[mirror_ubuntu-bionic-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[smp_processor_id()];
	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("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;

	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)
{
	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)
		vmbus_send_interrupt(child_relid);

	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	*/
37cdd991 SH	96	if (version >= VERSION_WIN8_1)
	97	msg->target_vcpu = hv_context.vp_index[smp_processor_id()];
	98	else
72686447	99	msg->target_vcpu = 0;
610071c3 S	100
	101	/*
	102	* Add to list before we send the request since we may
	103	* receive the response before returning from this routine
	104	*/
	105	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	106	list_add_tail(&msginfo->msglistentry,
	107	&vmbus_connection.chn_msg_list);
	108
	109	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	110
	111	ret = vmbus_post_msg(msg,
c0bb0392 VK	112	sizeof(struct vmbus_channel_initiate_contact),
c0bb0392 VK	113	true);
610071c3 S	114	if (ret != 0) {
	115	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	116	list_del(&msginfo->msglistentry);
	117	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
	118	flags);
	119	return ret;
	120	}
	121
	122	/* Wait for the connection response */
269f9794	123	wait_for_completion(&msginfo->waitevent);
610071c3 S	124
	125	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	126	list_del(&msginfo->msglistentry);
	127	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	128
	129	/* Check if successful */
	130	if (msginfo->response.version_response.version_supported) {
	131	vmbus_connection.conn_state = CONNECTED;
	132	} else {
610071c3 S	133	return -ECONNREFUSED;
	134	}
	135
	136	return ret;
	137	}
	138
3e189519	139	/*
c6977677	140	* vmbus_connect - Sends a connect request on the partition service connection
fd8b85ea	141	*/
c6977677	142	int vmbus_connect(void)
3e7ee490	143	{
fd8b85ea	144	int ret = 0;
15b2f647	145	struct vmbus_channel_msginfo *msginfo = NULL;
610071c3	146	__u32 version;
3e7ee490	147
454f18a9	148	/* Initialize the vmbus connection */
da9fcb72 HZ	149	vmbus_connection.conn_state = CONNECTING;
	150	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
	151	if (!vmbus_connection.work_queue) {
3a7546d9	152	ret = -ENOMEM;
b0043863	153	goto cleanup;
de65a384	154	}
3e7ee490	155
da9fcb72	156	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
15b2f647	157	spin_lock_init(&vmbus_connection.channelmsg_lock);
3e7ee490	158
da9fcb72	159	INIT_LIST_HEAD(&vmbus_connection.chn_list);
d6f591e3	160	mutex_init(&vmbus_connection.channel_mutex);
3e7ee490	161
454f18a9 BP	162	/*
	163	* Setup the vmbus event connection for channel interrupt
	164	* abstraction stuff
	165	*/
df3493e0 S	166	vmbus_connection.int_page =
df3493e0 S	167	(void *)__get_free_pages(GFP_KERNEL\|__GFP_ZERO, 0);
da9fcb72	168	if (vmbus_connection.int_page == NULL) {
3a7546d9	169	ret = -ENOMEM;
b0043863	170	goto cleanup;
3e7ee490 HJ	171	}
3e7ee490 HJ	172
da9fcb72 HZ	173	vmbus_connection.recv_int_page = vmbus_connection.int_page;
	174	vmbus_connection.send_int_page =
	175	(void *)((unsigned long)vmbus_connection.int_page +
fd8b85ea	176	(PAGE_SIZE >> 1));
3e7ee490	177
fd8b85ea GKH	178	/*
	179	* Setup the monitor notification facility. The 1st page for
	180	* parent->child and the 2nd page for child->parent
454f18a9	181	*/
8681db44 GKH	182	vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	183	vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	184	if ((vmbus_connection.monitor_pages[0] == NULL) \|\|
	185	(vmbus_connection.monitor_pages[1] == NULL)) {
3a7546d9	186	ret = -ENOMEM;
b0043863	187	goto cleanup;
3e7ee490 HJ	188	}
3e7ee490 HJ	189
15b2f647	190	msginfo = kzalloc(sizeof(*msginfo) +
fd8b85ea GKH	191	sizeof(struct vmbus_channel_initiate_contact),
fd8b85ea GKH	192	GFP_KERNEL);
15b2f647	193	if (msginfo == NULL) {
8cad0af9	194	ret = -ENOMEM;
b0043863	195	goto cleanup;
3e7ee490 HJ	196	}
3e7ee490 HJ	197
454f18a9	198	/*
610071c3 S	199	* Negotiate a compatible VMBUS version number with the
	200	* host. We start with the highest number we can support
	201	* and work our way down until we negotiate a compatible
	202	* version.
