summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/xe/xe_guc_ct.c
blob: 9c505d3517cd1af753f32507ffb44651ccbc0e80 (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
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
// SPDX-License-Identifier: MIT
/*
 * Copyright © 2022 Intel Corporation
 */

#include "xe_guc_ct.h"

#include <linux/bitfield.h>
#include <linux/circ_buf.h>
#include <linux/delay.h>

#include <kunit/static_stub.h>

#include <drm/drm_managed.h>

#include "abi/guc_actions_abi.h"
#include "abi/guc_actions_sriov_abi.h"
#include "abi/guc_klvs_abi.h"
#include "xe_bo.h"
#include "xe_device.h"
#include "xe_gt.h"
#include "xe_gt_pagefault.h"
#include "xe_gt_printk.h"
#include "xe_gt_sriov_pf_control.h"
#include "xe_gt_sriov_pf_monitor.h"
#include "xe_gt_tlb_invalidation.h"
#include "xe_guc.h"
#include "xe_guc_relay.h"
#include "xe_guc_submit.h"
#include "xe_map.h"
#include "xe_pm.h"
#include "xe_trace_guc.h"

/* Used when a CT send wants to block and / or receive data */
struct g2h_fence {
	u32 *response_buffer;
	u32 seqno;
	u32 response_data;
	u16 response_len;
	u16 error;
	u16 hint;
	u16 reason;
	bool retry;
	bool fail;
	bool done;
};

static void g2h_fence_init(struct g2h_fence *g2h_fence, u32 *response_buffer)
{
	g2h_fence->response_buffer = response_buffer;
	g2h_fence->response_data = 0;
	g2h_fence->response_len = 0;
	g2h_fence->fail = false;
	g2h_fence->retry = false;
	g2h_fence->done = false;
	g2h_fence->seqno = ~0x0;
}

static bool g2h_fence_needs_alloc(struct g2h_fence *g2h_fence)
{
	return g2h_fence->seqno == ~0x0;
}

static struct xe_guc *
ct_to_guc(struct xe_guc_ct *ct)
{
	return container_of(ct, struct xe_guc, ct);
}

static struct xe_gt *
ct_to_gt(struct xe_guc_ct *ct)
{
	return container_of(ct, struct xe_gt, uc.guc.ct);
}

static struct xe_device *
ct_to_xe(struct xe_guc_ct *ct)
{
	return gt_to_xe(ct_to_gt(ct));
}

/**
 * DOC: GuC CTB Blob
 *
 * We allocate single blob to hold both CTB descriptors and buffers:
 *
 *      +--------+-----------------------------------------------+------+
 *      | offset | contents                                      | size |
 *      +========+===============================================+======+
 *      | 0x0000 | H2G CTB Descriptor (send)                     |      |
 *      +--------+-----------------------------------------------+  4K  |
 *      | 0x0800 | G2H CTB Descriptor (g2h)                      |      |
 *      +--------+-----------------------------------------------+------+
 *      | 0x1000 | H2G CT Buffer (send)                          | n*4K |
 *      |        |                                               |      |
 *      +--------+-----------------------------------------------+------+
 *      | 0x1000 | G2H CT Buffer (g2h)                           | m*4K |
 *      | + n*4K |                                               |      |
 *      +--------+-----------------------------------------------+------+
 *
 * Size of each ``CT Buffer`` must be multiple of 4K.
 * We don't expect too many messages in flight at any time, unless we are
 * using the GuC submission. In that case each request requires a minimum
 * 2 dwords which gives us a maximum 256 queue'd requests. Hopefully this
 * enough space to avoid backpressure on the driver. We increase the size
 * of the receive buffer (relative to the send) to ensure a G2H response
 * CTB has a landing spot.
 *
 * In addition to submissions, the G2H buffer needs to be able to hold
 * enough space for recoverable page fault notifications. The number of
 * page faults is interrupt driven and can be as much as the number of
 * compute resources available. However, most of the actual work for these
 * is in a separate page fault worker thread. Therefore we only need to
 * make sure the queue has enough space to handle all of the submissions
 * and responses and an extra buffer for incoming page faults.
 */

#define CTB_DESC_SIZE		ALIGN(sizeof(struct guc_ct_buffer_desc), SZ_2K)
#define CTB_H2G_BUFFER_SIZE	(SZ_4K)
#define CTB_G2H_BUFFER_SIZE	(SZ_128K)
#define G2H_ROOM_BUFFER_SIZE	(CTB_G2H_BUFFER_SIZE / 2)

/**
 * xe_guc_ct_queue_proc_time_jiffies - Return maximum time to process a full
 * CT command queue
 * @ct: the &xe_guc_ct. Unused at this moment but will be used in the future.
 *
 * Observation is that a 4KiB buffer full of commands takes a little over a
 * second to process. Use that to calculate maximum time to process a full CT
 * command queue.
 *
 * Return: Maximum time to process a full CT queue in jiffies.
 */
long xe_guc_ct_queue_proc_time_jiffies(struct xe_guc_ct *ct)
{
	BUILD_BUG_ON(!IS_ALIGNED(CTB_H2G_BUFFER_SIZE, SZ_4));
	return (CTB_H2G_BUFFER_SIZE / SZ_4K) * HZ;
}

static size_t guc_ct_size(void)
{
	return 2 * CTB_DESC_SIZE + CTB_H2G_BUFFER_SIZE +
		CTB_G2H_BUFFER_SIZE;
}

static void guc_ct_fini(struct drm_device *drm, void *arg)
{
	struct xe_guc_ct *ct = arg;

	destroy_workqueue(ct->g2h_wq);
	xa_destroy(&ct->fence_lookup);
}

static void receive_g2h(struct xe_guc_ct *ct);
static void g2h_worker_func(struct work_struct *w);
static void safe_mode_worker_func(struct work_struct *w);

static void primelockdep(struct xe_guc_ct *ct)
{
	if (!IS_ENABLED(CONFIG_LOCKDEP))
		return;

	fs_reclaim_acquire(GFP_KERNEL);
	might_lock(&ct->lock);
	fs_reclaim_release(GFP_KERNEL);
}

int xe_guc_ct_init(struct xe_guc_ct *ct)
{
	struct xe_device *xe = ct_to_xe(ct);
	struct xe_gt *gt = ct_to_gt(ct);
	struct xe_tile *tile = gt_to_tile(gt);
	struct xe_bo *bo;
	int err;

	xe_gt_assert(gt, !(guc_ct_size() % PAGE_SIZE));

	ct->g2h_wq = alloc_ordered_workqueue("xe-g2h-wq", 0);
	if (!ct->g2h_wq)
		return -ENOMEM;

	spin_lock_init(&ct->fast_lock);
	xa_init(&ct->fence_lookup);
	INIT_WORK(&ct->g2h_worker, g2h_worker_func);
	INIT_DELAYED_WORK(&ct->safe_mode_worker,  safe_mode_worker_func);
	init_waitqueue_head(&ct->wq);
	init_waitqueue_head(&ct->g2h_fence_wq);

	err = drmm_mutex_init(&xe->drm, &ct->lock);
	if (err)
		return err;

	primelockdep(ct);

	bo = xe_managed_bo_create_pin_map(xe, tile, guc_ct_size(),
					  XE_BO_FLAG_SYSTEM |
					  XE_BO_FLAG_GGTT |
					  XE_BO_FLAG_GGTT_INVALIDATE);
	if (IS_ERR(bo))
		return PTR_ERR(bo);

	ct->bo = bo;

	err = drmm_add_action_or_reset(&xe->drm, guc_ct_fini, ct);
	if (err)
		return err;

	xe_gt_assert(gt, ct->state == XE_GUC_CT_STATE_NOT_INITIALIZED);
	ct->state = XE_GUC_CT_STATE_DISABLED;
	return 0;
}

