summaryrefslogtreecommitdiff
path: root/drivers/misc/sgi-xp/xpc_partition.c
blob: 7dd4b5812c422e844b399a1cb5624833cb0f5eb3 (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
/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (c) 2004-2008 Silicon Graphics, Inc.  All Rights Reserved.
 */

/*
 * Cross Partition Communication (XPC) partition support.
 *
 *	This is the part of XPC that detects the presence/absence of
 *	other partitions. It provides a heartbeat and monitors the
 *	heartbeats of other partitions.
 *
 */

#include <linux/kernel.h>
#include <linux/sysctl.h>
#include <linux/cache.h>
#include <linux/mmzone.h>
#include <linux/nodemask.h>
#include <asm/uncached.h>
#include <asm/sn/bte.h>
#include <asm/sn/intr.h>
#include <asm/sn/sn_sal.h>
#include <asm/sn/nodepda.h>
#include <asm/sn/addrs.h>
#include "xpc.h"

/* XPC is exiting flag */
int xpc_exiting;

/* SH_IPI_ACCESS shub register value on startup */
static u64 xpc_sh1_IPI_access;
static u64 xpc_sh2_IPI_access0;
static u64 xpc_sh2_IPI_access1;
static u64 xpc_sh2_IPI_access2;
static u64 xpc_sh2_IPI_access3;

/* original protection values for each node */
u64 xpc_prot_vec[MAX_NUMNODES];

/* this partition's reserved page pointers */
struct xpc_rsvd_page *xpc_rsvd_page;
static u64 *xpc_part_nasids;
static u64 *xpc_mach_nasids;
struct xpc_vars *xpc_vars;
struct xpc_vars_part *xpc_vars_part;

static int xp_nasid_mask_bytes;	/* actual size in bytes of nasid mask */
static int xp_nasid_mask_words;	/* actual size in words of nasid mask */

/*
 * For performance reasons, each entry of xpc_partitions[] is cacheline
 * aligned. And xpc_partitions[] is padded with an additional entry at the
 * end so that the last legitimate entry doesn't share its cacheline with
 * another variable.
 */
struct xpc_partition xpc_partitions[XP_MAX_PARTITIONS + 1];

/*
 * Generic buffer used to store a local copy of portions of a remote
 * partition's reserved page (either its header and part_nasids mask,
 * or its vars).
 */
char *xpc_remote_copy_buffer;
void *xpc_remote_copy_buffer_base;

/*
 * Guarantee that the kmalloc'd memory is cacheline aligned.
 */
void *
xpc_kmalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
{
	/* see if kmalloc will give us cachline aligned memory by default */
	*base = kmalloc(size, flags);
	if (*base == NULL)
		return NULL;

	if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
		return *base;

	kfree(*base);

	/* nope, we'll have to do it ourselves */
	*base = kmalloc(size + L1_CACHE_BYTES, flags);
	if (*base == NULL)
		return NULL;

	return (void *)L1_CACHE_ALIGN((u64)*base);
}

/*
 * Given a nasid, get the physical address of the  partition's reserved page
 * for that nasid. This function returns 0 on any error.
 */
static u64
xpc_get_rsvd_page_pa(int nasid)
{
	bte_result_t bte_res;
	s64 status;
	u64 cookie = 0;
	u64 rp_pa = nasid;	/* seed with nasid */
	u64 len = 0;
	u64 buf = buf;
	u64 buf_len = 0;
	void *buf_base = NULL;

	while (1) {

		status = sn_partition_reserved_page_pa(buf, &cookie, &rp_pa,
						       &len);

		dev_dbg(xpc_part, "SAL returned with status=%li, cookie="
			"0x%016lx, address=0x%016lx, len=0x%016lx\n",
			status, cookie, rp_pa, len);

		if (status != SALRET_MORE_PASSES)
			break;

		if (L1_CACHE_ALIGN(len) > buf_len) {
			kfree(buf_base);
			buf_len = L1_CACHE_ALIGN(len);
			buf = (u64)xpc_kmalloc_cacheline_aligned(buf_len,
								 GFP_KERNEL,
								 &buf_base);
			if (buf_base == NULL) {
				dev_err(xpc_part, "unable to kmalloc "
					"len=0x%016lx\n", buf_len);
				status = SALRET_ERROR;
				break;
			}
		}

		bte_res = xp_bte_copy(rp_pa, buf, buf_len,
				      (BTE_NOTIFY | BTE_WACQUIRE), NULL);
		if (bte_res != BTE_SUCCESS) {
			dev_dbg(xpc_part, "xp_bte_copy failed %i\n", bte_res);
			status = SALRET_ERROR;
			break;
		}
	}

	kfree(buf_base);

	if (status != SALRET_OK)
		rp_pa = 0;

	dev_dbg(xpc_part, "reserved page at phys address 0x%016lx\n", rp_pa);
	return rp_pa;
}

