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[get_cpu()];
85		put_cpu();
86	}
87
88	/*
89	 * Add to list before we send the request since we may
90	 * receive the response before returning from this routine
91	 */
92	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
93	list_add_tail(&msginfo->msglistentry,
94		      &vmbus_connection.chn_msg_list);
95
96	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
97
98	ret = vmbus_post_msg(msg,
99			       sizeof(struct vmbus_channel_initiate_contact));
100	if (ret != 0) {
101		spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
102		list_del(&msginfo->msglistentry);
103		spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
104					flags);
105		return ret;
106	}
107
108	/* Wait for the connection response */
109	wait_for_completion(&msginfo->waitevent);
110
111	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
112	list_del(&msginfo->msglistentry);
113	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
114
115	/* Check if successful */
116	if (msginfo->response.version_response.version_supported) {
117		vmbus_connection.conn_state = CONNECTED;
118	} else {
119		return -ECONNREFUSED;
120	}
121
122	return ret;
123}
124
125/*
126 * vmbus_connect - Sends a connect request on the partition service connection
127 */
128int vmbus_connect(void)
129{
130	int ret = 0;
131	struct vmbus_channel_msginfo *msginfo = NULL;
132	__u32 version;
133
134	/* Initialize the vmbus connection */
135	vmbus_connection.conn_state = CONNECTING;
136	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
137	if (!vmbus_connection.work_queue) {
138		ret = -ENOMEM;
139		goto cleanup;
140	}
141
142	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
143	spin_lock_init(&vmbus_connection.channelmsg_lock);
144
145	INIT_LIST_HEAD(&vmbus_connection.chn_list);
146	spin_lock_init(&vmbus_connection.channel_lock);
147
148	/*
149	 * Setup the vmbus event connection for channel interrupt
150	 * abstraction stuff
151	 */
152	vmbus_connection.int_page =
153	(void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
154	if (vmbus_connection.int_page == NULL) {
155		ret = -ENOMEM;
156		goto cleanup;
157	}
158
159	vmbus_connection.recv_int_page = vmbus_connection.int_page;
160	vmbus_connection.send_int_page =
161		(void *)((unsigned long)vmbus_connection.int_page +
162			(PAGE_SIZE >> 1));
163
164	/*
165	 * Setup the monitor notification facility. The 1st page for
166	 * parent->child and the 2nd page for child->parent
167	 */
168	vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
169	vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
170	if ((vmbus_connection.monitor_pages[0] == NULL) ||
171	    (vmbus_connection.monitor_pages[1] == NULL)) {
172		ret = -ENOMEM;
173		goto cleanup;
174	}
175
176	msginfo = kzalloc(sizeof(*msginfo) +
177			  sizeof(struct vmbus_channel_initiate_contact),
178			  GFP_KERNEL);
179	if (msginfo == NULL) {
180		ret = -ENOMEM;
181		goto cleanup;
182	}
183
184	/*
185	 * Negotiate a compatible VMBUS version number with the
186	 * host. We start with the highest number we can support
187	 * and work our way down until we negotiate a compatible
188	 * version.
189	 */
190
191	version = VERSION_CURRENT;
192
193	do {
194		ret = vmbus_negotiate_version(msginfo, version);
195		if (ret == -ETIMEDOUT)
196			goto cleanup;
197
198		if (vmbus_connection.conn_state == CONNECTED)
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
220	vmbus_connection.conn_state = DISCONNECTED;
221	vmbus_disconnect();
222
223	kfree(msginfo);
224
225	return ret;
226}
227
228void vmbus_disconnect(void)
229{
230	if (vmbus_connection.work_queue) {
231		drain_workqueue(vmbus_connection.work_queue);
232		destroy_workqueue(vmbus_connection.work_queue);
233	}
234
235	if (vmbus_connection.int_page) {
236		free_pages((unsigned long)vmbus_connection.int_page, 0);
237		vmbus_connection.int_page = NULL;
238	}
239
240	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
241	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
242	vmbus_connection.monitor_pages[0] = NULL;
243	vmbus_connection.monitor_pages[1] = NULL;
244}
245
246/*
247 * Map the given relid to the corresponding channel based on the
248 * per-cpu list of channels that have been affinitized to this CPU.
249 * This will be used in the channel callback path as we can do this
250 * mapping in a lock-free fashion.
251 */
252static struct vmbus_channel *pcpu_relid2channel(u32 relid)
253{
254	struct vmbus_channel *channel;
255	struct vmbus_channel *found_channel  = NULL;
256	int cpu = smp_processor_id();
257	struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
258
259	list_for_each_entry(channel, pcpu_head, percpu_list) {
260		if (channel->offermsg.child_relid == relid) {
261			found_channel = channel;
262			break;
263		}
264	}
265
266	return found_channel;
267}
268
269/*
270 * relid2channel - Get the channel object given its
271 * child relative id (ie channel id)
272 */
273struct vmbus_channel *relid2channel(u32 relid)
274{
275	struct vmbus_channel *channel;
276	struct vmbus_channel *found_channel  = NULL;
277	unsigned long flags;
278	struct list_head *cur, *tmp;
279	struct vmbus_channel *cur_sc;
280
281	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
282	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
283		if (channel->offermsg.child_relid == relid) {
284			found_channel = channel;
285			break;
286		} else if (!list_empty(&channel->sc_list)) {
287			/*
288			 * Deal with sub-channels.