#define desc_read(xe_, guc_ctb__, field_)			\
	xe_map_rd_field(xe_, &guc_ctb__->desc, 0,		\
			struct guc_ct_buffer_desc, field_)

#define desc_write(xe_, guc_ctb__, field_, val_)		\
	xe_map_wr_field(xe_, &guc_ctb__->desc, 0,		\
			struct guc_ct_buffer_desc, field_, val_)

static void guc_ct_ctb_h2g_init(struct xe_device *xe, struct guc_ctb *h2g,
				struct iosys_map *map)
{
	h2g->info.size = CTB_H2G_BUFFER_SIZE / sizeof(u32);
	h2g->info.resv_space = 0;
	h2g->info.tail = 0;
	h2g->info.head = 0;
	h2g->info.space = CIRC_SPACE(h2g->info.tail, h2g->info.head,
				     h2g->info.size) -
			  h2g->info.resv_space;
	h2g->info.broken = false;

	h2g->desc = *map;
	xe_map_memset(xe, &h2g->desc, 0, 0, sizeof(struct guc_ct_buffer_desc));

	h2g->cmds = IOSYS_MAP_INIT_OFFSET(map, CTB_DESC_SIZE * 2);
}

static void guc_ct_ctb_g2h_init(struct xe_device *xe, struct guc_ctb *g2h,
				struct iosys_map *map)
{
	g2h->info.size = CTB_G2H_BUFFER_SIZE / sizeof(u32);
	g2h->info.resv_space = G2H_ROOM_BUFFER_SIZE / sizeof(u32);
	g2h->info.head = 0;
	g2h->info.tail = 0;
	g2h->info.space = CIRC_SPACE(g2h->info.tail, g2h->info.head,
				     g2h->info.size) -
			  g2h->info.resv_space;
	g2h->info.broken = false;

	g2h->desc = IOSYS_MAP_INIT_OFFSET(map, CTB_DESC_SIZE);
	xe_map_memset(xe, &g2h->desc, 0, 0, sizeof(struct guc_ct_buffer_desc));

	g2h->cmds = IOSYS_MAP_INIT_OFFSET(map, CTB_DESC_SIZE * 2 +
					    CTB_H2G_BUFFER_SIZE);
}

static int guc_ct_ctb_h2g_register(struct xe_guc_ct *ct)
{
	struct xe_guc *guc = ct_to_guc(ct);
	u32 desc_addr, ctb_addr, size;
	int err;

	desc_addr = xe_bo_ggtt_addr(ct->bo);
	ctb_addr = xe_bo_ggtt_addr(ct->bo) + CTB_DESC_SIZE * 2;
	size = ct->ctbs.h2g.info.size * sizeof(u32);

	err = xe_guc_self_cfg64(guc,
				GUC_KLV_SELF_CFG_H2G_CTB_DESCRIPTOR_ADDR_KEY,
				desc_addr);
	if (err)
		return err;

	err = xe_guc_self_cfg64(guc,
				GUC_KLV_SELF_CFG_H2G_CTB_ADDR_KEY,
				ctb_addr);
	if (err)
		return err;

	return xe_guc_self_cfg32(guc,
				 GUC_KLV_SELF_CFG_H2G_CTB_SIZE_KEY,
				 size);
}

static int guc_ct_ctb_g2h_register(struct xe_guc_ct *ct)
{
	struct xe_guc *guc = ct_to_guc(ct);
	u32 desc_addr, ctb_addr, size;
	int err;

	desc_addr = xe_bo_ggtt_addr(ct->bo) + CTB_DESC_SIZE;
	ctb_addr = xe_bo_ggtt_addr(ct->bo) + CTB_DESC_SIZE * 2 +
		CTB_H2G_BUFFER_SIZE;
	size = ct->ctbs.g2h.info.size * sizeof(u32);

	err = xe_guc_self_cfg64(guc,
				GUC_KLV_SELF_CFG_G2H_CTB_DESCRIPTOR_ADDR_KEY,
				desc_addr);
	if (err)
		return err;

	err = xe_guc_self_cfg64(guc,
				GUC_KLV_SELF_CFG_G2H_CTB_ADDR_KEY,
				ctb_addr);
	if (err)
		return err;

	return xe_guc_self_cfg32(guc,
				 GUC_KLV_SELF_CFG_G2H_CTB_SIZE_KEY,
				 size);
}

static int guc_ct_control_toggle(struct xe_guc_ct *ct, bool enable)
{
	u32 request[HOST2GUC_CONTROL_CTB_REQUEST_MSG_LEN] = {
		FIELD_PREP(GUC_HXG_MSG_0_ORIGIN, GUC_HXG_ORIGIN_HOST) |
		FIELD_PREP(GUC_HXG_MSG_0_TYPE, GUC_HXG_TYPE_REQUEST) |
		FIELD_PREP(GUC_HXG_REQUEST_MSG_0_ACTION,
			   GUC_ACTION_HOST2GUC_CONTROL_CTB),
		FIELD_PREP(HOST2GUC_CONTROL_CTB_REQUEST_MSG_1_CONTROL,
			   enable ? GUC_CTB_CONTROL_ENABLE :
			   GUC_CTB_CONTROL_DISABLE),
	};
	int ret = xe_guc_mmio_send(ct_to_guc(ct), request, ARRAY_SIZE(request));

	return ret > 0 ? -EPROTO : ret;
}

static void xe_guc_ct_set_state(struct xe_guc_ct *ct,
				enum xe_guc_ct_state state)
{
	mutex_lock(&ct->lock);		/* Serialise dequeue_one_g2h() */
	spin_lock_irq(&ct->fast_lock);	/* Serialise CT fast-path */

	xe_gt_assert(ct_to_gt(ct), ct->g2h_outstanding == 0 ||
		     state == XE_GUC_CT_STATE_STOPPED);

	if (ct->g2h_outstanding)
		xe_pm_runtime_put(ct_to_xe(ct));
	ct->g2h_outstanding = 0;
	ct->state = state;

	spin_unlock_irq(&ct->fast_lock);

	/*
	 * Lockdep doesn't like this under the fast lock and he destroy only
	 * needs to be serialized with the send path which ct lock provides.
	 */
	xa_destroy(&ct->fence_lookup);

	mutex_unlock(&ct->lock);
}

static bool ct_needs_safe_mode(struct xe_guc_ct *ct)
{
	return !pci_dev_msi_enabled(to_pci_dev(ct_to_xe(ct)->drm.dev));
}

static bool ct_restart_safe_mode_worker(struct xe_guc_ct *ct)
{
	if (!ct_needs_safe_mode(ct))
		return false;

	queue_delayed_work(ct->g2h_wq, &ct->safe_mode_worker, HZ / 10);
	return true;
}

static void safe_mode_worker_func(struct work_struct *w)
{
	struct xe_guc_ct *ct = container_of(w, struct xe_guc_ct, safe_mode_worker.work);

	receive_g2h(ct);

	if (!ct_restart_safe_mode_worker(ct))
		xe_gt_dbg(ct_to_gt(ct), "GuC CT safe-mode canceled\n");
}

static void ct_enter_safe_mode(struct xe_guc_ct *ct)
{
	if (ct_restart_safe_mode_worker(ct))
		xe_gt_dbg(ct_to_gt(ct), "GuC CT safe-mode enabled\n");
}

static void ct_exit_safe_mode(struct xe_guc_ct *ct)
{
	if (cancel_delayed_work_sync(&ct->safe_mode_worker))
		xe_gt_dbg(ct_to_gt(ct), "GuC CT safe-mode disabled\n");
}

