aboutsummaryrefslogtreecommitdiff
path: root/drivers/net/hyperv/netvsc.c
blob: 2b0480416b31a2586afd0467ab539e1065caeb5b (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
/*
 * 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>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/if_ether.h>

#include "hyperv_net.h"


static struct netvsc_device *alloc_net_device(struct hv_device *device)
{
	struct netvsc_device *net_device;
	struct net_device *ndev = hv_get_drvdata(device);

	net_device = kzalloc(sizeof(struct netvsc_device), GFP_KERNEL);
	if (!net_device)
		return NULL;

	init_waitqueue_head(&net_device->wait_drain);
	net_device->start_remove = false;
	net_device->destroy = false;
	net_device->dev = device;
	net_device->ndev = ndev;

	hv_set_drvdata(device, net_device);
	return net_device;
}

static struct netvsc_device *get_outbound_net_device(struct hv_device *device)
{
	struct netvsc_device *net_device;

	net_device = hv_get_drvdata(device);
	if (net_device && net_device->destroy)
		net_device = NULL;

	return net_device;
}

static struct netvsc_device *get_inbound_net_device(struct hv_device *device)
{
	struct netvsc_device *net_device;

	net_device = hv_get_drvdata(device);

	if (!net_device)
		goto get_in_err;

	if (net_device->destroy &&
		atomic_read(&net_device->num_outstanding_sends) == 0)
		net_device = NULL;

get_in_err:
	return net_device;
}


static int netvsc_destroy_recv_buf(struct netvsc_device *net_device)
{
	struct nvsp_message *revoke_packet;
	int ret = 0;
	struct net_device *ndev = net_device->ndev;

	/*
	 * If we got a section count, it means we received a
	 * SendReceiveBufferComplete msg (ie sent
	 * NvspMessage1TypeSendReceiveBuffer msg) therefore, we need
	 * to send a revoke msg here
	 */
	if (net_device->recv_section_cnt) {
		/* Send the revoke receive buffer */
		revoke_packet = &net_device->revoke_packet;
		memset(revoke_packet, 0, sizeof(struct nvsp_message));

		revoke_packet->hdr.msg_type =
			NVSP_MSG1_TYPE_REVOKE_RECV_BUF;
		revoke_packet->msg.v1_msg.
		revoke_recv_buf.id = NETVSC_RECEIVE_BUFFER_ID;

		ret = vmbus_sendpacket(net_device->dev->channel,
				       revoke_packet,
				       sizeof(struct nvsp_message),
				       (unsigned long)revoke_packet,
				       VM_PKT_DATA_INBAND, 0);
		/*
		 * If we failed here, we might as well return and
		 * have a leak rather than continue and a bugchk
		 */
		if (ret != 0) {
			netdev_err(ndev, "unable to send "
				"revoke receive buffer to netvsp\n");
			return ret;
		}
	}

	/* Teardown the gpadl on the vsp end */
	if (net_device->recv_buf_gpadl_handle) {
		ret = vmbus_teardown_gpadl(net_device->dev->channel,
			   net_device->recv_buf_gpadl_handle);

		/* If we failed here, we might as well return and have a leak
		 * rather than continue and a bugchk
		 */
		if (ret != 0) {
			netdev_err(ndev,
				   "unable to teardown receive buffer's gpadl\n");
			return ret;
		}
		net_device->recv_buf_gpadl_handle = 0;
	}

	if (net_device->recv_buf) {
		/* Free up the receive buffer */
		free_pages((unsigned long)net_device->recv_buf,
			get_order(net_device->recv_buf_size));
		net_device->recv_buf = NULL;
	}

	if (net_device->recv_section) {
		net_device->recv_section_cnt = 0;
		kfree(net_device->recv_section);
		net_device->recv_section = NULL;
	}

	return ret;
}

static int netvsc_init_recv_buf(struct hv_device *device)
{
	int ret = 0;
	int t;
	struct netvsc_device *net_device;
	struct nvsp_message *init_packet;
	struct net_device *ndev;

	net_device = get_outbound_net_device(device);
	if (!net_device)
		return -ENODEV;
	ndev = net_device->ndev;

	net_device->recv_buf =
		(void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
				get_order(net_device->recv_buf_size));
	if (!net_device->recv_buf) {
		netdev_err(ndev, "unable to allocate receive "
			"buffer of size %d\n", net_device->recv_buf_size);
		ret = -ENOMEM;
		goto cleanup;
	}

