summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/platforms/pseries/hotplug-cpu.c
blob: 6afd1efd3633f2a2b89fdf7d28b88cd2326c3900 (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
/*
 * pseries CPU Hotplug infrastructure.
 *
 * Split out from arch/powerpc/platforms/pseries/setup.c
 *  arch/powerpc/kernel/rtas.c, and arch/powerpc/platforms/pseries/smp.c
 *
 * Peter Bergner, IBM	March 2001.
 * Copyright (C) 2001 IBM.
 * Dave Engebretsen, Peter Bergner, and
 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
 * Plus various changes from other IBM teams...
 *
 * Copyright (C) 2006 Michael Ellerman, IBM Corporation
 *
 *      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)     "pseries-hotplug-cpu: " fmt

#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/sched.h>	/* for idle_task_exit */
#include <linux/sched/hotplug.h>
#include <linux/cpu.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/firmware.h>
#include <asm/machdep.h>
#include <asm/vdso_datapage.h>
#include <asm/xics.h>
#include <asm/plpar_wrappers.h>

#include "pseries.h"
#include "offline_states.h"

/* This version can't take the spinlock, because it never returns */
static int rtas_stop_self_token = RTAS_UNKNOWN_SERVICE;

static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) =
							CPU_STATE_OFFLINE;
static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE;

static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE;

static bool cede_offline_enabled __read_mostly = true;

/*
 * Enable/disable cede_offline when available.
 */
static int __init setup_cede_offline(char *str)
{
	return (kstrtobool(str, &cede_offline_enabled) == 0);
}

__setup("cede_offline=", setup_cede_offline);

enum cpu_state_vals get_cpu_current_state(int cpu)
{
	return per_cpu(current_state, cpu);
}

void set_cpu_current_state(int cpu, enum cpu_state_vals state)
{
	per_cpu(current_state, cpu) = state;
}

enum cpu_state_vals get_preferred_offline_state(int cpu)
{
	return per_cpu(preferred_offline_state, cpu);
}

void set_preferred_offline_state(int cpu, enum cpu_state_vals state)
{
	per_cpu(preferred_offline_state, cpu) = state;
}

void set_default_offline_state(int cpu)
{
	per_cpu(preferred_offline_state, cpu) = default_offline_state;
}

static void rtas_stop_self(void)
{
	static struct rtas_args args;

	local_irq_disable();

	BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE);

	printk("cpu %u (hwid %u) Ready to die...\n",
	       smp_processor_id(), hard_smp_processor_id());

	rtas_call_unlocked(&args, rtas_stop_self_token, 0, 1, NULL);

	panic("Alas, I survived.\n");
}

static void pseries_mach_cpu_die(void)
{
	unsigned int cpu = smp_processor_id();
	unsigned int hwcpu = hard_smp_processor_id();
	u8 cede_latency_hint = 0;

	local_irq_disable();
	idle_task_exit();
	xics_teardown_cpu();

	if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
		set_cpu_current_state(cpu, CPU_STATE_INACTIVE);
		if (ppc_md.suspend_disable_cpu)
			ppc_md.suspend_disable_cpu();

		cede_latency_hint = 2;

		get_lppaca()->idle = 1;
		if (!lppaca_shared_proc(get_lppaca()))
			get_lppaca()->donate_dedicated_cpu = 1;

		while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
			while (!prep_irq_for_idle()) {
				local_irq_enable();
				local_irq_disable();
			}

			extended_cede_processor(cede_latency_hint);
		}

		local_irq_disable();

		if (!lppaca_shared_proc(get_lppaca()))
			get_lppaca()->donate_dedicated_cpu = 0;
		get_lppaca()->idle = 0;

		if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
			unregister_slb_shadow(hwcpu);

			hard_irq_disable();
			/*
			 * Call to start_secondary_resume() will not return.
			 * Kernel stack will be reset and start_secondary()
			 * will be called to continue the online operation.
			 */
			start_secondary_resume();
		}
	}

	/* Requested state is CPU_STATE_OFFLINE at this point */
	WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE);

	set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
	unregister_slb_shadow(hwcpu);
	rtas_stop_self();