int xe_guc_ct_enable(struct xe_guc_ct *ct)
{
	struct xe_device *xe = ct_to_xe(ct);
	struct xe_gt *gt = ct_to_gt(ct);
	int err;

	xe_gt_assert(gt, !xe_guc_ct_enabled(ct));

	guc_ct_ctb_h2g_init(xe, &ct->ctbs.h2g, &ct->bo->vmap);
	guc_ct_ctb_g2h_init(xe, &ct->ctbs.g2h, &ct->bo->vmap);

	err = guc_ct_ctb_h2g_register(ct);
	if (err)
		goto err_out;

	err = guc_ct_ctb_g2h_register(ct);
	if (err)
		goto err_out;

	err = guc_ct_control_toggle(ct, true);
	if (err)
		goto err_out;

	xe_guc_ct_set_state(ct, XE_GUC_CT_STATE_ENABLED);

	smp_mb();
	wake_up_all(&ct->wq);
	xe_gt_dbg(gt, "GuC CT communication channel enabled\n");

	if (ct_needs_safe_mode(ct))
		ct_enter_safe_mode(ct);

	return 0;

err_out:
	xe_gt_err(gt, "Failed to enable GuC CT (%pe)\n", ERR_PTR(err));

	return err;
}

static void stop_g2h_handler(struct xe_guc_ct *ct)
{
	cancel_work_sync(&ct->g2h_worker);
}

/**
 * xe_guc_ct_disable - Set GuC to disabled state
 * @ct: the &xe_guc_ct
 *
 * Set GuC CT to disabled state and stop g2h handler. No outstanding g2h expected
 * in this transition.
 */
void xe_guc_ct_disable(struct xe_guc_ct *ct)
{
	xe_guc_ct_set_state(ct, XE_GUC_CT_STATE_DISABLED);
	ct_exit_safe_mode(ct);
	stop_g2h_handler(ct);
}

/**
 * xe_guc_ct_stop - Set GuC to stopped state
 * @ct: the &xe_guc_ct
 *
 * Set GuC CT to stopped state, stop g2h handler, and clear any outstanding g2h
 */
void xe_guc_ct_stop(struct xe_guc_ct *ct)
{
	xe_guc_ct_set_state(ct, XE_GUC_CT_STATE_STOPPED);
	stop_g2h_handler(ct);
}

static bool h2g_has_room(struct xe_guc_ct *ct, u32 cmd_len)
{
	struct guc_ctb *h2g = &ct->ctbs.h2g;

	lockdep_assert_held(&ct->lock);

	if (cmd_len > h2g->info.space) {
		h2g->info.head = desc_read(ct_to_xe(ct), h2g, head);
		h2g->info.space = CIRC_SPACE(h2g->info.tail, h2g->info.head,
					     h2g->info.size) -
				  h2g->info.resv_space;
		if (cmd_len > h2g->info.space)
			return false;
	}

	return true;
}

static bool g2h_has_room(struct xe_guc_ct *ct, u32 g2h_len)
{
	if (!g2h_len)
		return true;

	lockdep_assert_held(&ct->fast_lock);

	return ct->ctbs.g2h.info.space > g2h_len;
}

static int has_room(struct xe_guc_ct *ct, u32 cmd_len, u32 g2h_len)
{
	lockdep_assert_held(&ct->lock);

	if (!g2h_has_room(ct, g2h_len) || !h2g_has_room(ct, cmd_len))
		return -EBUSY;

	return 0;
}

static void h2g_reserve_space(struct xe_guc_ct *ct, u32 cmd_len)
{
	lockdep_assert_held(&ct->lock);
	ct->ctbs.h2g.info.space -= cmd_len;
}

static void __g2h_reserve_space(struct xe_guc_ct *ct, u32 g2h_len, u32 num_g2h)
{
	xe_gt_assert(ct_to_gt(ct), g2h_len <= ct->ctbs.g2h.info.space);
	xe_gt_assert(ct_to_gt(ct), (!g2h_len && !num_g2h) ||
		     (g2h_len && num_g2h));

	if (g2h_len) {
		lockdep_assert_held(&ct->fast_lock);

		if (!ct->g2h_outstanding)
			xe_pm_runtime_get_noresume(ct_to_xe(ct));

		ct->ctbs.g2h.info.space -= g2h_len;
		ct->g2h_outstanding += num_g2h;
	}
}

static void __g2h_release_space(struct xe_guc_ct *ct, u32 g2h_len)
{
	lockdep_assert_held(&ct->fast_lock);
	xe_gt_assert(ct_to_gt(ct), ct->ctbs.g2h.info.space + g2h_len <=
		     ct->ctbs.g2h.info.size - ct->ctbs.g2h.info.resv_space);
	xe_gt_assert(ct_to_gt(ct), ct->g2h_outstanding);

	ct->ctbs.g2h.info.space += g2h_len;
	if (!--ct->g2h_outstanding)
		xe_pm_runtime_put(ct_to_xe(ct));
}

static void g2h_release_space(struct xe_guc_ct *ct, u32 g2h_len)
{
	spin_lock_irq(&ct->fast_lock);
	__g2h_release_space(ct, g2h_len);
	spin_unlock_irq(&ct->fast_lock);
}

#define H2G_CT_HEADERS (GUC_CTB_HDR_LEN + 1) /* one DW CTB header and one DW HxG header */

static int h2g_write(struct xe_guc_ct *ct, const u32 *action, u32 len,
		     u32 ct_fence_value, bool want_response)
{
	struct xe_device *xe = ct_to_xe(ct);
	struct xe_gt *gt = ct_to_gt(ct);
	struct guc_ctb *h2g = &ct->ctbs.h2g;
	u32 cmd[H2G_CT_HEADERS];
	u32 tail = h2g->info.tail;
	u32 full_len;
	struct iosys_map map = IOSYS_MAP_INIT_OFFSET(&h2g->cmds,
							 tail * sizeof(u32));

	full_len = len + GUC_CTB_HDR_LEN;

	lockdep_assert_held(&ct->lock);
	xe_gt_assert(gt, full_len <= GUC_CTB_MSG_MAX_LEN);
	xe_gt_assert(gt, tail <= h2g->info.size);

	/* Command will wrap, zero fill (NOPs), return and check credits again */
	if (tail + full_len > h2g->info.size) {
		xe_map_memset(xe, &map, 0, 0,
			      (h2g->info.size - tail) * sizeof(u32));
		h2g_reserve_space(ct, (h2g->info.size - tail));
		h2g->info.tail = 0;
		desc_write(xe, h2g, tail, h2g->info.tail);

		return -EAGAIN;
	}

	/*
	 * dw0: CT header (including fence)
	 * dw1: HXG header (including action code)
	 * dw2+: action data
	 */
	cmd[0] = FIELD_PREP(GUC_CTB_MSG_0_FORMAT, GUC_CTB_FORMAT_HXG) |
		FIELD_PREP(GUC_CTB_MSG_0_NUM_DWORDS, len) |
		FIELD_PREP(GUC_CTB_MSG_0_FENCE, ct_fence_value);
	if (want_response) {
		cmd[1] =
			FIELD_PREP(GUC_HXG_MSG_0_TYPE, GUC_HXG_TYPE_REQUEST) |
			FIELD_PREP(GUC_HXG_EVENT_MSG_0_ACTION |
				   GUC_HXG_EVENT_MSG_0_DATA0, action[0]);
	} else {
		cmd[1] =
			FIELD_PREP(GUC_HXG_MSG_0_TYPE, GUC_HXG_TYPE_FAST_REQUEST) |
			FIELD_PREP(GUC_HXG_EVENT_MSG_0_ACTION |
				   GUC_HXG_EVENT_MSG_0_DATA0, action[0]);
	}

