connection.c revision 03367ef5ea811475187a0732aada068919e14d61 
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_WIN8_1):
59		return VERSION_WIN8;
60
61	case (VERSION_WS2008):
62	default:
63		return VERSION_INVAL;
64	}
65}
66
67static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
68					__u32 version)
69{
70	int ret = 0;
71	struct vmbus_channel_initiate_contact *msg;
72	unsigned long flags;
73
74	init_completion(&msginfo->waitevent);
75
76	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
77
78	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
79	msg->vmbus_version_requested = version;
80	msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
81	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
82	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
83	if (version == VERSION_WIN8_1)
84		msg->target_vcpu = hv_context.vp_index[smp_processor_id()];
85
86	/*
87	 * Add to list before we send the request since we may
88	 * receive the response before returning from this routine
89	 */
90	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
91	list_add_tail(&msginfo->msglistentry,
92		      &vmbus_connection.chn_msg_list);
93
94	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
95
96	ret = vmbus_post_msg(msg,
97			       sizeof(struct vmbus_channel_initiate_contact));
98	if (ret != 0) {
99		spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
100		list_del(&msginfo->msglistentry);
101		spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
102					flags);
103		return ret;
104	}
105
106	/* Wait for the connection response */
107	wait_for_completion(&msginfo->waitevent);
108
109	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
110	list_del(&msginfo->msglistentry);
111	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
112
113	/* Check if successful */
114	if (msginfo->response.version_response.version_supported) {
115		vmbus_connection.conn_state = CONNECTED;
116	} else {
117		return -ECONNREFUSED;
118	}
119
120	return ret;
121}
122
123/*
124 * vmbus_connect - Sends a connect request on the partition service connection
125 */
126int vmbus_connect(void)
127{
128	int ret = 0;
129	struct vmbus_channel_msginfo *msginfo = NULL;
130	__u32 version;
131
132	/* Initialize the vmbus connection */
133	vmbus_connection.conn_state = CONNECTING;
134	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
135	if (!vmbus_connection.work_queue) {
136		ret = -ENOMEM;
137		goto cleanup;
138	}
139
140	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
141	spin_lock_init(&vmbus_connection.channelmsg_lock);
142
143	INIT_LIST_HEAD(&vmbus_connection.chn_list);
144	spin_lock_init(&vmbus_connection.channel_lock);
145
146	/*
147	 * Setup the vmbus event connection for channel interrupt
148	 * abstraction stuff
149	 */
150	vmbus_connection.int_page =
151	(void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
152	if (vmbus_connection.int_page == NULL) {
153		ret = -ENOMEM;
154		goto cleanup;
155	}
156
157	vmbus_connection.recv_int_page = vmbus_connection.int_page;
158	vmbus_connection.send_int_page =
159		(void *)((unsigned long)vmbus_connection.int_page +
160			(PAGE_SIZE >> 1));
161
162	/*
163	 * Setup the monitor notification facility. The 1st page for
164	 * parent->child and the 2nd page for child->parent
165	 */
166	vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
167	vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
168	if ((vmbus_connection.monitor_pages[0] == NULL) ||
169	    (vmbus_connection.monitor_pages[1] == NULL)) {
170		ret = -ENOMEM;
171		goto cleanup;
172	}
173
174	msginfo = kzalloc(sizeof(*msginfo) +
175			  sizeof(struct vmbus_channel_initiate_contact),
176			  GFP_KERNEL);
177	if (msginfo == NULL) {
178		ret = -ENOMEM;
179		goto cleanup;
180	}
181
182	/*
183	 * Negotiate a compatible VMBUS version number with the
184	 * host. We start with the highest number we can support
185	 * and work our way down until we negotiate a compatible
186	 * version.
