summaryrefslogtreecommitdiffstats
path: root/drivers/hv/hv_balloon.c
blob: bbc497373aaf21c392adcc760366116be50b82f6 (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
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
/*
 * Copyright (c) 2012, Microsoft Corporation.
 *
 * Author:
 *   K. Y. Srinivasan <kys@microsoft.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/mman.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/completion.h>
#include <linux/memory_hotplug.h>
#include <linux/memory.h>
#include <linux/notifier.h>
#include <linux/mman.h>
#include <linux/percpu_counter.h>

#include <linux/hyperv.h>

/*
 * We begin with definitions supporting the Dynamic Memory protocol
 * with the host.
 *
 * Begin protocol definitions.
 */



/*
 * Protocol versions. The low word is the minor version, the high word the major
 * version.
 *
 * History:
 * Initial version 1.0
 * Changed to 0.1 on 2009/03/25
 * Changes to 0.2 on 2009/05/14
 * Changes to 0.3 on 2009/12/03
 * Changed to 1.0 on 2011/04/05
 */

#define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor)))
#define DYNMEM_MAJOR_VERSION(Version) ((__u32)(Version) >> 16)
#define DYNMEM_MINOR_VERSION(Version) ((__u32)(Version) & 0xff)

enum {
	DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3),
	DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0),

	DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1,
	DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2,

	DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN8
};



/*
 * Message Types
 */

enum dm_message_type {
	/*
	 * Version 0.3
	 */
	DM_ERROR			= 0,
	DM_VERSION_REQUEST		= 1,
	DM_VERSION_RESPONSE		= 2,
	DM_CAPABILITIES_REPORT		= 3,
	DM_CAPABILITIES_RESPONSE	= 4,
	DM_STATUS_REPORT		= 5,
	DM_BALLOON_REQUEST		= 6,
	DM_BALLOON_RESPONSE		= 7,
	DM_UNBALLOON_REQUEST		= 8,
	DM_UNBALLOON_RESPONSE		= 9,
	DM_MEM_HOT_ADD_REQUEST		= 10,
	DM_MEM_HOT_ADD_RESPONSE		= 11,
	DM_VERSION_03_MAX		= 11,
	/*
	 * Version 1.0.
	 */
	DM_INFO_MESSAGE			= 12,
	DM_VERSION_1_MAX		= 12
};


/*
 * Structures defining the dynamic memory management
 * protocol.
 */

union dm_version {
	struct {
		__u16 minor_version;
		__u16 major_version;
	};
	__u32 version;
} __packed;


union dm_caps {
	struct {
		__u64 balloon:1;
		__u64 hot_add:1;
		__u64 reservedz:62;
	} cap_bits;
	__u64 caps;
} __packed;

union dm_mem_page_range {
	struct  {
		/*
		 * The PFN number of the first page in the range.
		 * 40 bits is the architectural limit of a PFN
		 * number for AMD64.
		 */
		__u64 start_page:40;
		/*
		 * The number of pages in the range.
		 */
		__u64 page_cnt:24;
	} finfo;
	__u64  page_range;
} __packed;



/*
 * The header for all dynamic memory messages:
 *
 * type: Type of the message.
 * size: Size of the message in bytes; including the header.
 * trans_id: The guest is responsible for manufacturing this ID.
 */

struct dm_header {
	__u16 type;
	__u16 size;
	__u32 trans_id;
} __packed;

/*
 * A generic message format for dynamic memory.
 * Specific message formats are defined later in the file.
 */

struct dm_message {
	struct dm_header hdr;
	__u8 data[]; /* enclosed message */
} __packed;


/*
 * Specific message types supporting the dynamic memory protocol.
 */

/*
 * Version negotiation message. Sent from the guest to the host.
 * The guest is free to try different versions until the host
 * accepts the version.
 *
 * dm_version: The protocol version requested.
 * is_last_attempt: If TRUE, this is the last version guest will request.
 * reservedz: Reserved field, set to zero.
 */

struct dm_version_request {
	struct dm_header hdr;
	union dm_version version;
	__u32 is_last_attempt:1;
	__u32 reservedz:31;
} __packed;

/*
 * Version response message; Host to Guest and indicates
 * if the host has accepted the version sent by the guest.
 *
 * is_accepted: If TRUE, host has accepted the version and the guest
 * should proceed to the next stage of the protocol. FALSE indicates that
 * guest should re-try with a different version.
 *
 * reservedz: Reserved field, set to zero.
 */

struct dm_version_response {
	struct dm_header hdr;
	__u64 is_accepted:1;
	__u64 reservedz:63;
} __packed;