	/* Should never get here... */
	BUG();
	for(;;);
}

static int pseries_cpu_disable(void)
{
	int cpu = smp_processor_id();

	set_cpu_online(cpu, false);
	vdso_data->processorCount--;

	/*fix boot_cpuid here*/
	if (cpu == boot_cpuid)
		boot_cpuid = cpumask_any(cpu_online_mask);

	/* FIXME: abstract this to not be platform specific later on */
	xics_migrate_irqs_away();
	return 0;
}

/*
 * pseries_cpu_die: Wait for the cpu to die.
 * @cpu: logical processor id of the CPU whose death we're awaiting.
 *
 * This function is called from the context of the thread which is performing
 * the cpu-offline. Here we wait for long enough to allow the cpu in question
 * to self-destroy so that the cpu-offline thread can send the CPU_DEAD
 * notifications.
 *
 * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to
 * self-destruct.
 */
static void pseries_cpu_die(unsigned int cpu)
{
	int tries;
	int cpu_status = 1;
	unsigned int pcpu = get_hard_smp_processor_id(cpu);

	if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
		cpu_status = 1;
		for (tries = 0; tries < 5000; tries++) {
			if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) {
				cpu_status = 0;
				break;
			}
			msleep(1);
		}
	} else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {

		for (tries = 0; tries < 25; tries++) {
			cpu_status = smp_query_cpu_stopped(pcpu);
			if (cpu_status == QCSS_STOPPED ||
			    cpu_status == QCSS_HARDWARE_ERROR)
				break;
			cpu_relax();
		}
	}

	if (cpu_status != 0) {
		printk("Querying DEAD? cpu %i (%i) shows %i\n",
		       cpu, pcpu, cpu_status);
	}

	/* Isolation and deallocation are definitely done by
	 * drslot_chrp_cpu.  If they were not they would be
	 * done here.  Change isolate state to Isolate and
	 * change allocation-state to Unusable.
	 */
	paca[cpu].cpu_start = 0;
}

/*
 * Update cpu_present_mask and paca(s) for a new cpu node.  The wrinkle
 * here is that a cpu device node may represent up to two logical cpus
 * in the SMT case.  We must honor the assumption in other code that
 * the logical ids for sibling SMT threads x and y are adjacent, such
 * that x^1 == y and y^1 == x.
 */
static int pseries_add_processor(struct device_node *np)
{
	unsigned int cpu;
	cpumask_var_t candidate_mask, tmp;
	int err = -ENOSPC, len, nthreads, i;
	const __be32 *intserv;

	intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
	if (!intserv)
		return 0;

	zalloc_cpumask_var(&candidate_mask, GFP_KERNEL);
	zalloc_cpumask_var(&tmp, GFP_KERNEL);

	nthreads = len / sizeof(u32);
	for (i = 0; i < nthreads; i++)
		cpumask_set_cpu(i, tmp);

	cpu_maps_update_begin();

	BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask));

	/* Get a bitmap of unoccupied slots. */
	cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask);
	if (cpumask_empty(candidate_mask)) {
		/* If we get here, it most likely means that NR_CPUS is
		 * less than the partition's max processors setting.
		 */
		printk(KERN_ERR "Cannot add cpu %s; this system configuration"
		       " supports %d logical cpus.\n", np->full_name,
		       num_possible_cpus());
		goto out_unlock;
	}

	while (!cpumask_empty(tmp))
		if (cpumask_subset(tmp, candidate_mask))
			/* Found a range where we can insert the new cpu(s) */
			break;
		else
			cpumask_shift_left(tmp, tmp, nthreads);

	if (cpumask_empty(tmp)) {
		printk(KERN_ERR "Unable to find space in cpu_present_mask for"
		       " processor %s with %d thread(s)\n", np->name,
		       nthreads);
		goto out_unlock;
	}

	for_each_cpu(cpu, tmp) {
		BUG_ON(cpu_present(cpu));
		set_cpu_present(cpu, true);
		set_hard_smp_processor_id(cpu, be32_to_cpu(*intserv++));
	}
	err = 0;
out_unlock:
	cpu_maps_update_done();
	free_cpumask_var(candidate_mask);
	free_cpumask_var(tmp);
	return err;
}

