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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};
42EXPORT_SYMBOL_GPL(vmbus_connection);
43
44/*
45 * Negotiated protocol version with the host.
46 */
47__u32 vmbus_proto_version;
48EXPORT_SYMBOL_GPL(vmbus_proto_version);
49
50static __u32 vmbus_get_next_version(__u32 current_version)
51{
52 switch (current_version) {
53 case (VERSION_WIN7):
54 return VERSION_WS2008;
55
56 case (VERSION_WIN8):
57 return VERSION_WIN7;
58
59 case (VERSION_WIN8_1):
60 return VERSION_WIN8;
61
62 case (VERSION_WIN10):
63 return VERSION_WIN8_1;
64
65 case (VERSION_WS2008):
66 default:
67 return VERSION_INVAL;
68 }
69}
70
71static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
72 __u32 version)
73{
74 int ret = 0;
75 struct vmbus_channel_initiate_contact *msg;
76 unsigned long flags;
77
78 init_completion(&msginfo->waitevent);
79
80 msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
81
82 msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
83 msg->vmbus_version_requested = version;
84 msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
85 msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
86 msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
87 /*
88 * We want all channel messages to be delivered on CPU 0.
89 * This has been the behavior pre-win8. This is not
90 * perf issue and having all channel messages delivered on CPU 0
91 * would be ok.
92 * For post win8 hosts, we support receiving channel messagges on
93 * all the CPUs. This is needed for kexec to work correctly where
94 * the CPU attempting to connect may not be CPU 0.
95 */
96 if (version >= VERSION_WIN8_1) {
97 msg->target_vcpu = hv_context.vp_index[get_cpu()];
98 put_cpu();
99 } else {
100 msg->target_vcpu = 0;
101 }
102
103 /*
104 * Add to list before we send the request since we may
105 * receive the response before returning from this routine
106 */
107 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
108 list_add_tail(&msginfo->msglistentry,
109 &vmbus_connection.chn_msg_list);
110
111 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
112
113 ret = vmbus_post_msg(msg,
114 sizeof(struct vmbus_channel_initiate_contact),
115 true);
116 if (ret != 0) {
117 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
118 list_del(&msginfo->msglistentry);
119 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
120 flags);
121 return ret;
122 }
123
124 /* Wait for the connection response */
125 wait_for_completion(&msginfo->waitevent);
126
127 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
128 list_del(&msginfo->msglistentry);
129 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
130
131 /* Check if successful */
132 if (msginfo->response.version_response.version_supported) {
133 vmbus_connection.conn_state = CONNECTED;
134 } else {
135 return -ECONNREFUSED;
136 }
137
138 return ret;
139}
140
141/*
142 * vmbus_connect - Sends a connect request on the partition service connection
143 */
144int vmbus_connect(void)
145{
146 int ret = 0;
147 struct vmbus_channel_msginfo *msginfo = NULL;
148 __u32 version;
149
150 /* Initialize the vmbus connection */
151 vmbus_connection.conn_state = CONNECTING;
152 vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
153 if (!vmbus_connection.work_queue) {
154 ret = -ENOMEM;
155 goto cleanup;
156 }
157
158 INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
159 spin_lock_init(&vmbus_connection.channelmsg_lock);
160
161 INIT_LIST_HEAD(&vmbus_connection.chn_list);
162 mutex_init(&vmbus_connection.channel_mutex);
163
164 /*
165 * Setup the vmbus event connection for channel interrupt
166 * abstraction stuff
167 */
168 vmbus_connection.int_page =
169 (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
170 if (vmbus_connection.int_page == NULL) {
171 ret = -ENOMEM;
172 goto cleanup;
173 }
174
175 vmbus_connection.recv_int_page = vmbus_connection.int_page;
176 vmbus_connection.send_int_page =
177 (void *)((unsigned long)vmbus_connection.int_page +
178 (PAGE_SIZE >> 1));
179
180 /*
181 * Setup the monitor notification facility. The 1st page for
182 * parent->child and the 2nd page for child->parent
183 */
184 vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
185 vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
186 if ((vmbus_connection.monitor_pages[0] == NULL) ||
187 (vmbus_connection.monitor_pages[1] == NULL)) {
188 ret = -ENOMEM;
189 goto cleanup;
190 }
191
192 msginfo = kzalloc(sizeof(*msginfo) +
193 sizeof(struct vmbus_channel_initiate_contact),
194 GFP_KERNEL);
195 if (msginfo == NULL) {
196 ret = -ENOMEM;
197 goto cleanup;
198 }
199
200 /*
201 * Negotiate a compatible VMBUS version number with the
202 * host. We start with the highest number we can support
203 * and work our way down until we negotiate a compatible
204 * version.
