summaryrefslogtreecommitdiff
path: root/arch/powerpc/platforms/powernv/vas-window.c
blob: ff9f488123310b0503dcb1b139af6d3ee4afe567 (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
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
/*
 * Copyright 2016-17 IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#define pr_fmt(fmt) "vas: " fmt

#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/log2.h>
#include <linux/rcupdate.h>
#include <linux/cred.h>
#include <asm/switch_to.h>
#include <asm/ppc-opcode.h>
#include "vas.h"
#include "copy-paste.h"

#define CREATE_TRACE_POINTS
#include "vas-trace.h"

/*
 * Compute the paste address region for the window @window using the
 * ->paste_base_addr and ->paste_win_id_shift we got from device tree.
 */
static void compute_paste_address(struct vas_window *window, u64 *addr, int *len)
{
	int winid;
	u64 base, shift;

	base = window->vinst->paste_base_addr;
	shift = window->vinst->paste_win_id_shift;
	winid = window->winid;

	*addr  = base + (winid << shift);
	if (len)
		*len = PAGE_SIZE;

	pr_debug("Txwin #%d: Paste addr 0x%llx\n", winid, *addr);
}

u64 vas_win_paste_addr(struct vas_window *win)
{
	u64 addr;

	compute_paste_address(win, &addr, NULL);

	return addr;
}
EXPORT_SYMBOL(vas_win_paste_addr);

static inline void get_hvwc_mmio_bar(struct vas_window *window,
			u64 *start, int *len)
{
	u64 pbaddr;

	pbaddr = window->vinst->hvwc_bar_start;
	*start = pbaddr + window->winid * VAS_HVWC_SIZE;
	*len = VAS_HVWC_SIZE;
}

static inline void get_uwc_mmio_bar(struct vas_window *window,
			u64 *start, int *len)
{
	u64 pbaddr;

	pbaddr = window->vinst->uwc_bar_start;
	*start = pbaddr + window->winid * VAS_UWC_SIZE;
	*len = VAS_UWC_SIZE;
}

/*
 * Map the paste bus address of the given send window into kernel address
 * space. Unlike MMIO regions (map_mmio_region() below), paste region must
 * be mapped cache-able and is only applicable to send windows.
 */
static void *map_paste_region(struct vas_window *txwin)
{
	int len;
	void *map;
	char *name;
	u64 start;

	name = kasprintf(GFP_KERNEL, "window-v%d-w%d", txwin->vinst->vas_id,
				txwin->winid);
	if (!name)
		goto free_name;

	txwin->paste_addr_name = name;
	compute_paste_address(txwin, &start, &len);

	if (!request_mem_region(start, len, name)) {
		pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
				__func__, start, len);
		goto free_name;
	}

	map = ioremap_cache(start, len);
	if (!map) {
		pr_devel("%s(): ioremap_cache(0x%llx, %d) failed\n", __func__,
				start, len);
		goto free_name;
	}

	pr_devel("Mapped paste addr 0x%llx to kaddr 0x%p\n", start, map);
	return map;

free_name:
	kfree(name);
	return ERR_PTR(-ENOMEM);
}

static void *map_mmio_region(char *name, u64 start, int len)
{
	void *map;

	if (!request_mem_region(start, len, name)) {
		pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
				__func__, start, len);
		return NULL;
	}

	map = ioremap(start, len);
	if (!map) {
		pr_devel("%s(): ioremap(0x%llx, %d) failed\n", __func__, start,
				len);
		return NULL;
	}

	return map;
}

static void unmap_region(void *addr, u64 start, int len)
{
	iounmap(addr);
	release_mem_region((phys_addr_t)start, len);
}

/*
 * Unmap the paste address region for a window.
 */
static void unmap_paste_region(struct vas_window *window)
{
	int len;
	u64 busaddr_start;

	if (window->paste_kaddr) {
		compute_paste_address(window, &busaddr_start, &len);
		unmap_region(window->paste_kaddr, busaddr_start, len);
		window->paste_kaddr = NULL;
		kfree(window->paste_addr_name);
		window->paste_addr_name = NULL;
	}
}

/*
 * Unmap the MMIO regions for a window. Hold the vas_mutex so we don't
 * unmap when the window's debugfs dir is in use. This serializes close
 * of a window even on another VAS instance but since its not a critical
 * path, just minimize the time we hold the mutex for now. We can add
 * a per-instance mutex later if necessary.
 */
static void unmap_winctx_mmio_bars(struct vas_window *window)
{
	int len;
	void *uwc_map;
	void *hvwc_map;
	u64 busaddr_start;

	mutex_lock(&vas_mutex);

	hvwc_map = window->hvwc_map;
	window->hvwc_map = NULL;

	uwc_map = window->uwc_map;
	window->uwc_map = NULL;

	mutex_unlock(&vas_mutex);

	if (hvwc_map) {
		get_hvwc_mmio_bar(window, &busaddr_start, &len);
		unmap_region(hvwc_map, busaddr_start, len);
	}

	if (uwc_map) {
		get_uwc_mmio_bar(window, &busaddr_start, &len);
		unmap_region(uwc_map, busaddr_start, len);
	}
}

