[mirror_ubuntu-jammy-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),
};

/*
 * 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;

	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]);
	if (version == VERSION_WIN8)
		msg->target_vcpu = hv_context.vp_index[smp_processor_id()];

	/*
	 * 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 */
	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);
	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[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;

	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;
	}

	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 1);
	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 1);
	vmbus_connection.monitor_pages[0] = NULL;
	vmbus_connection.monitor_pages[1] = 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;
	struct list_head *cur, *tmp;
	struct vmbus_channel *cur_sc;

	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;
		} 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;
				}
			}
		}
	}
	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;
610071c3 S	70
	71	init_completion(&msginfo->waitevent);
	72
	73	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
	74
	75	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
	76	msg->vmbus_version_requested = version;
	77	msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
8681db44 GKH	78	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
8681db44 GKH	79	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
e28bab48 S	80	if (version == VERSION_WIN8)
e28bab48 S	81	msg->target_vcpu = hv_context.vp_index[smp_processor_id()];
610071c3 S	82
	83	/*
	84	* Add to list before we send the request since we may
	85	* receive the response before returning from this routine
	86	*/
	87	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	88	list_add_tail(&msginfo->msglistentry,
	89	&vmbus_connection.chn_msg_list);
	90
	91	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	92
	93	ret = vmbus_post_msg(msg,
	94	sizeof(struct vmbus_channel_initiate_contact));
	95	if (ret != 0) {
	96	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	97	list_del(&msginfo->msglistentry);
	98	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
	99	flags);
	100	return ret;
	101	}
	102
	103	/* Wait for the connection response */
269f9794	104	wait_for_completion(&msginfo->waitevent);
610071c3 S	105
	106	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
	107	list_del(&msginfo->msglistentry);
	108	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
	109
	110	/* Check if successful */
	111	if (msginfo->response.version_response.version_supported) {
	112	vmbus_connection.conn_state = CONNECTED;
	113	} else {
610071c3 S	114	return -ECONNREFUSED;
	115	}
	116
	117	return ret;
	118	}
	119
3e189519	120	/*
c6977677	121	* vmbus_connect - Sends a connect request on the partition service connection
fd8b85ea	122	*/
c6977677	123	int vmbus_connect(void)
3e7ee490	124	{
fd8b85ea	125	int ret = 0;
15b2f647	126	struct vmbus_channel_msginfo *msginfo = NULL;
610071c3	127	__u32 version;
3e7ee490	128
454f18a9	129	/* Initialize the vmbus connection */
da9fcb72 HZ	130	vmbus_connection.conn_state = CONNECTING;
	131	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
	132	if (!vmbus_connection.work_queue) {
3a7546d9	133	ret = -ENOMEM;
b0043863	134	goto cleanup;
de65a384	135	}
3e7ee490	136
da9fcb72	137	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
15b2f647	138	spin_lock_init(&vmbus_connection.channelmsg_lock);
3e7ee490	139
da9fcb72	140	INIT_LIST_HEAD(&vmbus_connection.chn_list);
15b2f647	141	spin_lock_init(&vmbus_connection.channel_lock);
3e7ee490	142
454f18a9 BP	143	/*
	144	* Setup the vmbus event connection for channel interrupt
	145	* abstraction stuff
	146	*/
df3493e0 S	147	vmbus_connection.int_page =
df3493e0 S	148	(void *)__get_free_pages(GFP_KERNEL\|__GFP_ZERO, 0);
da9fcb72	149	if (vmbus_connection.int_page == NULL) {
3a7546d9	150	ret = -ENOMEM;
b0043863	151	goto cleanup;
3e7ee490 HJ	152	}
3e7ee490 HJ	153
da9fcb72 HZ	154	vmbus_connection.recv_int_page = vmbus_connection.int_page;
	155	vmbus_connection.send_int_page =
	156	(void *)((unsigned long)vmbus_connection.int_page +
fd8b85ea	157	(PAGE_SIZE >> 1));
3e7ee490	158
fd8b85ea GKH	159	/*
	160	* Setup the monitor notification facility. The 1st page for
	161	* parent->child and the 2nd page for child->parent
454f18a9	162	*/