205 */
206
207 version = VERSION_CURRENT;
208
209 do {
210 ret = vmbus_negotiate_version(msginfo, version);
211 if (ret == -ETIMEDOUT)
212 goto cleanup;
213
214 if (vmbus_connection.conn_state == CONNECTED)
215 break;
216
217 version = vmbus_get_next_version(version);
218 } while (version != VERSION_INVAL);
219
220 if (version == VERSION_INVAL)
221 goto cleanup;
222
223 vmbus_proto_version = version;
224 pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
225 host_info_eax, host_info_ebx >> 16,
226 host_info_ebx & 0xFFFF, host_info_ecx,
227 host_info_edx >> 24, host_info_edx & 0xFFFFFF,
228 version >> 16, version & 0xFFFF);
229
230 kfree(msginfo);
231 return 0;
232
233cleanup:
234 pr_err("Unable to connect to host\n");
235
236 vmbus_connection.conn_state = DISCONNECTED;
237 vmbus_disconnect();
238
239 kfree(msginfo);
240
241 return ret;
242}
243
244void vmbus_disconnect(void)
245{
246 /*
247 * First send the unload request to the host.
248 */
249 vmbus_initiate_unload(false);
250
251 if (vmbus_connection.work_queue) {
252 drain_workqueue(vmbus_connection.work_queue);
253 destroy_workqueue(vmbus_connection.work_queue);
254 }
255
256 if (vmbus_connection.int_page) {
257 free_pages((unsigned long)vmbus_connection.int_page, 0);
258 vmbus_connection.int_page = NULL;
259 }
260
261 free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
262 free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
263 vmbus_connection.monitor_pages[0] = NULL;
264 vmbus_connection.monitor_pages[1] = NULL;
265}
266
267/*
268 * Map the given relid to the corresponding channel based on the
269 * per-cpu list of channels that have been affinitized to this CPU.
270 * This will be used in the channel callback path as we can do this
271 * mapping in a lock-free fashion.
272 */
273static struct vmbus_channel *pcpu_relid2channel(u32 relid)
274{
275 struct vmbus_channel *channel;
276 struct vmbus_channel *found_channel = NULL;
277 int cpu = smp_processor_id();
278 struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
279
280 list_for_each_entry(channel, pcpu_head, percpu_list) {
281 if (channel->offermsg.child_relid == relid) {
282 found_channel = channel;
283 break;
284 }
285 }
286
287 return found_channel;
288}
289
290/*
291 * relid2channel - Get the channel object given its
292 * child relative id (ie channel id)
293 */
294struct vmbus_channel *relid2channel(u32 relid)
295{
296 struct vmbus_channel *channel;
297 struct vmbus_channel *found_channel = NULL;
298 struct list_head *cur, *tmp;
299 struct vmbus_channel *cur_sc;
300
301 BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
302
303 list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
304 if (channel->offermsg.child_relid == relid) {
305 found_channel = channel;
306 break;
307 } else if (!list_empty(&channel->sc_list)) {
308 /*
309 * Deal with sub-channels.
310 */
311 list_for_each_safe(cur, tmp, &channel->sc_list) {
312 cur_sc = list_entry(cur, struct vmbus_channel,
313 sc_list);
314 if (cur_sc->offermsg.child_relid == relid) {
315 found_channel = cur_sc;
316 break;
317 }
318 }
319 }
320 }
321
322 return found_channel;
323}
324
325/*
326 * process_chn_event - Process a channel event notification
327 */
328static void process_chn_event(u32 relid)
329{
330 struct vmbus_channel *channel;
331 void *arg;
332 bool read_state;
333 u32 bytes_to_read;
334
335 /*
336 * Find the channel based on this relid and invokes the
337 * channel callback to process the event
338 */
339 channel = pcpu_relid2channel(relid);
340
341 if (!channel)
342 return;
343
344 /*
345 * A channel once created is persistent even when there
346 * is no driver handling the device. An unloading driver
347 * sets the onchannel_callback to NULL on the same CPU
348 * as where this interrupt is handled (in an interrupt context).
349 * Thus, checking and invoking the driver specific callback takes
350 * care of orderly unloading of the driver.