	/* H2G header in cmd[1] replaces action[0] so: */
	--len;
	++action;

	/* Write H2G ensuring visable before descriptor update */
	xe_map_memcpy_to(xe, &map, 0, cmd, H2G_CT_HEADERS * sizeof(u32));
	xe_map_memcpy_to(xe, &map, H2G_CT_HEADERS * sizeof(u32), action, len * sizeof(u32));
	xe_device_wmb(xe);

	/* Update local copies */
	h2g->info.tail = (tail + full_len) % h2g->info.size;
	h2g_reserve_space(ct, full_len);

	/* Update descriptor */
	desc_write(xe, h2g, tail, h2g->info.tail);

	trace_xe_guc_ctb_h2g(xe, gt->info.id, *(action - 1), full_len,
			     desc_read(xe, h2g, head), h2g->info.tail);

	return 0;
}

/*
 * The CT protocol accepts a 16 bits fence. This field is fully owned by the
 * driver, the GuC will just copy it to the reply message. Since we need to
 * be able to distinguish between replies to REQUEST and FAST_REQUEST messages,
 * we use one bit of the seqno as an indicator for that and a rolling counter
 * for the remaining 15 bits.
 */
#define CT_SEQNO_MASK GENMASK(14, 0)
#define CT_SEQNO_UNTRACKED BIT(15)
static u16 next_ct_seqno(struct xe_guc_ct *ct, bool is_g2h_fence)
{
	u32 seqno = ct->fence_seqno++ & CT_SEQNO_MASK;

	if (!is_g2h_fence)
		seqno |= CT_SEQNO_UNTRACKED;

	return seqno;
}

static int __guc_ct_send_locked(struct xe_guc_ct *ct, const u32 *action,
				u32 len, u32 g2h_len, u32 num_g2h,
				struct g2h_fence *g2h_fence)
{
	struct xe_gt *gt __maybe_unused = ct_to_gt(ct);
	u16 seqno;
	int ret;

	xe_gt_assert(gt, ct->state != XE_GUC_CT_STATE_NOT_INITIALIZED);
	xe_gt_assert(gt, !g2h_len || !g2h_fence);
	xe_gt_assert(gt, !num_g2h || !g2h_fence);
	xe_gt_assert(gt, !g2h_len || num_g2h);
	xe_gt_assert(gt, g2h_len || !num_g2h);
	lockdep_assert_held(&ct->lock);

	if (unlikely(ct->ctbs.h2g.info.broken)) {
		ret = -EPIPE;
		goto out;
	}

	if (ct->state == XE_GUC_CT_STATE_DISABLED) {
		ret = -ENODEV;
		goto out;
	}

	if (ct->state == XE_GUC_CT_STATE_STOPPED) {
		ret = -ECANCELED;
		goto out;
	}

	xe_gt_assert(gt, xe_guc_ct_enabled(ct));

	if (g2h_fence) {
		g2h_len = GUC_CTB_HXG_MSG_MAX_LEN;
		num_g2h = 1;

		if (g2h_fence_needs_alloc(g2h_fence)) {
			g2h_fence->seqno = next_ct_seqno(ct, true);
			ret = xa_err(xa_store(&ct->fence_lookup,
					      g2h_fence->seqno, g2h_fence,
					      GFP_ATOMIC));
			if (ret)
				goto out;
		}

		seqno = g2h_fence->seqno;
	} else {
		seqno = next_ct_seqno(ct, false);
	}

	if (g2h_len)
		spin_lock_irq(&ct->fast_lock);
retry:
	ret = has_room(ct, len + GUC_CTB_HDR_LEN, g2h_len);
	if (unlikely(ret))
		goto out_unlock;

	ret = h2g_write(ct, action, len, seqno, !!g2h_fence);
	if (unlikely(ret)) {
		if (ret == -EAGAIN)
			goto retry;
		goto out_unlock;
	}

	__g2h_reserve_space(ct, g2h_len, num_g2h);
	xe_guc_notify(ct_to_guc(ct));
out_unlock:
	if (g2h_len)
		spin_unlock_irq(&ct->fast_lock);
out:
	return ret;
}

static void kick_reset(struct xe_guc_ct *ct)
{
	xe_gt_reset_async(ct_to_gt(ct));
}

static int dequeue_one_g2h(struct xe_guc_ct *ct);

static int guc_ct_send_locked(struct xe_guc_ct *ct, const u32 *action, u32 len,
			      u32 g2h_len, u32 num_g2h,
			      struct g2h_fence *g2h_fence)
{
	struct xe_device *xe = ct_to_xe(ct);
	struct xe_gt *gt = ct_to_gt(ct);
	struct drm_printer p = xe_gt_info_printer(gt);
	unsigned int sleep_period_ms = 1;
	int ret;

	xe_gt_assert(gt, !g2h_len || !g2h_fence);
	lockdep_assert_held(&ct->lock);
	xe_device_assert_mem_access(ct_to_xe(ct));

try_again:
	ret = __guc_ct_send_locked(ct, action, len, g2h_len, num_g2h,
				   g2h_fence);

	/*
	 * We wait to try to restore credits for about 1 second before bailing.
	 * In the case of H2G credits we have no choice but just to wait for the
	 * GuC to consume H2Gs in the channel so we use a wait / sleep loop. In
	 * the case of G2H we process any G2H in the channel, hopefully freeing
	 * credits as we consume the G2H messages.
	 */
	if (unlikely(ret == -EBUSY &&
		     !h2g_has_room(ct, len + GUC_CTB_HDR_LEN))) {
		struct guc_ctb *h2g = &ct->ctbs.h2g;

		if (sleep_period_ms == 1024)
			goto broken;

		trace_xe_guc_ct_h2g_flow_control(xe, h2g->info.head, h2g->info.tail,
						 h2g->info.size,
						 h2g->info.space,
						 len + GUC_CTB_HDR_LEN);
		msleep(sleep_period_ms);
		sleep_period_ms <<= 1;

		goto try_again;
	} else if (unlikely(ret == -EBUSY)) {
		struct xe_device *xe = ct_to_xe(ct);
		struct guc_ctb *g2h = &ct->ctbs.g2h;

		trace_xe_guc_ct_g2h_flow_control(xe, g2h->info.head,
						 desc_read(xe, g2h, tail),
						 g2h->info.size,
						 g2h->info.space,
						 g2h_fence ?
						 GUC_CTB_HXG_MSG_MAX_LEN :
						 g2h_len);