	/*
	 * Establish the gpadl handle for this buffer on this
	 * channel.  Note: This call uses the vmbus connection rather
	 * than the channel to establish the gpadl handle.
	 */
	ret = vmbus_establish_gpadl(device->channel, net_device->recv_buf,
				    net_device->recv_buf_size,
				    &net_device->recv_buf_gpadl_handle);
	if (ret != 0) {
		netdev_err(ndev,
			"unable to establish receive buffer's gpadl\n");
		goto cleanup;
	}


	/* Notify the NetVsp of the gpadl handle */
	init_packet = &net_device->channel_init_pkt;

	memset(init_packet, 0, sizeof(struct nvsp_message));

	init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_RECV_BUF;
	init_packet->msg.v1_msg.send_recv_buf.
		gpadl_handle = net_device->recv_buf_gpadl_handle;
	init_packet->msg.v1_msg.
		send_recv_buf.id = NETVSC_RECEIVE_BUFFER_ID;

	/* Send the gpadl notification request */
	ret = vmbus_sendpacket(device->channel, init_packet,
			       sizeof(struct nvsp_message),
			       (unsigned long)init_packet,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
	if (ret != 0) {
		netdev_err(ndev,
			"unable to send receive buffer's gpadl to netvsp\n");
		goto cleanup;
	}

	t = wait_for_completion_timeout(&net_device->channel_init_wait, 5*HZ);
	BUG_ON(t == 0);


	/* Check the response */
	if (init_packet->msg.v1_msg.
	    send_recv_buf_complete.status != NVSP_STAT_SUCCESS) {
		netdev_err(ndev, "Unable to complete receive buffer "
			   "initialization with NetVsp - status %d\n",
			   init_packet->msg.v1_msg.
			   send_recv_buf_complete.status);
		ret = -EINVAL;
		goto cleanup;
	}

	/* Parse the response */

	net_device->recv_section_cnt = init_packet->msg.
		v1_msg.send_recv_buf_complete.num_sections;

	net_device->recv_section = kmemdup(
		init_packet->msg.v1_msg.send_recv_buf_complete.sections,
		net_device->recv_section_cnt *
		sizeof(struct nvsp_1_receive_buffer_section),
		GFP_KERNEL);
	if (net_device->recv_section == NULL) {
		ret = -EINVAL;
		goto cleanup;
	}

	/*
	 * For 1st release, there should only be 1 section that represents the
	 * entire receive buffer
	 */
	if (net_device->recv_section_cnt != 1 ||
	    net_device->recv_section->offset != 0) {
		ret = -EINVAL;
		goto cleanup;
	}

	goto exit;

cleanup:
	netvsc_destroy_recv_buf(net_device);

exit:
	return ret;
}


/* Negotiate NVSP protocol version */
static int negotiate_nvsp_ver(struct hv_device *device,
			      struct netvsc_device *net_device,
			      struct nvsp_message *init_packet,
			      u32 nvsp_ver)
{
	int ret, t;

	memset(init_packet, 0, sizeof(struct nvsp_message));
	init_packet->hdr.msg_type = NVSP_MSG_TYPE_INIT;
	init_packet->msg.init_msg.init.min_protocol_ver = nvsp_ver;
	init_packet->msg.init_msg.init.max_protocol_ver = nvsp_ver;

	/* Send the init request */
	ret = vmbus_sendpacket(device->channel, init_packet,
			       sizeof(struct nvsp_message),
			       (unsigned long)init_packet,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

	if (ret != 0)
		return ret;

	t = wait_for_completion_timeout(&net_device->channel_init_wait, 5*HZ);

	if (t == 0)
		return -ETIMEDOUT;

	if (init_packet->msg.init_msg.init_complete.status !=
	    NVSP_STAT_SUCCESS)
		return -EINVAL;

	if (nvsp_ver != NVSP_PROTOCOL_VERSION_2)
		return 0;

