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/mshyperv.h>
35
36#include "hyperv_vmbus.h"
37
38
39struct vmbus_connection vmbus_connection = {
40 .conn_state = DISCONNECTED,
41 .next_gpadl_handle = ATOMIC_INIT(0xE1E10),
42};
43EXPORT_SYMBOL_GPL(vmbus_connection);
44
45/*
46 * Negotiated protocol version with the host.
47 */
48__u32 vmbus_proto_version;
49EXPORT_SYMBOL_GPL(vmbus_proto_version);
50
51static __u32 vmbus_get_next_version(__u32 current_version)
52{
53 switch (current_version) {
54 case (VERSION_WIN7):
55 return VERSION_WS2008;
56
57 case (VERSION_WIN8):
58 return VERSION_WIN7;
59
60 case (VERSION_WIN8_1):
61 return VERSION_WIN8;
62
63 case (VERSION_WIN10):
64 return VERSION_WIN8_1;
65
66 case (VERSION_WIN10_V5):
67 return VERSION_WIN10;
68
69 case (VERSION_WS2008):
70 default:
71 return VERSION_INVAL;
72 }
73}
74
75static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
76 __u32 version)
77{
78 int ret = 0;
79 unsigned int cur_cpu;
80 struct vmbus_channel_initiate_contact *msg;
81 unsigned long flags;
82
83 init_completion(&msginfo->waitevent);
84
85 msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
86
87 memset(msg, 0, sizeof(*msg));
88 msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
89 msg->vmbus_version_requested = version;
90
91 /*
92 * VMBus protocol 5.0 (VERSION_WIN10_V5) requires that we must use
93 * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
94 * and for subsequent messages, we must use the Message Connection ID
95 * field in the host-returned Version Response Message. And, with
96 * VERSION_WIN10_V5, we don't use msg->interrupt_page, but we tell
97 * the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
98 * compatibility.
99 *
100 * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
101 */
102 if (version >= VERSION_WIN10_V5) {
103 msg->msg_sint = VMBUS_MESSAGE_SINT;
104 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
105 } else {
106 msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
107 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
108 }
109
110 msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
111 msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
112 /*
113 * We want all channel messages to be delivered on CPU 0.
114 * This has been the behavior pre-win8. This is not
115 * perf issue and having all channel messages delivered on CPU 0
116 * would be ok.
117 * For post win8 hosts, we support receiving channel messagges on
118 * all the CPUs. This is needed for kexec to work correctly where
119 * the CPU attempting to connect may not be CPU 0.
120 */
121 if (version >= VERSION_WIN8_1) {
122 cur_cpu = get_cpu();
123 msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
124 vmbus_connection.connect_cpu = cur_cpu;
125 put_cpu();
126 } else {
127 msg->target_vcpu = 0;
128 vmbus_connection.connect_cpu = 0;
129 }
130
131 /*
132 * Add to list before we send the request since we may
133 * receive the response before returning from this routine
134 */
135 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
136 list_add_tail(&msginfo->msglistentry,
137 &vmbus_connection.chn_msg_list);
138
139 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
140
141 ret = vmbus_post_msg(msg,
142 sizeof(struct vmbus_channel_initiate_contact),
143 true);
144
145 trace_vmbus_negotiate_version(msg, ret);
146
147 if (ret != 0) {
148 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
149 list_del(&msginfo->msglistentry);
150 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
151 flags);
152 return ret;
153 }
154
155 /* Wait for the connection response */
156 wait_for_completion(&msginfo->waitevent);
157
158 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
159 list_del(&msginfo->msglistentry);
160 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
161
162 /* Check if successful */
163 if (msginfo->response.version_response.version_supported) {
164 vmbus_connection.conn_state = CONNECTED;
165
166 if (version >= VERSION_WIN10_V5)
167 vmbus_connection.msg_conn_id =
168 msginfo->response.version_response.msg_conn_id;
169 } else {
170 return -ECONNREFUSED;
171 }
172
173 return ret;
174}
175
176/*
177 * vmbus_connect - Sends a connect request on the partition service connection
178 */
179int vmbus_connect(void)
180{
181 int ret = 0;
