aboutsummaryrefslogtreecommitdiff
path: root/drivers/hv/vmbus_drv.c
blob: 077bb1bdac34ef4ed87c65c7bf0d204fd42001b4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 *   K. Y. Srinivasan <kys@microsoft.com>
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/completion.h>
#include <linux/hyperv.h>
#include <linux/kernel_stat.h>
#include <asm/hyperv.h>
#include <asm/hypervisor.h>
#include <asm/mshyperv.h>
#include "hyperv_vmbus.h"

static struct acpi_device  *hv_acpi_dev;

static struct tasklet_struct msg_dpc;
static struct completion probe_event;
static int irq;

static int vmbus_exists(void)
{
	if (hv_acpi_dev == NULL)
		return -ENODEV;

	return 0;
}

#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid) * 2)
static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
{
	int i;
	for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
		sprintf(&alias_name[i], "%02x", hv_dev->dev_type.b[i/2]);
}

static u8 channel_monitor_group(struct vmbus_channel *channel)
{
	return (u8)channel->offermsg.monitorid / 32;
}

static u8 channel_monitor_offset(struct vmbus_channel *channel)
{
	return (u8)channel->offermsg.monitorid % 32;
}

static u32 channel_pending(struct vmbus_channel *channel,
			   struct hv_monitor_page *monitor_page)
{
	u8 monitor_group = channel_monitor_group(channel);
	return monitor_page->trigger_group[monitor_group].pending;
}

static u32 channel_latency(struct vmbus_channel *channel,
			   struct hv_monitor_page *monitor_page)
{
	u8 monitor_group = channel_monitor_group(channel);
	u8 monitor_offset = channel_monitor_offset(channel);
	return monitor_page->latency[monitor_group][monitor_offset];
}

static u32 channel_conn_id(struct vmbus_channel *channel,
			   struct hv_monitor_page *monitor_page)
{
	u8 monitor_group = channel_monitor_group(channel);
	u8 monitor_offset = channel_monitor_offset(channel);
	return monitor_page->parameter[monitor_group][monitor_offset].connectionid.u.id;
}

static ssize_t id_show(struct device *dev, struct device_attribute *dev_attr,
		       char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "%d\n", hv_dev->channel->offermsg.child_relid);
}
static DEVICE_ATTR_RO(id);

static ssize_t state_show(struct device *dev, struct device_attribute *dev_attr,
			  char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "%d\n", hv_dev->channel->state);
}
static DEVICE_ATTR_RO(state);

static ssize_t monitor_id_show(struct device *dev,
			       struct device_attribute *dev_attr, char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "%d\n", hv_dev->channel->offermsg.monitorid);
}
static DEVICE_ATTR_RO(monitor_id);

static ssize_t class_id_show(struct device *dev,
			       struct device_attribute *dev_attr, char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "{%pUl}\n",
		       hv_dev->channel->offermsg.offer.if_type.b);
}
static DEVICE_ATTR_RO(class_id);

static ssize_t device_id_show(struct device *dev,
			      struct device_attribute *dev_attr, char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "{%pUl}\n",
		       hv_dev->channel->offermsg.offer.if_instance.b);
}
static DEVICE_ATTR_RO(device_id);

static ssize_t modalias_show(struct device *dev,
			     struct device_attribute *dev_attr, char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	char alias_name[VMBUS_ALIAS_LEN + 1];

	print_alias_name(hv_dev, alias_name);
	return sprintf(buf, "vmbus:%s\n", alias_name);
}
static DEVICE_ATTR_RO(modalias);

static ssize_t server_monitor_pending_show(struct device *dev,
					   struct device_attribute *dev_attr,
					   char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "%d\n",
		       channel_pending(hv_dev->channel,
				       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(server_monitor_pending);

static ssize_t client_monitor_pending_show(struct device *dev,
					   struct device_attribute *dev_attr,
					   char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "%d\n",
		       channel_pending(hv_dev->channel,
				       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(client_monitor_pending);