/*
 * Update the present map for a cpu node which is going away, and set
 * the hard id in the paca(s) to -1 to be consistent with boot time
 * convention for non-present cpus.
 */
static void pseries_remove_processor(struct device_node *np)
{
	unsigned int cpu;
	int len, nthreads, i;
	const __be32 *intserv;
	u32 thread;

	intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
	if (!intserv)
		return;

	nthreads = len / sizeof(u32);

	cpu_maps_update_begin();
	for (i = 0; i < nthreads; i++) {
		thread = be32_to_cpu(intserv[i]);
		for_each_present_cpu(cpu) {
			if (get_hard_smp_processor_id(cpu) != thread)
				continue;
			BUG_ON(cpu_online(cpu));
			set_cpu_present(cpu, false);
			set_hard_smp_processor_id(cpu, -1);
			break;
		}
		if (cpu >= nr_cpu_ids)
			printk(KERN_WARNING "Could not find cpu to remove "
			       "with physical id 0x%x\n", thread);
	}
	cpu_maps_update_done();
}

static int dlpar_online_cpu(struct device_node *dn)
{
	int rc = 0;
	unsigned int cpu;
	int len, nthreads, i;
	const __be32 *intserv;
	u32 thread;

	intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
	if (!intserv)
		return -EINVAL;

	nthreads = len / sizeof(u32);

	cpu_maps_update_begin();
	for (i = 0; i < nthreads; i++) {
		thread = be32_to_cpu(intserv[i]);
		for_each_present_cpu(cpu) {
			if (get_hard_smp_processor_id(cpu) != thread)
				continue;
			BUG_ON(get_cpu_current_state(cpu)
					!= CPU_STATE_OFFLINE);
			cpu_maps_update_done();
			rc = device_online(get_cpu_device(cpu));
			if (rc)
				goto out;
			cpu_maps_update_begin();

			break;
		}
		if (cpu == num_possible_cpus())
			printk(KERN_WARNING "Could not find cpu to online "
			       "with physical id 0x%x\n", thread);
	}
	cpu_maps_update_done();

out:
	return rc;

}

static bool dlpar_cpu_exists(struct device_node *parent, u32 drc_index)
{
	struct device_node *child = NULL;
	u32 my_drc_index;
	bool found;
	int rc;

	/* Assume cpu doesn't exist */
	found = false;

	for_each_child_of_node(parent, child) {
		rc = of_property_read_u32(child, "ibm,my-drc-index",
					  &my_drc_index);
		if (rc)
			continue;

		if (my_drc_index == drc_index) {
			of_node_put(child);
			found = true;
			break;
		}
	}

	return found;
}

static bool valid_cpu_drc_index(struct device_node *parent, u32 drc_index)
{
	bool found = false;
	int rc, index;

	index = 0;
	while (!found) {
		u32 drc;

		rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
						index++, &drc);
		if (rc)
			break;

		if (drc == drc_index)
			found = true;
	}

	return found;
}

static ssize_t dlpar_cpu_add(u32 drc_index)
{
	struct device_node *dn, *parent;
	int rc, saved_rc;

	pr_debug("Attempting to add CPU, drc index: %x\n", drc_index);

	parent = of_find_node_by_path("/cpus");
	if (!parent) {
		pr_warn("Failed to find CPU root node \"/cpus\"\n");
		return -ENODEV;
	}

	if (dlpar_cpu_exists(parent, drc_index)) {
		of_node_put(parent);
		pr_warn("CPU with drc index %x already exists\n", drc_index);
		return -EINVAL;
	}

	if (!valid_cpu_drc_index(parent, drc_index)) {
		of_node_put(parent);
		pr_warn("Cannot find CPU (drc index %x) to add.\n", drc_index);
		return -EINVAL;
	}

	rc = dlpar_acquire_drc(drc_index);
	if (rc) {
		pr_warn("Failed to acquire DRC, rc: %d, drc index: %x\n",
			rc, drc_index);
		of_node_put(parent);
		return -EINVAL;
	}