	/* NVSPv2 only: Send NDIS config */
	memset(init_packet, 0, sizeof(struct nvsp_message));
	init_packet->hdr.msg_type = NVSP_MSG2_TYPE_SEND_NDIS_CONFIG;
	init_packet->msg.v2_msg.send_ndis_config.mtu = net_device->ndev->mtu;
	init_packet->msg.v2_msg.send_ndis_config.capability.ieee8021q = 1;

	ret = vmbus_sendpacket(device->channel, init_packet,
				sizeof(struct nvsp_message),
				(unsigned long)init_packet,
				VM_PKT_DATA_INBAND, 0);

	return ret;
}

static int netvsc_connect_vsp(struct hv_device *device)
{
	int ret;
	struct netvsc_device *net_device;
	struct nvsp_message *init_packet;
	int ndis_version;
	struct net_device *ndev;

	net_device = get_outbound_net_device(device);
	if (!net_device)
		return -ENODEV;
	ndev = net_device->ndev;

	init_packet = &net_device->channel_init_pkt;

	/* Negotiate the latest NVSP protocol supported */
	if (negotiate_nvsp_ver(device, net_device, init_packet,
			       NVSP_PROTOCOL_VERSION_2) == 0) {
		net_device->nvsp_version = NVSP_PROTOCOL_VERSION_2;
	} else if (negotiate_nvsp_ver(device, net_device, init_packet,
				    NVSP_PROTOCOL_VERSION_1) == 0) {
		net_device->nvsp_version = NVSP_PROTOCOL_VERSION_1;
	} else {
		ret = -EPROTO;
		goto cleanup;
	}

	pr_debug("Negotiated NVSP version:%x\n", net_device->nvsp_version);

	/* Send the ndis version */
	memset(init_packet, 0, sizeof(struct nvsp_message));

	ndis_version = 0x00050001;

	init_packet->hdr.msg_type = NVSP_MSG1_TYPE_SEND_NDIS_VER;
	init_packet->msg.v1_msg.
		send_ndis_ver.ndis_major_ver =
				(ndis_version & 0xFFFF0000) >> 16;
	init_packet->msg.v1_msg.
		send_ndis_ver.ndis_minor_ver =
				ndis_version & 0xFFFF;

	/* Send the init request */
	ret = vmbus_sendpacket(device->channel, init_packet,
				sizeof(struct nvsp_message),
				(unsigned long)init_packet,
				VM_PKT_DATA_INBAND, 0);
	if (ret != 0)
		goto cleanup;

	/* Post the big receive buffer to NetVSP */
	ret = netvsc_init_recv_buf(device);

cleanup:
	return ret;
}

static void netvsc_disconnect_vsp(struct netvsc_device *net_device)
{
	netvsc_destroy_recv_buf(net_device);
}

/*
 * netvsc_device_remove - Callback when the root bus device is removed
 */
int netvsc_device_remove(struct hv_device *device)
{
	struct netvsc_device *net_device;
	struct hv_netvsc_packet *netvsc_packet, *pos;
	unsigned long flags;

	net_device = hv_get_drvdata(device);

	netvsc_disconnect_vsp(net_device);

	/*
	 * Since we have already drained, we don't need to busy wait
	 * as was done in final_release_stor_device()
	 * Note that we cannot set the ext pointer to NULL until
	 * we have drained - to drain the outgoing packets, we need to
	 * allow incoming packets.
	 */

	spin_lock_irqsave(&device->channel->inbound_lock, flags);
	hv_set_drvdata(device, NULL);
	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);

	/*
	 * At this point, no one should be accessing net_device
	 * except in here
	 */
	dev_notice(&device->device, "net device safe to remove\n");

	/* Now, we can close the channel safely */
	vmbus_close(device->channel);

	/* Release all resources */
	list_for_each_entry_safe(netvsc_packet, pos,
				 &net_device->recv_pkt_list, list_ent) {
		list_del(&netvsc_packet->list_ent);
		kfree(netvsc_packet);
	}

	kfree(net_device);
	return 0;
}


#define RING_AVAIL_PERCENT_HIWATER 20
#define RING_AVAIL_PERCENT_LOWATER 10

/*
 * Get the percentage of available bytes to write in the ring.
 * The return value is in range from 0 to 100.
 */
static inline u32 hv_ringbuf_avail_percent(
		struct hv_ring_buffer_info *ring_info)
{
	u32 avail_read, avail_write;

	hv_get_ringbuffer_availbytes(ring_info, &avail_read, &avail_write);

	return avail_write * 100 / ring_info->ring_datasize;
}

static void netvsc_send_completion(struct hv_device *device,
				   struct vmpacket_descriptor *packet)
{
	struct netvsc_device *net_device;
	struct nvsp_message *nvsp_packet;
	struct hv_netvsc_packet *nvsc_packet;
	struct net_device *ndev;