/*
 * Fill the partition reserved page with the information needed by
 * other partitions to discover we are alive and establish initial
 * communications.
 */
struct xpc_rsvd_page *
xpc_rsvd_page_init(void)
{
	struct xpc_rsvd_page *rp;
	AMO_t *amos_page;
	u64 rp_pa, nasid_array = 0;
	int i, ret;

	/* get the local reserved page's address */

	preempt_disable();
	rp_pa = xpc_get_rsvd_page_pa(cpuid_to_nasid(smp_processor_id()));
	preempt_enable();
	if (rp_pa == 0) {
		dev_err(xpc_part, "SAL failed to locate the reserved page\n");
		return NULL;
	}
	rp = (struct xpc_rsvd_page *)__va(rp_pa);

	if (rp->partid != sn_partition_id) {
		dev_err(xpc_part, "the reserved page's partid of %d should be "
			"%d\n", rp->partid, sn_partition_id);
		return NULL;
	}

	rp->version = XPC_RP_VERSION;

	/* establish the actual sizes of the nasid masks */
	if (rp->SAL_version == 1) {
		/* SAL_version 1 didn't set the nasids_size field */
		rp->nasids_size = 128;
	}
	xp_nasid_mask_bytes = rp->nasids_size;
	xp_nasid_mask_words = xp_nasid_mask_bytes / 8;

	/* setup the pointers to the various items in the reserved page */
	xpc_part_nasids = XPC_RP_PART_NASIDS(rp);
	xpc_mach_nasids = XPC_RP_MACH_NASIDS(rp);
	xpc_vars = XPC_RP_VARS(rp);
	xpc_vars_part = XPC_RP_VARS_PART(rp);

	/*
	 * Before clearing xpc_vars, see if a page of AMOs had been previously
	 * allocated. If not we'll need to allocate one and set permissions
	 * so that cross-partition AMOs are allowed.
	 *
	 * The allocated AMO page needs MCA reporting to remain disabled after
	 * XPC has unloaded.  To make this work, we keep a copy of the pointer
	 * to this page (i.e., amos_page) in the struct xpc_vars structure,
	 * which is pointed to by the reserved page, and re-use that saved copy
	 * on subsequent loads of XPC. This AMO page is never freed, and its
	 * memory protections are never restricted.
	 */
	amos_page = xpc_vars->amos_page;
	if (amos_page == NULL) {
		amos_page = (AMO_t *)TO_AMO(uncached_alloc_page(0, 1));
		if (amos_page == NULL) {
			dev_err(xpc_part, "can't allocate page of AMOs\n");
			return NULL;
		}

		/*
		 * Open up AMO-R/W to cpu.  This is done for Shub 1.1 systems
		 * when xpc_allow_IPI_ops() is called via xpc_hb_init().
		 */
		if (!enable_shub_wars_1_1()) {
			ret = sn_change_memprotect(ia64_tpa((u64)amos_page),
						   PAGE_SIZE,
						   SN_MEMPROT_ACCESS_CLASS_1,
						   &nasid_array);
			if (ret != 0) {
				dev_err(xpc_part, "can't change memory "
					"protections\n");
				uncached_free_page(__IA64_UNCACHED_OFFSET |
						   TO_PHYS((u64)amos_page), 1);
				return NULL;
			}
		}
	} else if (!IS_AMO_ADDRESS((u64)amos_page)) {
		/*
		 * EFI's XPBOOT can also set amos_page in the reserved page,
		 * but it happens to leave it as an uncached physical address
		 * and we need it to be an uncached virtual, so we'll have to
		 * convert it.
		 */
		if (!IS_AMO_PHYS_ADDRESS((u64)amos_page)) {
			dev_err(xpc_part, "previously used amos_page address "
				"is bad = 0x%p\n", (void *)amos_page);
			return NULL;
		}
		amos_page = (AMO_t *)TO_AMO((u64)amos_page);
	}

	/* clear xpc_vars */
	memset(xpc_vars, 0, sizeof(struct xpc_vars));

	xpc_vars->version = XPC_V_VERSION;
	xpc_vars->act_nasid = cpuid_to_nasid(0);
	xpc_vars->act_phys_cpuid = cpu_physical_id(0);
	xpc_vars->vars_part_pa = __pa(xpc_vars_part);
	xpc_vars->amos_page_pa = ia64_tpa((u64)amos_page);
	xpc_vars->amos_page = amos_page;	/* save for next load of XPC */

	/* clear xpc_vars_part */
	memset((u64 *)xpc_vars_part, 0, sizeof(struct xpc_vars_part) *
	       XP_MAX_PARTITIONS);

	/* initialize the activate IRQ related AMO variables */
	for (i = 0; i < xp_nasid_mask_words; i++)
		(void)xpc_IPI_init(XPC_ACTIVATE_IRQ_AMOS + i);