454f18a9	203	*/
3e7ee490	204
2a5c43a8	205	version = VERSION_CURRENT;
3e7ee490	206
610071c3 S	207	do {
610071c3 S	208	ret = vmbus_negotiate_version(msginfo, version);
8bbf9f44	209	if (ret == -ETIMEDOUT)
666b9adc S	210	goto cleanup;
	211
	212	if (vmbus_connection.conn_state == CONNECTED)
610071c3	213	break;
3e7ee490	214
610071c3 S	215	version = vmbus_get_next_version(version);
610071c3 S	216	} while (version != VERSION_INVAL);
3e7ee490	217
610071c3	218	if (version == VERSION_INVAL)
b0043863	219	goto cleanup;
3e7ee490	220
37f7278b	221	vmbus_proto_version = version;
8de8af7e S	222	pr_info("Vmbus version:%d.%d\n",
8de8af7e S	223	version >> 16, version & 0xFFFF);
3bacaf0c	224
15b2f647	225	kfree(msginfo);
3e7ee490 HJ	226	return 0;
3e7ee490 HJ	227
b0043863	228	cleanup:
3bacaf0c	229	pr_err("Unable to connect to host\n");
09a19628	230
da9fcb72	231	vmbus_connection.conn_state = DISCONNECTED;
09a19628 VK	232	vmbus_disconnect();
	233
	234	kfree(msginfo);
	235
	236	return ret;
	237	}
3e7ee490	238
09a19628 VK	239	void vmbus_disconnect(void)
09a19628 VK	240	{
2db84eff S	241	/*
	242	* First send the unload request to the host.
	243	*/
75ff3a8a	244	vmbus_initiate_unload(false);
2db84eff	245
09a19628 VK	246	if (vmbus_connection.work_queue) {
09a19628 VK	247	drain_workqueue(vmbus_connection.work_queue);
da9fcb72	248	destroy_workqueue(vmbus_connection.work_queue);
09a19628	249	}
3e7ee490	250
da9fcb72	251	if (vmbus_connection.int_page) {
df3493e0	252	free_pages((unsigned long)vmbus_connection.int_page, 0);
da9fcb72	253	vmbus_connection.int_page = NULL;
3e7ee490 HJ	254	}
3e7ee490 HJ	255
a100d88d RK	256	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
a100d88d RK	257	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
8681db44 GKH	258	vmbus_connection.monitor_pages[0] = NULL;
8681db44 GKH	259	vmbus_connection.monitor_pages[1] = NULL;
3e7ee490 HJ	260	}
3e7ee490 HJ	261
3e189519	262	/*
c6977677 HZ	263	* relid2channel - Get the channel object given its
c6977677 HZ	264	* child relative id (ie channel id)
fd8b85ea	265	*/
d43e2fe7	266	struct vmbus_channel *relid2channel(u32 relid)
3e7ee490	267	{
aded7165	268	struct vmbus_channel *channel;
15b2f647	269	struct vmbus_channel *found_channel = NULL;
e68d2971 S	270	struct list_head cur, tmp;
e68d2971 S	271	struct vmbus_channel *cur_sc;
3e7ee490	272
85d9aa70 DC	273	BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
85d9aa70 DC	274
da9fcb72	275	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
15b2f647 HZ	276	if (channel->offermsg.child_relid == relid) {
15b2f647 HZ	277	found_channel = channel;
3e7ee490	278	break;
e68d2971 S	279	} else if (!list_empty(&channel->sc_list)) {
	280	/*
	281	* Deal with sub-channels.
	282	*/
	283	list_for_each_safe(cur, tmp, &channel->sc_list) {
	284	cur_sc = list_entry(cur, struct vmbus_channel,
	285	sc_list);
	286	if (cur_sc->offermsg.child_relid == relid) {
	287	found_channel = cur_sc;
	288	break;
	289	}
	290	}
3e7ee490 HJ	291	}
3e7ee490 HJ	292	}
3e7ee490	293
15b2f647	294	return found_channel;
3e7ee490 HJ	295	}
3e7ee490 HJ	296
3e189519	297	/*
631e63a9	298	* vmbus_on_event - Process a channel event notification
ada6eb11 SH	299	*
	300	* For batched channels (default) optimize host to guest signaling
	301	* by ensuring:
	302	* 1. While reading the channel, we disable interrupts from host.