static ssize_t server_monitor_latency_show(struct device *dev,
					   struct device_attribute *dev_attr,
					   char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "%d\n",
		       channel_latency(hv_dev->channel,
				       vmbus_connection.monitor_pages[0]));
}
static DEVICE_ATTR_RO(server_monitor_latency);

static ssize_t client_monitor_latency_show(struct device *dev,
					   struct device_attribute *dev_attr,
					   char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "%d\n",
		       channel_latency(hv_dev->channel,
				       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(client_monitor_latency);

static ssize_t server_monitor_conn_id_show(struct device *dev,
					   struct device_attribute *dev_attr,
					   char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "%d\n",
		       channel_conn_id(hv_dev->channel,
				       vmbus_connection.monitor_pages[0]));
}
static DEVICE_ATTR_RO(server_monitor_conn_id);

static ssize_t client_monitor_conn_id_show(struct device *dev,
					   struct device_attribute *dev_attr,
					   char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);

	if (!hv_dev->channel)
		return -ENODEV;
	return sprintf(buf, "%d\n",
		       channel_conn_id(hv_dev->channel,
				       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(client_monitor_conn_id);

static ssize_t out_intr_mask_show(struct device *dev,
				  struct device_attribute *dev_attr, char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info outbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
	return sprintf(buf, "%d\n", outbound.current_interrupt_mask);
}
static DEVICE_ATTR_RO(out_intr_mask);

static ssize_t out_read_index_show(struct device *dev,
				   struct device_attribute *dev_attr, char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info outbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
	return sprintf(buf, "%d\n", outbound.current_read_index);
}
static DEVICE_ATTR_RO(out_read_index);

static ssize_t out_write_index_show(struct device *dev,
				    struct device_attribute *dev_attr,
				    char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info outbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
	return sprintf(buf, "%d\n", outbound.current_write_index);
}
static DEVICE_ATTR_RO(out_write_index);

static ssize_t out_read_bytes_avail_show(struct device *dev,
					 struct device_attribute *dev_attr,
					 char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info outbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
	return sprintf(buf, "%d\n", outbound.bytes_avail_toread);
}
static DEVICE_ATTR_RO(out_read_bytes_avail);

static ssize_t out_write_bytes_avail_show(struct device *dev,
					  struct device_attribute *dev_attr,
					  char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info outbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
	return sprintf(buf, "%d\n", outbound.bytes_avail_towrite);
}
static DEVICE_ATTR_RO(out_write_bytes_avail);

static ssize_t in_intr_mask_show(struct device *dev,
				 struct device_attribute *dev_attr, char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info inbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
	return sprintf(buf, "%d\n", inbound.current_interrupt_mask);
}
static DEVICE_ATTR_RO(in_intr_mask);

static ssize_t in_read_index_show(struct device *dev,
				  struct device_attribute *dev_attr, char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info inbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
	return sprintf(buf, "%d\n", inbound.current_read_index);
}
static DEVICE_ATTR_RO(in_read_index);

static ssize_t in_write_index_show(struct device *dev,
				   struct device_attribute *dev_attr, char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info inbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
	return sprintf(buf, "%d\n", inbound.current_write_index);
}
static DEVICE_ATTR_RO(in_write_index);

static ssize_t in_read_bytes_avail_show(struct device *dev,
					struct device_attribute *dev_attr,
					char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info inbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
	return sprintf(buf, "%d\n", inbound.bytes_avail_toread);
}
static DEVICE_ATTR_RO(in_read_bytes_avail);

static ssize_t in_write_bytes_avail_show(struct device *dev,
					 struct device_attribute *dev_attr,
					 char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_ring_buffer_debug_info inbound;

	if (!hv_dev->channel)
		return -ENODEV;
	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
	return sprintf(buf, "%d\n", inbound.bytes_avail_towrite);
}
static DEVICE_ATTR_RO(in_write_bytes_avail);