	net_device = get_inbound_net_device(device);
	if (!net_device)
		return;
	ndev = net_device->ndev;

	nvsp_packet = (struct nvsp_message *)((unsigned long)packet +
			(packet->offset8 << 3));

	if ((nvsp_packet->hdr.msg_type == NVSP_MSG_TYPE_INIT_COMPLETE) ||
	    (nvsp_packet->hdr.msg_type ==
	     NVSP_MSG1_TYPE_SEND_RECV_BUF_COMPLETE) ||
	    (nvsp_packet->hdr.msg_type ==
	     NVSP_MSG1_TYPE_SEND_SEND_BUF_COMPLETE)) {
		/* Copy the response back */
		memcpy(&net_device->channel_init_pkt, nvsp_packet,
		       sizeof(struct nvsp_message));
		complete(&net_device->channel_init_wait);
	} else if (nvsp_packet->hdr.msg_type ==
		   NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE) {
		int num_outstanding_sends;

		/* Get the send context */
		nvsc_packet = (struct hv_netvsc_packet *)(unsigned long)
			packet->trans_id;

		/* Notify the layer above us */
		if (nvsc_packet)
			nvsc_packet->completion.send.send_completion(
				nvsc_packet->completion.send.
				send_completion_ctx);

		num_outstanding_sends =
			atomic_dec_return(&net_device->num_outstanding_sends);

		if (net_device->destroy && num_outstanding_sends == 0)
			wake_up(&net_device->wait_drain);

		if (netif_queue_stopped(ndev) && !net_device->start_remove &&
			(hv_ringbuf_avail_percent(&device->channel->outbound)
			> RING_AVAIL_PERCENT_HIWATER ||
			num_outstanding_sends < 1))
				netif_wake_queue(ndev);
	} else {
		netdev_err(ndev, "Unknown send completion packet type- "
			   "%d received!!\n", nvsp_packet->hdr.msg_type);
	}

}

int netvsc_send(struct hv_device *device,
			struct hv_netvsc_packet *packet)
{
	struct netvsc_device *net_device;
	int ret = 0;
	struct nvsp_message sendMessage;
	struct net_device *ndev;
	u64 req_id;

	net_device = get_outbound_net_device(device);
	if (!net_device)
		return -ENODEV;
	ndev = net_device->ndev;

	sendMessage.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT;
	if (packet->is_data_pkt) {
		/* 0 is RMC_DATA; */
		sendMessage.msg.v1_msg.send_rndis_pkt.channel_type = 0;
	} else {
		/* 1 is RMC_CONTROL; */
		sendMessage.msg.v1_msg.send_rndis_pkt.channel_type = 1;
	}

	/* Not using send buffer section */
	sendMessage.msg.v1_msg.send_rndis_pkt.send_buf_section_index =
		0xFFFFFFFF;
	sendMessage.msg.v1_msg.send_rndis_pkt.send_buf_section_size = 0;

	if (packet->completion.send.send_completion)
		req_id = (ulong)packet;
	else
		req_id = 0;

	if (packet->page_buf_cnt) {
		ret = vmbus_sendpacket_pagebuffer(device->channel,
						  packet->page_buf,
						  packet->page_buf_cnt,
						  &sendMessage,
						  sizeof(struct nvsp_message),
						  req_id);
	} else {
		ret = vmbus_sendpacket(device->channel, &sendMessage,
				sizeof(struct nvsp_message),
				req_id,
				VM_PKT_DATA_INBAND,
				VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
	}

	if (ret == 0) {
		atomic_inc(&net_device->num_outstanding_sends);
		if (hv_ringbuf_avail_percent(&device->channel->outbound) <
			RING_AVAIL_PERCENT_LOWATER) {
			netif_stop_queue(ndev);
			if (atomic_read(&net_device->
				num_outstanding_sends) < 1)
				netif_wake_queue(ndev);
		}
	} else if (ret == -EAGAIN) {
		netif_stop_queue(ndev);
		if (atomic_read(&net_device->num_outstanding_sends) < 1) {
			netif_wake_queue(ndev);
			ret = -ENOSPC;
		}
	} else {
		netdev_err(ndev, "Unable to send packet %p ret %d\n",
			   packet, ret);
	}

