connection.c revision 37f7278b81a9ab9b76cf4d716ba420444ca4a616 
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 * 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
58/*
59 * Negotiated protocol version with the host.
60 */
61__u32 vmbus_proto_version;
62EXPORT_SYMBOL_GPL(vmbus_proto_version);
63
64static __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
79static 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
147/*
148 * vmbus_connect - Sends a connect request on the partition service connection
149 */
150int vmbus_connect(void)
151{
152	int ret = 0;
153	struct vmbus_channel_msginfo *msginfo = NULL;
154	__u32 version;
155
156	/* Initialize the vmbus connection */
157	vmbus_connection.conn_state = CONNECTING;
158	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
159	if (!vmbus_connection.work_queue) {
160		ret = -ENOMEM;
161		goto cleanup;
162	}
163
164	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
165	spin_lock_init(&vmbus_connection.channelmsg_lock);
166
167	INIT_LIST_HEAD(&vmbus_connection.chn_list);
168	spin_lock_init(&vmbus_connection.channel_lock);
169
170	/*
171	 * Setup the vmbus event connection for channel interrupt
172	 * abstraction stuff
173	 */
174	vmbus_connection.int_page =
175	(void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
176	if (vmbus_connection.int_page == NULL) {
177		ret = -ENOMEM;
178		goto cleanup;
179	}
180
181	vmbus_connection.recv_int_page = vmbus_connection.int_page;
182	vmbus_connection.send_int_page =
183		(void *)((unsigned long)vmbus_connection.int_page +
184			(PAGE_SIZE >> 1));
185
186	/*
187	 * Setup the monitor notification facility. The 1st page for
188	 * parent->child and the 2nd page for child->parent
189	 */
190	vmbus_connection.monitor_pages =
191	(void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 1);
192	if (vmbus_connection.monitor_pages == NULL) {
193		ret = -ENOMEM;
194		goto cleanup;
195	}
196
197	msginfo = kzalloc(sizeof(*msginfo) +
198			  sizeof(struct vmbus_channel_initiate_contact),
199			  GFP_KERNEL);
200	if (msginfo == NULL) {
201		ret = -ENOMEM;
202		goto cleanup;
203	}
204
205	/*
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.
210	 */
211
212	version = VERSION_WS2008;
213
214	do {
215		ret = vmbus_negotiate_version(msginfo, version);
216		if (ret == 0)
217			break;
218
219		version = vmbus_get_next_version(version);
220	} while (version != VERSION_INVAL);
221
222	if (version == VERSION_INVAL)
223		goto cleanup;
224
225	vmbus_proto_version = version;
226	pr_info("Negotiated host information %d\n", version);
227	kfree(msginfo);
228	return 0;
229
230cleanup:
231	vmbus_connection.conn_state = DISCONNECTED;
232
233	if (vmbus_connection.work_queue)
234		destroy_workqueue(vmbus_connection.work_queue);
235
236	if (vmbus_connection.int_page) {
237		free_pages((unsigned long)vmbus_connection.int_page, 0);
238		vmbus_connection.int_page = NULL;
239	}
240
241	if (vmbus_connection.monitor_pages) {
242		free_pages((unsigned long)vmbus_connection.monitor_pages, 1);
243		vmbus_connection.monitor_pages = NULL;
244	}
245
246	kfree(msginfo);
247
248	return ret;
249}
250
251
252/*
253 * relid2channel - Get the channel object given its
254 * child relative id (ie channel id)
255 */
256struct vmbus_channel *relid2channel(u32 relid)
257{
258	struct vmbus_channel *channel;
259	struct vmbus_channel *found_channel  = NULL;
260	unsigned long flags;
261
262	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
263	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
264		if (channel->offermsg.child_relid == relid) {
265			found_channel = channel;
266			break;
267		}
268	}
269	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
270
271	return found_channel;
272}
273
274/*
275 * process_chn_event - Process a channel event notification
276 */
277static void process_chn_event(u32 relid)
278{
279	struct vmbus_channel *channel;
280	unsigned long flags;
281	void *arg;
282	bool read_state;
283	u32 bytes_to_read;
284
285	/*
286	 * Find the channel based on this relid and invokes the
287	 * channel callback to process the event
288	 */
289	channel = relid2channel(relid);
290
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
305	spin_lock_irqsave(&channel->inbound_lock, flags);
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 {
327		pr_err("no channel callback for relid - %u\n", relid);
328	}
329
330	spin_unlock_irqrestore(&channel->inbound_lock, flags);
331}
332
333/*
334 * vmbus_on_event - Handler for events
335 */
336void vmbus_on_event(unsigned long data)
337{
338	u32 dword;
339	u32 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
340	int bit;
341	u32 relid;
342	u32 *recv_int_page = vmbus_connection.recv_int_page;
343
344	/* Check events */
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++) {
351			if (sync_test_and_clear_bit(bit,
352				(unsigned long *)&recv_int_page[dword])) {
353				relid = (dword << 5) + bit;
354
355				if (relid == 0)
356					/*
357					 * Special case - vmbus
358					 * channel protocol msg
359					 */
360					continue;
361
362				process_chn_event(relid);
363			}
364		}
365	}
366}
367
368/*
369 * vmbus_post_msg - Send a msg on the vmbus's message connection
370 */
371int vmbus_post_msg(void *buffer, size_t buflen)
372{
373	union hv_connection_id conn_id;
374	int ret = 0;
375	int retries = 0;
376
377	conn_id.asu32 = 0;
378	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
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;
393}
394
395/*
396 * vmbus_set_event - Send an event notification to the parent
397 */
398int vmbus_set_event(u32 child_relid)
399{
400	/* Each u32 represents 32 channels */
401	sync_set_bit(child_relid & 31,
402		(unsigned long *)vmbus_connection.send_int_page +
403		(child_relid >> 5));
404
405	return hv_signal_event();
406}
407