/*
 * Find the Hypervisor Window Context (HVWC) MMIO Base Address Region and the
 * OS/User Window Context (UWC) MMIO Base Address Region for the given window.
 * Map these bus addresses and save the mapped kernel addresses in @window.
 */
int map_winctx_mmio_bars(struct vas_window *window)
{
	int len;
	u64 start;

	get_hvwc_mmio_bar(window, &start, &len);
	window->hvwc_map = map_mmio_region("HVWCM_Window", start, len);

	get_uwc_mmio_bar(window, &start, &len);
	window->uwc_map = map_mmio_region("UWCM_Window", start, len);

	if (!window->hvwc_map || !window->uwc_map) {
		unmap_winctx_mmio_bars(window);
		return -1;
	}

	return 0;
}

/*
 * Reset all valid registers in the HV and OS/User Window Contexts for
 * the window identified by @window.
 *
 * NOTE: We cannot really use a for loop to reset window context. Not all
 *	 offsets in a window context are valid registers and the valid
 *	 registers are not sequential. And, we can only write to offsets
 *	 with valid registers.
 */
void reset_window_regs(struct vas_window *window)
{
	write_hvwc_reg(window, VREG(LPID), 0ULL);
	write_hvwc_reg(window, VREG(PID), 0ULL);
	write_hvwc_reg(window, VREG(XLATE_MSR), 0ULL);
	write_hvwc_reg(window, VREG(XLATE_LPCR), 0ULL);
	write_hvwc_reg(window, VREG(XLATE_CTL), 0ULL);
	write_hvwc_reg(window, VREG(AMR), 0ULL);
	write_hvwc_reg(window, VREG(SEIDR), 0ULL);
	write_hvwc_reg(window, VREG(FAULT_TX_WIN), 0ULL);
	write_hvwc_reg(window, VREG(OSU_INTR_SRC_RA), 0ULL);
	write_hvwc_reg(window, VREG(HV_INTR_SRC_RA), 0ULL);
	write_hvwc_reg(window, VREG(PSWID), 0ULL);
	write_hvwc_reg(window, VREG(LFIFO_BAR), 0ULL);
	write_hvwc_reg(window, VREG(LDATA_STAMP_CTL), 0ULL);
	write_hvwc_reg(window, VREG(LDMA_CACHE_CTL), 0ULL);
	write_hvwc_reg(window, VREG(LRFIFO_PUSH), 0ULL);
	write_hvwc_reg(window, VREG(CURR_MSG_COUNT), 0ULL);
	write_hvwc_reg(window, VREG(LNOTIFY_AFTER_COUNT), 0ULL);
	write_hvwc_reg(window, VREG(LRX_WCRED), 0ULL);
	write_hvwc_reg(window, VREG(LRX_WCRED_ADDER), 0ULL);
	write_hvwc_reg(window, VREG(TX_WCRED), 0ULL);
	write_hvwc_reg(window, VREG(TX_WCRED_ADDER), 0ULL);
	write_hvwc_reg(window, VREG(LFIFO_SIZE), 0ULL);
	write_hvwc_reg(window, VREG(WINCTL), 0ULL);
	write_hvwc_reg(window, VREG(WIN_STATUS), 0ULL);
	write_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL), 0ULL);
	write_hvwc_reg(window, VREG(TX_RSVD_BUF_COUNT), 0ULL);
	write_hvwc_reg(window, VREG(LRFIFO_WIN_PTR), 0ULL);
	write_hvwc_reg(window, VREG(LNOTIFY_CTL), 0ULL);
	write_hvwc_reg(window, VREG(LNOTIFY_PID), 0ULL);
	write_hvwc_reg(window, VREG(LNOTIFY_LPID), 0ULL);
	write_hvwc_reg(window, VREG(LNOTIFY_TID), 0ULL);
	write_hvwc_reg(window, VREG(LNOTIFY_SCOPE), 0ULL);
	write_hvwc_reg(window, VREG(NX_UTIL_ADDER), 0ULL);

	/* Skip read-only registers: NX_UTIL and NX_UTIL_SE */

	/*
	 * The send and receive window credit adder registers are also
	 * accessible from HVWC and have been initialized above. We don't
	 * need to initialize from the OS/User Window Context, so skip
	 * following calls:
	 *
	 *	write_uwc_reg(window, VREG(TX_WCRED_ADDER), 0ULL);
	 *	write_uwc_reg(window, VREG(LRX_WCRED_ADDER), 0ULL);
	 */
}

/*
 * Initialize window context registers related to Address Translation.
 * These registers are common to send/receive windows although they
 * differ for user/kernel windows. As we resolve the TODOs we may
 * want to add fields to vas_winctx and move the initialization to
 * init_vas_winctx_regs().
 */
static void init_xlate_regs(struct vas_window *window, bool user_win)
{
	u64 lpcr, val;

	/*
	 * MSR_TA, MSR_US are false for both kernel and user.
	 * MSR_DR and MSR_PR are false for kernel.
	 */
	val = 0ULL;
	val = SET_FIELD(VAS_XLATE_MSR_HV, val, 1);
	val = SET_FIELD(VAS_XLATE_MSR_SF, val, 1);
	if (user_win) {
		val = SET_FIELD(VAS_XLATE_MSR_DR, val, 1);
		val = SET_FIELD(VAS_XLATE_MSR_PR, val, 1);
	}
	write_hvwc_reg(window, VREG(XLATE_MSR), val);

	lpcr = mfspr(SPRN_LPCR);
	val = 0ULL;
	/*
	 * NOTE: From Section 5.7.8.1 Segment Lookaside Buffer of the
	 *	 Power ISA, v3.0B, Page size encoding is 0 = 4KB, 5 = 64KB.
	 *
	 * NOTE: From Section 1.3.1, Address Translation Context of the
	 *	 Nest MMU Workbook, LPCR_SC should be 0 for Power9.
	 */
	val = SET_FIELD(VAS_XLATE_LPCR_PAGE_SIZE, val, 5);
	val = SET_FIELD(VAS_XLATE_LPCR_ISL, val, lpcr & LPCR_ISL);
	val = SET_FIELD(VAS_XLATE_LPCR_TC, val, lpcr & LPCR_TC);
	val = SET_FIELD(VAS_XLATE_LPCR_SC, val, 0);
	write_hvwc_reg(window, VREG(XLATE_LPCR), val);

	/*
	 * Section 1.3.1 (Address translation Context) of NMMU workbook.
	 *	0b00	Hashed Page Table mode
	 *	0b01	Reserved
	 *	0b10	Radix on HPT
	 *	0b11	Radix on Radix
	 */
	val = 0ULL;
	val = SET_FIELD(VAS_XLATE_MODE, val, radix_enabled() ? 3 : 2);
	write_hvwc_reg(window, VREG(XLATE_CTL), val);