	/* initialize the engaged remote partitions related AMO variables */
	(void)xpc_IPI_init(XPC_ENGAGED_PARTITIONS_AMO);
	(void)xpc_IPI_init(XPC_DISENGAGE_REQUEST_AMO);

	/* timestamp of when reserved page was setup by XPC */
	rp->stamp = CURRENT_TIME;

	/*
	 * This signifies to the remote partition that our reserved
	 * page is initialized.
	 */
	rp->vars_pa = __pa(xpc_vars);

	return rp;
}

/*
 * Change protections to allow IPI operations (and AMO operations on
 * Shub 1.1 systems).
 */
void
xpc_allow_IPI_ops(void)
{
	int node;
	int nasid;

	/* >>> Change SH_IPI_ACCESS code to use SAL call once it is available */

	if (is_shub2()) {
		xpc_sh2_IPI_access0 =
		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH2_IPI_ACCESS0));
		xpc_sh2_IPI_access1 =
		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH2_IPI_ACCESS1));
		xpc_sh2_IPI_access2 =
		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH2_IPI_ACCESS2));
		xpc_sh2_IPI_access3 =
		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH2_IPI_ACCESS3));

		for_each_online_node(node) {
			nasid = cnodeid_to_nasid(node);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS0),
			      -1UL);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS1),
			      -1UL);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS2),
			      -1UL);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS3),
			      -1UL);
		}

	} else {
		xpc_sh1_IPI_access =
		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH1_IPI_ACCESS));

		for_each_online_node(node) {
			nasid = cnodeid_to_nasid(node);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH1_IPI_ACCESS),
			      -1UL);

			/*
			 * Since the BIST collides with memory operations on
			 * SHUB 1.1 sn_change_memprotect() cannot be used.
			 */
			if (enable_shub_wars_1_1()) {
				/* open up everything */
				xpc_prot_vec[node] = (u64)HUB_L((u64 *)
								GLOBAL_MMR_ADDR
								(nasid,
						  SH1_MD_DQLP_MMR_DIR_PRIVEC0));
				HUB_S((u64 *)
				      GLOBAL_MMR_ADDR(nasid,
						   SH1_MD_DQLP_MMR_DIR_PRIVEC0),
				      -1UL);
				HUB_S((u64 *)
				      GLOBAL_MMR_ADDR(nasid,
						   SH1_MD_DQRP_MMR_DIR_PRIVEC0),
				      -1UL);
			}
		}
	}
}

/*
 * Restrict protections to disallow IPI operations (and AMO operations on
 * Shub 1.1 systems).
 */
void
xpc_restrict_IPI_ops(void)
{
	int node;
	int nasid;

	/* >>> Change SH_IPI_ACCESS code to use SAL call once it is available */

	if (is_shub2()) {

		for_each_online_node(node) {
			nasid = cnodeid_to_nasid(node);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS0),
			      xpc_sh2_IPI_access0);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS1),
			      xpc_sh2_IPI_access1);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS2),
			      xpc_sh2_IPI_access2);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS3),
			      xpc_sh2_IPI_access3);
		}

	} else {

		for_each_online_node(node) {
			nasid = cnodeid_to_nasid(node);
			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH1_IPI_ACCESS),
			      xpc_sh1_IPI_access);

			if (enable_shub_wars_1_1()) {
				HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid,
						   SH1_MD_DQLP_MMR_DIR_PRIVEC0),
				      xpc_prot_vec[node]);
				HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid,
						   SH1_MD_DQRP_MMR_DIR_PRIVEC0),
				      xpc_prot_vec[node]);
			}
		}
	}
}

/*
 * At periodic intervals, scan through all active partitions and ensure
 * their heartbeat is still active.  If not, the partition is deactivated.
 */
void
xpc_check_remote_hb(void)
{
	struct xpc_vars *remote_vars;
	struct xpc_partition *part;
	short partid;
	bte_result_t bres;

	remote_vars = (struct xpc_vars *)xpc_remote_copy_buffer;

	for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {

		if (xpc_exiting)
			break;

		if (partid == sn_partition_id)
			continue;

		part = &xpc_partitions[partid];

		if (part->act_state == XPC_P_INACTIVE ||
		    part->act_state == XPC_P_DEACTIVATING) {
			continue;
		}

		/* pull the remote_hb cache line */
		bres = xp_bte_copy(part->remote_vars_pa,
				   (u64)remote_vars,
				   XPC_RP_VARS_SIZE,
				   (BTE_NOTIFY | BTE_WACQUIRE), NULL);
		if (bres != BTE_SUCCESS) {
			XPC_DEACTIVATE_PARTITION(part,
						 xpc_map_bte_errors(bres));
			continue;
		}

		dev_dbg(xpc_part, "partid = %d, heartbeat = %ld, last_heartbeat"
			" = %ld, heartbeat_offline = %ld, HB_mask = 0x%lx\n",
			partid, remote_vars->heartbeat, part->last_heartbeat,
			remote_vars->heartbeat_offline,
			remote_vars->heartbeating_to_mask);

		if (((remote_vars->heartbeat == part->last_heartbeat) &&
		     (remote_vars->heartbeat_offline == 0)) ||
		    !xpc_hb_allowed(sn_partition_id, remote_vars)) {

