[linux-block.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),
};

/*
 * 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_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;
	int t;

	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);
	msg->monitor_page2 = virt_to_phys(
			(void *)((unsigned long)vmbus_connection.monitor_pages +
				 PAGE_SIZE));

	/*
	 * 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));
	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 */
	t =  wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
	if (t == 0) {
		spin_lock_irqsave(&vmbus_connection.channelmsg_lock,
				flags);
		list_del(&msginfo->msglistentry);
		spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
					flags);
		return -ETIMEDOUT;
	}

	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 {
		pr_err("Unable to connect, "
			"Version %d not supported by Hyper-V\n",
			version);
		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);
	spin_lock_init(&vmbus_connection.channel_lock);

	/*
	 * 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 =
	(void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 1);
	if (vmbus_connection.monitor_pages == 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 == 0)
			break;

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

	if (version == VERSION_INVAL)
		goto cleanup;

	vmbus_proto_version = version;
	pr_info("Negotiated host information %d\n", version);
	kfree(msginfo);
	return 0;

cleanup:
	vmbus_connection.conn_state = DISCONNECTED;

	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;
	}

	if (vmbus_connection.monitor_pages) {
		free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
		vmbus_connection.monitor_pages = NULL;
	}

	kfree(msginfo);

	return ret;
}


/*
 * 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;
	unsigned long flags;

	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
		if (channel->offermsg.child_relid == relid) {
			found_channel = channel;
			break;
		}
	}
	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);

	return found_channel;
}

/*
 * process_chn_event - Process a channel event notification
 */
static void process_chn_event(u32 relid)
{
	struct vmbus_channel *channel;
	unsigned long flags;
	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 = relid2channel(relid);

	if (!channel) {
		pr_err("channel not found for relid - %u\n", relid);
		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 under the
	 * protection of the channel inbound_lock. Thus, checking
	 * and invoking the driver specific callback takes care of
	 * orderly unloading of the driver.
	 */

	spin_lock_irqsave(&channel->inbound_lock, flags);
	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 {
			hv_begin_read(&channel->inbound);
			channel->onchannel_callback(arg);
			bytes_to_read = hv_end_read(&channel->inbound);
		} while (read_state && (bytes_to_read != 0));
	} else {
		pr_err("no channel callback for relid - %u\n", relid);
	}

	spin_unlock_irqrestore(&channel->inbound_lock, flags);
}

/*
 * 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_WS2008) ||
		(vmbus_proto_version == VERSION_WIN7)) {
		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)
{
	union hv_connection_id conn_id;
	int ret = 0;
	int retries = 0;

	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 < 3) {
		ret =  hv_post_message(conn_id, 1, buffer, buflen);
		if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
			return ret;
		retries++;
		msleep(100);
	}
	return ret;
}

/*
 * vmbus_set_event - Send an event notification to the parent
 */
int 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));
	}

