[linux-2.6-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),
};

/*
 * VMBUS version is 32 bit entity broken up into
 * two 16 bit quantities: major_number. minor_number.
 *
 * 0 . 13 (Windows Server 2008)
 * 1 . 1  (Windows 7)
 * 2 . 4  (Windows 8)
 */

#define VERSION_WS2008	((0 << 16) | (13))
#define VERSION_WIN7	((1 << 16) | (1))
#define VERSION_WIN8	((2 << 16) | (4))

#define VERSION_INVAL -1

/*
 * 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_WS2008;

	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 = MAX_NUM_CHANNELS_SUPPORTED >> 5;
	int bit;
	u32 relid;
	u32 *recv_int_page = vmbus_connection.recv_int_page;

	/* 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(u32 child_relid)
{
	/* 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(hv_context.signal_event_param);
}
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
610071c3 S	43	/*
	44	* VMBUS version is 32 bit entity broken up into
	45	* two 16 bit quantities: major_number. minor_number.
	46	*
	47	* 0 . 13 (Windows Server 2008)
	48	* 1 . 1 (Windows 7)
	49	* 2 . 4 (Windows 8)
	50	*/
	51
	52	#define VERSION_WS2008 ((0 << 16) \| (13))
	53	#define VERSION_WIN7 ((1 << 16) \| (1))
	54	#define VERSION_WIN8 ((2 << 16) \| (4))
	55
	56	#define VERSION_INVAL -1
	57
37f7278b S	58	/*
	59	* Negotiated protocol version with the host.
	60	*/
	61	__u32 vmbus_proto_version;
	62	EXPORT_SYMBOL_GPL(vmbus_proto_version);
	63
610071c3 S	64	static __u32 vmbus_get_next_version(__u32 current_version)
	65	{
	66	switch (current_version) {
	67	case (VERSION_WIN7):
	68	return VERSION_WS2008;
	69
	70	case (VERSION_WIN8):
	71	return VERSION_WIN7;
	72
	73	case (VERSION_WS2008):
	74	default:
	75	return VERSION_INVAL;
	76	}
	77	}
	78
	79	static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
	80	__u32 version)
	81	{
	82	int ret = 0;
	83	struct vmbus_channel_initiate_contact *msg;
	84	unsigned long flags;
	85	int t;
	86
	87	init_completion(&msginfo->waitevent);
	88
	89	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
	90
	91	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
	92	msg->vmbus_version_requested = version;
	93	msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
	94	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages);
	95	msg->monitor_page2 = virt_to_phys(
	96	(void *)((unsigned long)vmbus_connection.monitor_pages +
	97	PAGE_SIZE));
	98
	99	/*
	100	* Add to list before we send the request since we may
	101	* receive the response before returning from this routine
	102	*/
	103	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	104	list_add_tail(&msginfo->msglistentry,
	105	&vmbus_connection.chn_msg_list);
	106
	107	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	108
	109	ret = vmbus_post_msg(msg,
	110	sizeof(struct vmbus_channel_initiate_contact));
	111	if (ret != 0) {
	112	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	113	list_del(&msginfo->msglistentry);
	114	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
	115	flags);
	116	return ret;
	117	}
	118
	119	/* Wait for the connection response */
	120	t = wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
	121	if (t == 0) {
	122	spin_lock_irqsave(&vmbus_connection.channelmsg_lock,
	123	flags);
	124	list_del(&msginfo->msglistentry);
	125	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
	126	flags);
	127	return -ETIMEDOUT;
128	}
129
130	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
131	list_del(&msginfo->msglistentry);
132	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
133
134	/* Check if successful */
135	if (msginfo->response.version_response.version_supported) {
136	vmbus_connection.conn_state = CONNECTED;
137	} else {
138	pr_err("Unable to connect, "
139	"Version %d not supported by Hyper-V\n",
140	version);
141	return -ECONNREFUSED;
142	}
143
144	return ret;
145	}
146
3e189519	147	/*
c6977677	148	* vmbus_connect - Sends a connect request on the partition service connection
fd8b85ea	149	*/
c6977677	150	int vmbus_connect(void)
3e7ee490	151	{
fd8b85ea	152	int ret = 0;
15b2f647	153	struct vmbus_channel_msginfo *msginfo = NULL;
610071c3	154	__u32 version;
3e7ee490	155
454f18a9	156	/* Initialize the vmbus connection */
da9fcb72 HZ	157	vmbus_connection.conn_state = CONNECTING;