			XPC_DEACTIVATE_PARTITION(part, xpNoHeartbeat);
			continue;
		}

		part->last_heartbeat = remote_vars->heartbeat;
	}
}

/*
 * Get a copy of a portion of the remote partition's rsvd page.
 *
 * remote_rp points to a buffer that is cacheline aligned for BTE copies and
 * is large enough to contain a copy of their reserved page header and
 * part_nasids mask.
 */
static enum xp_retval
xpc_get_remote_rp(int nasid, u64 *discovered_nasids,
		  struct xpc_rsvd_page *remote_rp, u64 *remote_rp_pa)
{
	int bres, i;

	/* get the reserved page's physical address */

	*remote_rp_pa = xpc_get_rsvd_page_pa(nasid);
	if (*remote_rp_pa == 0)
		return xpNoRsvdPageAddr;

	/* pull over the reserved page header and part_nasids mask */
	bres = xp_bte_copy(*remote_rp_pa, (u64)remote_rp,
			   XPC_RP_HEADER_SIZE + xp_nasid_mask_bytes,
			   (BTE_NOTIFY | BTE_WACQUIRE), NULL);
	if (bres != BTE_SUCCESS)
		return xpc_map_bte_errors(bres);

	if (discovered_nasids != NULL) {
		u64 *remote_part_nasids = XPC_RP_PART_NASIDS(remote_rp);

		for (i = 0; i < xp_nasid_mask_words; i++)
			discovered_nasids[i] |= remote_part_nasids[i];
	}

	/* check that the partid is for another partition */

	if (remote_rp->partid < 1 ||
	    remote_rp->partid > (XP_MAX_PARTITIONS - 1)) {
		return xpInvalidPartid;
	}

	if (remote_rp->partid == sn_partition_id)
		return xpLocalPartid;

	if (XPC_VERSION_MAJOR(remote_rp->version) !=
	    XPC_VERSION_MAJOR(XPC_RP_VERSION)) {
		return xpBadVersion;
	}

	return xpSuccess;
}

/*
 * Get a copy of the remote partition's XPC variables from the reserved page.
 *
 * remote_vars points to a buffer that is cacheline aligned for BTE copies and
 * assumed to be of size XPC_RP_VARS_SIZE.
 */
static enum xp_retval
xpc_get_remote_vars(u64 remote_vars_pa, struct xpc_vars *remote_vars)
{
	int bres;

	if (remote_vars_pa == 0)
		return xpVarsNotSet;

	/* pull over the cross partition variables */
	bres = xp_bte_copy(remote_vars_pa, (u64)remote_vars, XPC_RP_VARS_SIZE,
			   (BTE_NOTIFY | BTE_WACQUIRE), NULL);
	if (bres != BTE_SUCCESS)
		return xpc_map_bte_errors(bres);

	if (XPC_VERSION_MAJOR(remote_vars->version) !=
	    XPC_VERSION_MAJOR(XPC_V_VERSION)) {
		return xpBadVersion;
	}

	return xpSuccess;
}

/*
 * Update the remote partition's info.
 */
static void
xpc_update_partition_info(struct xpc_partition *part, u8 remote_rp_version,
			  struct timespec *remote_rp_stamp, u64 remote_rp_pa,
			  u64 remote_vars_pa, struct xpc_vars *remote_vars)
{
	part->remote_rp_version = remote_rp_version;
	dev_dbg(xpc_part, "  remote_rp_version = 0x%016x\n",
		part->remote_rp_version);

	part->remote_rp_stamp = *remote_rp_stamp;
	dev_dbg(xpc_part, "  remote_rp_stamp (tv_sec = 0x%lx tv_nsec = 0x%lx\n",
		part->remote_rp_stamp.tv_sec, part->remote_rp_stamp.tv_nsec);

	part->remote_rp_pa = remote_rp_pa;
	dev_dbg(xpc_part, "  remote_rp_pa = 0x%016lx\n", part->remote_rp_pa);

	part->remote_vars_pa = remote_vars_pa;
	dev_dbg(xpc_part, "  remote_vars_pa = 0x%016lx\n",
		part->remote_vars_pa);

	part->last_heartbeat = remote_vars->heartbeat;
	dev_dbg(xpc_part, "  last_heartbeat = 0x%016lx\n",
		part->last_heartbeat);

	part->remote_vars_part_pa = remote_vars->vars_part_pa;
	dev_dbg(xpc_part, "  remote_vars_part_pa = 0x%016lx\n",
		part->remote_vars_part_pa);

	part->remote_act_nasid = remote_vars->act_nasid;
	dev_dbg(xpc_part, "  remote_act_nasid = 0x%x\n",
		part->remote_act_nasid);

	part->remote_act_phys_cpuid = remote_vars->act_phys_cpuid;
	dev_dbg(xpc_part, "  remote_act_phys_cpuid = 0x%x\n",
		part->remote_act_phys_cpuid);

	part->remote_amos_page_pa = remote_vars->amos_page_pa;
	dev_dbg(xpc_part, "  remote_amos_page_pa = 0x%lx\n",
		part->remote_amos_page_pa);

	part->remote_vars_version = remote_vars->version;
	dev_dbg(xpc_part, "  remote_vars_version = 0x%x\n",
		part->remote_vars_version);
}