	/*
	 * TODO: Can we mfspr(AMR) even for user windows?
	 */
	val = 0ULL;
	val = SET_FIELD(VAS_AMR, val, mfspr(SPRN_AMR));
	write_hvwc_reg(window, VREG(AMR), val);

	val = 0ULL;
	val = SET_FIELD(VAS_SEIDR, val, 0);
	write_hvwc_reg(window, VREG(SEIDR), val);
}

/*
 * Initialize Reserved Send Buffer Count for the send window. It involves
 * writing to the register, reading it back to confirm that the hardware
 * has enough buffers to reserve. See section 1.3.1.2.1 of VAS workbook.
 *
 * Since we can only make a best-effort attempt to fulfill the request,
 * we don't return any errors if we cannot.
 *
 * TODO: Reserved (aka dedicated) send buffers are not supported yet.
 */
static void init_rsvd_tx_buf_count(struct vas_window *txwin,
				struct vas_winctx *winctx)
{
	write_hvwc_reg(txwin, VREG(TX_RSVD_BUF_COUNT), 0ULL);
}

/*
 * init_winctx_regs()
 *	Initialize window context registers for a receive window.
 *	Except for caching control and marking window open, the registers
 *	are initialized in the order listed in Section 3.1.4 (Window Context
 *	Cache Register Details) of the VAS workbook although they don't need
 *	to be.
 *
 * Design note: For NX receive windows, NX allocates the FIFO buffer in OPAL
 *	(so that it can get a large contiguous area) and passes that buffer
 *	to kernel via device tree. We now write that buffer address to the
 *	FIFO BAR. Would it make sense to do this all in OPAL? i.e have OPAL
 *	write the per-chip RX FIFO addresses to the windows during boot-up
 *	as a one-time task? That could work for NX but what about other
 *	receivers?  Let the receivers tell us the rx-fifo buffers for now.
 */
int init_winctx_regs(struct vas_window *window, struct vas_winctx *winctx)
{
	u64 val;
	int fifo_size;

	reset_window_regs(window);

	val = 0ULL;
	val = SET_FIELD(VAS_LPID, val, winctx->lpid);
	write_hvwc_reg(window, VREG(LPID), val);

	val = 0ULL;
	val = SET_FIELD(VAS_PID_ID, val, winctx->pidr);
	write_hvwc_reg(window, VREG(PID), val);

	init_xlate_regs(window, winctx->user_win);

	val = 0ULL;
	val = SET_FIELD(VAS_FAULT_TX_WIN, val, 0);
	write_hvwc_reg(window, VREG(FAULT_TX_WIN), val);

	/* In PowerNV, interrupts go to HV. */
	write_hvwc_reg(window, VREG(OSU_INTR_SRC_RA), 0ULL);

	val = 0ULL;
	val = SET_FIELD(VAS_HV_INTR_SRC_RA, val, winctx->irq_port);
	write_hvwc_reg(window, VREG(HV_INTR_SRC_RA), val);

	val = 0ULL;
	val = SET_FIELD(VAS_PSWID_EA_HANDLE, val, winctx->pswid);
	write_hvwc_reg(window, VREG(PSWID), val);

	write_hvwc_reg(window, VREG(SPARE1), 0ULL);
	write_hvwc_reg(window, VREG(SPARE2), 0ULL);
	write_hvwc_reg(window, VREG(SPARE3), 0ULL);

	/*
	 * NOTE: VAS expects the FIFO address to be copied into the LFIFO_BAR
	 *	 register as is - do NOT shift the address into VAS_LFIFO_BAR
	 *	 bit fields! Ok to set the page migration select fields -
	 *	 VAS ignores the lower 10+ bits in the address anyway, because
	 *	 the minimum FIFO size is 1K?
	 *
	 * See also: Design note in function header.
	 */
	val = __pa(winctx->rx_fifo);
	val = SET_FIELD(VAS_PAGE_MIGRATION_SELECT, val, 0);
	write_hvwc_reg(window, VREG(LFIFO_BAR), val);

	val = 0ULL;
	val = SET_FIELD(VAS_LDATA_STAMP, val, winctx->data_stamp);
	write_hvwc_reg(window, VREG(LDATA_STAMP_CTL), val);

	val = 0ULL;
	val = SET_FIELD(VAS_LDMA_TYPE, val, winctx->dma_type);
	val = SET_FIELD(VAS_LDMA_FIFO_DISABLE, val, winctx->fifo_disable);
	write_hvwc_reg(window, VREG(LDMA_CACHE_CTL), val);

	write_hvwc_reg(window, VREG(LRFIFO_PUSH), 0ULL);
	write_hvwc_reg(window, VREG(CURR_MSG_COUNT), 0ULL);
	write_hvwc_reg(window, VREG(LNOTIFY_AFTER_COUNT), 0ULL);

	val = 0ULL;
	val = SET_FIELD(VAS_LRX_WCRED, val, winctx->wcreds_max);
	write_hvwc_reg(window, VREG(LRX_WCRED), val);

	val = 0ULL;
	val = SET_FIELD(VAS_TX_WCRED, val, winctx->wcreds_max);
	write_hvwc_reg(window, VREG(TX_WCRED), val);

	write_hvwc_reg(window, VREG(LRX_WCRED_ADDER), 0ULL);
	write_hvwc_reg(window, VREG(TX_WCRED_ADDER), 0ULL);

	fifo_size = winctx->rx_fifo_size / 1024;

	val = 0ULL;
	val = SET_FIELD(VAS_LFIFO_SIZE, val, ilog2(fifo_size));
	write_hvwc_reg(window, VREG(LFIFO_SIZE), val);

