connection.c revision e68d2971d26577b932a16333ce165af98a96e068 
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 */
23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
24
25#include <linux/kernel.h>
26#include <linux/sched.h>
27#include <linux/wait.h>
28#include <linux/delay.h>
29#include <linux/mm.h>
30#include <linux/slab.h>
31#include <linux/vmalloc.h>
32#include <linux/hyperv.h>
33#include <linux/export.h>
34#include <asm/hyperv.h>
35#include "hyperv_vmbus.h"
36
37
38struct vmbus_connection vmbus_connection = {
39	.conn_state		= DISCONNECTED,
40	.next_gpadl_handle	= ATOMIC_INIT(0xE1E10),
41};
42
43/*
44 * Negotiated protocol version with the host.
45 */
46__u32 vmbus_proto_version;
47EXPORT_SYMBOL_GPL(vmbus_proto_version);
48
49static __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
64static 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		return -ECONNREFUSED;
124	}
125
126	return ret;
127}
128
129/*
130 * vmbus_connect - Sends a connect request on the partition service connection
131 */
132int vmbus_connect(void)
133{
134	int ret = 0;
135	struct vmbus_channel_msginfo *msginfo = NULL;
136	__u32 version;
137
138	/* Initialize the vmbus connection */
139	vmbus_connection.conn_state = CONNECTING;
140	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
141	if (!vmbus_connection.work_queue) {
142		ret = -ENOMEM;
143		goto cleanup;
144	}
145
146	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
147	spin_lock_init(&vmbus_connection.channelmsg_lock);
148
149	INIT_LIST_HEAD(&vmbus_connection.chn_list);
150	spin_lock_init(&vmbus_connection.channel_lock);
151
152	/*
153	 * Setup the vmbus event connection for channel interrupt
154	 * abstraction stuff
155	 */
156	vmbus_connection.int_page =
157	(void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
158	if (vmbus_connection.int_page == NULL) {
159		ret = -ENOMEM;
160		goto cleanup;
161	}
162
163	vmbus_connection.recv_int_page = vmbus_connection.int_page;
164	vmbus_connection.send_int_page =
165		(void *)((unsigned long)vmbus_connection.int_page +
166			(PAGE_SIZE >> 1));
167
168	/*
169	 * Setup the monitor notification facility. The 1st page for
170	 * parent->child and the 2nd page for child->parent
171	 */
172	vmbus_connection.monitor_pages =
173	(void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 1);
174	if (vmbus_connection.monitor_pages == NULL) {
175		ret = -ENOMEM;
176		goto cleanup;
177	}
178
179	msginfo = kzalloc(sizeof(*msginfo) +
180			  sizeof(struct vmbus_channel_initiate_contact),
181			  GFP_KERNEL);
182	if (msginfo == NULL) {
183		ret = -ENOMEM;
184		goto cleanup;
185	}
186
187	/*
188	 * Negotiate a compatible VMBUS version number with the
189	 * host. We start with the highest number we can support
190	 * and work our way down until we negotiate a compatible
191	 * version.
192	 */
193
194	version = VERSION_CURRENT;
195
196	do {
197		ret = vmbus_negotiate_version(msginfo, version);
198		if (ret == 0)
199			break;
200
201		version = vmbus_get_next_version(version);
202	} while (version != VERSION_INVAL);
203
204	if (version == VERSION_INVAL)
205		goto cleanup;
206
207	vmbus_proto_version = version;
208	pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
209		    host_info_eax, host_info_ebx >> 16,
210		    host_info_ebx & 0xFFFF, host_info_ecx,
211		    host_info_edx >> 24, host_info_edx & 0xFFFFFF,
212		    version >> 16, version & 0xFFFF);
213
214	kfree(msginfo);
215	return 0;
216
217cleanup:
218	pr_err("Unable to connect to host\n");
219	vmbus_connection.conn_state = DISCONNECTED;
220
221	if (vmbus_connection.work_queue)
222		destroy_workqueue(vmbus_connection.work_queue);
223
224	if (vmbus_connection.int_page) {
225		free_pages((unsigned long)vmbus_connection.int_page, 0);
226		vmbus_connection.int_page = NULL;
227	}
228
229	if (vmbus_connection.monitor_pages) {
230		free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
231		vmbus_connection.monitor_pages = NULL;
232	}
233
234	kfree(msginfo);
235
236	return ret;
237}
238
239
240/*
241 * relid2channel - Get the channel object given its
242 * child relative id (ie channel id)
243 */
244struct vmbus_channel *relid2channel(u32 relid)
245{
246	struct vmbus_channel *channel;
247	struct vmbus_channel *found_channel  = NULL;
248	unsigned long flags;
249	struct list_head *cur, *tmp;
250	struct vmbus_channel *cur_sc;
251
252	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
253	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
254		if (channel->offermsg.child_relid == relid) {
255			found_channel = channel;
256			break;
257		} else if (!list_empty(&channel->sc_list)) {
258			/*
259			 * Deal with sub-channels.