/*
 * Prior code has determined the nasid which generated an IPI.  Inspect
 * that nasid to determine if its partition needs to be activated or
 * deactivated.
 *
 * A partition is consider "awaiting activation" if our partition
 * flags indicate it is not active and it has a heartbeat.  A
 * partition is considered "awaiting deactivation" if our partition
 * flags indicate it is active but it has no heartbeat or it is not
 * sending its heartbeat to us.
 *
 * To determine the heartbeat, the remote nasid must have a properly
 * initialized reserved page.
 */
static void
xpc_identify_act_IRQ_req(int nasid)
{
	struct xpc_rsvd_page *remote_rp;
	struct xpc_vars *remote_vars;
	u64 remote_rp_pa;
	u64 remote_vars_pa;
	int remote_rp_version;
	int reactivate = 0;
	int stamp_diff;
	struct timespec remote_rp_stamp = { 0, 0 };
	short partid;
	struct xpc_partition *part;
	enum xp_retval ret;

	/* pull over the reserved page structure */

	remote_rp = (struct xpc_rsvd_page *)xpc_remote_copy_buffer;

	ret = xpc_get_remote_rp(nasid, NULL, remote_rp, &remote_rp_pa);
	if (ret != xpSuccess) {
		dev_warn(xpc_part, "unable to get reserved page from nasid %d, "
			 "which sent interrupt, reason=%d\n", nasid, ret);
		return;
	}

	remote_vars_pa = remote_rp->vars_pa;
	remote_rp_version = remote_rp->version;
	if (XPC_SUPPORTS_RP_STAMP(remote_rp_version))
		remote_rp_stamp = remote_rp->stamp;

	partid = remote_rp->partid;
	part = &xpc_partitions[partid];

	/* pull over the cross partition variables */

	remote_vars = (struct xpc_vars *)xpc_remote_copy_buffer;

	ret = xpc_get_remote_vars(remote_vars_pa, remote_vars);
	if (ret != xpSuccess) {

		dev_warn(xpc_part, "unable to get XPC variables from nasid %d, "
			 "which sent interrupt, reason=%d\n", nasid, ret);

		XPC_DEACTIVATE_PARTITION(part, ret);
		return;
	}

	part->act_IRQ_rcvd++;

	dev_dbg(xpc_part, "partid for nasid %d is %d; IRQs = %d; HB = "
		"%ld:0x%lx\n", (int)nasid, (int)partid, part->act_IRQ_rcvd,
		remote_vars->heartbeat, remote_vars->heartbeating_to_mask);

	if (xpc_partition_disengaged(part) &&
	    part->act_state == XPC_P_INACTIVE) {

		xpc_update_partition_info(part, remote_rp_version,
					  &remote_rp_stamp, remote_rp_pa,
					  remote_vars_pa, remote_vars);

		if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version)) {
			if (xpc_partition_disengage_requested(1UL << partid)) {
				/*
				 * Other side is waiting on us to disengage,
				 * even though we already have.
				 */
				return;
			}
		} else {
			/* other side doesn't support disengage requests */
			xpc_clear_partition_disengage_request(1UL << partid);
		}

		xpc_activate_partition(part);
		return;
	}

	DBUG_ON(part->remote_rp_version == 0);
	DBUG_ON(part->remote_vars_version == 0);

	if (!XPC_SUPPORTS_RP_STAMP(part->remote_rp_version)) {
		DBUG_ON(XPC_SUPPORTS_DISENGAGE_REQUEST(part->
						       remote_vars_version));

		if (!XPC_SUPPORTS_RP_STAMP(remote_rp_version)) {
			DBUG_ON(XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->
							       version));
			/* see if the other side rebooted */
			if (part->remote_amos_page_pa ==
			    remote_vars->amos_page_pa &&
			    xpc_hb_allowed(sn_partition_id, remote_vars)) {
				/* doesn't look that way, so ignore the IPI */
				return;
			}
		}

		/*
		 * Other side rebooted and previous XPC didn't support the
		 * disengage request, so we don't need to do anything special.
		 */

		xpc_update_partition_info(part, remote_rp_version,
					  &remote_rp_stamp, remote_rp_pa,
					  remote_vars_pa, remote_vars);
		part->reactivate_nasid = nasid;
		XPC_DEACTIVATE_PARTITION(part, xpReactivating);
		return;
	}