	/* Update window control and caching control registers last so
	 * we mark the window open only after fully initializing it and
	 * pushing context to cache.
	 */

	write_hvwc_reg(window, VREG(WIN_STATUS), 0ULL);

	init_rsvd_tx_buf_count(window, winctx);

	/* for a send window, point to the matching receive window */
	val = 0ULL;
	val = SET_FIELD(VAS_LRX_WIN_ID, val, winctx->rx_win_id);
	write_hvwc_reg(window, VREG(LRFIFO_WIN_PTR), val);

	write_hvwc_reg(window, VREG(SPARE4), 0ULL);

	val = 0ULL;
	val = SET_FIELD(VAS_NOTIFY_DISABLE, val, winctx->notify_disable);
	val = SET_FIELD(VAS_INTR_DISABLE, val, winctx->intr_disable);
	val = SET_FIELD(VAS_NOTIFY_EARLY, val, winctx->notify_early);
	val = SET_FIELD(VAS_NOTIFY_OSU_INTR, val, winctx->notify_os_intr_reg);
	write_hvwc_reg(window, VREG(LNOTIFY_CTL), val);

	val = 0ULL;
	val = SET_FIELD(VAS_LNOTIFY_PID, val, winctx->lnotify_pid);
	write_hvwc_reg(window, VREG(LNOTIFY_PID), val);

	val = 0ULL;
	val = SET_FIELD(VAS_LNOTIFY_LPID, val, winctx->lnotify_lpid);
	write_hvwc_reg(window, VREG(LNOTIFY_LPID), val);

	val = 0ULL;
	val = SET_FIELD(VAS_LNOTIFY_TID, val, winctx->lnotify_tid);
	write_hvwc_reg(window, VREG(LNOTIFY_TID), val);

	val = 0ULL;
	val = SET_FIELD(VAS_LNOTIFY_MIN_SCOPE, val, winctx->min_scope);
	val = SET_FIELD(VAS_LNOTIFY_MAX_SCOPE, val, winctx->max_scope);
	write_hvwc_reg(window, VREG(LNOTIFY_SCOPE), val);

	/* Skip read-only registers NX_UTIL and NX_UTIL_SE */

	write_hvwc_reg(window, VREG(SPARE5), 0ULL);
	write_hvwc_reg(window, VREG(NX_UTIL_ADDER), 0ULL);
	write_hvwc_reg(window, VREG(SPARE6), 0ULL);

	/* Finally, push window context to memory and... */
	val = 0ULL;
	val = SET_FIELD(VAS_PUSH_TO_MEM, val, 1);
	write_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL), val);

	/* ... mark the window open for business */
	val = 0ULL;
	val = SET_FIELD(VAS_WINCTL_REJ_NO_CREDIT, val, winctx->rej_no_credit);
	val = SET_FIELD(VAS_WINCTL_PIN, val, winctx->pin_win);
	val = SET_FIELD(VAS_WINCTL_TX_WCRED_MODE, val, winctx->tx_wcred_mode);
	val = SET_FIELD(VAS_WINCTL_RX_WCRED_MODE, val, winctx->rx_wcred_mode);
	val = SET_FIELD(VAS_WINCTL_TX_WORD_MODE, val, winctx->tx_word_mode);
	val = SET_FIELD(VAS_WINCTL_RX_WORD_MODE, val, winctx->rx_word_mode);
	val = SET_FIELD(VAS_WINCTL_FAULT_WIN, val, winctx->fault_win);
	val = SET_FIELD(VAS_WINCTL_NX_WIN, val, winctx->nx_win);
	val = SET_FIELD(VAS_WINCTL_OPEN, val, 1);
	write_hvwc_reg(window, VREG(WINCTL), val);

	return 0;
}

static DEFINE_SPINLOCK(vas_ida_lock);

static void vas_release_window_id(struct ida *ida, int winid)
{
	spin_lock(&vas_ida_lock);
	ida_remove(ida, winid);
	spin_unlock(&vas_ida_lock);
}

static int vas_assign_window_id(struct ida *ida)
{
	int rc, winid;

	do {
		rc = ida_pre_get(ida, GFP_KERNEL);
		if (!rc)
			return -EAGAIN;

		spin_lock(&vas_ida_lock);
		rc = ida_get_new(ida, &winid);
		spin_unlock(&vas_ida_lock);
	} while (rc == -EAGAIN);

	if (rc)
		return rc;

	if (winid > VAS_WINDOWS_PER_CHIP) {
		pr_err("Too many (%d) open windows\n", winid);
		vas_release_window_id(ida, winid);
		return -EAGAIN;
	}

	return winid;
}

static void vas_window_free(struct vas_window *window)
{
	int winid = window->winid;
	struct vas_instance *vinst = window->vinst;

	unmap_winctx_mmio_bars(window);

	vas_window_free_dbgdir(window);

	kfree(window);

	vas_release_window_id(&vinst->ida, winid);
}

static struct vas_window *vas_window_alloc(struct vas_instance *vinst)
{
	int winid;
	struct vas_window *window;

	winid = vas_assign_window_id(&vinst->ida);
	if (winid < 0)
		return ERR_PTR(winid);

	window = kzalloc(sizeof(*window), GFP_KERNEL);
	if (!window)
		goto out_free;

	window->vinst = vinst;
	window->winid = winid;

	if (map_winctx_mmio_bars(window))
		goto out_free;

	vas_window_init_dbgdir(window);

	return window;

out_free:
	kfree(window);
	vas_release_window_id(&vinst->ida, winid);
	return ERR_PTR(-ENOMEM);
}

static void put_rx_win(struct vas_window *rxwin)
{
	/* Better not be a send window! */
	WARN_ON_ONCE(rxwin->tx_win);