8681db44 GKH	163	vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	164	vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL\|__GFP_ZERO), 0);
	165	if ((vmbus_connection.monitor_pages[0] == NULL) \|\|
	166	(vmbus_connection.monitor_pages[1] == NULL)) {
3a7546d9	167	ret = -ENOMEM;
b0043863	168	goto cleanup;
3e7ee490 HJ	169	}
3e7ee490 HJ	170
15b2f647	171	msginfo = kzalloc(sizeof(*msginfo) +
fd8b85ea GKH	172	sizeof(struct vmbus_channel_initiate_contact),
fd8b85ea GKH	173	GFP_KERNEL);
15b2f647	174	if (msginfo == NULL) {
8cad0af9	175	ret = -ENOMEM;
b0043863	176	goto cleanup;
3e7ee490 HJ	177	}
3e7ee490 HJ	178
454f18a9	179	/*
610071c3 S	180	* Negotiate a compatible VMBUS version number with the
	181	* host. We start with the highest number we can support
	182	* and work our way down until we negotiate a compatible
	183	* version.
454f18a9	184	*/
3e7ee490	185
2a5c43a8	186	version = VERSION_CURRENT;
3e7ee490	187
610071c3 S	188	do {
610071c3 S	189	ret = vmbus_negotiate_version(msginfo, version);
8bbf9f44	190	if (ret == -ETIMEDOUT)
666b9adc S	191	goto cleanup;
	192
	193	if (vmbus_connection.conn_state == CONNECTED)
610071c3	194	break;
3e7ee490	195
610071c3 S	196	version = vmbus_get_next_version(version);
610071c3 S	197	} while (version != VERSION_INVAL);
3e7ee490	198
610071c3	199	if (version == VERSION_INVAL)
b0043863	200	goto cleanup;
3e7ee490	201
37f7278b	202	vmbus_proto_version = version;
3bacaf0c S	203	pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
	204	host_info_eax, host_info_ebx >> 16,
	205	host_info_ebx & 0xFFFF, host_info_ecx,
	206	host_info_edx >> 24, host_info_edx & 0xFFFFFF,
	207	version >> 16, version & 0xFFFF);
	208
15b2f647	209	kfree(msginfo);
3e7ee490 HJ	210	return 0;
3e7ee490 HJ	211
b0043863	212	cleanup:
3bacaf0c	213	pr_err("Unable to connect to host\n");
da9fcb72	214	vmbus_connection.conn_state = DISCONNECTED;
3e7ee490	215
da9fcb72 HZ	216	if (vmbus_connection.work_queue)
da9fcb72 HZ	217	destroy_workqueue(vmbus_connection.work_queue);
3e7ee490	218
da9fcb72	219	if (vmbus_connection.int_page) {
df3493e0	220	free_pages((unsigned long)vmbus_connection.int_page, 0);
da9fcb72	221	vmbus_connection.int_page = NULL;
3e7ee490 HJ	222	}
3e7ee490 HJ	223
8681db44 GKH	224	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 1);
	225	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 1);
	226	vmbus_connection.monitor_pages[0] = NULL;
	227	vmbus_connection.monitor_pages[1] = NULL;
3e7ee490	228
dd9b15dc	229	kfree(msginfo);
3e7ee490	230
3e7ee490 HJ	231	return ret;
	232	}
	233
3e7ee490	234
3e189519	235	/*
c6977677 HZ	236	* relid2channel - Get the channel object given its
c6977677 HZ	237	* child relative id (ie channel id)
fd8b85ea	238	*/
c6977677	239	struct vmbus_channel *relid2channel(u32 relid)
3e7ee490	240	{
aded7165	241	struct vmbus_channel *channel;
15b2f647	242	struct vmbus_channel *found_channel = NULL;
0f5e44ca	243	unsigned long flags;
e68d2971 S	244	struct list_head cur, tmp;
e68d2971 S	245	struct vmbus_channel *cur_sc;
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	251	break;
e68d2971 S	252	} else if (!list_empty(&channel->sc_list)) {
	253	/*
	254	* Deal with sub-channels.
	255	*/
	256	list_for_each_safe(cur, tmp, &channel->sc_list) {
	257	cur_sc = list_entry(cur, struct vmbus_channel,
	258	sc_list);
	259	if (cur_sc->offermsg.child_relid == relid) {
	260	found_channel = cur_sc;
	261	break;
	262	}
	263	}
3e7ee490 HJ	264	}
3e7ee490 HJ	265	}
15b2f647	266	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
3e7ee490	267
15b2f647	268	return found_channel;
3e7ee490 HJ	269	}
3e7ee490 HJ	270
3e189519	271	/*
c6977677	272	* process_chn_event - Process a channel event notification
fd8b85ea	273	*/
35436487	274	static void process_chn_event(u32 relid)
3e7ee490	275	{
aded7165	276	struct vmbus_channel *channel;
dad76bf7	277	unsigned long flags;
f878f3d5 S	278	void *arg;
	279	bool read_state;
	280	u32 bytes_to_read;
3e7ee490	281
454f18a9 BP	282	/*
	283	* Find the channel based on this relid and invokes the
	284	* channel callback to process the event
	285	*/
c6977677	286	channel = relid2channel(relid);
3e7ee490	287
24326039 S	288	if (!channel) {
	289	pr_err("channel not found for relid - %u\n", relid);
	290	return;
	291	}
	292
	293	/*
	294	* A channel once created is persistent even when there
	295	* is no driver handling the device. An unloading driver
	296	* sets the onchannel_callback to NULL under the