	return ret;
}

static void netvsc_send_recv_completion(struct hv_device *device,
					u64 transaction_id, u32 status)
{
	struct nvsp_message recvcompMessage;
	int retries = 0;
	int ret;
	struct net_device *ndev;
	struct netvsc_device *net_device = hv_get_drvdata(device);

	ndev = net_device->ndev;

	recvcompMessage.hdr.msg_type =
				NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE;

	recvcompMessage.msg.v1_msg.send_rndis_pkt_complete.status = status;

retry_send_cmplt:
	/* Send the completion */
	ret = vmbus_sendpacket(device->channel, &recvcompMessage,
			       sizeof(struct nvsp_message), transaction_id,
			       VM_PKT_COMP, 0);
	if (ret == 0) {
		/* success */
		/* no-op */
	} else if (ret == -EAGAIN) {
		/* no more room...wait a bit and attempt to retry 3 times */
		retries++;
		netdev_err(ndev, "unable to send receive completion pkt"
			" (tid %llx)...retrying %d\n", transaction_id, retries);

		if (retries < 4) {
			udelay(100);
			goto retry_send_cmplt;
		} else {
			netdev_err(ndev, "unable to send receive "
				"completion pkt (tid %llx)...give up retrying\n",
				transaction_id);
		}
	} else {
		netdev_err(ndev, "unable to send receive "
			"completion pkt - %llx\n", transaction_id);
	}
}

/* Send a receive completion packet to RNDIS device (ie NetVsp) */
static void netvsc_receive_completion(void *context)
{
	struct hv_netvsc_packet *packet = context;
	struct hv_device *device = packet->device;
	struct netvsc_device *net_device;
	u64 transaction_id = 0;
	bool fsend_receive_comp = false;
	unsigned long flags;
	struct net_device *ndev;
	u32 status = NVSP_STAT_NONE;

	/*
	 * Even though it seems logical to do a GetOutboundNetDevice() here to
	 * send out receive completion, we are using GetInboundNetDevice()
	 * since we may have disable outbound traffic already.
	 */
	net_device = get_inbound_net_device(device);
	if (!net_device)
		return;
	ndev = net_device->ndev;

	/* Overloading use of the lock. */
	spin_lock_irqsave(&net_device->recv_pkt_list_lock, flags);

	if (packet->status != NVSP_STAT_SUCCESS)
		packet->xfer_page_pkt->status = NVSP_STAT_FAIL;

	packet->xfer_page_pkt->count--;

	/*
	 * Last one in the line that represent 1 xfer page packet.
	 * Return the xfer page packet itself to the freelist
	 */
	if (packet->xfer_page_pkt->count == 0) {
		fsend_receive_comp = true;
		transaction_id = packet->completion.recv.recv_completion_tid;
		status = packet->xfer_page_pkt->status;
		list_add_tail(&packet->xfer_page_pkt->list_ent,
			      &net_device->recv_pkt_list);

	}

	/* Put the packet back */
	list_add_tail(&packet->list_ent, &net_device->recv_pkt_list);
	spin_unlock_irqrestore(&net_device->recv_pkt_list_lock, flags);

	/* Send a receive completion for the xfer page packet */
	if (fsend_receive_comp)
		netvsc_send_recv_completion(device, transaction_id, status);

}

static void netvsc_receive(struct hv_device *device,
			    struct vmpacket_descriptor *packet)
{
	struct netvsc_device *net_device;
	struct vmtransfer_page_packet_header *vmxferpage_packet;
	struct nvsp_message *nvsp_packet;
	struct hv_netvsc_packet *netvsc_packet = NULL;
	/* struct netvsc_driver *netvscDriver; */
	struct xferpage_packet *xferpage_packet = NULL;
	int i;
	int count = 0;
	unsigned long flags;
	struct net_device *ndev;

	LIST_HEAD(listHead);

	net_device = get_inbound_net_device(device);
	if (!net_device)
		return;
	ndev = net_device->ndev;

	/*
	 * All inbound packets other than send completion should be xfer page
	 * packet
	 */
	if (packet->type != VM_PKT_DATA_USING_XFER_PAGES) {
		netdev_err(ndev, "Unknown packet type received - %d\n",
			   packet->type);
		return;
	}

	nvsp_packet = (struct nvsp_message *)((unsigned long)packet +
			(packet->offset8 << 3));