#define g2h_avail(ct)	\
	(desc_read(ct_to_xe(ct), (&ct->ctbs.g2h), tail) != ct->ctbs.g2h.info.head)
		if (!wait_event_timeout(ct->wq, !ct->g2h_outstanding ||
					g2h_avail(ct), HZ))
			goto broken;
#undef g2h_avail

		if (dequeue_one_g2h(ct) < 0)
			goto broken;

		goto try_again;
	}

	return ret;

broken:
	xe_gt_err(gt, "No forward process on H2G, reset required\n");
	xe_guc_ct_print(ct, &p, true);
	ct->ctbs.h2g.info.broken = true;

	return -EDEADLK;
}

static int guc_ct_send(struct xe_guc_ct *ct, const u32 *action, u32 len,
		       u32 g2h_len, u32 num_g2h, struct g2h_fence *g2h_fence)
{
	int ret;

	xe_gt_assert(ct_to_gt(ct), !g2h_len || !g2h_fence);

	mutex_lock(&ct->lock);
	ret = guc_ct_send_locked(ct, action, len, g2h_len, num_g2h, g2h_fence);
	mutex_unlock(&ct->lock);

	return ret;
}

int xe_guc_ct_send(struct xe_guc_ct *ct, const u32 *action, u32 len,
		   u32 g2h_len, u32 num_g2h)
{
	int ret;

	ret = guc_ct_send(ct, action, len, g2h_len, num_g2h, NULL);
	if (ret == -EDEADLK)
		kick_reset(ct);

	return ret;
}

int xe_guc_ct_send_locked(struct xe_guc_ct *ct, const u32 *action, u32 len,
			  u32 g2h_len, u32 num_g2h)
{
	int ret;

	ret = guc_ct_send_locked(ct, action, len, g2h_len, num_g2h, NULL);
	if (ret == -EDEADLK)
		kick_reset(ct);

	return ret;
}

int xe_guc_ct_send_g2h_handler(struct xe_guc_ct *ct, const u32 *action, u32 len)
{
	int ret;

	lockdep_assert_held(&ct->lock);

	ret = guc_ct_send_locked(ct, action, len, 0, 0, NULL);
	if (ret == -EDEADLK)
		kick_reset(ct);

	return ret;
}

/*
 * Check if a GT reset is in progress or will occur and if GT reset brought the
 * CT back up. Randomly picking 5 seconds for an upper limit to do a GT a reset.
 */
static bool retry_failure(struct xe_guc_ct *ct, int ret)
{
	if (!(ret == -EDEADLK || ret == -EPIPE || ret == -ENODEV))
		return false;

#define ct_alive(ct)	\
	(xe_guc_ct_enabled(ct) && !ct->ctbs.h2g.info.broken && \
	 !ct->ctbs.g2h.info.broken)
	if (!wait_event_interruptible_timeout(ct->wq, ct_alive(ct),  HZ * 5))
		return false;
#undef ct_alive

	return true;
}

static int guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len,
			    u32 *response_buffer, bool no_fail)
{
	struct xe_gt *gt = ct_to_gt(ct);
	struct g2h_fence g2h_fence;
	int ret = 0;

	/*
	 * We use a fence to implement blocking sends / receiving response data.
	 * The seqno of the fence is sent in the H2G, returned in the G2H, and
	 * an xarray is used as storage media with the seqno being to key.
	 * Fields in the fence hold success, failure, retry status and the
	 * response data. Safe to allocate on the stack as the xarray is the
	 * only reference and it cannot be present after this function exits.
	 */
retry:
	g2h_fence_init(&g2h_fence, response_buffer);
retry_same_fence:
	ret = guc_ct_send(ct, action, len, 0, 0, &g2h_fence);
	if (unlikely(ret == -ENOMEM)) {
		/* Retry allocation /w GFP_KERNEL */
		ret = xa_err(xa_store(&ct->fence_lookup, g2h_fence.seqno,
				      &g2h_fence, GFP_KERNEL));
		if (ret)
			return ret;

		goto retry_same_fence;
	} else if (unlikely(ret)) {
		if (ret == -EDEADLK)
			kick_reset(ct);

		if (no_fail && retry_failure(ct, ret))
			goto retry_same_fence;

		if (!g2h_fence_needs_alloc(&g2h_fence))
			xa_erase_irq(&ct->fence_lookup, g2h_fence.seqno);

		return ret;
	}

	ret = wait_event_timeout(ct->g2h_fence_wq, g2h_fence.done, HZ);

	if (!ret) {
		LNL_FLUSH_WORK(&ct->g2h_worker);
		if (g2h_fence.done) {
			xe_gt_warn(gt, "G2H fence %u, action %04x, done\n",
				   g2h_fence.seqno, action[0]);
			ret = 1;
		}
	}

	/*
	 * Ensure we serialize with completion side to prevent UAF with fence going out of scope on
	 * the stack, since we have no clue if it will fire after the timeout before we can erase
	 * from the xa. Also we have some dependent loads and stores below for which we need the
	 * correct ordering, and we lack the needed barriers.
	 */
	mutex_lock(&ct->lock);
	if (!ret) {
		xe_gt_err(gt, "Timed out wait for G2H, fence %u, action %04x, done %s",
			  g2h_fence.seqno, action[0], str_yes_no(g2h_fence.done));
		xa_erase_irq(&ct->fence_lookup, g2h_fence.seqno);
		mutex_unlock(&ct->lock);
		return -ETIME;
	}

	if (g2h_fence.retry) {
		xe_gt_dbg(gt, "H2G action %#x retrying: reason %#x\n",
			  action[0], g2h_fence.reason);
		mutex_unlock(&ct->lock);
		goto retry;
	}
	if (g2h_fence.fail) {
		xe_gt_err(gt, "H2G request %#x failed: error %#x hint %#x\n",
			  action[0], g2h_fence.error, g2h_fence.hint);
		ret = -EIO;
	}

	if (ret > 0)
		ret = response_buffer ? g2h_fence.response_len : g2h_fence.response_data;

	mutex_unlock(&ct->lock);

	return ret;
}

/**
 * xe_guc_ct_send_recv - Send and receive HXG to the GuC
 * @ct: the &xe_guc_ct
 * @action: the dword array with `HXG Request`_ message (can't be NULL)
 * @len: length of the `HXG Request`_ message (in dwords, can't be 0)
 * @response_buffer: placeholder for the `HXG Response`_ message (can be NULL)
 *
 * Send a `HXG Request`_ message to the GuC over CT communication channel and
 * blocks until GuC replies with a `HXG Response`_ message.
 *
 * For non-blocking communication with GuC use xe_guc_ct_send().
 *
 * Note: The size of &response_buffer must be at least GUC_CTB_MAX_DWORDS_.
 *
 * Return: response length (in dwords) if &response_buffer was not NULL, or
 *         DATA0 from `HXG Response`_ if &response_buffer was NULL, or
 *         a negative error code on failure.
 */
int xe_guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len,
			u32 *response_buffer)
{
	KUNIT_STATIC_STUB_REDIRECT(xe_guc_ct_send_recv, ct, action, len, response_buffer);
	return guc_ct_send_recv(ct, action, len, response_buffer, false);
}

int xe_guc_ct_send_recv_no_fail(struct xe_guc_ct *ct, const u32 *action,
				u32 len, u32 *response_buffer)
{
	return guc_ct_send_recv(ct, action, len, response_buffer, true);
}

static u32 *msg_to_hxg(u32 *msg)
{
	return msg + GUC_CTB_MSG_MIN_LEN;
}

static u32 msg_len_to_hxg_len(u32 len)
{
	return len - GUC_CTB_MSG_MIN_LEN;
}

static int parse_g2h_event(struct xe_guc_ct *ct, u32 *msg, u32 len)
{
	u32 *hxg = msg_to_hxg(msg);
	u32 action = FIELD_GET(GUC_HXG_EVENT_MSG_0_ACTION, hxg[0]);

	lockdep_assert_held(&ct->lock);

	switch (action) {
	case XE_GUC_ACTION_SCHED_CONTEXT_MODE_DONE:
	case XE_GUC_ACTION_DEREGISTER_CONTEXT_DONE:
	case XE_GUC_ACTION_SCHED_ENGINE_MODE_DONE:
	case XE_GUC_ACTION_TLB_INVALIDATION_DONE:
		g2h_release_space(ct, len);
	}

	return 0;
}

static int parse_g2h_response(struct xe_guc_ct *ct, u32 *msg, u32 len)
{
	struct xe_gt *gt =  ct_to_gt(ct);
	u32 *hxg = msg_to_hxg(msg);
	u32 hxg_len = msg_len_to_hxg_len(len);
	u32 fence = FIELD_GET(GUC_CTB_MSG_0_FENCE, msg[0]);
	u32 type = FIELD_GET(GUC_HXG_MSG_0_TYPE, hxg[0]);
	struct g2h_fence *g2h_fence;

	lockdep_assert_held(&ct->lock);