260			 */
261			list_for_each_safe(cur, tmp, &channel->sc_list) {
262				cur_sc = list_entry(cur, struct vmbus_channel,
263							sc_list);
264				if (cur_sc->offermsg.child_relid == relid) {
265					found_channel = cur_sc;
266					break;
267				}
268			}
269		}
270	}
271	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
272
273	return found_channel;
274}
275
276/*
277 * process_chn_event - Process a channel event notification
278 */
279static void process_chn_event(u32 relid)
280{
281	struct vmbus_channel *channel;
282	unsigned long flags;
283	void *arg;
284	bool read_state;
285	u32 bytes_to_read;
286
287	/*
288	 * Find the channel based on this relid and invokes the
289	 * channel callback to process the event
290	 */
291	channel = relid2channel(relid);
292
293	if (!channel) {
294		pr_err("channel not found for relid - %u\n", relid);
295		return;
296	}
297
298	/*
299	 * A channel once created is persistent even when there
300	 * is no driver handling the device. An unloading driver
301	 * sets the onchannel_callback to NULL under the
302	 * protection of the channel inbound_lock. Thus, checking
303	 * and invoking the driver specific callback takes care of
304	 * orderly unloading of the driver.
305	 */
306
307	spin_lock_irqsave(&channel->inbound_lock, flags);
308	if (channel->onchannel_callback != NULL) {
309		arg = channel->channel_callback_context;
310		read_state = channel->batched_reading;
311		/*
312		 * This callback reads the messages sent by the host.
313		 * We can optimize host to guest signaling by ensuring:
314		 * 1. While reading the channel, we disable interrupts from
315		 *    host.
316		 * 2. Ensure that we process all posted messages from the host
317		 *    before returning from this callback.
318		 * 3. Once we return, enable signaling from the host. Once this
319		 *    state is set we check to see if additional packets are
320		 *    available to read. In this case we repeat the process.
321		 */
322
323		do {
324			hv_begin_read(&channel->inbound);
325			channel->onchannel_callback(arg);
326			bytes_to_read = hv_end_read(&channel->inbound);
327		} while (read_state && (bytes_to_read != 0));
328	} else {
329		pr_err("no channel callback for relid - %u\n", relid);
330	}
331
332	spin_unlock_irqrestore(&channel->inbound_lock, flags);
333}
334
335/*
336 * vmbus_on_event - Handler for events
337 */
338void vmbus_on_event(unsigned long data)
339{
340	u32 dword;
341	u32 maxdword;
342	int bit;
343	u32 relid;
344	u32 *recv_int_page = NULL;
345	void *page_addr;
346	int cpu = smp_processor_id();
347	union hv_synic_event_flags *event;
348
349	if ((vmbus_proto_version == VERSION_WS2008) ||
350		(vmbus_proto_version == VERSION_WIN7)) {
351		maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
352		recv_int_page = vmbus_connection.recv_int_page;
353	} else {
354		/*
355		 * When the host is win8 and beyond, the event page
356		 * can be directly checked to get the id of the channel
357		 * that has the interrupt pending.
358		 */
359		maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
360		page_addr = hv_context.synic_event_page[cpu];
361		event = (union hv_synic_event_flags *)page_addr +
362						 VMBUS_MESSAGE_SINT;
363		recv_int_page = event->flags32;
364	}
365
366
367
368	/* Check events */
369	if (!recv_int_page)
370		return;
371	for (dword = 0; dword < maxdword; dword++) {
372		if (!recv_int_page[dword])
373			continue;
374		for (bit = 0; bit < 32; bit++) {
375			if (sync_test_and_clear_bit(bit,
376				(unsigned long *)&recv_int_page[dword])) {
377				relid = (dword << 5) + bit;
378
379				if (relid == 0)
380					/*
381					 * Special case - vmbus
382					 * channel protocol msg
383					 */
384					continue;
385
386				process_chn_event(relid);
387			}
388		}
389	}
390}
391
392/*
393 * vmbus_post_msg - Send a msg on the vmbus's message connection
394 */
395int vmbus_post_msg(void *buffer, size_t buflen)
396{
397	union hv_connection_id conn_id;
398	int ret = 0;
399	int retries = 0;
400
401	conn_id.asu32 = 0;
402	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
403
404	/*
405	 * hv_post_message() can have transient failures because of
406	 * insufficient resources. Retry the operation a couple of
407	 * times before giving up.
408	 */
409	while (retries < 3) {
410		ret =  hv_post_message(conn_id, 1, buffer, buflen);
411		if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
412			return ret;
413		retries++;
414		msleep(100);
415	}
416	return ret;
417}
418
419/*
420 * vmbus_set_event - Send an event notification to the parent
421 */
422int vmbus_set_event(struct vmbus_channel *channel)
423{
424	u32 child_relid = channel->offermsg.child_relid;
425
426	if (!channel->is_dedicated_interrupt) {
427		/* Each u32 represents 32 channels */
428		sync_set_bit(child_relid & 31,
429			(unsigned long *)vmbus_connection.send_int_page +
430			(child_relid >> 5));
431	}
432
433	return hv_signal_event(channel->sig_event);
434}
435