	/* Make sure this is a valid nvsp packet */
	if (nvsp_packet->hdr.msg_type !=
	    NVSP_MSG1_TYPE_SEND_RNDIS_PKT) {
		netdev_err(ndev, "Unknown nvsp packet type received-"
			" %d\n", nvsp_packet->hdr.msg_type);
		return;
	}

	vmxferpage_packet = (struct vmtransfer_page_packet_header *)packet;

	if (vmxferpage_packet->xfer_pageset_id != NETVSC_RECEIVE_BUFFER_ID) {
		netdev_err(ndev, "Invalid xfer page set id - "
			   "expecting %x got %x\n", NETVSC_RECEIVE_BUFFER_ID,
			   vmxferpage_packet->xfer_pageset_id);
		return;
	}

	/*
	 * Grab free packets (range count + 1) to represent this xfer
	 * page packet. +1 to represent the xfer page packet itself.
	 * We grab it here so that we know exactly how many we can
	 * fulfil
	 */
	spin_lock_irqsave(&net_device->recv_pkt_list_lock, flags);
	while (!list_empty(&net_device->recv_pkt_list)) {
		list_move_tail(net_device->recv_pkt_list.next, &listHead);
		if (++count == vmxferpage_packet->range_cnt + 1)
			break;
	}
	spin_unlock_irqrestore(&net_device->recv_pkt_list_lock, flags);

	/*
	 * We need at least 2 netvsc pkts (1 to represent the xfer
	 * page and at least 1 for the range) i.e. we can handled
	 * some of the xfer page packet ranges...
	 */
	if (count < 2) {
		netdev_err(ndev, "Got only %d netvsc pkt...needed "
			"%d pkts. Dropping this xfer page packet completely!\n",
			count, vmxferpage_packet->range_cnt + 1);

		/* Return it to the freelist */
		spin_lock_irqsave(&net_device->recv_pkt_list_lock, flags);
		for (i = count; i != 0; i--) {
			list_move_tail(listHead.next,
				       &net_device->recv_pkt_list);
		}
		spin_unlock_irqrestore(&net_device->recv_pkt_list_lock,
				       flags);

		netvsc_send_recv_completion(device,
					    vmxferpage_packet->d.trans_id,
					    NVSP_STAT_FAIL);

		return;
	}

	/* Remove the 1st packet to represent the xfer page packet itself */
	xferpage_packet = (struct xferpage_packet *)listHead.next;
	list_del(&xferpage_packet->list_ent);
	xferpage_packet->status = NVSP_STAT_SUCCESS;

	/* This is how much we can satisfy */
	xferpage_packet->count = count - 1;

	if (xferpage_packet->count != vmxferpage_packet->range_cnt) {
		netdev_err(ndev, "Needed %d netvsc pkts to satisfy "
			"this xfer page...got %d\n",
			vmxferpage_packet->range_cnt, xferpage_packet->count);
	}

	/* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
	for (i = 0; i < (count - 1); i++) {
		netvsc_packet = (struct hv_netvsc_packet *)listHead.next;
		list_del(&netvsc_packet->list_ent);

		/* Initialize the netvsc packet */
		netvsc_packet->status = NVSP_STAT_SUCCESS;
		netvsc_packet->xfer_page_pkt = xferpage_packet;
		netvsc_packet->completion.recv.recv_completion =
					netvsc_receive_completion;
		netvsc_packet->completion.recv.recv_completion_ctx =
					netvsc_packet;
		netvsc_packet->device = device;
		/* Save this so that we can send it back */
		netvsc_packet->completion.recv.recv_completion_tid =
					vmxferpage_packet->d.trans_id;

		netvsc_packet->data = (void *)((unsigned long)net_device->
			recv_buf + vmxferpage_packet->ranges[i].byte_offset);
		netvsc_packet->total_data_buflen =
					vmxferpage_packet->ranges[i].byte_count;

		/* Pass it to the upper layer */
		rndis_filter_receive(device, netvsc_packet);

		netvsc_receive_completion(netvsc_packet->
				completion.recv.recv_completion_ctx);
	}