/*
 * Message reporting capabilities. This is sent from the guest to the
 * host.
 */

struct dm_capabilities {
	struct dm_header hdr;
	union dm_caps caps;
	__u64 min_page_cnt;
	__u64 max_page_number;
} __packed;

/*
 * Response to the capabilities message. This is sent from the host to the
 * guest. This message notifies if the host has accepted the guest's
 * capabilities. If the host has not accepted, the guest must shutdown
 * the service.
 *
 * is_accepted: Indicates if the host has accepted guest's capabilities.
 * reservedz: Must be 0.
 */

struct dm_capabilities_resp_msg {
	struct dm_header hdr;
	__u64 is_accepted:1;
	__u64 reservedz:63;
} __packed;

/*
 * This message is used to report memory pressure from the guest.
 * This message is not part of any transaction and there is no
 * response to this message.
 *
 * num_avail: Available memory in pages.
 * num_committed: Committed memory in pages.
 * page_file_size: The accumulated size of all page files
 *		   in the system in pages.
 * zero_free: The nunber of zero and free pages.
 * page_file_writes: The writes to the page file in pages.
 * io_diff: An indicator of file cache efficiency or page file activity,
 *	    calculated as File Cache Page Fault Count - Page Read Count.
 *	    This value is in pages.
 *
 * Some of these metrics are Windows specific and fortunately
 * the algorithm on the host side that computes the guest memory
 * pressure only uses num_committed value.
 */

struct dm_status {
	struct dm_header hdr;
	__u64 num_avail;
	__u64 num_committed;
	__u64 page_file_size;
	__u64 zero_free;
	__u32 page_file_writes;
	__u32 io_diff;
} __packed;


/*
 * Message to ask the guest to allocate memory - balloon up message.
 * This message is sent from the host to the guest. The guest may not be
 * able to allocate as much memory as requested.
 *
 * num_pages: number of pages to allocate.
 */

struct dm_balloon {
	struct dm_header hdr;
	__u32 num_pages;
	__u32 reservedz;
} __packed;


/*
 * Balloon response message; this message is sent from the guest
 * to the host in response to the balloon message.
 *
 * reservedz: Reserved; must be set to zero.
 * more_pages: If FALSE, this is the last message of the transaction.
 * if TRUE there will atleast one more message from the guest.
 *
 * range_count: The number of ranges in the range array.
 *
 * range_array: An array of page ranges returned to the host.
 *
 */

struct dm_balloon_response {
	struct dm_header hdr;
	__u32 reservedz;
	__u32 more_pages:1;
	__u32 range_count:31;
	union dm_mem_page_range range_array[];
} __packed;

/*
 * Un-balloon message; this message is sent from the host
 * to the guest to give guest more memory.
 *
 * more_pages: If FALSE, this is the last message of the transaction.
 * if TRUE there will atleast one more message from the guest.
 *
 * reservedz: Reserved; must be set to zero.
 *
 * range_count: The number of ranges in the range array.
 *
 * range_array: An array of page ranges returned to the host.
 *
 */

struct dm_unballoon_request {
	struct dm_header hdr;
	__u32 more_pages:1;
	__u32 reservedz:31;
	__u32 range_count;
	union dm_mem_page_range range_array[];
} __packed;

/*
 * Un-balloon response message; this message is sent from the guest
 * to the host in response to an unballoon request.
 *
 */

struct dm_unballoon_response {
	struct dm_header hdr;
} __packed;


/*
 * Hot add request message. Message sent from the host to the guest.
 *
 * mem_range: Memory range to hot add.
 *
 * On Linux we currently don't support this since we cannot hot add
 * arbitrary granularity of memory.
 */

struct dm_hot_add {
	struct dm_header hdr;
	union dm_mem_page_range range;
} __packed;

/*
 * Hot add response message.
 * This message is sent by the guest to report the status of a hot add request.
 * If page_count is less than the requested page count, then the host should
 * assume all further hot add requests will fail, since this indicates that
 * the guest has hit an upper physical memory barrier.
 *
 * Hot adds may also fail due to low resources; in this case, the guest must
 * not complete this message until the hot add can succeed, and the host must
 * not send a new hot add request until the response is sent.
 * If VSC fails to hot add memory DYNMEM_NUMBER_OF_UNSUCCESSFUL_HOTADD_ATTEMPTS
 * times it fails the request.
 *
 *
 * page_count: number of pages that were successfully hot added.
 *
 * result: result of the operation 1: success, 0: failure.
 *
 */

struct dm_hot_add_response {
	struct dm_header hdr;
	__u32 page_count;
	__u32 result;
} __packed;