351 */
352
353 if (channel->onchannel_callback != NULL) {
354 arg = channel->channel_callback_context;
355 read_state = channel->batched_reading;
356 /*
357 * This callback reads the messages sent by the host.
358 * We can optimize host to guest signaling by ensuring:
359 * 1. While reading the channel, we disable interrupts from
360 * host.
361 * 2. Ensure that we process all posted messages from the host
362 * before returning from this callback.
363 * 3. Once we return, enable signaling from the host. Once this
364 * state is set we check to see if additional packets are
365 * available to read. In this case we repeat the process.
366 */
367
368 do {
369 if (read_state)
370 hv_begin_read(&channel->inbound);
371 channel->onchannel_callback(arg);
372 if (read_state)
373 bytes_to_read = hv_end_read(&channel->inbound);
374 else
375 bytes_to_read = 0;
376 } while (read_state && (bytes_to_read != 0));
377 }
378}
379
380/*
381 * vmbus_on_event - Handler for events
382 */
383void vmbus_on_event(unsigned long data)
384{
385 u32 dword;
386 u32 maxdword;
387 int bit;
388 u32 relid;
389 u32 *recv_int_page = NULL;
390 void *page_addr;
391 int cpu = smp_processor_id();
392 union hv_synic_event_flags *event;
393
394 if (vmbus_proto_version < VERSION_WIN8) {
395 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
396 recv_int_page = vmbus_connection.recv_int_page;
397 } else {
398 /*
399 * When the host is win8 and beyond, the event page
400 * can be directly checked to get the id of the channel
401 * that has the interrupt pending.
402 */
403 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
404 page_addr = hv_context.synic_event_page[cpu];
405 event = (union hv_synic_event_flags *)page_addr +
406 VMBUS_MESSAGE_SINT;
407 recv_int_page = event->flags32;
408 }
409
410
411
412 /* Check events */
413 if (!recv_int_page)
414 return;
415 for (dword = 0; dword < maxdword; dword++) {
416 if (!recv_int_page[dword])
417 continue;
418 for (bit = 0; bit < 32; bit++) {
419 if (sync_test_and_clear_bit(bit,
420 (unsigned long *)&recv_int_page[dword])) {
421 relid = (dword << 5) + bit;
422
423 if (relid == 0)
424 /*
425 * Special case - vmbus
426 * channel protocol msg
427 */
428 continue;
429
430 process_chn_event(relid);
431 }
432 }
433 }
434}
435
436/*
437 * vmbus_post_msg - Send a msg on the vmbus's message connection
438 */
439int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
440{
441 union hv_connection_id conn_id;
442 int ret = 0;
443 int retries = 0;
444 u32 usec = 1;
445
446 conn_id.asu32 = 0;
447 conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
448
449 /*
450 * hv_post_message() can have transient failures because of
451 * insufficient resources. Retry the operation a couple of
452 * times before giving up.
453 */
454 while (retries < 100) {
455 ret = hv_post_message(conn_id, 1, buffer, buflen);
456
457 switch (ret) {
458 case HV_STATUS_INVALID_CONNECTION_ID:
459 /*
460 * We could get this if we send messages too
461 * frequently.
462 */
463 ret = -EAGAIN;
464 break;
465 case HV_STATUS_INSUFFICIENT_MEMORY:
466 case HV_STATUS_INSUFFICIENT_BUFFERS:
467 ret = -ENOMEM;
468 break;
469 case HV_STATUS_SUCCESS:
470 return ret;
471 default:
472 pr_err("hv_post_msg() failed; error code:%d\n", ret);
473 return -EINVAL;
474 }
475
476 retries++;
477 if (can_sleep && usec > 1000)
478 msleep(usec / 1000);
479 else if (usec < MAX_UDELAY_MS * 1000)
480 udelay(usec);
481 else
482 mdelay(usec / 1000);
483
484 if (usec < 256000)
485 usec *= 2;
486 }
487 return ret;
488}
489
490/*
491 * vmbus_set_event - Send an event notification to the parent
492 */
493void vmbus_set_event(struct vmbus_channel *channel)
494{
495 u32 child_relid = channel->offermsg.child_relid;
496
497 if (!channel->is_dedicated_interrupt) {
498 /* Each u32 represents 32 channels */
499 sync_set_bit(child_relid & 31,
500 (unsigned long *)vmbus_connection.send_int_page +
501 (child_relid >> 5));
502 }
503
504 hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
505}
506EXPORT_SYMBOL_GPL(vmbus_set_event);