	atomic_dec(&rxwin->num_txwins);
}

/*
 * Find the user space receive window given the @pswid.
 *      - We must have a valid vasid and it must belong to this instance.
 *        (so both send and receive windows are on the same VAS instance)
 *      - The window must refer to an OPEN, FTW, RECEIVE window.
 *
 * NOTE: We access ->windows[] table and assume that vinst->mutex is held.
 */
static struct vas_window *get_user_rxwin(struct vas_instance *vinst, u32 pswid)
{
	int vasid, winid;
	struct vas_window *rxwin;

	decode_pswid(pswid, &vasid, &winid);

	if (vinst->vas_id != vasid)
		return ERR_PTR(-EINVAL);

	rxwin = vinst->windows[winid];

	if (!rxwin || rxwin->tx_win || rxwin->cop != VAS_COP_TYPE_FTW)
		return ERR_PTR(-EINVAL);

	return rxwin;
}

/*
 * Get the VAS receive window associated with NX engine identified
 * by @cop and if applicable, @pswid.
 *
 * See also function header of set_vinst_win().
 */
static struct vas_window *get_vinst_rxwin(struct vas_instance *vinst,
			enum vas_cop_type cop, u32 pswid)
{
	struct vas_window *rxwin;

	mutex_lock(&vinst->mutex);

	if (cop == VAS_COP_TYPE_FTW)
		rxwin = get_user_rxwin(vinst, pswid);
	else
		rxwin = vinst->rxwin[cop] ?: ERR_PTR(-EINVAL);

	if (!IS_ERR(rxwin))
		atomic_inc(&rxwin->num_txwins);

	mutex_unlock(&vinst->mutex);

	return rxwin;
}

/*
 * We have two tables of windows in a VAS instance. The first one,
 * ->windows[], contains all the windows in the instance and allows
 * looking up a window by its id. It is used to look up send windows
 * during fault handling and receive windows when pairing user space
 * send/receive windows.
 *
 * The second table, ->rxwin[], contains receive windows that are
 * associated with NX engines. This table has VAS_COP_TYPE_MAX
 * entries and is used to look up a receive window by its
 * coprocessor type.
 *
 * Here, we save @window in the ->windows[] table. If it is a receive
 * window, we also save the window in the ->rxwin[] table.
 */
static void set_vinst_win(struct vas_instance *vinst,
			struct vas_window *window)
{
	int id = window->winid;

	mutex_lock(&vinst->mutex);

	/*
	 * There should only be one receive window for a coprocessor type
	 * unless its a user (FTW) window.
	 */
	if (!window->user_win && !window->tx_win) {
		WARN_ON_ONCE(vinst->rxwin[window->cop]);
		vinst->rxwin[window->cop] = window;
	}

	WARN_ON_ONCE(vinst->windows[id] != NULL);
	vinst->windows[id] = window;

	mutex_unlock(&vinst->mutex);
}

/*
 * Clear this window from the table(s) of windows for this VAS instance.
 * See also function header of set_vinst_win().
 */
static void clear_vinst_win(struct vas_window *window)
{
	int id = window->winid;
	struct vas_instance *vinst = window->vinst;

	mutex_lock(&vinst->mutex);

	if (!window->user_win && !window->tx_win) {
		WARN_ON_ONCE(!vinst->rxwin[window->cop]);
		vinst->rxwin[window->cop] = NULL;
	}

	WARN_ON_ONCE(vinst->windows[id] != window);
	vinst->windows[id] = NULL;

	mutex_unlock(&vinst->mutex);
}

static void init_winctx_for_rxwin(struct vas_window *rxwin,
			struct vas_rx_win_attr *rxattr,
			struct vas_winctx *winctx)
{
	/*
	 * We first zero (memset()) all fields and only set non-zero fields.
	 * Following fields are 0/false but maybe deserve a comment:
	 *
	 *	->notify_os_intr_reg	In powerNV, send intrs to HV
	 *	->notify_disable	False for NX windows
	 *	->intr_disable		False for Fault Windows
	 *	->xtra_write		False for NX windows
	 *	->notify_early		NA for NX windows
	 *	->rsvd_txbuf_count	NA for Rx windows
	 *	->lpid, ->pid, ->tid	NA for Rx windows
	 */

	memset(winctx, 0, sizeof(struct vas_winctx));

	winctx->rx_fifo = rxattr->rx_fifo;
	winctx->rx_fifo_size = rxattr->rx_fifo_size;
	winctx->wcreds_max = rxwin->wcreds_max;
	winctx->pin_win = rxattr->pin_win;

	winctx->nx_win = rxattr->nx_win;
	winctx->fault_win = rxattr->fault_win;
	winctx->user_win = rxattr->user_win;
	winctx->rej_no_credit = rxattr->rej_no_credit;
	winctx->rx_word_mode = rxattr->rx_win_ord_mode;
	winctx->tx_word_mode = rxattr->tx_win_ord_mode;
	winctx->rx_wcred_mode = rxattr->rx_wcred_mode;
	winctx->tx_wcred_mode = rxattr->tx_wcred_mode;
	winctx->notify_early = rxattr->notify_early;

	if (winctx->nx_win) {
		winctx->data_stamp = true;
		winctx->intr_disable = true;
		winctx->pin_win = true;

		WARN_ON_ONCE(winctx->fault_win);
		WARN_ON_ONCE(!winctx->rx_word_mode);
		WARN_ON_ONCE(!winctx->tx_word_mode);
		WARN_ON_ONCE(winctx->notify_after_count);
	} else if (winctx->fault_win) {
		winctx->notify_disable = true;
	} else if (winctx->user_win) {
		/*
		 * Section 1.8.1 Low Latency Core-Core Wake up of
		 * the VAS workbook:
		 *
		 *      - disable credit checks ([tr]x_wcred_mode = false)
		 *      - disable FIFO writes
		 *      - enable ASB_Notify, disable interrupt
		 */
		winctx->fifo_disable = true;
		winctx->intr_disable = true;
		winctx->rx_fifo = NULL;
	}