289			 */
290			list_for_each_safe(cur, tmp, &channel->sc_list) {
291				cur_sc = list_entry(cur, struct vmbus_channel,
292							sc_list);
293				if (cur_sc->offermsg.child_relid == relid) {
294					found_channel = cur_sc;
295					break;
296				}
297			}
298		}
299	}
300	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
301
302	return found_channel;
303}
304
305/*
306 * process_chn_event - Process a channel event notification
307 */
308static void process_chn_event(u32 relid)
309{
310	struct vmbus_channel *channel;
311	void *arg;
312	bool read_state;
313	u32 bytes_to_read;
314
315	/*
316	 * Find the channel based on this relid and invokes the
317	 * channel callback to process the event
318	 */
319	channel = pcpu_relid2channel(relid);
320
321	if (!channel)
322		return;
323
324	/*
325	 * A channel once created is persistent even when there
326	 * is no driver handling the device. An unloading driver
327	 * sets the onchannel_callback to NULL on the same CPU
328	 * as where this interrupt is handled (in an interrupt context).
329	 * Thus, checking and invoking the driver specific callback takes
330	 * care of orderly unloading of the driver.
331	 */
332
333	if (channel->onchannel_callback != NULL) {
334		arg = channel->channel_callback_context;
335		read_state = channel->batched_reading;
336		/*
337		 * This callback reads the messages sent by the host.
338		 * We can optimize host to guest signaling by ensuring:
339		 * 1. While reading the channel, we disable interrupts from
340		 *    host.
341		 * 2. Ensure that we process all posted messages from the host
342		 *    before returning from this callback.
343		 * 3. Once we return, enable signaling from the host. Once this
344		 *    state is set we check to see if additional packets are
345		 *    available to read. In this case we repeat the process.
346		 */
347
348		do {
349			if (read_state)
350				hv_begin_read(&channel->inbound);
351			channel->onchannel_callback(arg);
352			if (read_state)
353				bytes_to_read = hv_end_read(&channel->inbound);
354			else
355				bytes_to_read = 0;
356		} while (read_state && (bytes_to_read != 0));
357	}
358}
359
360/*
361 * vmbus_on_event - Handler for events
362 */
363void vmbus_on_event(unsigned long data)
364{
365	u32 dword;
366	u32 maxdword;
367	int bit;
368	u32 relid;
369	u32 *recv_int_page = NULL;
370	void *page_addr;
371	int cpu = smp_processor_id();
372	union hv_synic_event_flags *event;
373
374	if ((vmbus_proto_version == VERSION_WS2008) ||
375		(vmbus_proto_version == VERSION_WIN7)) {
376		maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
377		recv_int_page = vmbus_connection.recv_int_page;
378	} else {
379		/*
380		 * When the host is win8 and beyond, the event page
381		 * can be directly checked to get the id of the channel
382		 * that has the interrupt pending.
383		 */
384		maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
385		page_addr = hv_context.synic_event_page[cpu];
386		event = (union hv_synic_event_flags *)page_addr +
387						 VMBUS_MESSAGE_SINT;
388		recv_int_page = event->flags32;
389	}
390
391
392
393	/* Check events */
394	if (!recv_int_page)
395		return;
396	for (dword = 0; dword < maxdword; dword++) {
397		if (!recv_int_page[dword])
398			continue;
399		for (bit = 0; bit < 32; bit++) {
400			if (sync_test_and_clear_bit(bit,
401				(unsigned long *)&recv_int_page[dword])) {
402				relid = (dword << 5) + bit;
403
404				if (relid == 0)
405					/*
406					 * Special case - vmbus
407					 * channel protocol msg
408					 */
409					continue;
410
411				process_chn_event(relid);
412			}
413		}
414	}
415}
416
417/*
418 * vmbus_post_msg - Send a msg on the vmbus's message connection
419 */
420int vmbus_post_msg(void *buffer, size_t buflen)
421{
422	union hv_connection_id conn_id;
423	int ret = 0;
424	int retries = 0;
425	u32 msec = 1;
426
427	conn_id.asu32 = 0;
428	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
429
430	/*
431	 * hv_post_message() can have transient failures because of
432	 * insufficient resources. Retry the operation a couple of
433	 * times before giving up.
434	 */
435	while (retries < 20) {
436		ret = hv_post_message(conn_id, 1, buffer, buflen);
437
438		switch (ret) {
439		case HV_STATUS_INVALID_CONNECTION_ID:
440			/*
441			 * We could get this if we send messages too
442			 * frequently.
443			 */
444			ret = -EAGAIN;
445			break;
446		case HV_STATUS_INSUFFICIENT_MEMORY:
447		case HV_STATUS_INSUFFICIENT_BUFFERS:
448			ret = -ENOMEM;
449			break;
450		case HV_STATUS_SUCCESS:
451			return ret;
452		default:
453			pr_err("hv_post_msg() failed; error code:%d\n", ret);
454			return -EINVAL;
455		}
456
457		retries++;
458		msleep(msec);
459		if (msec < 2048)
460			msec *= 2;
461	}
462	return ret;
463}
464
465/*
466 * vmbus_set_event - Send an event notification to the parent
467 */
468int vmbus_set_event(struct vmbus_channel *channel)
469{
470	u32 child_relid = channel->offermsg.child_relid;
471
472	if (!channel->is_dedicated_interrupt) {
473		/* Each u32 represents 32 channels */
474		sync_set_bit(child_relid & 31,
475			(unsigned long *)vmbus_connection.send_int_page +
476			(child_relid >> 5));
477	}
478
479	return hv_signal_event(channel->sig_event);
480}
481