channel->onchannel_callback != NULL) {
	354	arg = channel->channel_callback_context;
	355	read_state = channel->batched_reading;
	356	/*
	357	* This callback reads the messages sent by the host.
	358	* We can optimize host to guest signaling by ensuring:
	359	* 1. While reading the channel, we disable interrupts from
	360	* host.
	361	* 2. Ensure that we process all posted messages from the host
	362	* before returning from this callback.
	363	* 3. Once we return, enable signaling from the host. Once this
	364	* state is set we check to see if additional packets are
	365	* available to read. In this case we repeat the process.
	366	*/
	367
	368	do {
affb1aff S	369	if (read_state)
affb1aff S	370	hv_begin_read(&channel->inbound);
f878f3d5	371	channel->onchannel_callback(arg);
affb1aff S	372	if (read_state)
	373	bytes_to_read = hv_end_read(&channel->inbound);
	374	else
	375	bytes_to_read = 0;
f878f3d5	376	} while (read_state && (bytes_to_read != 0));
f878f3d5	377	}
3e7ee490 HJ	378	}
3e7ee490 HJ	379
3e189519	380	/*
c6977677	381	* vmbus_on_event - Handler for events
fd8b85ea	382	*/
6de3d6aa	383	void vmbus_on_event(unsigned long data)
3e7ee490	384	{
35436487	385	u32 dword;
6552ecd7	386	u32 maxdword;
3e7ee490	387	int bit;
35436487	388	u32 relid;
6552ecd7 S	389	u32 *recv_int_page = NULL;
	390	void *page_addr;
	391	int cpu = smp_processor_id();
	392	union hv_synic_event_flags *event;
	393
6c4e5f9c	394	if (vmbus_proto_version < VERSION_WIN8) {
6552ecd7 S	395	maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
	396	recv_int_page = vmbus_connection.recv_int_page;
	397	} else {
	398	/*
	399	* When the host is win8 and beyond, the event page
	400	* can be directly checked to get the id of the channel
	401	* that has the interrupt pending.
	402	*/
	403	maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
	404	page_addr = hv_context.synic_event_page[cpu];
	405	event = (union hv_synic_event_flags *)page_addr +
	406	VMBUS_MESSAGE_SINT;
	407	recv_int_page = event->flags32;
	408	}
	409
	410
3e7ee490	411
454f18a9	412	/* Check events */
242b45aa OH	413	if (!recv_int_page)
	414	return;
	415	for (dword = 0; dword < maxdword; dword++) {
	416	if (!recv_int_page[dword])
	417	continue;
	418	for (bit = 0; bit < 32; bit++) {
d9add43b S	419	if (sync_test_and_clear_bit(bit,
d9add43b S	420	(unsigned long *)&recv_int_page[dword])) {
242b45aa OH	421	relid = (dword << 5) + bit;
242b45aa OH	422
d9add43b	423	if (relid == 0)
6d81d330 S	424	/*
	425	* Special case - vmbus
	426	* channel protocol msg
	427	*/
242b45aa	428	continue;
d9add43b	429
35436487	430	process_chn_event(relid);
3e7ee490	431	}
242b45aa	432	}
3e7ee490	433	}
3e7ee490 HJ	434	}
3e7ee490 HJ	435
3e189519	436	/*
c6977677	437	* vmbus_post_msg - Send a msg on the vmbus's message connection
fd8b85ea	438	*/
816725f6	439	int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
3e7ee490	440	{
15b2f647	441	union hv_connection_id conn_id;
5289d3d1 S	442	int ret = 0;
5289d3d1 S	443	int retries = 0;
8de0d7e9	444	u32 usec = 1;
3e7ee490	445
15b2f647 HZ	446	conn_id.asu32 = 0;
15b2f647 HZ	447	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
5289d3d1 S	448
	449	/*
	450	* hv_post_message() can have transient failures because of
	451	* insufficient resources. Retry the operation a couple of
	452	* times before giving up.
	453	*/
816725f6	454	while (retries < 100) {
fdeebcc6 S	455	ret = hv_post_message(conn_id, 1, buffer, buflen);
	456
	457	switch (ret) {
89f9f679 DC	458	case HV_STATUS_INVALID_CONNECTION_ID:
	459	/*
	460	* We could get this if we send messages too
	461	* frequently.
	462	*/
	463	ret = -EAGAIN;
	464	break;
	465	case HV_STATUS_INSUFFICIENT_MEMORY:
fdeebcc6 S	466	case HV_STATUS_INSUFFICIENT_BUFFERS:
fdeebcc6 S	467	ret = -ENOMEM;
fdeebcc6 S	468	break;
fdeebcc6 S	469	case HV_STATUS_SUCCESS:
5289d3d1	470	return ret;
fdeebcc6 S	471	default:
	472	pr_err("hv_post_msg() failed; error code:%d\n", ret);
	473	return -EINVAL;
	474	}
	475
5289d3d1	476	retries++;
816725f6 VK	477	if (can_sleep && usec > 1000)
	478	msleep(usec / 1000);
	479	else if (usec < MAX_UDELAY_MS * 1000)
	480	udelay(usec);
	481	else
	482	mdelay(usec / 1000);
	483
	484	if (usec < 256000)
8de0d7e9	485	usec *= 2;
5289d3d1 S	486	}
5289d3d1 S	487	return ret;
3e7ee490 HJ	488	}
3e7ee490 HJ	489
3e189519	490	/*
c6977677	491	* vmbus_set_event - Send an event notification to the parent
fd8b85ea	492	*/
1b807e10	493	void vmbus_set_event(struct vmbus_channel *channel)
3e7ee490	494	{
21c3bef5	495	u32 child_relid = channel->offermsg.child_relid;
7c369f40	496
3be77774 S	497	if (!channel->is_dedicated_interrupt) {
	498	/* Each u32 represents 32 channels */
	499	sync_set_bit(child_relid & 31,
	500	(unsigned long *)vmbus_connection.send_int_page +
	501	(child_relid >> 5));
	502	}
	503
1b807e10	504	hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
3e7ee490	505	}
5cc47247	506	EXPORT_SYMBOL_GPL(vmbus_set_event);