187	 */
188
189	version = VERSION_CURRENT;
190
191	do {
192		ret = vmbus_negotiate_version(msginfo, version);
193		if (ret == -ETIMEDOUT)
194			goto cleanup;
195
196		if (vmbus_connection.conn_state == CONNECTED)
197			break;
198
199		version = vmbus_get_next_version(version);
200	} while (version != VERSION_INVAL);
201
202	if (version == VERSION_INVAL)
203		goto cleanup;
204
205	vmbus_proto_version = version;
206	pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
207		    host_info_eax, host_info_ebx >> 16,
208		    host_info_ebx & 0xFFFF, host_info_ecx,
209		    host_info_edx >> 24, host_info_edx & 0xFFFFFF,
210		    version >> 16, version & 0xFFFF);
211
212	kfree(msginfo);
213	return 0;
214
215cleanup:
216	pr_err("Unable to connect to host\n");
217	vmbus_connection.conn_state = DISCONNECTED;
218
219	if (vmbus_connection.work_queue)
220		destroy_workqueue(vmbus_connection.work_queue);
221
222	if (vmbus_connection.int_page) {
223		free_pages((unsigned long)vmbus_connection.int_page, 0);
224		vmbus_connection.int_page = NULL;
225	}
226
227	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 1);
228	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 1);
229	vmbus_connection.monitor_pages[0] = NULL;
230	vmbus_connection.monitor_pages[1] = NULL;
231
232	kfree(msginfo);
233
234	return ret;
235}
236
237
238/*
239 * relid2channel - Get the channel object given its
240 * child relative id (ie channel id)
241 */
242struct vmbus_channel *relid2channel(u32 relid)
243{
244	struct vmbus_channel *channel;
245	struct vmbus_channel *found_channel  = NULL;
246	unsigned long flags;
247	struct list_head *cur, *tmp;
248	struct vmbus_channel *cur_sc;
249
250	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
251	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
252		if (channel->offermsg.child_relid == relid) {
253			found_channel = channel;
254			break;
255		} else if (!list_empty(&channel->sc_list)) {
256			/*
257			 * Deal with sub-channels.
258			 */
259			list_for_each_safe(cur, tmp, &channel->sc_list) {
260				cur_sc = list_entry(cur, struct vmbus_channel,
261							sc_list);
262				if (cur_sc->offermsg.child_relid == relid) {
263					found_channel = cur_sc;
264					break;
265				}
266			}
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;
340	int bit;
341	u32 relid;
342	u32 *recv_int_page = NULL;
343	void *page_addr;
344	int cpu = smp_processor_id();
345	union hv_synic_event_flags *event;
346
347	if ((vmbus_proto_version == VERSION_WS2008) ||
348		(vmbus_proto_version == VERSION_WIN7)) {
349		maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
350		recv_int_page = vmbus_connection.recv_int_page;
351	} else {
352		/*
353		 * When the host is win8 and beyond, the event page
354		 * can be directly checked to get the id of the channel
355		 * that has the interrupt pending.
356		 */
357		maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
358		page_addr = hv_context.synic_event_page[cpu];
359		event = (union hv_synic_event_flags *)page_addr +
360						 VMBUS_MESSAGE_SINT;
361		recv_int_page = event->flags32;
362	}
363
364
365
366	/* Check events */
367	if (!recv_int_page)
368		return;
369	for (dword = 0; dword < maxdword; dword++) {
370		if (!recv_int_page[dword])
371			continue;
372		for (bit = 0; bit < 32; bit++) {
373			if (sync_test_and_clear_bit(bit,
374				(unsigned long *)&recv_int_page[dword])) {
375				relid = (dword << 5) + bit;
376
377				if (relid == 0)
378					/*
379					 * Special case - vmbus
380					 * channel protocol msg
381					 */
382					continue;
383
384				process_chn_event(relid);
385			}
386		}
387	}
388}
389
390/*
391 * vmbus_post_msg - Send a msg on the vmbus's message connection
392 */
393int vmbus_post_msg(void *buffer, size_t buflen)
394{
395	union hv_connection_id conn_id;
396	int ret = 0;
397	int retries = 0;
398
399	conn_id.asu32 = 0;
400	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
401
402	/*
403	 * hv_post_message() can have transient failures because of
404	 * insufficient resources. Retry the operation a couple of
405	 * times before giving up.
406	 */
407	while (retries < 3) {
408		ret =  hv_post_message(conn_id, 1, buffer, buflen);
409		if (ret != HV_STATUS_INSUFFICIENT_BUFFERS)
410			return ret;
411		retries++;
412		msleep(100);
413	}
414	return ret;
415}
416
417/*
418 * vmbus_set_event - Send an event notification to the parent
419 */
420int vmbus_set_event(struct vmbus_channel *channel)
421{
422	u32 child_relid = channel->offermsg.child_relid;
423
424	if (!channel->is_dedicated_interrupt) {
425		/* Each u32 represents 32 channels */
426		sync_set_bit(child_relid & 31,
427			(unsigned long *)vmbus_connection.send_int_page +
428			(child_relid >> 5));
429	}
430
431	return hv_signal_event(channel->sig_event);
432}
433