	DBUG_ON(!XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version));

	if (!XPC_SUPPORTS_RP_STAMP(remote_rp_version)) {
		DBUG_ON(!XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->version));

		/*
		 * Other side rebooted and previous XPC did support the
		 * disengage request, but the new one doesn't.
		 */

		xpc_clear_partition_engaged(1UL << partid);
		xpc_clear_partition_disengage_request(1UL << partid);

		xpc_update_partition_info(part, remote_rp_version,
					  &remote_rp_stamp, remote_rp_pa,
					  remote_vars_pa, remote_vars);
		reactivate = 1;

	} else {
		DBUG_ON(!XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->version));

		stamp_diff = xpc_compare_stamps(&part->remote_rp_stamp,
						&remote_rp_stamp);
		if (stamp_diff != 0) {
			DBUG_ON(stamp_diff >= 0);

			/*
			 * Other side rebooted and the previous XPC did support
			 * the disengage request, as does the new one.
			 */

			DBUG_ON(xpc_partition_engaged(1UL << partid));
			DBUG_ON(xpc_partition_disengage_requested(1UL <<
								  partid));

			xpc_update_partition_info(part, remote_rp_version,
						  &remote_rp_stamp,
						  remote_rp_pa, remote_vars_pa,
						  remote_vars);
			reactivate = 1;
		}
	}

	if (part->disengage_request_timeout > 0 &&
	    !xpc_partition_disengaged(part)) {
		/* still waiting on other side to disengage from us */
		return;
	}

	if (reactivate) {
		part->reactivate_nasid = nasid;
		XPC_DEACTIVATE_PARTITION(part, xpReactivating);

	} else if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version) &&
		   xpc_partition_disengage_requested(1UL << partid)) {
		XPC_DEACTIVATE_PARTITION(part, xpOtherGoingDown);
	}
}

/*
 * Loop through the activation AMO variables and process any bits
 * which are set.  Each bit indicates a nasid sending a partition
 * activation or deactivation request.
 *
 * Return #of IRQs detected.
 */
int
xpc_identify_act_IRQ_sender(void)
{
	int word, bit;
	u64 nasid_mask;
	u64 nasid;		/* remote nasid */
	int n_IRQs_detected = 0;
	AMO_t *act_amos;

	act_amos = xpc_vars->amos_page + XPC_ACTIVATE_IRQ_AMOS;

	/* scan through act AMO variable looking for non-zero entries */
	for (word = 0; word < xp_nasid_mask_words; word++) {

		if (xpc_exiting)
			break;

		nasid_mask = xpc_IPI_receive(&act_amos[word]);
		if (nasid_mask == 0) {
			/* no IRQs from nasids in this variable */
			continue;
		}

		dev_dbg(xpc_part, "AMO[%d] gave back 0x%lx\n", word,
			nasid_mask);

		/*
		 * If this nasid has been added to the machine since
		 * our partition was reset, this will retain the
		 * remote nasid in our reserved pages machine mask.
		 * This is used in the event of module reload.
		 */
		xpc_mach_nasids[word] |= nasid_mask;

		/* locate the nasid(s) which sent interrupts */

		for (bit = 0; bit < (8 * sizeof(u64)); bit++) {
			if (nasid_mask & (1UL << bit)) {
				n_IRQs_detected++;
				nasid = XPC_NASID_FROM_W_B(word, bit);
				dev_dbg(xpc_part, "interrupt from nasid %ld\n",
					nasid);
				xpc_identify_act_IRQ_req(nasid);
			}
		}
	}
	return n_IRQs_detected;
}

/*
 * See if the other side has responded to a partition disengage request
 * from us.
 */
int
xpc_partition_disengaged(struct xpc_partition *part)
{
	short partid = XPC_PARTID(part);
	int disengaged;

	disengaged = (xpc_partition_engaged(1UL << partid) == 0);
	if (part->disengage_request_timeout) {
		if (!disengaged) {
			if (time_before(jiffies,
			    part->disengage_request_timeout)) {
				/* timelimit hasn't been reached yet */
				return 0;
			}

			/*
			 * Other side hasn't responded to our disengage
			 * request in a timely fashion, so assume it's dead.
			 */

			dev_info(xpc_part, "disengage from remote partition %d "
				 "timed out\n", partid);
			xpc_disengage_request_timedout = 1;
			xpc_clear_partition_engaged(1UL << partid);
			disengaged = 1;
		}
		part->disengage_request_timeout = 0;

		/* cancel the timer function, provided it's not us */
		if (!in_interrupt()) {
			del_singleshot_timer_sync(&part->
						  disengage_request_timer);
		}