	dn = dlpar_configure_connector(cpu_to_be32(drc_index), parent);
	of_node_put(parent);
	if (!dn) {
		pr_warn("Failed call to configure-connector, drc index: %x\n",
			drc_index);
		dlpar_release_drc(drc_index);
		return -EINVAL;
	}

	rc = dlpar_attach_node(dn);
	if (rc) {
		saved_rc = rc;
		pr_warn("Failed to attach node %s, rc: %d, drc index: %x\n",
			dn->name, rc, drc_index);

		rc = dlpar_release_drc(drc_index);
		if (!rc)
			dlpar_free_cc_nodes(dn);

		return saved_rc;
	}

	rc = dlpar_online_cpu(dn);
	if (rc) {
		saved_rc = rc;
		pr_warn("Failed to online cpu %s, rc: %d, drc index: %x\n",
			dn->name, rc, drc_index);

		rc = dlpar_detach_node(dn);
		if (!rc)
			dlpar_release_drc(drc_index);

		return saved_rc;
	}

	pr_debug("Successfully added CPU %s, drc index: %x\n", dn->name,
		 drc_index);
	return rc;
}

static int dlpar_offline_cpu(struct device_node *dn)
{
	int rc = 0;
	unsigned int cpu;
	int len, nthreads, i;
	const __be32 *intserv;
	u32 thread;

	intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
	if (!intserv)
		return -EINVAL;

	nthreads = len / sizeof(u32);

	cpu_maps_update_begin();
	for (i = 0; i < nthreads; i++) {
		thread = be32_to_cpu(intserv[i]);
		for_each_present_cpu(cpu) {
			if (get_hard_smp_processor_id(cpu) != thread)
				continue;

			if (get_cpu_current_state(cpu) == CPU_STATE_OFFLINE)
				break;

			if (get_cpu_current_state(cpu) == CPU_STATE_ONLINE) {
				set_preferred_offline_state(cpu,
							    CPU_STATE_OFFLINE);
				cpu_maps_update_done();
				rc = device_offline(get_cpu_device(cpu));
				if (rc)
					goto out;
				cpu_maps_update_begin();
				break;

			}

			/*
			 * The cpu is in CPU_STATE_INACTIVE.
			 * Upgrade it's state to CPU_STATE_OFFLINE.
			 */
			set_preferred_offline_state(cpu, CPU_STATE_OFFLINE);
			BUG_ON(plpar_hcall_norets(H_PROD, thread)
								!= H_SUCCESS);
			__cpu_die(cpu);
			break;
		}
		if (cpu == num_possible_cpus())
			printk(KERN_WARNING "Could not find cpu to offline with physical id 0x%x\n", thread);
	}
	cpu_maps_update_done();

out:
	return rc;

}

static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
{
	int rc;

	pr_debug("Attempting to remove CPU %s, drc index: %x\n",
		 dn->name, drc_index);

	rc = dlpar_offline_cpu(dn);
	if (rc) {
		pr_warn("Failed to offline CPU %s, rc: %d\n", dn->name, rc);
		return -EINVAL;
	}

	rc = dlpar_release_drc(drc_index);
	if (rc) {
		pr_warn("Failed to release drc (%x) for CPU %s, rc: %d\n",
			drc_index, dn->name, rc);
		dlpar_online_cpu(dn);
		return rc;
	}

	rc = dlpar_detach_node(dn);
	if (rc) {
		int saved_rc = rc;

		pr_warn("Failed to detach CPU %s, rc: %d", dn->name, rc);

		rc = dlpar_acquire_drc(drc_index);
		if (!rc)
			dlpar_online_cpu(dn);

		return saved_rc;
	}

	pr_debug("Successfully removed CPU, drc index: %x\n", drc_index);
	return 0;
}

static struct device_node *cpu_drc_index_to_dn(u32 drc_index)
{
	struct device_node *dn;
	u32 my_index;
	int rc;