	winctx->lnotify_lpid = rxattr->lnotify_lpid;
	winctx->lnotify_pid = rxattr->lnotify_pid;
	winctx->lnotify_tid = rxattr->lnotify_tid;
	winctx->pswid = rxattr->pswid;
	winctx->dma_type = VAS_DMA_TYPE_INJECT;
	winctx->tc_mode = rxattr->tc_mode;

	winctx->min_scope = VAS_SCOPE_LOCAL;
	winctx->max_scope = VAS_SCOPE_VECTORED_GROUP;
}

static bool rx_win_args_valid(enum vas_cop_type cop,
			struct vas_rx_win_attr *attr)
{
	pr_debug("Rxattr: fault %d, notify %d, intr %d, early %d, fifo %d\n",
			attr->fault_win, attr->notify_disable,
			attr->intr_disable, attr->notify_early,
			attr->rx_fifo_size);

	if (cop >= VAS_COP_TYPE_MAX)
		return false;

	if (cop != VAS_COP_TYPE_FTW &&
				attr->rx_fifo_size < VAS_RX_FIFO_SIZE_MIN)
		return false;

	if (attr->rx_fifo_size > VAS_RX_FIFO_SIZE_MAX)
		return false;

	if (attr->wcreds_max > VAS_RX_WCREDS_MAX)
		return false;

	if (attr->nx_win) {
		/* cannot be fault or user window if it is nx */
		if (attr->fault_win || attr->user_win)
			return false;
		/*
		 * Section 3.1.4.32: NX Windows must not disable notification,
		 *	and must not enable interrupts or early notification.
		 */
		if (attr->notify_disable || !attr->intr_disable ||
				attr->notify_early)
			return false;
	} else if (attr->fault_win) {
		/* cannot be both fault and user window */
		if (attr->user_win)
			return false;

		/*
		 * Section 3.1.4.32: Fault windows must disable notification
		 *	but not interrupts.
		 */
		if (!attr->notify_disable || attr->intr_disable)
			return false;

	} else if (attr->user_win) {
		/*
		 * User receive windows are only for fast-thread-wakeup
		 * (FTW). They don't need a FIFO and must disable interrupts
		 */
		if (attr->rx_fifo || attr->rx_fifo_size || !attr->intr_disable)
			return false;
	} else {
		/* Rx window must be one of NX or Fault or User window. */
		return false;
	}

	return true;
}

void vas_init_rx_win_attr(struct vas_rx_win_attr *rxattr, enum vas_cop_type cop)
{
	memset(rxattr, 0, sizeof(*rxattr));

	if (cop == VAS_COP_TYPE_842 || cop == VAS_COP_TYPE_842_HIPRI) {
		rxattr->pin_win = true;
		rxattr->nx_win = true;
		rxattr->fault_win = false;
		rxattr->intr_disable = true;
		rxattr->rx_wcred_mode = true;
		rxattr->tx_wcred_mode = true;
		rxattr->rx_win_ord_mode = true;
		rxattr->tx_win_ord_mode = true;
	} else if (cop == VAS_COP_TYPE_FAULT) {
		rxattr->pin_win = true;
		rxattr->fault_win = true;
		rxattr->notify_disable = true;
		rxattr->rx_wcred_mode = true;
		rxattr->tx_wcred_mode = true;
		rxattr->rx_win_ord_mode = true;
		rxattr->tx_win_ord_mode = true;
	} else if (cop == VAS_COP_TYPE_FTW) {
		rxattr->user_win = true;
		rxattr->intr_disable = true;

		/*
		 * As noted in the VAS Workbook we disable credit checks.
		 * If we enable credit checks in the future, we must also
		 * implement a mechanism to return the user credits or new
		 * paste operations will fail.
		 */
	}
}
EXPORT_SYMBOL_GPL(vas_init_rx_win_attr);

struct vas_window *vas_rx_win_open(int vasid, enum vas_cop_type cop,
			struct vas_rx_win_attr *rxattr)
{
	struct vas_window *rxwin;
	struct vas_winctx winctx;
	struct vas_instance *vinst;

	trace_vas_rx_win_open(current, vasid, cop, rxattr);

	if (!rx_win_args_valid(cop, rxattr))
		return ERR_PTR(-EINVAL);

	vinst = find_vas_instance(vasid);
	if (!vinst) {
		pr_devel("vasid %d not found!\n", vasid);
		return ERR_PTR(-EINVAL);
	}
	pr_devel("Found instance %d\n", vasid);

	rxwin = vas_window_alloc(vinst);
	if (IS_ERR(rxwin)) {
		pr_devel("Unable to allocate memory for Rx window\n");
		return rxwin;
	}

	rxwin->tx_win = false;
	rxwin->nx_win = rxattr->nx_win;
	rxwin->user_win = rxattr->user_win;
	rxwin->cop = cop;
	rxwin->wcreds_max = rxattr->wcreds_max ?: VAS_WCREDS_DEFAULT;
	if (rxattr->user_win)
		rxwin->pid = task_pid_vnr(current);

	init_winctx_for_rxwin(rxwin, rxattr, &winctx);
	init_winctx_regs(rxwin, &winctx);

	set_vinst_win(vinst, rxwin);

	return rxwin;
}
EXPORT_SYMBOL_GPL(vas_rx_win_open);

void vas_init_tx_win_attr(struct vas_tx_win_attr *txattr, enum vas_cop_type cop)
{
	memset(txattr, 0, sizeof(*txattr));

	if (cop == VAS_COP_TYPE_842 || cop == VAS_COP_TYPE_842_HIPRI) {
		txattr->rej_no_credit = false;
		txattr->rx_wcred_mode = true;
		txattr->tx_wcred_mode = true;
		txattr->rx_win_ord_mode = true;
		txattr->tx_win_ord_mode = true;
	} else if (cop == VAS_COP_TYPE_FTW) {
		txattr->user_win = true;
	}
}
EXPORT_SYMBOL_GPL(vas_init_tx_win_attr);