		DBUG_ON(part->act_state != XPC_P_DEACTIVATING &&
			part->act_state != XPC_P_INACTIVE);
		if (part->act_state != XPC_P_INACTIVE)
			xpc_wakeup_channel_mgr(part);

		if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version))
			xpc_cancel_partition_disengage_request(part);
	}
	return disengaged;
}

/*
 * Mark specified partition as active.
 */
enum xp_retval
xpc_mark_partition_active(struct xpc_partition *part)
{
	unsigned long irq_flags;
	enum xp_retval ret;

	dev_dbg(xpc_part, "setting partition %d to ACTIVE\n", XPC_PARTID(part));

	spin_lock_irqsave(&part->act_lock, irq_flags);
	if (part->act_state == XPC_P_ACTIVATING) {
		part->act_state = XPC_P_ACTIVE;
		ret = xpSuccess;
	} else {
		DBUG_ON(part->reason == xpSuccess);
		ret = part->reason;
	}
	spin_unlock_irqrestore(&part->act_lock, irq_flags);

	return ret;
}

/*
 * Notify XPC that the partition is down.
 */
void
xpc_deactivate_partition(const int line, struct xpc_partition *part,
			 enum xp_retval reason)
{
	unsigned long irq_flags;

	spin_lock_irqsave(&part->act_lock, irq_flags);

	if (part->act_state == XPC_P_INACTIVE) {
		XPC_SET_REASON(part, reason, line);
		spin_unlock_irqrestore(&part->act_lock, irq_flags);
		if (reason == xpReactivating) {
			/* we interrupt ourselves to reactivate partition */
			xpc_IPI_send_reactivate(part);
		}
		return;
	}
	if (part->act_state == XPC_P_DEACTIVATING) {
		if ((part->reason == xpUnloading && reason != xpUnloading) ||
		    reason == xpReactivating) {
			XPC_SET_REASON(part, reason, line);
		}
		spin_unlock_irqrestore(&part->act_lock, irq_flags);
		return;
	}

	part->act_state = XPC_P_DEACTIVATING;
	XPC_SET_REASON(part, reason, line);

	spin_unlock_irqrestore(&part->act_lock, irq_flags);

	if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version)) {
		xpc_request_partition_disengage(part);
		xpc_IPI_send_disengage(part);

		/* set a timelimit on the disengage request */
		part->disengage_request_timeout = jiffies +
		    (xpc_disengage_request_timelimit * HZ);
		part->disengage_request_timer.expires =
		    part->disengage_request_timeout;
		add_timer(&part->disengage_request_timer);
	}

	dev_dbg(xpc_part, "bringing partition %d down, reason = %d\n",
		XPC_PARTID(part), reason);

	xpc_partition_going_down(part, reason);
}

/*
 * Mark specified partition as inactive.
 */
void
xpc_mark_partition_inactive(struct xpc_partition *part)
{
	unsigned long irq_flags;

	dev_dbg(xpc_part, "setting partition %d to INACTIVE\n",
		XPC_PARTID(part));

	spin_lock_irqsave(&part->act_lock, irq_flags);
	part->act_state = XPC_P_INACTIVE;
	spin_unlock_irqrestore(&part->act_lock, irq_flags);
	part->remote_rp_pa = 0;
}

/*
 * SAL has provided a partition and machine mask.  The partition mask
 * contains a bit for each even nasid in our partition.  The machine
 * mask contains a bit for each even nasid in the entire machine.
 *
 * Using those two bit arrays, we can determine which nasids are
 * known in the machine.  Each should also have a reserved page
 * initialized if they are available for partitioning.
 */
void
xpc_discovery(void)
{
	void *remote_rp_base;
	struct xpc_rsvd_page *remote_rp;
	struct xpc_vars *remote_vars;
	u64 remote_rp_pa;
	u64 remote_vars_pa;
	int region;
	int region_size;
	int max_regions;
	int nasid;
	struct xpc_rsvd_page *rp;
	short partid;
	struct xpc_partition *part;
	u64 *discovered_nasids;
	enum xp_retval ret;

	remote_rp = xpc_kmalloc_cacheline_aligned(XPC_RP_HEADER_SIZE +
						  xp_nasid_mask_bytes,
						  GFP_KERNEL, &remote_rp_base);
	if (remote_rp == NULL)
		return;

	remote_vars = (struct xpc_vars *)remote_rp;

	discovered_nasids = kzalloc(sizeof(u64) * xp_nasid_mask_words,
				    GFP_KERNEL);
	if (discovered_nasids == NULL) {
		kfree(remote_rp_base);
		return;
	}

	rp = (struct xpc_rsvd_page *)xpc_rsvd_page;