	/*
	 * Fences for FAST_REQUEST messages are not tracked in ct->fence_lookup.
	 * Those messages should never fail, so if we do get an error back it
	 * means we're likely doing an illegal operation and the GuC is
	 * rejecting it. We have no way to inform the code that submitted the
	 * H2G that the message was rejected, so we need to escalate the
	 * failure to trigger a reset.
	 */
	if (fence & CT_SEQNO_UNTRACKED) {
		if (type == GUC_HXG_TYPE_RESPONSE_FAILURE)
			xe_gt_err(gt, "FAST_REQ H2G fence 0x%x failed! e=0x%x, h=%u\n",
				  fence,
				  FIELD_GET(GUC_HXG_FAILURE_MSG_0_ERROR, hxg[0]),
				  FIELD_GET(GUC_HXG_FAILURE_MSG_0_HINT, hxg[0]));
		else
			xe_gt_err(gt, "unexpected response %u for FAST_REQ H2G fence 0x%x!\n",
				  type, fence);

		return -EPROTO;
	}

	g2h_fence = xa_erase(&ct->fence_lookup, fence);
	if (unlikely(!g2h_fence)) {
		/* Don't tear down channel, as send could've timed out */
		xe_gt_warn(gt, "G2H fence (%u) not found!\n", fence);
		g2h_release_space(ct, GUC_CTB_HXG_MSG_MAX_LEN);
		return 0;
	}

	xe_gt_assert(gt, fence == g2h_fence->seqno);

	if (type == GUC_HXG_TYPE_RESPONSE_FAILURE) {
		g2h_fence->fail = true;
		g2h_fence->error = FIELD_GET(GUC_HXG_FAILURE_MSG_0_ERROR, hxg[0]);
		g2h_fence->hint = FIELD_GET(GUC_HXG_FAILURE_MSG_0_HINT, hxg[0]);
	} else if (type == GUC_HXG_TYPE_NO_RESPONSE_RETRY) {
		g2h_fence->retry = true;
		g2h_fence->reason = FIELD_GET(GUC_HXG_RETRY_MSG_0_REASON, hxg[0]);
	} else if (g2h_fence->response_buffer) {
		g2h_fence->response_len = hxg_len;
		memcpy(g2h_fence->response_buffer, hxg, hxg_len * sizeof(u32));
	} else {
		g2h_fence->response_data = FIELD_GET(GUC_HXG_RESPONSE_MSG_0_DATA0, hxg[0]);
	}

	g2h_release_space(ct, GUC_CTB_HXG_MSG_MAX_LEN);

	g2h_fence->done = true;
	smp_mb();

	wake_up_all(&ct->g2h_fence_wq);

	return 0;
}

static int parse_g2h_msg(struct xe_guc_ct *ct, u32 *msg, u32 len)
{
	struct xe_gt *gt = ct_to_gt(ct);
	u32 *hxg = msg_to_hxg(msg);
	u32 origin, type;
	int ret;

	lockdep_assert_held(&ct->lock);

	origin = FIELD_GET(GUC_HXG_MSG_0_ORIGIN, hxg[0]);
	if (unlikely(origin != GUC_HXG_ORIGIN_GUC)) {
		xe_gt_err(gt, "G2H channel broken on read, origin=%u, reset required\n",
			  origin);
		ct->ctbs.g2h.info.broken = true;

		return -EPROTO;
	}

	type = FIELD_GET(GUC_HXG_MSG_0_TYPE, hxg[0]);
	switch (type) {
	case GUC_HXG_TYPE_EVENT:
		ret = parse_g2h_event(ct, msg, len);
		break;
	case GUC_HXG_TYPE_RESPONSE_SUCCESS:
	case GUC_HXG_TYPE_RESPONSE_FAILURE:
	case GUC_HXG_TYPE_NO_RESPONSE_RETRY:
		ret = parse_g2h_response(ct, msg, len);
		break;
	default:
		xe_gt_err(gt, "G2H channel broken on read, type=%u, reset required\n",
			  type);
		ct->ctbs.g2h.info.broken = true;

		ret = -EOPNOTSUPP;
	}

	return ret;
}

static int process_g2h_msg(struct xe_guc_ct *ct, u32 *msg, u32 len)
{
	struct xe_guc *guc = ct_to_guc(ct);
	struct xe_gt *gt = ct_to_gt(ct);
	u32 hxg_len = msg_len_to_hxg_len(len);
	u32 *hxg = msg_to_hxg(msg);
	u32 action, adj_len;
	u32 *payload;
	int ret = 0;

	if (FIELD_GET(GUC_HXG_MSG_0_TYPE, hxg[0]) != GUC_HXG_TYPE_EVENT)
		return 0;

	action = FIELD_GET(GUC_HXG_EVENT_MSG_0_ACTION, hxg[0]);
	payload = hxg + GUC_HXG_EVENT_MSG_MIN_LEN;
	adj_len = hxg_len - GUC_HXG_EVENT_MSG_MIN_LEN;

	switch (action) {
	case XE_GUC_ACTION_SCHED_CONTEXT_MODE_DONE:
		ret = xe_guc_sched_done_handler(guc, payload, adj_len);
		break;
	case XE_GUC_ACTION_DEREGISTER_CONTEXT_DONE:
		ret = xe_guc_deregister_done_handler(guc, payload, adj_len);
		break;
	case XE_GUC_ACTION_CONTEXT_RESET_NOTIFICATION:
		ret = xe_guc_exec_queue_reset_handler(guc, payload, adj_len);
		break;
	case XE_GUC_ACTION_ENGINE_FAILURE_NOTIFICATION:
		ret = xe_guc_exec_queue_reset_failure_handler(guc, payload,
							      adj_len);
		break;
	case XE_GUC_ACTION_SCHED_ENGINE_MODE_DONE:
		/* Selftest only at the moment */
		break;
	case XE_GUC_ACTION_STATE_CAPTURE_NOTIFICATION:
	case XE_GUC_ACTION_NOTIFY_FLUSH_LOG_BUFFER_TO_FILE:
		/* FIXME: Handle this */
		break;
	case XE_GUC_ACTION_NOTIFY_MEMORY_CAT_ERROR:
		ret = xe_guc_exec_queue_memory_cat_error_handler(guc, payload,
								 adj_len);
		break;
	case XE_GUC_ACTION_REPORT_PAGE_FAULT_REQ_DESC:
		ret = xe_guc_pagefault_handler(guc, payload, adj_len);
		break;
	case XE_GUC_ACTION_TLB_INVALIDATION_DONE:
		ret = xe_guc_tlb_invalidation_done_handler(guc, payload,
							   adj_len);
		break;
	case XE_GUC_ACTION_ACCESS_COUNTER_NOTIFY:
		ret = xe_guc_access_counter_notify_handler(guc, payload,
							   adj_len);
		break;
	case XE_GUC_ACTION_GUC2PF_RELAY_FROM_VF:
		ret = xe_guc_relay_process_guc2pf(&guc->relay, hxg, hxg_len);
		break;
	case XE_GUC_ACTION_GUC2VF_RELAY_FROM_PF:
		ret = xe_guc_relay_process_guc2vf(&guc->relay, hxg, hxg_len);
		break;
	case GUC_ACTION_GUC2PF_VF_STATE_NOTIFY:
		ret = xe_gt_sriov_pf_control_process_guc2pf(gt, hxg, hxg_len);
		break;
	case GUC_ACTION_GUC2PF_ADVERSE_EVENT:
		ret = xe_gt_sriov_pf_monitor_process_guc2pf(gt, hxg, hxg_len);
		break;
	default:
		xe_gt_err(gt, "unexpected G2H action 0x%04x\n", action);
	}