	158	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
	159	if (!vmbus_connection.work_queue) {
3a7546d9	160	ret = -ENOMEM;
b0043863	161	goto cleanup;
de65a384	162	}
3e7ee490	163
da9fcb72	164	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
15b2f647	165	spin_lock_init(&vmbus_connection.channelmsg_lock);
3e7ee490	166
da9fcb72	167	INIT_LIST_HEAD(&vmbus_connection.chn_list);
15b2f647	168	spin_lock_init(&vmbus_connection.channel_lock);
3e7ee490	169
454f18a9 BP	170	/*
	171	* Setup the vmbus event connection for channel interrupt
	172	* abstraction stuff
	173	*/
df3493e0 S	174	vmbus_connection.int_page =
df3493e0 S	175	(void *)__get_free_pages(GFP_KERNEL\|__GFP_ZERO, 0);
da9fcb72	176	if (vmbus_connection.int_page == NULL) {
3a7546d9	177	ret = -ENOMEM;
b0043863	178	goto cleanup;
3e7ee490 HJ	179	}
3e7ee490 HJ	180
da9fcb72 HZ	181	vmbus_connection.recv_int_page = vmbus_connection.int_page;
	182	vmbus_connection.send_int_page =
	183	(void *)((unsigned long)vmbus_connection.int_page +
fd8b85ea	184	(PAGE_SIZE >> 1));
3e7ee490	185
fd8b85ea GKH	186	/*
	187	* Setup the monitor notification facility. The 1st page for
	188	* parent->child and the 2nd page for child->parent
454f18a9	189	*/
df3493e0 S	190	vmbus_connection.monitor_pages =
df3493e0 S	191	(void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 1);
da9fcb72	192	if (vmbus_connection.monitor_pages == NULL) {
3a7546d9	193	ret = -ENOMEM;
b0043863	194	goto cleanup;
3e7ee490 HJ	195	}
3e7ee490 HJ	196
15b2f647	197	msginfo = kzalloc(sizeof(*msginfo) +
fd8b85ea GKH	198	sizeof(struct vmbus_channel_initiate_contact),
fd8b85ea GKH	199	GFP_KERNEL);
15b2f647	200	if (msginfo == NULL) {
8cad0af9	201	ret = -ENOMEM;
b0043863	202	goto cleanup;
3e7ee490 HJ	203	}
3e7ee490 HJ	204
454f18a9	205	/*
610071c3 S	206	* Negotiate a compatible VMBUS version number with the
	207	* host. We start with the highest number we can support
	208	* and work our way down until we negotiate a compatible
	209	* version.
454f18a9	210	*/
3e7ee490	211
610071c3	212	version = VERSION_WS2008;
3e7ee490	213
610071c3 S	214	do {
	215	ret = vmbus_negotiate_version(msginfo, version);
	216	if (ret == 0)
	217	break;
3e7ee490	218
610071c3 S	219	version = vmbus_get_next_version(version);
610071c3 S	220	} while (version != VERSION_INVAL);
3e7ee490	221
610071c3	222	if (version == VERSION_INVAL)
b0043863	223	goto cleanup;
3e7ee490	224
37f7278b S	225	vmbus_proto_version = version;
37f7278b S	226	pr_info("Negotiated host information %d\n", version);
15b2f647	227	kfree(msginfo);
3e7ee490 HJ	228	return 0;
3e7ee490 HJ	229
b0043863	230	cleanup:
da9fcb72	231	vmbus_connection.conn_state = DISCONNECTED;
3e7ee490	232
da9fcb72 HZ	233	if (vmbus_connection.work_queue)
da9fcb72 HZ	234	destroy_workqueue(vmbus_connection.work_queue);
3e7ee490	235
da9fcb72	236	if (vmbus_connection.int_page) {
df3493e0	237	free_pages((unsigned long)vmbus_connection.int_page, 0);
da9fcb72	238	vmbus_connection.int_page = NULL;
3e7ee490 HJ	239	}
3e7ee490 HJ	240
da9fcb72	241	if (vmbus_connection.monitor_pages) {
df3493e0	242	free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
da9fcb72	243	vmbus_connection.monitor_pages = NULL;
3e7ee490 HJ	244	}
3e7ee490 HJ	245
dd9b15dc	246	kfree(msginfo);
3e7ee490	247
3e7ee490 HJ	248	return ret;
	249	}
	250
3e7ee490	251
3e189519	252	/*
c6977677 HZ	253	* relid2channel - Get the channel object given its
c6977677 HZ	254	* child relative id (ie channel id)
fd8b85ea	255	*/
c6977677	256	struct vmbus_channel *relid2channel(u32 relid)
3e7ee490	257	{
aded7165	258	struct vmbus_channel *channel;
15b2f647	259	struct vmbus_channel *found_channel = NULL;
0f5e44ca	260	unsigned long flags;
3e7ee490	261
15b2f647	262	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
da9fcb72	263	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
15b2f647 HZ	264	if (channel->offermsg.child_relid == relid) {
15b2f647 HZ	265	found_channel = channel;
3e7ee490 HJ	266	break;
	267	}
	268	}
15b2f647	269	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
3e7ee490	270
15b2f647	271	return found_channel;
3e7ee490 HJ	272	}
3e7ee490 HJ	273
3e189519	274	/*
c6977677	275	* process_chn_event - Process a channel event notification
fd8b85ea	276	*/
35436487	277	static void process_chn_event(u32 relid)
3e7ee490	278	{
aded7165	279	struct vmbus_channel *channel;