/* Set up per device attributes in /sys/bus/vmbus/devices/<bus device> */
static struct attribute *vmbus_attrs[] = {
	&dev_attr_id.attr,
	&dev_attr_state.attr,
	&dev_attr_monitor_id.attr,
	&dev_attr_class_id.attr,
	&dev_attr_device_id.attr,
	&dev_attr_modalias.attr,
	&dev_attr_server_monitor_pending.attr,
	&dev_attr_client_monitor_pending.attr,
	&dev_attr_server_monitor_latency.attr,
	&dev_attr_client_monitor_latency.attr,
	&dev_attr_server_monitor_conn_id.attr,
	&dev_attr_client_monitor_conn_id.attr,
	&dev_attr_out_intr_mask.attr,
	&dev_attr_out_read_index.attr,
	&dev_attr_out_write_index.attr,
	&dev_attr_out_read_bytes_avail.attr,
	&dev_attr_out_write_bytes_avail.attr,
	&dev_attr_in_intr_mask.attr,
	&dev_attr_in_read_index.attr,
	&dev_attr_in_write_index.attr,
	&dev_attr_in_read_bytes_avail.attr,
	&dev_attr_in_write_bytes_avail.attr,
	NULL,
};
ATTRIBUTE_GROUPS(vmbus);

/*
 * vmbus_uevent - add uevent for our device
 *
 * This routine is invoked when a device is added or removed on the vmbus to
 * generate a uevent to udev in the userspace. The udev will then look at its
 * rule and the uevent generated here to load the appropriate driver
 *
 * The alias string will be of the form vmbus:guid where guid is the string
 * representation of the device guid (each byte of the guid will be
 * represented with two hex characters.
 */
static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
{
	struct hv_device *dev = device_to_hv_device(device);
	int ret;
	char alias_name[VMBUS_ALIAS_LEN + 1];

	print_alias_name(dev, alias_name);
	ret = add_uevent_var(env, "MODALIAS=vmbus:%s", alias_name);
	return ret;
}

static uuid_le null_guid;

static inline bool is_null_guid(const __u8 *guid)
{
	if (memcmp(guid, &null_guid, sizeof(uuid_le)))
		return false;
	return true;
}

/*
 * Return a matching hv_vmbus_device_id pointer.
 * If there is no match, return NULL.
 */
static const struct hv_vmbus_device_id *hv_vmbus_get_id(
					const struct hv_vmbus_device_id *id,
					__u8 *guid)
{
	for (; !is_null_guid(id->guid); id++)
		if (!memcmp(&id->guid, guid, sizeof(uuid_le)))
			return id;

	return NULL;
}



/*
 * vmbus_match - Attempt to match the specified device to the specified driver
 */
static int vmbus_match(struct device *device, struct device_driver *driver)
{
	struct hv_driver *drv = drv_to_hv_drv(driver);
	struct hv_device *hv_dev = device_to_hv_device(device);

	if (hv_vmbus_get_id(drv->id_table, hv_dev->dev_type.b))
		return 1;

	return 0;
}

/*
 * vmbus_probe - Add the new vmbus's child device
 */
static int vmbus_probe(struct device *child_device)
{
	int ret = 0;
	struct hv_driver *drv =
			drv_to_hv_drv(child_device->driver);
	struct hv_device *dev = device_to_hv_device(child_device);
	const struct hv_vmbus_device_id *dev_id;

	dev_id = hv_vmbus_get_id(drv->id_table, dev->dev_type.b);
	if (drv->probe) {
		ret = drv->probe(dev, dev_id);
		if (ret != 0)
			pr_err("probe failed for device %s (%d)\n",
			       dev_name(child_device), ret);

	} else {
		pr_err("probe not set for driver %s\n",
		       dev_name(child_device));
		ret = -ENODEV;
	}
	return ret;
}

/*
 * vmbus_remove - Remove a vmbus device
 */
static int vmbus_remove(struct device *child_device)
{
	struct hv_driver *drv = drv_to_hv_drv(child_device->driver);
	struct hv_device *dev = device_to_hv_device(child_device);

	if (drv->remove)
		drv->remove(dev);
	else
		pr_err("remove not set for driver %s\n",
			dev_name(child_device));

	return 0;
}


/*
 * vmbus_shutdown - Shutdown a vmbus device
 */
static void vmbus_shutdown(struct device *child_device)
{
	struct hv_driver *drv;
	struct hv_device *dev = device_to_hv_device(child_device);