	if (ret)
		xe_gt_err(gt, "G2H action 0x%04x failed (%pe)\n",
			  action, ERR_PTR(ret));

	return 0;
}

static int g2h_read(struct xe_guc_ct *ct, u32 *msg, bool fast_path)
{
	struct xe_device *xe = ct_to_xe(ct);
	struct xe_gt *gt = ct_to_gt(ct);
	struct guc_ctb *g2h = &ct->ctbs.g2h;
	u32 tail, head, len;
	s32 avail;
	u32 action;
	u32 *hxg;

	xe_gt_assert(gt, ct->state != XE_GUC_CT_STATE_NOT_INITIALIZED);
	lockdep_assert_held(&ct->fast_lock);

	if (ct->state == XE_GUC_CT_STATE_DISABLED)
		return -ENODEV;

	if (ct->state == XE_GUC_CT_STATE_STOPPED)
		return -ECANCELED;

	if (g2h->info.broken)
		return -EPIPE;

	xe_gt_assert(gt, xe_guc_ct_enabled(ct));

	/* Calculate DW available to read */
	tail = desc_read(xe, g2h, tail);
	avail = tail - g2h->info.head;
	if (unlikely(avail == 0))
		return 0;

	if (avail < 0)
		avail += g2h->info.size;

	/* Read header */
	xe_map_memcpy_from(xe, msg, &g2h->cmds, sizeof(u32) * g2h->info.head,
			   sizeof(u32));
	len = FIELD_GET(GUC_CTB_MSG_0_NUM_DWORDS, msg[0]) + GUC_CTB_MSG_MIN_LEN;
	if (len > avail) {
		xe_gt_err(gt, "G2H channel broken on read, avail=%d, len=%d, reset required\n",
			  avail, len);
		g2h->info.broken = true;

		return -EPROTO;
	}

	head = (g2h->info.head + 1) % g2h->info.size;
	avail = len - 1;

	/* Read G2H message */
	if (avail + head > g2h->info.size) {
		u32 avail_til_wrap = g2h->info.size - head;

		xe_map_memcpy_from(xe, msg + 1,
				   &g2h->cmds, sizeof(u32) * head,
				   avail_til_wrap * sizeof(u32));
		xe_map_memcpy_from(xe, msg + 1 + avail_til_wrap,
				   &g2h->cmds, 0,
				   (avail - avail_til_wrap) * sizeof(u32));
	} else {
		xe_map_memcpy_from(xe, msg + 1,
				   &g2h->cmds, sizeof(u32) * head,
				   avail * sizeof(u32));
	}

	hxg = msg_to_hxg(msg);
	action = FIELD_GET(GUC_HXG_EVENT_MSG_0_ACTION, hxg[0]);

	if (fast_path) {
		if (FIELD_GET(GUC_HXG_MSG_0_TYPE, hxg[0]) != GUC_HXG_TYPE_EVENT)
			return 0;

		switch (action) {
		case XE_GUC_ACTION_REPORT_PAGE_FAULT_REQ_DESC:
		case XE_GUC_ACTION_TLB_INVALIDATION_DONE:
			break;	/* Process these in fast-path */
		default:
			return 0;
		}
	}

	/* Update local / descriptor header */
	g2h->info.head = (head + avail) % g2h->info.size;
	desc_write(xe, g2h, head, g2h->info.head);

	trace_xe_guc_ctb_g2h(xe, ct_to_gt(ct)->info.id,
			     action, len, g2h->info.head, tail);

	return len;
}

static void g2h_fast_path(struct xe_guc_ct *ct, u32 *msg, u32 len)
{
	struct xe_gt *gt = ct_to_gt(ct);
	struct xe_guc *guc = ct_to_guc(ct);
	u32 hxg_len = msg_len_to_hxg_len(len);
	u32 *hxg = msg_to_hxg(msg);
	u32 action = FIELD_GET(GUC_HXG_EVENT_MSG_0_ACTION, hxg[0]);
	u32 *payload = hxg + GUC_HXG_MSG_MIN_LEN;
	u32 adj_len = hxg_len - GUC_HXG_MSG_MIN_LEN;
	int ret = 0;

	switch (action) {
	case XE_GUC_ACTION_REPORT_PAGE_FAULT_REQ_DESC:
		ret = xe_guc_pagefault_handler(guc, payload, adj_len);
		break;
	case XE_GUC_ACTION_TLB_INVALIDATION_DONE:
		__g2h_release_space(ct, len);
		ret = xe_guc_tlb_invalidation_done_handler(guc, payload,
							   adj_len);
		break;
	default:
		xe_gt_warn(gt, "NOT_POSSIBLE");
	}

	if (ret)
		xe_gt_err(gt, "G2H action 0x%04x failed (%pe)\n",
			  action, ERR_PTR(ret));
}

/**
 * xe_guc_ct_fast_path - process critical G2H in the IRQ handler
 * @ct: GuC CT object
 *
 * Anything related to page faults is critical for performance, process these
 * critical G2H in the IRQ. This is safe as these handlers either just wake up
 * waiters or queue another worker.
 */
void xe_guc_ct_fast_path(struct xe_guc_ct *ct)
{
	struct xe_device *xe = ct_to_xe(ct);
	bool ongoing;
	int len;

	ongoing = xe_pm_runtime_get_if_active(ct_to_xe(ct));
	if (!ongoing && xe_pm_read_callback_task(ct_to_xe(ct)) == NULL)
		return;

	spin_lock(&ct->fast_lock);
	do {
		len = g2h_read(ct, ct->fast_msg, true);
		if (len > 0)
			g2h_fast_path(ct, ct->fast_msg, len);
	} while (len > 0);
	spin_unlock(&ct->fast_lock);

	if (ongoing)
		xe_pm_runtime_put(xe);
}

/* Returns less than zero on error, 0 on done, 1 on more available */
static int dequeue_one_g2h(struct xe_guc_ct *ct)
{
	int len;
	int ret;

	lockdep_assert_held(&ct->lock);

	spin_lock_irq(&ct->fast_lock);
	len = g2h_read(ct, ct->msg, false);
	spin_unlock_irq(&ct->fast_lock);
	if (len <= 0)
		return len;

	ret = parse_g2h_msg(ct, ct->msg, len);
	if (unlikely(ret < 0))
		return ret;

	ret = process_g2h_msg(ct, ct->msg, len);
	if (unlikely(ret < 0))
		return ret;

	return 1;
}

static void receive_g2h(struct xe_guc_ct *ct)
{
	struct xe_gt *gt = ct_to_gt(ct);
	bool ongoing;
	int ret;