	return hv_signal_event(channel->sig_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 HJ	41	};
3e7ee490 HJ	42
37f7278b S	43	/*
	44	* Negotiated protocol version with the host.
	45	*/
	46	__u32 vmbus_proto_version;
	47	EXPORT_SYMBOL_GPL(vmbus_proto_version);
	48
610071c3 S	49	static __u32 vmbus_get_next_version(__u32 current_version)
	50	{
	51	switch (current_version) {
	52	case (VERSION_WIN7):
	53	return VERSION_WS2008;
	54
	55	case (VERSION_WIN8):
	56	return VERSION_WIN7;
	57
	58	case (VERSION_WS2008):
	59	default:
	60	return VERSION_INVAL;
	61	}
	62	}
	63
	64	static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
	65	__u32 version)
	66	{
	67	int ret = 0;
	68	struct vmbus_channel_initiate_contact *msg;
	69	unsigned long flags;
	70	int t;
	71
	72	init_completion(&msginfo->waitevent);
	73
	74	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
	75
	76	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
	77	msg->vmbus_version_requested = version;
	78	msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
	79	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages);
	80	msg->monitor_page2 = virt_to_phys(
	81	(void *)((unsigned long)vmbus_connection.monitor_pages +
	82	PAGE_SIZE));
	83
	84	/*
	85	* Add to list before we send the request since we may
	86	* receive the response before returning from this routine
	87	*/
	88	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	89	list_add_tail(&msginfo->msglistentry,
	90	&vmbus_connection.chn_msg_list);
	91
	92	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	93
	94	ret = vmbus_post_msg(msg,
	95	sizeof(struct vmbus_channel_initiate_contact));
	96	if (ret != 0) {
	97	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	98	list_del(&msginfo->msglistentry);
	99	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
	100	flags);
	101	return ret;
	102	}
	103
	104	/* Wait for the connection response */
	105	t = wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
	106	if (t == 0) {
	107	spin_lock_irqsave(&vmbus_connection.channelmsg_lock,
	108	flags);
	109	list_del(&msginfo->msglistentry);
	110	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
	111	flags);
	112	return -ETIMEDOUT;
113	}
114
115	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
116	list_del(&msginfo->msglistentry);
117	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
118
119	/* Check if successful */
120	if (msginfo->response.version_response.version_supported) {
121	vmbus_connection.conn_state = CONNECTED;
122	} else {
123	pr_err("Unable to connect, "
124	"Version %d not supported by Hyper-V\n",
125	version);
126	return -ECONNREFUSED;
127	}
128
129	return ret;
130	}
131
3e189519	132	/*
c6977677	133	* vmbus_connect - Sends a connect request on the partition service connection
fd8b85ea	134	*/
c6977677	135	int vmbus_connect(void)
3e7ee490	136	{
fd8b85ea	137	int ret = 0;
15b2f647	138	struct vmbus_channel_msginfo *msginfo = NULL;
610071c3	139	__u32 version;
3e7ee490	140
454f18a9	141	/* Initialize the vmbus connection */
da9fcb72 HZ	142	vmbus_connection.conn_state = CONNECTING;
	143	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
	144	if (!vmbus_connection.work_queue) {
3a7546d9	145	ret = -ENOMEM;
b0043863	146	goto cleanup;
de65a384	147	}
3e7ee490	148
da9fcb72	149	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
15b2f647	150	spin_lock_init(&vmbus_connection.channelmsg_lock);
3e7ee490	151
da9fcb72	152	INIT_LIST_HEAD(&vmbus_connection.chn_list);
15b2f647	153	spin_lock_init(&vmbus_connection.channel_lock);
3e7ee490	154
454f18a9 BP	155	/*
	156	* Setup the vmbus event connection for channel interrupt
	157	* abstraction stuff
	158	*/
df3493e0 S	159	vmbus_connection.int_page =
df3493e0 S	160	(void *)__get_free_pages(GFP_KERNEL\|__GFP_ZERO, 0);
da9fcb72	161	if (vmbus_connection.int_page == NULL) {
3a7546d9	162	ret = -ENOMEM;
b0043863	163	goto cleanup;
3e7ee490 HJ	164	}
3e7ee490 HJ	165
da9fcb72 HZ	166	vmbus_connection.recv_int_page = vmbus_connection.int_page;
	167	vmbus_connection.send_int_page =
	168	(void *)((unsigned long)vmbus_connection.int_page +
fd8b85ea	169	(PAGE_SIZE >> 1));
3e7ee490	170
fd8b85ea GKH	171	/*