	297	* protection of the channel inbound_lock. Thus, checking
	298	* and invoking the driver specific callback takes care of
	299	* orderly unloading of the driver.
	300	*/
	301
dad76bf7	302	spin_lock_irqsave(&channel->inbound_lock, flags);
f878f3d5 S	303	if (channel->onchannel_callback != NULL) {
	304	arg = channel->channel_callback_context;
	305	read_state = channel->batched_reading;
	306	/*
	307	* This callback reads the messages sent by the host.
	308	* We can optimize host to guest signaling by ensuring:
	309	* 1. While reading the channel, we disable interrupts from
	310	* host.
	311	* 2. Ensure that we process all posted messages from the host
	312	* before returning from this callback.
	313	* 3. Once we return, enable signaling from the host. Once this
	314	* state is set we check to see if additional packets are
	315	* available to read. In this case we repeat the process.
	316	*/
	317
	318	do {
	319	hv_begin_read(&channel->inbound);
	320	channel->onchannel_callback(arg);
	321	bytes_to_read = hv_end_read(&channel->inbound);
	322	} while (read_state && (bytes_to_read != 0));
	323	} else {
24326039	324	pr_err("no channel callback for relid - %u\n", relid);
f878f3d5	325	}
d9add43b	326
dad76bf7	327	spin_unlock_irqrestore(&channel->inbound_lock, flags);
3e7ee490 HJ	328	}
3e7ee490 HJ	329
3e189519	330	/*
c6977677	331	* vmbus_on_event - Handler for events
fd8b85ea	332	*/
6de3d6aa	333	void vmbus_on_event(unsigned long data)
3e7ee490	334	{
35436487	335	u32 dword;
6552ecd7	336	u32 maxdword;
3e7ee490	337	int bit;
35436487	338	u32 relid;
6552ecd7 S	339	u32 *recv_int_page = NULL;
	340	void *page_addr;
	341	int cpu = smp_processor_id();
	342	union hv_synic_event_flags *event;
	343
	344	if ((vmbus_proto_version == VERSION_WS2008) \|\|
	345	(vmbus_proto_version == VERSION_WIN7)) {
	346	maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
	347	recv_int_page = vmbus_connection.recv_int_page;
	348	} else {
	349	/*
	350	* When the host is win8 and beyond, the event page
	351	* can be directly checked to get the id of the channel
	352	* that has the interrupt pending.
	353	*/
	354	maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
	355	page_addr = hv_context.synic_event_page[cpu];
	356	event = (union hv_synic_event_flags *)page_addr +
	357	VMBUS_MESSAGE_SINT;
	358	recv_int_page = event->flags32;
	359	}
	360
	361
3e7ee490	362
454f18a9	363	/* Check events */
242b45aa OH	364	if (!recv_int_page)
	365	return;
	366	for (dword = 0; dword < maxdword; dword++) {
	367	if (!recv_int_page[dword])
	368	continue;
	369	for (bit = 0; bit < 32; bit++) {
d9add43b S	370	if (sync_test_and_clear_bit(bit,
d9add43b S	371	(unsigned long *)&recv_int_page[dword])) {
242b45aa OH	372	relid = (dword << 5) + bit;
242b45aa OH	373
d9add43b	374	if (relid == 0)
6d81d330 S	375	/*
	376	* Special case - vmbus
	377	* channel protocol msg
	378	*/
242b45aa	379	continue;
d9add43b	380
35436487	381	process_chn_event(relid);
3e7ee490	382	}
242b45aa	383	}
3e7ee490	384	}
3e7ee490 HJ	385	}
3e7ee490 HJ	386
3e189519	387	/*
c6977677	388	* vmbus_post_msg - Send a msg on the vmbus's message connection
fd8b85ea	389	*/
c6977677	390	int vmbus_post_msg(void *buffer, size_t buflen)
3e7ee490	391	{
15b2f647	392	union hv_connection_id conn_id;
5289d3d1 S	393	int ret = 0;
5289d3d1 S	394	int retries = 0;
3e7ee490	395
15b2f647 HZ	396	conn_id.asu32 = 0;
15b2f647 HZ	397	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
5289d3d1 S	398
	399	/*
	400	* hv_post_message() can have transient failures because of
	401	* insufficient resources. Retry the operation a couple of
	402	* times before giving up.
	403	*/
	404	while (retries < 3) {
	405	ret = hv_post_message(conn_id, 1, buffer, buflen);
	406	if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
	407	return ret;
	408	retries++;
	409	msleep(100);
	410	}
	411	return ret;
3e7ee490 HJ	412	}
3e7ee490 HJ	413
3e189519	414	/*
c6977677	415	* vmbus_set_event - Send an event notification to the parent
fd8b85ea	416	*/
21c3bef5	417	int vmbus_set_event(struct vmbus_channel *channel)
3e7ee490	418	{
21c3bef5	419	u32 child_relid = channel->offermsg.child_relid;
7c369f40	420
3be77774 S	421	if (!channel->is_dedicated_interrupt) {
	422	/* Each u32 represents 32 channels */
	423	sync_set_bit(child_relid & 31,
	424	(unsigned long *)vmbus_connection.send_int_page +
	425	(child_relid >> 5));
	426	}
	427
	428	return hv_signal_event(channel->sig_event);
3e7ee490	429	}