	for_each_node_by_type(dn, "cpu") {
		rc = of_property_read_u32(dn, "ibm,my-drc-index", &my_index);
		if (rc)
			continue;

		if (my_index == drc_index)
			break;
	}

	return dn;
}

static int dlpar_cpu_remove_by_index(u32 drc_index)
{
	struct device_node *dn;
	int rc;

	dn = cpu_drc_index_to_dn(drc_index);
	if (!dn) {
		pr_warn("Cannot find CPU (drc index %x) to remove\n",
			drc_index);
		return -ENODEV;
	}

	rc = dlpar_cpu_remove(dn, drc_index);
	of_node_put(dn);
	return rc;
}

static int find_dlpar_cpus_to_remove(u32 *cpu_drcs, int cpus_to_remove)
{
	struct device_node *dn;
	int cpus_found = 0;
	int rc;

	/* We want to find cpus_to_remove + 1 CPUs to ensure we do not
	 * remove the last CPU.
	 */
	for_each_node_by_type(dn, "cpu") {
		cpus_found++;

		if (cpus_found > cpus_to_remove) {
			of_node_put(dn);
			break;
		}

		/* Note that cpus_found is always 1 ahead of the index
		 * into the cpu_drcs array, so we use cpus_found - 1
		 */
		rc = of_property_read_u32(dn, "ibm,my-drc-index",
					  &cpu_drcs[cpus_found - 1]);
		if (rc) {
			pr_warn("Error occurred getting drc-index for %s\n",
				dn->name);
			of_node_put(dn);
			return -1;
		}
	}

	if (cpus_found < cpus_to_remove) {
		pr_warn("Failed to find enough CPUs (%d of %d) to remove\n",
			cpus_found, cpus_to_remove);
	} else if (cpus_found == cpus_to_remove) {
		pr_warn("Cannot remove all CPUs\n");
	}

	return cpus_found;
}

static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
{
	u32 *cpu_drcs;
	int cpus_found;
	int cpus_removed = 0;
	int i, rc;

	pr_debug("Attempting to hot-remove %d CPUs\n", cpus_to_remove);

	cpu_drcs = kcalloc(cpus_to_remove, sizeof(*cpu_drcs), GFP_KERNEL);
	if (!cpu_drcs)
		return -EINVAL;

	cpus_found = find_dlpar_cpus_to_remove(cpu_drcs, cpus_to_remove);
	if (cpus_found <= cpus_to_remove) {
		kfree(cpu_drcs);
		return -EINVAL;
	}

	for (i = 0; i < cpus_to_remove; i++) {
		rc = dlpar_cpu_remove_by_index(cpu_drcs[i]);
		if (rc)
			break;

		cpus_removed++;
	}

	if (cpus_removed != cpus_to_remove) {
		pr_warn("CPU hot-remove failed, adding back removed CPUs\n");

		for (i = 0; i < cpus_removed; i++)
			dlpar_cpu_add(cpu_drcs[i]);

		rc = -EINVAL;
	} else {
		rc = 0;
	}

	kfree(cpu_drcs);
	return rc;
}

static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
{
	struct device_node *parent;
	int cpus_found = 0;
	int index, rc;

	parent = of_find_node_by_path("/cpus");
	if (!parent) {
		pr_warn("Could not find CPU root node in device tree\n");
		kfree(cpu_drcs);
		return -1;
	}

	/* Search the ibm,drc-indexes array for possible CPU drcs to
	 * add. Note that the format of the ibm,drc-indexes array is
	 * the number of entries in the array followed by the array
	 * of drc values so we start looking at index = 1.
	 */
	index = 1;
	while (cpus_found < cpus_to_add) {
		u32 drc;

		rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
						index++, &drc);
		if (rc)
			break;

		if (dlpar_cpu_exists(parent, drc))
			continue;

		cpu_drcs[cpus_found++] = drc;
	}

	of_node_put(parent);
	return cpus_found;
}

static int dlpar_cpu_add_by_count(u32 cpus_to_add)
{
	u32 *cpu_drcs;
	int cpus_added = 0;
	int cpus_found;
	int i, rc;