182 struct vmbus_channel_msginfo *msginfo = NULL;
183 __u32 version;
184
185 /* Initialize the vmbus connection */
186 vmbus_connection.conn_state = CONNECTING;
187 vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
188 if (!vmbus_connection.work_queue) {
189 ret = -ENOMEM;
190 goto cleanup;
191 }
192
193 vmbus_connection.handle_primary_chan_wq =
194 create_workqueue("hv_pri_chan");
195 if (!vmbus_connection.handle_primary_chan_wq) {
196 ret = -ENOMEM;
197 goto cleanup;
198 }
199
200 vmbus_connection.handle_sub_chan_wq =
201 create_workqueue("hv_sub_chan");
202 if (!vmbus_connection.handle_sub_chan_wq) {
203 ret = -ENOMEM;
204 goto cleanup;
205 }
206
207 INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
208 spin_lock_init(&vmbus_connection.channelmsg_lock);
209
210 INIT_LIST_HEAD(&vmbus_connection.chn_list);
211 mutex_init(&vmbus_connection.channel_mutex);
212
213 /*
214 * Setup the vmbus event connection for channel interrupt
215 * abstraction stuff
216 */
217 vmbus_connection.int_page =
218 (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
219 if (vmbus_connection.int_page == NULL) {
220 ret = -ENOMEM;
221 goto cleanup;
222 }
223
224 vmbus_connection.recv_int_page = vmbus_connection.int_page;
225 vmbus_connection.send_int_page =
226 (void *)((unsigned long)vmbus_connection.int_page +
227 (PAGE_SIZE >> 1));
228
229 /*
230 * Setup the monitor notification facility. The 1st page for
231 * parent->child and the 2nd page for child->parent
232 */
233 vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
234 vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
235 if ((vmbus_connection.monitor_pages[0] == NULL) ||
236 (vmbus_connection.monitor_pages[1] == NULL)) {
237 ret = -ENOMEM;
238 goto cleanup;
239 }
240
241 msginfo = kzalloc(sizeof(*msginfo) +
242 sizeof(struct vmbus_channel_initiate_contact),
243 GFP_KERNEL);
244 if (msginfo == NULL) {
245 ret = -ENOMEM;
246 goto cleanup;
247 }
248
249 /*
250 * Negotiate a compatible VMBUS version number with the
251 * host. We start with the highest number we can support
252 * and work our way down until we negotiate a compatible
253 * version.
254 */
255
256 version = VERSION_CURRENT;
257
258 do {
259 ret = vmbus_negotiate_version(msginfo, version);
260 if (ret == -ETIMEDOUT)
261 goto cleanup;
262
263 if (vmbus_connection.conn_state == CONNECTED)
264 break;
265
266 version = vmbus_get_next_version(version);
267 } while (version != VERSION_INVAL);
268
269 if (version == VERSION_INVAL)
270 goto cleanup;
271
272 vmbus_proto_version = version;
273 pr_info("Vmbus version:%d.%d\n",
274 version >> 16, version & 0xFFFF);
275
276 kfree(msginfo);
277 return 0;
278
279cleanup:
280 pr_err("Unable to connect to host\n");
281
282 vmbus_connection.conn_state = DISCONNECTED;
283 vmbus_disconnect();
284
285 kfree(msginfo);
286
287 return ret;
288}
289
290void vmbus_disconnect(void)
291{
292 /*
293 * First send the unload request to the host.
294 */
295 vmbus_initiate_unload(false);
296
297 if (vmbus_connection.handle_sub_chan_wq)
298 destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
299
300 if (vmbus_connection.handle_primary_chan_wq)
301 destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
302
303 if (vmbus_connection.work_queue)
304 destroy_workqueue(vmbus_connection.work_queue);
305
306 if (vmbus_connection.int_page) {
307 free_pages((unsigned long)vmbus_connection.int_page, 0);
308 vmbus_connection.int_page = NULL;
309 }
310
311 free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
312 free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
313 vmbus_connection.monitor_pages[0] = NULL;
314 vmbus_connection.monitor_pages[1] = NULL;
315}
316
317/*
318 * relid2channel - Get the channel object given its
319 * child relative id (ie channel id)
320 */
321struct vmbus_channel *relid2channel(u32 relid)
322{
323 struct vmbus_channel *channel;
324 struct vmbus_channel *found_channel = NULL;
325 struct list_head *cur, *tmp;
326 struct vmbus_channel *cur_sc;
327
328 BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
329
330 list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
331 if (channel->offermsg.child_relid == relid) {
332 found_channel = channel;
333 break;
334 } else if (!list_empty(&channel->sc_list)) {
335 /*
336 * Deal with sub-channels.