	172	* Setup the monitor notification facility. The 1st page for
	173	* parent->child and the 2nd page for child->parent
454f18a9	174	*/
df3493e0 S	175	vmbus_connection.monitor_pages =
df3493e0 S	176	(void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 1);
da9fcb72	177	if (vmbus_connection.monitor_pages == NULL) {
3a7546d9	178	ret = -ENOMEM;
b0043863	179	goto cleanup;
3e7ee490 HJ	180	}
3e7ee490 HJ	181
15b2f647	182	msginfo = kzalloc(sizeof(*msginfo) +
fd8b85ea GKH	183	sizeof(struct vmbus_channel_initiate_contact),
fd8b85ea GKH	184	GFP_KERNEL);
15b2f647	185	if (msginfo == NULL) {
8cad0af9	186	ret = -ENOMEM;
b0043863	187	goto cleanup;
3e7ee490 HJ	188	}
3e7ee490 HJ	189
454f18a9	190	/*
610071c3 S	191	* Negotiate a compatible VMBUS version number with the
	192	* host. We start with the highest number we can support
	193	* and work our way down until we negotiate a compatible
	194	* version.
454f18a9	195	*/
3e7ee490	196
2a5c43a8	197	version = VERSION_CURRENT;
3e7ee490	198
610071c3 S	199	do {
	200	ret = vmbus_negotiate_version(msginfo, version);
	201	if (ret == 0)
	202	break;
3e7ee490	203
610071c3 S	204	version = vmbus_get_next_version(version);
610071c3 S	205	} while (version != VERSION_INVAL);
3e7ee490	206
610071c3	207	if (version == VERSION_INVAL)
b0043863	208	goto cleanup;
3e7ee490	209
37f7278b S	210	vmbus_proto_version = version;
37f7278b S	211	pr_info("Negotiated host information %d\n", version);
15b2f647	212	kfree(msginfo);
3e7ee490 HJ	213	return 0;
3e7ee490 HJ	214
b0043863	215	cleanup:
da9fcb72	216	vmbus_connection.conn_state = DISCONNECTED;
3e7ee490	217
da9fcb72 HZ	218	if (vmbus_connection.work_queue)
da9fcb72 HZ	219	destroy_workqueue(vmbus_connection.work_queue);
3e7ee490	220
da9fcb72	221	if (vmbus_connection.int_page) {
df3493e0	222	free_pages((unsigned long)vmbus_connection.int_page, 0);
da9fcb72	223	vmbus_connection.int_page = NULL;
3e7ee490 HJ	224	}
3e7ee490 HJ	225
da9fcb72	226	if (vmbus_connection.monitor_pages) {
df3493e0	227	free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
da9fcb72	228	vmbus_connection.monitor_pages = NULL;
3e7ee490 HJ	229	}
3e7ee490 HJ	230
dd9b15dc	231	kfree(msginfo);
3e7ee490	232
3e7ee490 HJ	233	return ret;
	234	}
	235
3e7ee490	236
3e189519	237	/*
c6977677 HZ	238	* relid2channel - Get the channel object given its
c6977677 HZ	239	* child relative id (ie channel id)
fd8b85ea	240	*/
c6977677	241	struct vmbus_channel *relid2channel(u32 relid)
3e7ee490	242	{
aded7165	243	struct vmbus_channel *channel;
15b2f647	244	struct vmbus_channel *found_channel = NULL;
0f5e44ca	245	unsigned long flags;
3e7ee490	246
15b2f647	247	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
da9fcb72	248	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
15b2f647 HZ	249	if (channel->offermsg.child_relid == relid) {
15b2f647 HZ	250	found_channel = channel;
3e7ee490 HJ	251	break;
	252	}
	253	}
15b2f647	254	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
3e7ee490	255
15b2f647	256	return found_channel;
3e7ee490 HJ	257	}
3e7ee490 HJ	258
3e189519	259	/*
c6977677	260	* process_chn_event - Process a channel event notification
fd8b85ea	261	*/
35436487	262	static void process_chn_event(u32 relid)
3e7ee490	263	{
aded7165	264	struct vmbus_channel *channel;
dad76bf7	265	unsigned long flags;
f878f3d5 S	266	void *arg;
	267	bool read_state;
	268	u32 bytes_to_read;
3e7ee490	269
454f18a9 BP	270	/*
	271	* Find the channel based on this relid and invokes the
	272	* channel callback to process the event
	273	*/
c6977677	274	channel = relid2channel(relid);
3e7ee490	275
24326039 S	276	if (!channel) {
	277	pr_err("channel not found for relid - %u\n", relid);
	278	return;
	279	}
	280
	281	/*
	282	* A channel once created is persistent even when there
	283	* is no driver handling the device. An unloading driver
	284	* sets the onchannel_callback to NULL under the
	285	* protection of the channel inbound_lock. Thus, checking
	286	* and invoking the driver specific callback takes care of
	287	* orderly unloading of the driver.
	288	*/
	289
dad76bf7	290	spin_lock_irqsave(&channel->inbound_lock, flags);
f878f3d5 S	291	if (channel->onchannel_callback != NULL) {