	303	* 2. Ensure that we process all posted messages from the host
	304	* before returning from this callback.
	305	* 3. Once we return, enable signaling from the host. Once this
	306	* state is set we check to see if additional packets are
	307	* available to read. In this case we repeat the process.
	308	* If this tasklet has been running for a long time
	309	* then reschedule ourselves.
fd8b85ea	310	*/
631e63a9	311	void vmbus_on_event(unsigned long data)
3e7ee490	312	{
631e63a9	313	struct vmbus_channel channel = (void ) data;
ada6eb11	314	unsigned long time_limit = jiffies + 2;
3e7ee490	315
ada6eb11 SH	316	do {
	317	void (callback_fn)(void );
	318
	319	/* A channel once created is persistent even when
	320	* there is no driver handling the device. An
	321	* unloading driver sets the onchannel_callback to NULL.
f878f3d5	322	*/
ada6eb11 SH	323	callback_fn = READ_ONCE(channel->onchannel_callback);
	324	if (unlikely(callback_fn == NULL))
	325	return;
f878f3d5	326
ada6eb11 SH	327	(*callback_fn)(channel->channel_callback_context);
	328
	329	if (channel->callback_mode != HV_CALL_BATCHED)
	330	return;
	331
	332	if (likely(hv_end_read(&channel->inbound) == 0))
	333	return;
	334
	335	hv_begin_read(&channel->inbound);
	336	} while (likely(time_before(jiffies, time_limit)));
	337
	338	/* The time limit (2 jiffies) has been reached */
	339	tasklet_schedule(&channel->callback_event);
3e7ee490 HJ	340	}
3e7ee490 HJ	341
3e189519	342	/*
c6977677	343	* vmbus_post_msg - Send a msg on the vmbus's message connection
fd8b85ea	344	*/
c0bb0392	345	int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
3e7ee490	346	{
15b2f647	347	union hv_connection_id conn_id;
5289d3d1 S	348	int ret = 0;
5289d3d1 S	349	int retries = 0;
8de0d7e9	350	u32 usec = 1;
3e7ee490	351
15b2f647 HZ	352	conn_id.asu32 = 0;
15b2f647 HZ	353	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
5289d3d1 S	354
	355	/*
	356	* hv_post_message() can have transient failures because of
	357	* insufficient resources. Retry the operation a couple of
	358	* times before giving up.
	359	*/
c0bb0392	360	while (retries < 100) {
fdeebcc6 S	361	ret = hv_post_message(conn_id, 1, buffer, buflen);
	362
	363	switch (ret) {
89f9f679 DC	364	case HV_STATUS_INVALID_CONNECTION_ID:
	365	/*
	366	* We could get this if we send messages too
	367	* frequently.
	368	*/
	369	ret = -EAGAIN;
	370	break;
	371	case HV_STATUS_INSUFFICIENT_MEMORY:
fdeebcc6 S	372	case HV_STATUS_INSUFFICIENT_BUFFERS:
fdeebcc6 S	373	ret = -ENOMEM;
fdeebcc6 S	374	break;
fdeebcc6 S	375	case HV_STATUS_SUCCESS:
5289d3d1	376	return ret;
fdeebcc6 S	377	default:
	378	pr_err("hv_post_msg() failed; error code:%d\n", ret);
	379	return -EINVAL;
	380	}
	381
5289d3d1	382	retries++;
c0bb0392 VK	383	if (can_sleep && usec > 1000)
	384	msleep(usec / 1000);
	385	else if (usec < MAX_UDELAY_MS * 1000)
	386	udelay(usec);
	387	else
	388	mdelay(usec / 1000);
	389
	390	if (usec < 256000)
8de0d7e9	391	usec *= 2;
5289d3d1 S	392	}
5289d3d1 S	393	return ret;
3e7ee490 HJ	394	}
3e7ee490 HJ	395
3e189519	396	/*
c6977677	397	* vmbus_set_event - Send an event notification to the parent
fd8b85ea	398	*/
1b807e10	399	void vmbus_set_event(struct vmbus_channel *channel)
3e7ee490	400	{
21c3bef5	401	u32 child_relid = channel->offermsg.child_relid;
7c369f40	402
5c1bec61 SH	403	if (!channel->is_dedicated_interrupt)
5c1bec61 SH	404	vmbus_send_interrupt(child_relid);
3be77774	405
1b807e10	406	hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
3e7ee490	407	}
5cc47247	408	EXPORT_SYMBOL_GPL(vmbus_set_event);