/*
 * Types of information sent from host to the guest.
 */

enum dm_info_type {
	INFO_TYPE_MAX_PAGE_CNT = 0,
	MAX_INFO_TYPE
};


/*
 * Header for the information message.
 */

struct dm_info_header {
	enum dm_info_type type;
	__u32 data_size;
} __packed;

/*
 * This message is sent from the host to the guest to pass
 * some relevant information (win8 addition).
 *
 * reserved: no used.
 * info_size: size of the information blob.
 * info: information blob.
 */

struct dm_info_msg {
	struct dm_info_header header;
	__u32 reserved;
	__u32 info_size;
	__u8  info[];
};

/*
 * End protocol definitions.
 */

static bool hot_add;
static bool do_hot_add;

module_param(hot_add, bool, (S_IRUGO | S_IWUSR));
MODULE_PARM_DESC(hot_add, "If set attempt memory hot_add");

static atomic_t trans_id = ATOMIC_INIT(0);

static int dm_ring_size = (5 * PAGE_SIZE);

/*
 * Driver specific state.
 */

enum hv_dm_state {
	DM_INITIALIZING = 0,
	DM_INITIALIZED,
	DM_BALLOON_UP,
	DM_BALLOON_DOWN,
	DM_HOT_ADD,
	DM_INIT_ERROR
};


static __u8 recv_buffer[PAGE_SIZE];
static __u8 *send_buffer;
#define PAGES_IN_2M	512

struct hv_dynmem_device {
	struct hv_device *dev;
	enum hv_dm_state state;
	struct completion host_event;
	struct completion config_event;

	/*
	 * Number of pages we have currently ballooned out.
	 */
	unsigned int num_pages_ballooned;

	/*
	 * This thread handles both balloon/hot-add
	 * requests from the host as well as notifying
	 * the host with regards to memory pressure in
	 * the guest.
	 */
	struct task_struct *thread;

	/*
	 * We start with the highest version we can support
	 * and downgrade based on the host; we save here the
	 * next version to try.
	 */
	__u32 next_version;
};

static struct hv_dynmem_device dm_device;

static void hot_add_req(struct hv_dynmem_device *dm, struct dm_hot_add *msg)
{

	struct dm_hot_add_response resp;

	if (do_hot_add) {

		pr_info("Memory hot add not supported\n");

		/*
		 * Currently we do not support hot add.
		 * Just fail the request.
		 */
	}

	memset(&resp, 0, sizeof(struct dm_hot_add_response));
	resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE;
	resp.hdr.size = sizeof(struct dm_hot_add_response);
	resp.hdr.trans_id = atomic_inc_return(&trans_id);

	resp.page_count = 0;
	resp.result = 0;

	dm->state = DM_INITIALIZED;
	vmbus_sendpacket(dm->dev->channel, &resp,
			sizeof(struct dm_hot_add_response),
			(unsigned long)NULL,
			VM_PKT_DATA_INBAND, 0);

}

static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
{
	switch (msg->header.type) {
	case INFO_TYPE_MAX_PAGE_CNT:
		pr_info("Received INFO_TYPE_MAX_PAGE_CNT\n");
		pr_info("Data Size is %d\n", msg->header.data_size);
		break;
	default:
		pr_info("Received Unknown type: %d\n", msg->header.type);
	}
}

/*
 * Post our status as it relates memory pressure to the
 * host. Host expects the guests to post this status
 * periodically at 1 second intervals.
 *
 * The metrics specified in this protocol are very Windows
 * specific and so we cook up numbers here to convey our memory
 * pressure.
 */

static void post_status(struct hv_dynmem_device *dm)
{
	struct dm_status status;


	memset(&status, 0, sizeof(struct dm_status));
	status.hdr.type = DM_STATUS_REPORT;
	status.hdr.size = sizeof(struct dm_status);
	status.hdr.trans_id = atomic_inc_return(&trans_id);


	status.num_committed = vm_memory_committed();

	vmbus_sendpacket(dm->dev->channel, &status,
				sizeof(struct dm_status),
				(unsigned long)NULL,
				VM_PKT_DATA_INBAND, 0);