}

static void netvsc_channel_cb(void *context)
{
	int ret;
	struct hv_device *device = context;
	struct netvsc_device *net_device;
	u32 bytes_recvd;
	u64 request_id;
	unsigned char *packet;
	struct vmpacket_descriptor *desc;
	unsigned char *buffer;
	int bufferlen = NETVSC_PACKET_SIZE;
	struct net_device *ndev;

	packet = kzalloc(NETVSC_PACKET_SIZE * sizeof(unsigned char),
			 GFP_ATOMIC);
	if (!packet)
		return;
	buffer = packet;

	net_device = get_inbound_net_device(device);
	if (!net_device)
		goto out;
	ndev = net_device->ndev;

	do {
		ret = vmbus_recvpacket_raw(device->channel, buffer, bufferlen,
					   &bytes_recvd, &request_id);
		if (ret == 0) {
			if (bytes_recvd > 0) {
				desc = (struct vmpacket_descriptor *)buffer;
				switch (desc->type) {
				case VM_PKT_COMP:
					netvsc_send_completion(device, desc);
					break;

				case VM_PKT_DATA_USING_XFER_PAGES:
					netvsc_receive(device, desc);
					break;

				default:
					netdev_err(ndev,
						   "unhandled packet type %d, "
						   "tid %llx len %d\n",
						   desc->type, request_id,
						   bytes_recvd);
					break;
				}

				/* reset */
				if (bufferlen > NETVSC_PACKET_SIZE) {
					kfree(buffer);
					buffer = packet;
					bufferlen = NETVSC_PACKET_SIZE;
				}
			} else {
				/* reset */
				if (bufferlen > NETVSC_PACKET_SIZE) {
					kfree(buffer);
					buffer = packet;
					bufferlen = NETVSC_PACKET_SIZE;
				}

				break;
			}
		} else if (ret == -ENOBUFS) {
			/* Handle large packet */
			buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
			if (buffer == NULL) {
				/* Try again next time around */
				netdev_err(ndev,
					   "unable to allocate buffer of size "
					   "(%d)!!\n", bytes_recvd);
				break;
			}

			bufferlen = bytes_recvd;
		}
	} while (1);

out:
	kfree(buffer);
	return;
}

/*
 * netvsc_device_add - Callback when the device belonging to this
 * driver is added
 */
int netvsc_device_add(struct hv_device *device, void *additional_info)
{
	int ret = 0;
	int i;
	int ring_size =
	((struct netvsc_device_info *)additional_info)->ring_size;
	struct netvsc_device *net_device;
	struct hv_netvsc_packet *packet, *pos;
	struct net_device *ndev;

	net_device = alloc_net_device(device);
	if (!net_device) {
		ret = -ENOMEM;
		goto cleanup;
	}

	/*
	 * Coming into this function, struct net_device * is
	 * registered as the driver private data.
	 * In alloc_net_device(), we register struct netvsc_device *
	 * as the driver private data and stash away struct net_device *
	 * in struct netvsc_device *.
	 */
	ndev = net_device->ndev;

	/* Initialize the NetVSC channel extension */
	net_device->recv_buf_size = NETVSC_RECEIVE_BUFFER_SIZE;
	spin_lock_init(&net_device->recv_pkt_list_lock);

	INIT_LIST_HEAD(&net_device->recv_pkt_list);

	for (i = 0; i < NETVSC_RECEIVE_PACKETLIST_COUNT; i++) {
		packet = kzalloc(sizeof(struct hv_netvsc_packet), GFP_KERNEL);
		if (!packet)
			break;

		list_add_tail(&packet->list_ent,
			      &net_device->recv_pkt_list);
	}
	init_completion(&net_device->channel_init_wait);

	/* Open the channel */
	ret = vmbus_open(device->channel, ring_size * PAGE_SIZE,
			 ring_size * PAGE_SIZE, NULL, 0,
			 netvsc_channel_cb, device);

	if (ret != 0) {
		netdev_err(ndev, "unable to open channel: %d\n", ret);
		goto cleanup;
	}

	/* Channel is opened */
	pr_info("hv_netvsc channel opened successfully\n");

	/* Connect with the NetVsp */
	ret = netvsc_connect_vsp(device);
	if (ret != 0) {
		netdev_err(ndev,
			"unable to connect to NetVSP - %d\n", ret);
		goto close;
	}

	return ret;

close:
	/* Now, we can close the channel safely */
	vmbus_close(device->channel);

cleanup:

	if (net_device) {
		list_for_each_entry_safe(packet, pos,
					 &net_device->recv_pkt_list,
					 list_ent) {
			list_del(&packet->list_ent);
			kfree(packet);
		}

		kfree(net_device);
	}

	return ret;
}