	/*
	 * The term 'region' in this context refers to the minimum number of
	 * nodes that can comprise an access protection grouping. The access
	 * protection is in regards to memory, IOI and IPI.
	 */
	max_regions = 64;
	region_size = sn_region_size;

	switch (region_size) {
	case 128:
		max_regions *= 2;
	case 64:
		max_regions *= 2;
	case 32:
		max_regions *= 2;
		region_size = 16;
		DBUG_ON(!is_shub2());
	}

	for (region = 0; region < max_regions; region++) {

		if (xpc_exiting)
			break;

		dev_dbg(xpc_part, "searching region %d\n", region);

		for (nasid = (region * region_size * 2);
		     nasid < ((region + 1) * region_size * 2); nasid += 2) {

			if (xpc_exiting)
				break;

			dev_dbg(xpc_part, "checking nasid %d\n", nasid);

			if (XPC_NASID_IN_ARRAY(nasid, xpc_part_nasids)) {
				dev_dbg(xpc_part, "PROM indicates Nasid %d is "
					"part of the local partition; skipping "
					"region\n", nasid);
				break;
			}

			if (!(XPC_NASID_IN_ARRAY(nasid, xpc_mach_nasids))) {
				dev_dbg(xpc_part, "PROM indicates Nasid %d was "
					"not on Numa-Link network at reset\n",
					nasid);
				continue;
			}

			if (XPC_NASID_IN_ARRAY(nasid, discovered_nasids)) {
				dev_dbg(xpc_part, "Nasid %d is part of a "
					"partition which was previously "
					"discovered\n", nasid);
				continue;
			}

			/* pull over the reserved page structure */

			ret = xpc_get_remote_rp(nasid, discovered_nasids,
						remote_rp, &remote_rp_pa);
			if (ret != xpSuccess) {
				dev_dbg(xpc_part, "unable to get reserved page "
					"from nasid %d, reason=%d\n", nasid,
					ret);

				if (ret == xpLocalPartid)
					break;

				continue;
			}

			remote_vars_pa = remote_rp->vars_pa;

			partid = remote_rp->partid;
			part = &xpc_partitions[partid];

			/* pull over the cross partition variables */

			ret = xpc_get_remote_vars(remote_vars_pa, remote_vars);
			if (ret != xpSuccess) {
				dev_dbg(xpc_part, "unable to get XPC variables "
					"from nasid %d, reason=%d\n", nasid,
					ret);

				XPC_DEACTIVATE_PARTITION(part, ret);
				continue;
			}

			if (part->act_state != XPC_P_INACTIVE) {
				dev_dbg(xpc_part, "partition %d on nasid %d is "
					"already activating\n", partid, nasid);
				break;
			}

			/*
			 * Register the remote partition's AMOs with SAL so it
			 * can handle and cleanup errors within that address
			 * range should the remote partition go down. We don't
			 * unregister this range because it is difficult to
			 * tell when outstanding writes to the remote partition
			 * are finished and thus when it is thus safe to
			 * unregister. This should not result in wasted space
			 * in the SAL xp_addr_region table because we should
			 * get the same page for remote_act_amos_pa after
			 * module reloads and system reboots.
			 */
			if (sn_register_xp_addr_region
			    (remote_vars->amos_page_pa, PAGE_SIZE, 1) < 0) {
				dev_dbg(xpc_part,
					"partition %d failed to "
					"register xp_addr region 0x%016lx\n",
					partid, remote_vars->amos_page_pa);

				XPC_SET_REASON(part, xpPhysAddrRegFailed,
					       __LINE__);
				break;
			}

			/*
			 * The remote nasid is valid and available.
			 * Send an interrupt to that nasid to notify
			 * it that we are ready to begin activation.
			 */
			dev_dbg(xpc_part, "sending an interrupt to AMO 0x%lx, "
				"nasid %d, phys_cpuid 0x%x\n",
				remote_vars->amos_page_pa,
				remote_vars->act_nasid,
				remote_vars->act_phys_cpuid);

			if (XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->
							   version)) {
				part->remote_amos_page_pa =
				    remote_vars->amos_page_pa;
				xpc_mark_partition_disengaged(part);
				xpc_cancel_partition_disengage_request(part);
			}
			xpc_IPI_send_activate(remote_vars);
		}
	}

	kfree(discovered_nasids);
	kfree(remote_rp_base);
}

/*
 * Given a partid, get the nasids owned by that partition from the
 * remote partition's reserved page.
 */
enum xp_retval
xpc_initiate_partid_to_nasids(short partid, void *nasid_mask)
{
	struct xpc_partition *part;
	u64 part_nasid_pa;
	int bte_res;

	part = &xpc_partitions[partid];
	if (part->remote_rp_pa == 0)
		return xpPartitionDown;

	memset(nasid_mask, 0, XP_NASID_MASK_BYTES);

	part_nasid_pa = (u64)XPC_RP_PART_NASIDS(part->remote_rp_pa);

	bte_res = xp_bte_copy(part_nasid_pa, (u64)nasid_mask,
			      xp_nasid_mask_bytes, (BTE_NOTIFY | BTE_WACQUIRE),
			      NULL);

	return xpc_map_bte_errors(bte_res);
}