	/* The device may not be attached yet */
	if (!child_device->driver)
		return;

	drv = drv_to_hv_drv(child_device->driver);

	if (drv->shutdown)
		drv->shutdown(dev);

	return;
}


/*
 * vmbus_device_release - Final callback release of the vmbus child device
 */
static void vmbus_device_release(struct device *device)
{
	struct hv_device *hv_dev = device_to_hv_device(device);

	kfree(hv_dev);

}

/* The one and only one */
static struct bus_type  hv_bus = {
	.name =		"vmbus",
	.match =		vmbus_match,
	.shutdown =		vmbus_shutdown,
	.remove =		vmbus_remove,
	.probe =		vmbus_probe,
	.uevent =		vmbus_uevent,
	.dev_groups =		vmbus_groups,
};

static const char *driver_name = "hyperv";


struct onmessage_work_context {
	struct work_struct work;
	struct hv_message msg;
};

static void vmbus_onmessage_work(struct work_struct *work)
{
	struct onmessage_work_context *ctx;

	ctx = container_of(work, struct onmessage_work_context,
			   work);
	vmbus_onmessage(&ctx->msg);
	kfree(ctx);
}

static void vmbus_on_msg_dpc(unsigned long data)
{
	int cpu = smp_processor_id();
	void *page_addr = hv_context.synic_message_page[cpu];
	struct hv_message *msg = (struct hv_message *)page_addr +
				  VMBUS_MESSAGE_SINT;
	struct onmessage_work_context *ctx;

	while (1) {
		if (msg->header.message_type == HVMSG_NONE) {
			/* no msg */
			break;
		} else {
			ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
			if (ctx == NULL)
				continue;
			INIT_WORK(&ctx->work, vmbus_onmessage_work);
			memcpy(&ctx->msg, msg, sizeof(*msg));
			queue_work(vmbus_connection.work_queue, &ctx->work);
		}

		msg->header.message_type = HVMSG_NONE;

		/*
		 * Make sure the write to MessageType (ie set to
		 * HVMSG_NONE) happens before we read the
		 * MessagePending and EOMing. Otherwise, the EOMing
		 * will not deliver any more messages since there is
		 * no empty slot
		 */
		mb();

		if (msg->header.message_flags.msg_pending) {
			/*
			 * This will cause message queue rescan to
			 * possibly deliver another msg from the
			 * hypervisor
			 */
			wrmsrl(HV_X64_MSR_EOM, 0);
		}
	}
}

static irqreturn_t vmbus_isr(int irq, void *dev_id)
{
	int cpu = smp_processor_id();
	void *page_addr;
	struct hv_message *msg;
	union hv_synic_event_flags *event;
	bool handled = false;

	page_addr = hv_context.synic_event_page[cpu];
	if (page_addr == NULL)
		return IRQ_NONE;

	event = (union hv_synic_event_flags *)page_addr +
					 VMBUS_MESSAGE_SINT;
	/*
	 * Check for events before checking for messages. This is the order
	 * in which events and messages are checked in Windows guests on
	 * Hyper-V, and the Windows team suggested we do the same.
	 */

	if ((vmbus_proto_version == VERSION_WS2008) ||
		(vmbus_proto_version == VERSION_WIN7)) {

		/* Since we are a child, we only need to check bit 0 */
		if (sync_test_and_clear_bit(0,
			(unsigned long *) &event->flags32[0])) {
			handled = true;
		}
	} else {
		/*
		 * Our host is win8 or above. The signaling mechanism
		 * has changed and we can directly look at the event page.
		 * If bit n is set then we have an interrup on the channel
		 * whose id is n.
		 */
		handled = true;
	}

	if (handled)
		tasklet_schedule(hv_context.event_dpc[cpu]);


	page_addr = hv_context.synic_message_page[cpu];
	msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;