	292	arg = channel->channel_callback_context;
	293	read_state = channel->batched_reading;
	294	/*
	295	* This callback reads the messages sent by the host.
	296	* We can optimize host to guest signaling by ensuring:
	297	* 1. While reading the channel, we disable interrupts from
	298	* host.
	299	* 2. Ensure that we process all posted messages from the host
	300	* before returning from this callback.
	301	* 3. Once we return, enable signaling from the host. Once this
	302	* state is set we check to see if additional packets are
	303	* available to read. In this case we repeat the process.
	304	*/
	305
	306	do {
	307	hv_begin_read(&channel->inbound);
	308	channel->onchannel_callback(arg);
	309	bytes_to_read = hv_end_read(&channel->inbound);
	310	} while (read_state && (bytes_to_read != 0));
	311	} else {
24326039	312	pr_err("no channel callback for relid - %u\n", relid);
f878f3d5	313	}
d9add43b	314
dad76bf7	315	spin_unlock_irqrestore(&channel->inbound_lock, flags);
3e7ee490 HJ	316	}
3e7ee490 HJ	317
3e189519	318	/*
c6977677	319	* vmbus_on_event - Handler for events
fd8b85ea	320	*/
6de3d6aa	321	void vmbus_on_event(unsigned long data)
3e7ee490	322	{
35436487	323	u32 dword;
6552ecd7	324	u32 maxdword;
3e7ee490	325	int bit;
35436487	326	u32 relid;
6552ecd7 S	327	u32 *recv_int_page = NULL;
	328	void *page_addr;
	329	int cpu = smp_processor_id();
	330	union hv_synic_event_flags *event;
	331
	332	if ((vmbus_proto_version == VERSION_WS2008) \|\|
	333	(vmbus_proto_version == VERSION_WIN7)) {
	334	maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
	335	recv_int_page = vmbus_connection.recv_int_page;
	336	} else {
	337	/*
	338	* When the host is win8 and beyond, the event page
	339	* can be directly checked to get the id of the channel
	340	* that has the interrupt pending.
	341	*/
	342	maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
	343	page_addr = hv_context.synic_event_page[cpu];
	344	event = (union hv_synic_event_flags *)page_addr +
	345	VMBUS_MESSAGE_SINT;
	346	recv_int_page = event->flags32;
	347	}
	348
	349
3e7ee490	350
454f18a9	351	/* Check events */
242b45aa OH	352	if (!recv_int_page)
	353	return;
	354	for (dword = 0; dword < maxdword; dword++) {
	355	if (!recv_int_page[dword])
	356	continue;
	357	for (bit = 0; bit < 32; bit++) {
d9add43b S	358	if (sync_test_and_clear_bit(bit,
d9add43b S	359	(unsigned long *)&recv_int_page[dword])) {
242b45aa OH	360	relid = (dword << 5) + bit;
242b45aa OH	361
d9add43b	362	if (relid == 0)
6d81d330 S	363	/*
	364	* Special case - vmbus
	365	* channel protocol msg
	366	*/
242b45aa	367	continue;
d9add43b	368
35436487	369	process_chn_event(relid);
3e7ee490	370	}
242b45aa	371	}
3e7ee490	372	}
3e7ee490 HJ	373	}
3e7ee490 HJ	374
3e189519	375	/*
c6977677	376	* vmbus_post_msg - Send a msg on the vmbus's message connection
fd8b85ea	377	*/
c6977677	378	int vmbus_post_msg(void *buffer, size_t buflen)
3e7ee490	379	{
15b2f647	380	union hv_connection_id conn_id;
5289d3d1 S	381	int ret = 0;
5289d3d1 S	382	int retries = 0;
3e7ee490	383
15b2f647 HZ	384	conn_id.asu32 = 0;
15b2f647 HZ	385	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
5289d3d1 S	386
	387	/*
	388	* hv_post_message() can have transient failures because of
	389	* insufficient resources. Retry the operation a couple of
	390	* times before giving up.
	391	*/
	392	while (retries < 3) {
	393	ret = hv_post_message(conn_id, 1, buffer, buflen);
	394	if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
	395	return ret;
	396	retries++;
	397	msleep(100);
	398	}
	399	return ret;
3e7ee490 HJ	400	}
3e7ee490 HJ	401
3e189519	402	/*
c6977677	403	* vmbus_set_event - Send an event notification to the parent
fd8b85ea	404	*/
21c3bef5	405	int vmbus_set_event(struct vmbus_channel *channel)
3e7ee490	406	{
21c3bef5	407	u32 child_relid = channel->offermsg.child_relid;
7c369f40	408
3be77774 S	409	if (!channel->is_dedicated_interrupt) {
	410	/* Each u32 represents 32 channels */
	411	sync_set_bit(child_relid & 31,
	412	(unsigned long *)vmbus_connection.send_int_page +
	413	(child_relid >> 5));
	414	}
	415
	416	return hv_signal_event(channel->sig_event);
3e7ee490	417	}