337 */
338 list_for_each_safe(cur, tmp, &channel->sc_list) {
339 cur_sc = list_entry(cur, struct vmbus_channel,
340 sc_list);
341 if (cur_sc->offermsg.child_relid == relid) {
342 found_channel = cur_sc;
343 break;
344 }
345 }
346 }
347 }
348
349 return found_channel;
350}
351
352/*
353 * vmbus_on_event - Process a channel event notification
354 *
355 * For batched channels (default) optimize host to guest signaling
356 * by ensuring:
357 * 1. While reading the channel, we disable interrupts from host.
358 * 2. Ensure that we process all posted messages from the host
359 * before returning from this callback.
360 * 3. Once we return, enable signaling from the host. Once this
361 * state is set we check to see if additional packets are
362 * available to read. In this case we repeat the process.
363 * If this tasklet has been running for a long time
364 * then reschedule ourselves.
365 */
366void vmbus_on_event(unsigned long data)
367{
368 struct vmbus_channel *channel = (void *) data;
369 unsigned long time_limit = jiffies + 2;
370
371 trace_vmbus_on_event(channel);
372
373 do {
374 void (*callback_fn)(void *);
375
376 /* A channel once created is persistent even when
377 * there is no driver handling the device. An
378 * unloading driver sets the onchannel_callback to NULL.
379 */
380 callback_fn = READ_ONCE(channel->onchannel_callback);
381 if (unlikely(callback_fn == NULL))
382 return;
383
384 (*callback_fn)(channel->channel_callback_context);
385
386 if (channel->callback_mode != HV_CALL_BATCHED)
387 return;
388
389 if (likely(hv_end_read(&channel->inbound) == 0))
390 return;
391
392 hv_begin_read(&channel->inbound);
393 } while (likely(time_before(jiffies, time_limit)));
394
395 /* The time limit (2 jiffies) has been reached */
396 tasklet_schedule(&channel->callback_event);
397}
398
399/*
400 * vmbus_post_msg - Send a msg on the vmbus's message connection
401 */
402int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
403{
404 struct vmbus_channel_message_header *hdr;
405 union hv_connection_id conn_id;
406 int ret = 0;
407 int retries = 0;
408 u32 usec = 1;
409
410 conn_id.asu32 = 0;
411 conn_id.u.id = vmbus_connection.msg_conn_id;
412
413 /*
414 * hv_post_message() can have transient failures because of
415 * insufficient resources. Retry the operation a couple of
416 * times before giving up.
417 */
418 while (retries < 100) {
419 ret = hv_post_message(conn_id, 1, buffer, buflen);
420
421 switch (ret) {
422 case HV_STATUS_INVALID_CONNECTION_ID:
423 /*
424 * See vmbus_negotiate_version(): VMBus protocol 5.0
425 * requires that we must use
426 * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
427 * Contact message, but on old hosts that only
428 * support VMBus protocol 4.0 or lower, here we get
429 * HV_STATUS_INVALID_CONNECTION_ID and we should
430 * return an error immediately without retrying.
431 */
432 hdr = buffer;
433 if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
434 return -EINVAL;
435 /*
436 * We could get this if we send messages too
437 * frequently.
438 */
439 ret = -EAGAIN;
440 break;
441 case HV_STATUS_INSUFFICIENT_MEMORY:
442 case HV_STATUS_INSUFFICIENT_BUFFERS:
443 ret = -ENOBUFS;
444 break;
445 case HV_STATUS_SUCCESS:
446 return ret;
447 default:
448 pr_err("hv_post_msg() failed; error code:%d\n", ret);
449 return -EINVAL;
450 }
451
452 retries++;
453 if (can_sleep && usec > 1000)
454 msleep(usec / 1000);
455 else if (usec < MAX_UDELAY_MS * 1000)
456 udelay(usec);
457 else
458 mdelay(usec / 1000);
459
460 if (retries < 22)
461 usec *= 2;
462 }
463 return ret;
464}
465
466/*
467 * vmbus_set_event - Send an event notification to the parent
468 */
469void vmbus_set_event(struct vmbus_channel *channel)
470{
471 u32 child_relid = channel->offermsg.child_relid;
472
473 if (!channel->is_dedicated_interrupt)
474 vmbus_send_interrupt(child_relid);
475
476 ++channel->sig_events;
477
478 hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
479}
480EXPORT_SYMBOL_GPL(vmbus_set_event);
481