}



void free_balloon_pages(struct hv_dynmem_device *dm,
			 union dm_mem_page_range *range_array)
{
	int num_pages = range_array->finfo.page_cnt;
	__u64 start_frame = range_array->finfo.start_page;
	struct page *pg;
	int i;

	for (i = 0; i < num_pages; i++) {
		pg = pfn_to_page(i + start_frame);
		__free_page(pg);
		dm->num_pages_ballooned--;
	}
}



static int  alloc_balloon_pages(struct hv_dynmem_device *dm, int num_pages,
			 struct dm_balloon_response *bl_resp, int alloc_unit,
			 bool *alloc_error)
{
	int i = 0;
	struct page *pg;

	if (num_pages < alloc_unit)
		return 0;

	for (i = 0; (i * alloc_unit) < num_pages; i++) {
		if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) >
			PAGE_SIZE)
			return i * alloc_unit;

		/*
		 * We execute this code in a thread context. Furthermore,
		 * we don't want the kernel to try too hard.
		 */
		pg = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
				__GFP_NOMEMALLOC | __GFP_NOWARN,
				get_order(alloc_unit << PAGE_SHIFT));

		if (!pg) {
			*alloc_error = true;
			return i * alloc_unit;
		}


		dm->num_pages_ballooned += alloc_unit;

		bl_resp->range_count++;
		bl_resp->range_array[i].finfo.start_page =
			page_to_pfn(pg);
		bl_resp->range_array[i].finfo.page_cnt = alloc_unit;
		bl_resp->hdr.size += sizeof(union dm_mem_page_range);

	}

	return num_pages;
}



static void balloon_up(struct hv_dynmem_device *dm, struct dm_balloon *req)
{
	int num_pages = req->num_pages;
	int num_ballooned = 0;
	struct dm_balloon_response *bl_resp;
	int alloc_unit;
	int ret;
	bool alloc_error = false;
	bool done = false;
	int i;


	/*
	 * Currently, we only support 4k allocations.
	 */
	alloc_unit = 1;

	while (!done) {
		bl_resp = (struct dm_balloon_response *)send_buffer;
		memset(send_buffer, 0, PAGE_SIZE);
		bl_resp->hdr.type = DM_BALLOON_RESPONSE;
		bl_resp->hdr.trans_id = atomic_inc_return(&trans_id);
		bl_resp->hdr.size = sizeof(struct dm_balloon_response);
		bl_resp->more_pages = 1;


		num_pages -= num_ballooned;
		num_ballooned = alloc_balloon_pages(dm, num_pages,
						bl_resp, alloc_unit,
						 &alloc_error);

		if ((alloc_error) || (num_ballooned == num_pages)) {
			bl_resp->more_pages = 0;
			done = true;
			dm->state = DM_INITIALIZED;
		}

		/*
		 * We are pushing a lot of data through the channel;
		 * deal with transient failures caused because of the
		 * lack of space in the ring buffer.
		 */

		do {
			ret = vmbus_sendpacket(dm_device.dev->channel,
						bl_resp,
						bl_resp->hdr.size,
						(unsigned long)NULL,
						VM_PKT_DATA_INBAND, 0);

			if (ret == -EAGAIN)
				msleep(20);

		} while (ret == -EAGAIN);

		if (ret) {
			/*
			 * Free up the memory we allocatted.
			 */
			pr_info("Balloon response failed\n");

			for (i = 0; i < bl_resp->range_count; i++)
				free_balloon_pages(dm,
						 &bl_resp->range_array[i]);

			done = true;
		}
	}

}

static void balloon_down(struct hv_dynmem_device *dm,
			struct dm_unballoon_request *req)
{
	union dm_mem_page_range *range_array = req->range_array;
	int range_count = req->range_count;
	struct dm_unballoon_response resp;
	int i;

	for (i = 0; i < range_count; i++)
		free_balloon_pages(dm, &range_array[i]);

	if (req->more_pages == 1)
		return;

	memset(&resp, 0, sizeof(struct dm_unballoon_response));
	resp.hdr.type = DM_UNBALLOON_RESPONSE;
	resp.hdr.trans_id = atomic_inc_return(&trans_id);
	resp.hdr.size = sizeof(struct dm_unballoon_response);

	vmbus_sendpacket(dm_device.dev->channel, &resp,
				sizeof(struct dm_unballoon_response),
				(unsigned long)NULL,
				VM_PKT_DATA_INBAND, 0);

	dm->state = DM_INITIALIZED;
}

static void balloon_onchannelcallback(void *context);

static int dm_thread_func(void *dm_dev)
{
	struct hv_dynmem_device *dm = dm_dev;
	int t;
	unsigned long  scan_start;