	/* Check if there are actual msgs to be processed */
	if (msg->header.message_type != HVMSG_NONE) {
		handled = true;
		tasklet_schedule(&msg_dpc);
	}

	if (handled)
		return IRQ_HANDLED;
	else
		return IRQ_NONE;
}

/*
 * vmbus interrupt flow handler:
 * vmbus interrupts can concurrently occur on multiple CPUs and
 * can be handled concurrently.
 */

static void vmbus_flow_handler(unsigned int irq, struct irq_desc *desc)
{
	kstat_incr_irqs_this_cpu(irq, desc);

	desc->action->handler(irq, desc->action->dev_id);
}

/*
 * vmbus_bus_init -Main vmbus driver initialization routine.
 *
 * Here, we
 *	- initialize the vmbus driver context
 *	- invoke the vmbus hv main init routine
 *	- get the irq resource
 *	- retrieve the channel offers
 */
static int vmbus_bus_init(int irq)
{
	int ret;

	/* Hypervisor initialization...setup hypercall page..etc */
	ret = hv_init();
	if (ret != 0) {
		pr_err("Unable to initialize the hypervisor - 0x%x\n", ret);
		return ret;
	}

	tasklet_init(&msg_dpc, vmbus_on_msg_dpc, 0);

	ret = bus_register(&hv_bus);
	if (ret)
		goto err_cleanup;

	ret = request_irq(irq, vmbus_isr, 0, driver_name, hv_acpi_dev);

	if (ret != 0) {
		pr_err("Unable to request IRQ %d\n",
			   irq);
		goto err_unregister;
	}

	/*
	 * Vmbus interrupts can be handled concurrently on
	 * different CPUs. Establish an appropriate interrupt flow
	 * handler that can support this model.
	 */
	irq_set_handler(irq, vmbus_flow_handler);

	/*
	 * Register our interrupt handler.
	 */
	hv_register_vmbus_handler(irq, vmbus_isr);

	ret = hv_synic_alloc();
	if (ret)
		goto err_alloc;
	/*
	 * Initialize the per-cpu interrupt state and
	 * connect to the host.
	 */
	on_each_cpu(hv_synic_init, NULL, 1);
	ret = vmbus_connect();
	if (ret)
		goto err_alloc;

	vmbus_request_offers();

	return 0;

err_alloc:
	hv_synic_free();
	free_irq(irq, hv_acpi_dev);

err_unregister:
	bus_unregister(&hv_bus);

err_cleanup:
	hv_cleanup();

	return ret;
}

/**
 * __vmbus_child_driver_register - Register a vmbus's driver
 * @drv: Pointer to driver structure you want to register
 * @owner: owner module of the drv
 * @mod_name: module name string
 *
 * Registers the given driver with Linux through the 'driver_register()' call
 * and sets up the hyper-v vmbus handling for this driver.
 * It will return the state of the 'driver_register()' call.
 *
 */
int __vmbus_driver_register(struct hv_driver *hv_driver, struct module *owner, const char *mod_name)
{
	int ret;

	pr_info("registering driver %s\n", hv_driver->name);

	ret = vmbus_exists();
	if (ret < 0)
		return ret;

	hv_driver->driver.name = hv_driver->name;
	hv_driver->driver.owner = owner;
	hv_driver->driver.mod_name = mod_name;
	hv_driver->driver.bus = &hv_bus;

	ret = driver_register(&hv_driver->driver);

	return ret;
}
EXPORT_SYMBOL_GPL(__vmbus_driver_register);

/**
 * vmbus_driver_unregister() - Unregister a vmbus's driver
 * @drv: Pointer to driver structure you want to un-register
 *
 * Un-register the given driver that was previous registered with a call to
 * vmbus_driver_register()
 */
void vmbus_driver_unregister(struct hv_driver *hv_driver)
{
	pr_info("unregistering driver %s\n", hv_driver->name);

	if (!vmbus_exists())
		driver_unregister(&hv_driver->driver);
}
EXPORT_SYMBOL_GPL(vmbus_driver_unregister);