static void init_winctx_for_txwin(struct vas_window *txwin,
			struct vas_tx_win_attr *txattr,
			struct vas_winctx *winctx)
{
	/*
	 * We first zero all fields and only set non-zero ones. Following
	 * are some fields set to 0/false for the stated reason:
	 *
	 *	->notify_os_intr_reg	In powernv, send intrs to HV
	 *	->rsvd_txbuf_count	Not supported yet.
	 *	->notify_disable	False for NX windows
	 *	->xtra_write		False for NX windows
	 *	->notify_early		NA for NX windows
	 *	->lnotify_lpid		NA for Tx windows
	 *	->lnotify_pid		NA for Tx windows
	 *	->lnotify_tid		NA for Tx windows
	 *	->tx_win_cred_mode	Ignore for now for NX windows
	 *	->rx_win_cred_mode	Ignore for now for NX windows
	 */
	memset(winctx, 0, sizeof(struct vas_winctx));

	winctx->wcreds_max = txwin->wcreds_max;

	winctx->user_win = txattr->user_win;
	winctx->nx_win = txwin->rxwin->nx_win;
	winctx->pin_win = txattr->pin_win;
	winctx->rej_no_credit = txattr->rej_no_credit;
	winctx->rsvd_txbuf_enable = txattr->rsvd_txbuf_enable;

	winctx->rx_wcred_mode = txattr->rx_wcred_mode;
	winctx->tx_wcred_mode = txattr->tx_wcred_mode;
	winctx->rx_word_mode = txattr->rx_win_ord_mode;
	winctx->tx_word_mode = txattr->tx_win_ord_mode;
	winctx->rsvd_txbuf_count = txattr->rsvd_txbuf_count;

	winctx->intr_disable = true;
	if (winctx->nx_win)
		winctx->data_stamp = true;

	winctx->lpid = txattr->lpid;
	winctx->pidr = txattr->pidr;
	winctx->rx_win_id = txwin->rxwin->winid;

	winctx->dma_type = VAS_DMA_TYPE_INJECT;
	winctx->tc_mode = txattr->tc_mode;
	winctx->min_scope = VAS_SCOPE_LOCAL;
	winctx->max_scope = VAS_SCOPE_VECTORED_GROUP;

	winctx->pswid = 0;
}

static bool tx_win_args_valid(enum vas_cop_type cop,
			struct vas_tx_win_attr *attr)
{
	if (attr->tc_mode != VAS_THRESH_DISABLED)
		return false;

	if (cop > VAS_COP_TYPE_MAX)
		return false;

	if (attr->wcreds_max > VAS_TX_WCREDS_MAX)
		return false;

	if (attr->user_win &&
			(cop != VAS_COP_TYPE_FTW || attr->rsvd_txbuf_count))
		return false;

	return true;
}

struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
			struct vas_tx_win_attr *attr)
{
	int rc;
	struct vas_window *txwin;
	struct vas_window *rxwin;
	struct vas_winctx winctx;
	struct vas_instance *vinst;

	trace_vas_tx_win_open(current, vasid, cop, attr);

	if (!tx_win_args_valid(cop, attr))
		return ERR_PTR(-EINVAL);

	/*
	 * If caller did not specify a vasid but specified the PSWID of a
	 * receive window (applicable only to FTW windows), use the vasid
	 * from that receive window.
	 */
	if (vasid == -1 && attr->pswid)
		decode_pswid(attr->pswid, &vasid, NULL);

	vinst = find_vas_instance(vasid);
	if (!vinst) {
		pr_devel("vasid %d not found!\n", vasid);
		return ERR_PTR(-EINVAL);
	}

	rxwin = get_vinst_rxwin(vinst, cop, attr->pswid);
	if (IS_ERR(rxwin)) {
		pr_devel("No RxWin for vasid %d, cop %d\n", vasid, cop);
		return rxwin;
	}

	txwin = vas_window_alloc(vinst);
	if (IS_ERR(txwin)) {
		rc = PTR_ERR(txwin);
		goto put_rxwin;
	}

	txwin->cop = cop;
	txwin->tx_win = 1;
	txwin->rxwin = rxwin;
	txwin->nx_win = txwin->rxwin->nx_win;
	txwin->pid = attr->pid;
	txwin->user_win = attr->user_win;
	txwin->wcreds_max = attr->wcreds_max ?: VAS_WCREDS_DEFAULT;

	init_winctx_for_txwin(txwin, attr, &winctx);

	init_winctx_regs(txwin, &winctx);

	/*
	 * If its a kernel send window, map the window address into the
	 * kernel's address space. For user windows, user must issue an
	 * mmap() to map the window into their address space.
	 *
	 * NOTE: If kernel ever resubmits a user CRB after handling a page
	 *	 fault, we will need to map this into kernel as well.
	 */
	if (!txwin->user_win) {
		txwin->paste_kaddr = map_paste_region(txwin);
		if (IS_ERR(txwin->paste_kaddr)) {
			rc = PTR_ERR(txwin->paste_kaddr);
			goto free_window;
		}
	} else {
		/*
		 * A user mapping must ensure that context switch issues
		 * CP_ABORT for this thread.
		 */
		rc = set_thread_uses_vas();
		if (rc)
			goto free_window;
	}

	set_vinst_win(vinst, txwin);

	return txwin;

free_window:
	vas_window_free(txwin);

put_rxwin:
	put_rx_win(rxwin);
	return ERR_PTR(rc);

}
EXPORT_SYMBOL_GPL(vas_tx_win_open);

int vas_copy_crb(void *crb, int offset)
{
	return vas_copy(crb, offset);
}
EXPORT_SYMBOL_GPL(vas_copy_crb);

#define RMA_LSMP_REPORT_ENABLE PPC_BIT(53)
int vas_paste_crb(struct vas_window *txwin, int offset, bool re)
{
	int rc;
	void *addr;
	uint64_t val;

	trace_vas_paste_crb(current, txwin);