	while (!kthread_should_stop()) {
		t = wait_for_completion_timeout(&dm_device.config_event, 1*HZ);
		/*
		 * The host expects us to post information on the memory
		 * pressure every second.
		 */

		if (t == 0)
			post_status(dm);

		scan_start = jiffies;
		switch (dm->state) {
		case DM_BALLOON_UP:
			balloon_up(dm, (struct dm_balloon *)recv_buffer);
			break;

		case DM_HOT_ADD:
			hot_add_req(dm, (struct dm_hot_add *)recv_buffer);
			break;
		default:
			break;
		}

		if (!time_in_range(jiffies, scan_start, scan_start + HZ))
			post_status(dm);

	}

	return 0;
}


static void version_resp(struct hv_dynmem_device *dm,
			struct dm_version_response *vresp)
{
	struct dm_version_request version_req;
	int ret;

	if (vresp->is_accepted) {
		/*
		 * We are done; wakeup the
		 * context waiting for version
		 * negotiation.
		 */
		complete(&dm->host_event);
		return;
	}
	/*
	 * If there are more versions to try, continue
	 * with negotiations; if not
	 * shutdown the service since we are not able
	 * to negotiate a suitable version number
	 * with the host.
	 */
	if (dm->next_version == 0)
		goto version_error;

	dm->next_version = 0;
	memset(&version_req, 0, sizeof(struct dm_version_request));
	version_req.hdr.type = DM_VERSION_REQUEST;
	version_req.hdr.size = sizeof(struct dm_version_request);
	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN7;
	version_req.is_last_attempt = 1;

	ret = vmbus_sendpacket(dm->dev->channel, &version_req,
				sizeof(struct dm_version_request),
				(unsigned long)NULL,
				VM_PKT_DATA_INBAND, 0);

	if (ret)
		goto version_error;

	return;

version_error:
	dm->state = DM_INIT_ERROR;
	complete(&dm->host_event);
}

static void cap_resp(struct hv_dynmem_device *dm,
			struct dm_capabilities_resp_msg *cap_resp)
{
	if (!cap_resp->is_accepted) {
		pr_info("Capabilities not accepted by host\n");
		dm->state = DM_INIT_ERROR;
	}
	complete(&dm->host_event);
}

static void balloon_onchannelcallback(void *context)
{
	struct hv_device *dev = context;
	u32 recvlen;
	u64 requestid;
	struct dm_message *dm_msg;
	struct dm_header *dm_hdr;
	struct hv_dynmem_device *dm = hv_get_drvdata(dev);

	memset(recv_buffer, 0, sizeof(recv_buffer));
	vmbus_recvpacket(dev->channel, recv_buffer,
			 PAGE_SIZE, &recvlen, &requestid);

	if (recvlen > 0) {
		dm_msg = (struct dm_message *)recv_buffer;
		dm_hdr = &dm_msg->hdr;

		switch (dm_hdr->type) {
		case DM_VERSION_RESPONSE:
			version_resp(dm,
				 (struct dm_version_response *)dm_msg);
			break;

		case DM_CAPABILITIES_RESPONSE:
			cap_resp(dm,
				 (struct dm_capabilities_resp_msg *)dm_msg);
			break;

		case DM_BALLOON_REQUEST:
			dm->state = DM_BALLOON_UP;
			complete(&dm->config_event);
			break;

		case DM_UNBALLOON_REQUEST:
			dm->state = DM_BALLOON_DOWN;
			balloon_down(dm,
				 (struct dm_unballoon_request *)recv_buffer);
			break;

		case DM_MEM_HOT_ADD_REQUEST:
			dm->state = DM_HOT_ADD;
			complete(&dm->config_event);
			break;

		case DM_INFO_MESSAGE:
			process_info(dm, (struct dm_info_msg *)dm_msg);
			break;

		default:
			pr_err("Unhandled message: type: %d\n", dm_hdr->type);

		}
	}

}

static int balloon_probe(struct hv_device *dev,
			const struct hv_vmbus_device_id *dev_id)
{
	int ret, t;
	struct dm_version_request version_req;
	struct dm_capabilities cap_msg;

	do_hot_add = hot_add;