/*
 * vmbus_device_create - Creates and registers a new child device
 * on the vmbus.
 */
struct hv_device *vmbus_device_create(uuid_le *type,
					    uuid_le *instance,
					    struct vmbus_channel *channel)
{
	struct hv_device *child_device_obj;

	child_device_obj = kzalloc(sizeof(struct hv_device), GFP_KERNEL);
	if (!child_device_obj) {
		pr_err("Unable to allocate device object for child device\n");
		return NULL;
	}

	child_device_obj->channel = channel;
	memcpy(&child_device_obj->dev_type, type, sizeof(uuid_le));
	memcpy(&child_device_obj->dev_instance, instance,
	       sizeof(uuid_le));


	return child_device_obj;
}

/*
 * vmbus_device_register - Register the child device
 */
int vmbus_device_register(struct hv_device *child_device_obj)
{
	int ret = 0;

	static atomic_t device_num = ATOMIC_INIT(0);

	dev_set_name(&child_device_obj->device, "vmbus_0_%d",
		     atomic_inc_return(&device_num));

	child_device_obj->device.bus = &hv_bus;
	child_device_obj->device.parent = &hv_acpi_dev->dev;
	child_device_obj->device.release = vmbus_device_release;

	/*
	 * Register with the LDM. This will kick off the driver/device
	 * binding...which will eventually call vmbus_match() and vmbus_probe()
	 */
	ret = device_register(&child_device_obj->device);

	if (ret)
		pr_err("Unable to register child device\n");
	else
		pr_debug("child device %s registered\n",
			dev_name(&child_device_obj->device));

	return ret;
}

/*
 * vmbus_device_unregister - Remove the specified child device
 * from the vmbus.
 */
void vmbus_device_unregister(struct hv_device *device_obj)
{
	pr_debug("child device %s unregistered\n",
		dev_name(&device_obj->device));

	/*
	 * Kick off the process of unregistering the device.
	 * This will call vmbus_remove() and eventually vmbus_device_release()
	 */
	device_unregister(&device_obj->device);
}


/*
 * VMBUS is an acpi enumerated device. Get the the IRQ information
 * from DSDT.
 */

static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *irq)
{

	if (res->type == ACPI_RESOURCE_TYPE_IRQ) {
		struct acpi_resource_irq *irqp;
		irqp = &res->data.irq;

		*((unsigned int *)irq) = irqp->interrupts[0];
	}

	return AE_OK;
}

static int vmbus_acpi_add(struct acpi_device *device)
{
	acpi_status result;

	hv_acpi_dev = device;

	result = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
					vmbus_walk_resources, &irq);

	if (ACPI_FAILURE(result)) {
		complete(&probe_event);
		return -ENODEV;
	}
	complete(&probe_event);
	return 0;
}

static const struct acpi_device_id vmbus_acpi_device_ids[] = {
	{"VMBUS", 0},
	{"VMBus", 0},
	{"", 0},
};
MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);

static struct acpi_driver vmbus_acpi_driver = {
	.name = "vmbus",
	.ids = vmbus_acpi_device_ids,
	.ops = {
		.add = vmbus_acpi_add,
	},
};

static int __init hv_acpi_init(void)
{
	int ret, t;

	if (x86_hyper != &x86_hyper_ms_hyperv)
		return -ENODEV;

	init_completion(&probe_event);

	/*
	 * Get irq resources first.
	 */

	ret = acpi_bus_register_driver(&vmbus_acpi_driver);

	if (ret)
		return ret;

	t = wait_for_completion_timeout(&probe_event, 5*HZ);
	if (t == 0) {
		ret = -ETIMEDOUT;
		goto cleanup;
	}

	if (irq <= 0) {
		ret = -ENODEV;
		goto cleanup;
	}

	ret = vmbus_bus_init(irq);
	if (ret)
		goto cleanup;

	return 0;

cleanup:
	acpi_bus_unregister_driver(&vmbus_acpi_driver);
	hv_acpi_dev = NULL;
	return ret;
}

static void __exit vmbus_exit(void)
{

	free_irq(irq, hv_acpi_dev);
	vmbus_free_channels();
	bus_unregister(&hv_bus);
	hv_cleanup();
	acpi_bus_unregister_driver(&vmbus_acpi_driver);
}


MODULE_LICENSE("GPL");

subsys_initcall(hv_acpi_init);
module_exit(vmbus_exit);