	/*
	 * Normal users must always hold mem_access.ref around CT calls. However
	 * during the runtime pm callbacks we rely on CT to talk to the GuC, but
	 * at this stage we can't rely on mem_access.ref and even the
	 * callback_task will be different than current.  For such cases we just
	 * need to ensure we always process the responses from any blocking
	 * ct_send requests or where we otherwise expect some response when
	 * initiated from those callbacks (which will need to wait for the below
	 * dequeue_one_g2h()).  The dequeue_one_g2h() will gracefully fail if
	 * the device has suspended to the point that the CT communication has
	 * been disabled.
	 *
	 * If we are inside the runtime pm callback, we can be the only task
	 * still issuing CT requests (since that requires having the
	 * mem_access.ref).  It seems like it might in theory be possible to
	 * receive unsolicited events from the GuC just as we are
	 * suspending-resuming, but those will currently anyway be lost when
	 * eventually exiting from suspend, hence no need to wake up the device
	 * here. If we ever need something stronger than get_if_ongoing() then
	 * we need to be careful with blocking the pm callbacks from getting CT
	 * responses, if the worker here is blocked on those callbacks
	 * completing, creating a deadlock.
	 */
	ongoing = xe_pm_runtime_get_if_active(ct_to_xe(ct));
	if (!ongoing && xe_pm_read_callback_task(ct_to_xe(ct)) == NULL)
		return;

	do {
		mutex_lock(&ct->lock);
		ret = dequeue_one_g2h(ct);
		mutex_unlock(&ct->lock);

		if (unlikely(ret == -EPROTO || ret == -EOPNOTSUPP)) {
			struct drm_printer p = xe_gt_info_printer(gt);

			xe_guc_ct_print(ct, &p, false);
			kick_reset(ct);
		}
	} while (ret == 1);

	if (ongoing)
		xe_pm_runtime_put(ct_to_xe(ct));
}

static void g2h_worker_func(struct work_struct *w)
{
	struct xe_guc_ct *ct = container_of(w, struct xe_guc_ct, g2h_worker);

	receive_g2h(ct);
}

static void guc_ctb_snapshot_capture(struct xe_device *xe, struct guc_ctb *ctb,
				     struct guc_ctb_snapshot *snapshot,
				     bool atomic)
{
	u32 head, tail;

	xe_map_memcpy_from(xe, &snapshot->desc, &ctb->desc, 0,
			   sizeof(struct guc_ct_buffer_desc));
	memcpy(&snapshot->info, &ctb->info, sizeof(struct guc_ctb_info));

	snapshot->cmds = kmalloc_array(ctb->info.size, sizeof(u32),
				       atomic ? GFP_ATOMIC : GFP_KERNEL);

	if (!snapshot->cmds) {
		drm_err(&xe->drm, "Skipping CTB commands snapshot. Only CTB info will be available.\n");
		return;
	}

	head = snapshot->desc.head;
	tail = snapshot->desc.tail;

	if (head != tail) {
		struct iosys_map map =
			IOSYS_MAP_INIT_OFFSET(&ctb->cmds, head * sizeof(u32));

		while (head != tail) {
			snapshot->cmds[head] = xe_map_rd(xe, &map, 0, u32);
			++head;
			if (head == ctb->info.size) {
				head = 0;
				map = ctb->cmds;
			} else {
				iosys_map_incr(&map, sizeof(u32));
			}
		}
	}
}

static void guc_ctb_snapshot_print(struct guc_ctb_snapshot *snapshot,
				   struct drm_printer *p)
{
	u32 head, tail;

	drm_printf(p, "\tsize: %d\n", snapshot->info.size);
	drm_printf(p, "\tresv_space: %d\n", snapshot->info.resv_space);
	drm_printf(p, "\thead: %d\n", snapshot->info.head);
	drm_printf(p, "\ttail: %d\n", snapshot->info.tail);
	drm_printf(p, "\tspace: %d\n", snapshot->info.space);
	drm_printf(p, "\tbroken: %d\n", snapshot->info.broken);
	drm_printf(p, "\thead (memory): %d\n", snapshot->desc.head);
	drm_printf(p, "\ttail (memory): %d\n", snapshot->desc.tail);
	drm_printf(p, "\tstatus (memory): 0x%x\n", snapshot->desc.status);

	if (!snapshot->cmds)
		return;

	head = snapshot->desc.head;
	tail = snapshot->desc.tail;

	while (head != tail) {
		drm_printf(p, "\tcmd[%d]: 0x%08x\n", head,
			   snapshot->cmds[head]);
		++head;
		if (head == snapshot->info.size)
			head = 0;
	}
}

static void guc_ctb_snapshot_free(struct guc_ctb_snapshot *snapshot)
{
	kfree(snapshot->cmds);
}

/**
 * xe_guc_ct_snapshot_capture - Take a quick snapshot of the CT state.
 * @ct: GuC CT object.
 * @atomic: Boolean to indicate if this is called from atomic context like
 * reset or CTB handler or from some regular path like debugfs.
 *
 * This can be printed out in a later stage like during dev_coredump
 * analysis.
 *
 * Returns: a GuC CT snapshot object that must be freed by the caller
 * by using `xe_guc_ct_snapshot_free`.
 */
struct xe_guc_ct_snapshot *xe_guc_ct_snapshot_capture(struct xe_guc_ct *ct,
						      bool atomic)
{
	struct xe_device *xe = ct_to_xe(ct);
	struct xe_guc_ct_snapshot *snapshot;

	snapshot = kzalloc(sizeof(*snapshot),
			   atomic ? GFP_ATOMIC : GFP_KERNEL);

	if (!snapshot) {
		drm_err(&xe->drm, "Skipping CTB snapshot entirely.\n");
		return NULL;
	}

	if (xe_guc_ct_enabled(ct) || ct->state == XE_GUC_CT_STATE_STOPPED) {
		snapshot->ct_enabled = true;
		snapshot->g2h_outstanding = READ_ONCE(ct->g2h_outstanding);
		guc_ctb_snapshot_capture(xe, &ct->ctbs.h2g,
					 &snapshot->h2g, atomic);
		guc_ctb_snapshot_capture(xe, &ct->ctbs.g2h,
					 &snapshot->g2h, atomic);
	}

	return snapshot;
}

/**
 * xe_guc_ct_snapshot_print - Print out a given GuC CT snapshot.
 * @snapshot: GuC CT snapshot object.
 * @p: drm_printer where it will be printed out.
 *
 * This function prints out a given GuC CT snapshot object.
 */
void xe_guc_ct_snapshot_print(struct xe_guc_ct_snapshot *snapshot,
			      struct drm_printer *p)
{
	if (!snapshot)
		return;

	if (snapshot->ct_enabled) {
		drm_puts(p, "H2G CTB (all sizes in DW):\n");
		guc_ctb_snapshot_print(&snapshot->h2g, p);

		drm_puts(p, "\nG2H CTB (all sizes in DW):\n");
		guc_ctb_snapshot_print(&snapshot->g2h, p);

		drm_printf(p, "\tg2h outstanding: %d\n",
			   snapshot->g2h_outstanding);
	} else {
		drm_puts(p, "CT disabled\n");
	}
}

/**
 * xe_guc_ct_snapshot_free - Free all allocated objects for a given snapshot.
 * @snapshot: GuC CT snapshot object.
 *
 * This function free all the memory that needed to be allocated at capture
 * time.
 */
void xe_guc_ct_snapshot_free(struct xe_guc_ct_snapshot *snapshot)
{
	if (!snapshot)
		return;

	guc_ctb_snapshot_free(&snapshot->h2g);
	guc_ctb_snapshot_free(&snapshot->g2h);
	kfree(snapshot);
}

/**
 * xe_guc_ct_print - GuC CT Print.
 * @ct: GuC CT.
 * @p: drm_printer where it will be printed out.
 * @atomic: Boolean to indicate if this is called from atomic context like
 * reset or CTB handler or from some regular path like debugfs.
 *
 * This function quickly capture a snapshot and immediately print it out.
 */
void xe_guc_ct_print(struct xe_guc_ct *ct, struct drm_printer *p, bool atomic)
{
	struct xe_guc_ct_snapshot *snapshot;

	snapshot = xe_guc_ct_snapshot_capture(ct, atomic);
	xe_guc_ct_snapshot_print(snapshot, p);
	xe_guc_ct_snapshot_free(snapshot);
}