	/*
	 * First allocate a send buffer.
	 */

	send_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!send_buffer)
		return -ENOMEM;

	ret = vmbus_open(dev->channel, dm_ring_size, dm_ring_size, NULL, 0,
			balloon_onchannelcallback, dev);

	if (ret)
		return ret;

	dm_device.dev = dev;
	dm_device.state = DM_INITIALIZING;
	dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
	init_completion(&dm_device.host_event);
	init_completion(&dm_device.config_event);

	dm_device.thread =
		 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
	if (IS_ERR(dm_device.thread)) {
		ret = PTR_ERR(dm_device.thread);
		goto probe_error0;
	}

	hv_set_drvdata(dev, &dm_device);
	/*
	 * Initiate the hand shake with the host and negotiate
	 * a version that the host can support. We start with the
	 * highest version number and go down if the host cannot
	 * support it.
	 */
	memset(&version_req, 0, sizeof(struct dm_version_request));
	version_req.hdr.type = DM_VERSION_REQUEST;
	version_req.hdr.size = sizeof(struct dm_version_request);
	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN8;
	version_req.is_last_attempt = 0;

	ret = vmbus_sendpacket(dev->channel, &version_req,
				sizeof(struct dm_version_request),
				(unsigned long)NULL,
				VM_PKT_DATA_INBAND,
				VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
	if (ret)
		goto probe_error1;

	t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
	if (t == 0) {
		ret = -ETIMEDOUT;
		goto probe_error1;
	}

	/*
	 * If we could not negotiate a compatible version with the host
	 * fail the probe function.
	 */
	if (dm_device.state == DM_INIT_ERROR) {
		ret = -ETIMEDOUT;
		goto probe_error1;
	}
	/*
	 * Now submit our capabilities to the host.
	 */
	memset(&cap_msg, 0, sizeof(struct dm_capabilities));
	cap_msg.hdr.type = DM_CAPABILITIES_REPORT;
	cap_msg.hdr.size = sizeof(struct dm_capabilities);
	cap_msg.hdr.trans_id = atomic_inc_return(&trans_id);

	cap_msg.caps.cap_bits.balloon = 1;
	/*
	 * While we currently don't support hot-add,
	 * we still advertise this capability since the
	 * host requires that guests partcipating in the
	 * dynamic memory protocol support hot add.
	 */
	cap_msg.caps.cap_bits.hot_add = 1;

	/*
	 * Currently the host does not use these
	 * values and we set them to what is done in the
	 * Windows driver.
	 */
	cap_msg.min_page_cnt = 0;
	cap_msg.max_page_number = -1;

	ret = vmbus_sendpacket(dev->channel, &cap_msg,
				sizeof(struct dm_capabilities),
				(unsigned long)NULL,
				VM_PKT_DATA_INBAND,
				VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
	if (ret)
		goto probe_error1;

	t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
	if (t == 0) {
		ret = -ETIMEDOUT;
		goto probe_error1;
	}

	/*
	 * If the host does not like our capabilities,
	 * fail the probe function.
	 */
	if (dm_device.state == DM_INIT_ERROR) {
		ret = -ETIMEDOUT;
		goto probe_error1;
	}

	dm_device.state = DM_INITIALIZED;

	return 0;

probe_error1:
	kthread_stop(dm_device.thread);

probe_error0:
	vmbus_close(dev->channel);
	return ret;
}

static int balloon_remove(struct hv_device *dev)
{
	struct hv_dynmem_device *dm = hv_get_drvdata(dev);

	if (dm->num_pages_ballooned != 0)
		pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned);

	vmbus_close(dev->channel);
	kthread_stop(dm->thread);

	return 0;
}

static const struct hv_vmbus_device_id id_table[] = {
	/* Dynamic Memory Class ID */
	/* 525074DC-8985-46e2-8057-A307DC18A502 */
	{ VMBUS_DEVICE(0xdc, 0x74, 0x50, 0X52, 0x85, 0x89, 0xe2, 0x46,
		       0x80, 0x57, 0xa3, 0x07, 0xdc, 0x18, 0xa5, 0x02)
	},
	{ },
};

MODULE_DEVICE_TABLE(vmbus, id_table);

static  struct hv_driver balloon_drv = {
	.name = "hv_balloon",
	.id_table = id_table,
	.probe =  balloon_probe,
	.remove =  balloon_remove,
};

static int __init init_balloon_drv(void)
{

	return vmbus_driver_register(&balloon_drv);
}

static void exit_balloon_drv(void)
{

	vmbus_driver_unregister(&balloon_drv);
}

module_init(init_balloon_drv);
module_exit(exit_balloon_drv);

MODULE_DESCRIPTION("Hyper-V Balloon");
MODULE_VERSION(HV_DRV_VERSION);
MODULE_LICENSE("GPL");