	/*
	 * Only NX windows are supported for now and hardware assumes
	 * report-enable flag is set for NX windows. Ensure software
	 * complies too.
	 */
	WARN_ON_ONCE(txwin->nx_win && !re);

	addr = txwin->paste_kaddr;
	if (re) {
		/*
		 * Set the REPORT_ENABLE bit (equivalent to writing
		 * to 1K offset of the paste address)
		 */
		val = SET_FIELD(RMA_LSMP_REPORT_ENABLE, 0ULL, 1);
		addr += val;
	}

	/*
	 * Map the raw CR value from vas_paste() to an error code (there
	 * is just pass or fail for now though).
	 */
	rc = vas_paste(addr, offset);
	if (rc == 2)
		rc = 0;
	else
		rc = -EINVAL;

	pr_debug("Txwin #%d: Msg count %llu\n", txwin->winid,
			read_hvwc_reg(txwin, VREG(LRFIFO_PUSH)));

	return rc;
}
EXPORT_SYMBOL_GPL(vas_paste_crb);

/*
 * If credit checking is enabled for this window, poll for the return
 * of window credits (i.e for NX engines to process any outstanding CRBs).
 * Since NX-842 waits for the CRBs to be processed before closing the
 * window, we should not have to wait for too long.
 *
 * TODO: We retry in 10ms intervals now. We could/should probably peek at
 *	the VAS_LRFIFO_PUSH_OFFSET register to get an estimate of pending
 *	CRBs on the FIFO and compute the delay dynamically on each retry.
 *	But that is not really needed until we support NX-GZIP access from
 *	user space. (NX-842 driver waits for CSB and Fast thread-wakeup
 *	doesn't use credit checking).
 */
static void poll_window_credits(struct vas_window *window)
{
	u64 val;
	int creds, mode;

	val = read_hvwc_reg(window, VREG(WINCTL));
	if (window->tx_win)
		mode = GET_FIELD(VAS_WINCTL_TX_WCRED_MODE, val);
	else
		mode = GET_FIELD(VAS_WINCTL_RX_WCRED_MODE, val);

	if (!mode)
		return;
retry:
	if (window->tx_win) {
		val = read_hvwc_reg(window, VREG(TX_WCRED));
		creds = GET_FIELD(VAS_TX_WCRED, val);
	} else {
		val = read_hvwc_reg(window, VREG(LRX_WCRED));
		creds = GET_FIELD(VAS_LRX_WCRED, val);
	}

	if (creds < window->wcreds_max) {
		val = 0;
		set_current_state(TASK_UNINTERRUPTIBLE);
		schedule_timeout(msecs_to_jiffies(10));
		goto retry;
	}
}

/*
 * Wait for the window to go to "not-busy" state. It should only take a
 * short time to queue a CRB, so window should not be busy for too long.
 * Trying 5ms intervals.
 */
static void poll_window_busy_state(struct vas_window *window)
{
	int busy;
	u64 val;

retry:
	val = read_hvwc_reg(window, VREG(WIN_STATUS));
	busy = GET_FIELD(VAS_WIN_BUSY, val);
	if (busy) {
		val = 0;
		set_current_state(TASK_UNINTERRUPTIBLE);
		schedule_timeout(msecs_to_jiffies(5));
		goto retry;
	}
}

/*
 * Have the hardware cast a window out of cache and wait for it to
 * be completed.
 *
 * NOTE: It can take a relatively long time to cast the window context
 *	out of the cache. It is not strictly necessary to cast out if:
 *
 *	- we clear the "Pin Window" bit (so hardware is free to evict)
 *
 *	- we re-initialize the window context when it is reassigned.
 *
 *	We do the former in vas_win_close() and latter in vas_win_open().
 *	So, ignoring the cast-out for now. We can add it as needed. If
 *	casting out becomes necessary we should consider offloading the
 *	job to a worker thread, so the window close can proceed quickly.
 */
static void poll_window_castout(struct vas_window *window)
{
	/* stub for now */
}

/*
 * Unpin and close a window so no new requests are accepted and the
 * hardware can evict this window from cache if necessary.
 */
static void unpin_close_window(struct vas_window *window)
{
	u64 val;

	val = read_hvwc_reg(window, VREG(WINCTL));
	val = SET_FIELD(VAS_WINCTL_PIN, val, 0);
	val = SET_FIELD(VAS_WINCTL_OPEN, val, 0);
	write_hvwc_reg(window, VREG(WINCTL), val);
}

/*
 * Close a window.
 *
 * See Section 1.12.1 of VAS workbook v1.05 for details on closing window:
 *	- Disable new paste operations (unmap paste address)
 *	- Poll for the "Window Busy" bit to be cleared
 *	- Clear the Open/Enable bit for the Window.
 *	- Poll for return of window Credits (implies FIFO empty for Rx win?)
 *	- Unpin and cast window context out of cache
 *
 * Besides the hardware, kernel has some bookkeeping of course.
 */
int vas_win_close(struct vas_window *window)
{
	if (!window)
		return 0;

	if (!window->tx_win && atomic_read(&window->num_txwins) != 0) {
		pr_devel("Attempting to close an active Rx window!\n");
		WARN_ON_ONCE(1);
		return -EBUSY;
	}

	unmap_paste_region(window);

	clear_vinst_win(window);

	poll_window_busy_state(window);

	unpin_close_window(window);

	poll_window_credits(window);

	poll_window_castout(window);

	/* if send window, drop reference to matching receive window */
	if (window->tx_win)
		put_rx_win(window->rxwin);

	vas_window_free(window);

	return 0;
}
EXPORT_SYMBOL_GPL(vas_win_close);

/*
 * Return a system-wide unique window id for the window @win.
 */
u32 vas_win_id(struct vas_window *win)
{
	return encode_pswid(win->vinst->vas_id, win->winid);
}
EXPORT_SYMBOL_GPL(vas_win_id);