dad76bf7	280	unsigned long flags;
f878f3d5 S	281	void *arg;
	282	bool read_state;
	283	u32 bytes_to_read;
3e7ee490	284
454f18a9 BP	285	/*
	286	* Find the channel based on this relid and invokes the
	287	* channel callback to process the event
	288	*/
c6977677	289	channel = relid2channel(relid);
3e7ee490	290
24326039 S	291	if (!channel) {
	292	pr_err("channel not found for relid - %u\n", relid);
	293	return;
	294	}
	295
	296	/*
	297	* A channel once created is persistent even when there
	298	* is no driver handling the device. An unloading driver
	299	* sets the onchannel_callback to NULL under the
	300	* protection of the channel inbound_lock. Thus, checking
	301	* and invoking the driver specific callback takes care of
	302	* orderly unloading of the driver.
	303	*/
	304
dad76bf7	305	spin_lock_irqsave(&channel->inbound_lock, flags);
f878f3d5 S	306	if (channel->onchannel_callback != NULL) {
	307	arg = channel->channel_callback_context;
	308	read_state = channel->batched_reading;
	309	/*
	310	* This callback reads the messages sent by the host.
	311	* We can optimize host to guest signaling by ensuring:
	312	* 1. While reading the channel, we disable interrupts from
	313	* host.
	314	* 2. Ensure that we process all posted messages from the host
	315	* before returning from this callback.
	316	* 3. Once we return, enable signaling from the host. Once this
	317	* state is set we check to see if additional packets are
	318	* available to read. In this case we repeat the process.
	319	*/
	320
	321	do {
	322	hv_begin_read(&channel->inbound);
	323	channel->onchannel_callback(arg);
	324	bytes_to_read = hv_end_read(&channel->inbound);
	325	} while (read_state && (bytes_to_read != 0));
	326	} else {
24326039	327	pr_err("no channel callback for relid - %u\n", relid);
f878f3d5	328	}
d9add43b	329
dad76bf7	330	spin_unlock_irqrestore(&channel->inbound_lock, flags);
3e7ee490 HJ	331	}
3e7ee490 HJ	332
3e189519	333	/*
c6977677	334	* vmbus_on_event - Handler for events
fd8b85ea	335	*/
6de3d6aa	336	void vmbus_on_event(unsigned long data)
3e7ee490	337	{
35436487 OH	338	u32 dword;
35436487 OH	339	u32 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
3e7ee490	340	int bit;
35436487	341	u32 relid;
da9fcb72	342	u32 *recv_int_page = vmbus_connection.recv_int_page;
3e7ee490	343
454f18a9	344	/* Check events */
242b45aa OH	345	if (!recv_int_page)
	346	return;
	347	for (dword = 0; dword < maxdword; dword++) {
	348	if (!recv_int_page[dword])
	349	continue;
	350	for (bit = 0; bit < 32; bit++) {
d9add43b S	351	if (sync_test_and_clear_bit(bit,
d9add43b S	352	(unsigned long *)&recv_int_page[dword])) {
242b45aa OH	353	relid = (dword << 5) + bit;
242b45aa OH	354
d9add43b	355	if (relid == 0)
6d81d330 S	356	/*
	357	* Special case - vmbus
	358	* channel protocol msg
	359	*/
242b45aa	360	continue;
d9add43b	361
35436487	362	process_chn_event(relid);
3e7ee490	363	}
242b45aa	364	}
3e7ee490	365	}
3e7ee490 HJ	366	}
3e7ee490 HJ	367
3e189519	368	/*
c6977677	369	* vmbus_post_msg - Send a msg on the vmbus's message connection
fd8b85ea	370	*/
c6977677	371	int vmbus_post_msg(void *buffer, size_t buflen)
3e7ee490	372	{
15b2f647	373	union hv_connection_id conn_id;
5289d3d1 S	374	int ret = 0;
5289d3d1 S	375	int retries = 0;
3e7ee490	376
15b2f647 HZ	377	conn_id.asu32 = 0;
15b2f647 HZ	378	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
5289d3d1 S	379
	380	/*
	381	* hv_post_message() can have transient failures because of
	382	* insufficient resources. Retry the operation a couple of
	383	* times before giving up.
	384	*/
	385	while (retries < 3) {
	386	ret = hv_post_message(conn_id, 1, buffer, buflen);
	387	if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
	388	return ret;
	389	retries++;
	390	msleep(100);
	391	}
	392	return ret;
3e7ee490 HJ	393	}
3e7ee490 HJ	394
3e189519	395	/*
c6977677	396	* vmbus_set_event - Send an event notification to the parent
fd8b85ea	397	*/
c6977677	398	int vmbus_set_event(u32 child_relid)
3e7ee490	399	{
454f18a9	400	/* Each u32 represents 32 channels */
22356585	401	sync_set_bit(child_relid & 31,
da9fcb72	402	(unsigned long *)vmbus_connection.send_int_page +
15b2f647	403	(child_relid >> 5));
7c369f40	404
1f42248d	405	return hv_signal_event(hv_context.signal_event_param);
3e7ee490	406	}