	pr_debug("Attempting to hot-add %d CPUs\n", cpus_to_add);

	cpu_drcs = kcalloc(cpus_to_add, sizeof(*cpu_drcs), GFP_KERNEL);
	if (!cpu_drcs)
		return -EINVAL;

	cpus_found = find_dlpar_cpus_to_add(cpu_drcs, cpus_to_add);
	if (cpus_found < cpus_to_add) {
		pr_warn("Failed to find enough CPUs (%d of %d) to add\n",
			cpus_found, cpus_to_add);
		kfree(cpu_drcs);
		return -EINVAL;
	}

	for (i = 0; i < cpus_to_add; i++) {
		rc = dlpar_cpu_add(cpu_drcs[i]);
		if (rc)
			break;

		cpus_added++;
	}

	if (cpus_added < cpus_to_add) {
		pr_warn("CPU hot-add failed, removing any added CPUs\n");

		for (i = 0; i < cpus_added; i++)
			dlpar_cpu_remove_by_index(cpu_drcs[i]);

		rc = -EINVAL;
	} else {
		rc = 0;
	}

	kfree(cpu_drcs);
	return rc;
}

int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
{
	u32 count, drc_index;
	int rc;

	count = hp_elog->_drc_u.drc_count;
	drc_index = hp_elog->_drc_u.drc_index;

	lock_device_hotplug();

	switch (hp_elog->action) {
	case PSERIES_HP_ELOG_ACTION_REMOVE:
		if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
			rc = dlpar_cpu_remove_by_count(count);
		else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
			rc = dlpar_cpu_remove_by_index(drc_index);
		else
			rc = -EINVAL;
		break;
	case PSERIES_HP_ELOG_ACTION_ADD:
		if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
			rc = dlpar_cpu_add_by_count(count);
		else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
			rc = dlpar_cpu_add(drc_index);
		else
			rc = -EINVAL;
		break;
	default:
		pr_err("Invalid action (%d) specified\n", hp_elog->action);
		rc = -EINVAL;
		break;
	}

	unlock_device_hotplug();
	return rc;
}

#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE

static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
{
	u32 drc_index;
	int rc;

	rc = kstrtou32(buf, 0, &drc_index);
	if (rc)
		return -EINVAL;

	rc = dlpar_cpu_add(drc_index);

	return rc ? rc : count;
}

static ssize_t dlpar_cpu_release(const char *buf, size_t count)
{
	struct device_node *dn;
	u32 drc_index;
	int rc;

	dn = of_find_node_by_path(buf);
	if (!dn)
		return -EINVAL;

	rc = of_property_read_u32(dn, "ibm,my-drc-index", &drc_index);
	if (rc) {
		of_node_put(dn);
		return -EINVAL;
	}

	rc = dlpar_cpu_remove(dn, drc_index);
	of_node_put(dn);

	return rc ? rc : count;
}

#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */

static int pseries_smp_notifier(struct notifier_block *nb,
				unsigned long action, void *data)
{
	struct of_reconfig_data *rd = data;
	int err = 0;

	switch (action) {
	case OF_RECONFIG_ATTACH_NODE:
		err = pseries_add_processor(rd->dn);
		break;
	case OF_RECONFIG_DETACH_NODE:
		pseries_remove_processor(rd->dn);
		break;
	}
	return notifier_from_errno(err);
}

static struct notifier_block pseries_smp_nb = {
	.notifier_call = pseries_smp_notifier,
};

#define MAX_CEDE_LATENCY_LEVELS		4
#define	CEDE_LATENCY_PARAM_LENGTH	10
#define CEDE_LATENCY_PARAM_MAX_LENGTH	\
	(MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char))
#define CEDE_LATENCY_TOKEN		45

static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH];

static int parse_cede_parameters(void)
{
	memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH);
	return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
			 NULL,
			 CEDE_LATENCY_TOKEN,
			 __pa(cede_parameters),
			 CEDE_LATENCY_PARAM_MAX_LENGTH);
}

static int __init pseries_cpu_hotplug_init(void)
{
	int cpu;
	int qcss_tok;

#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
	ppc_md.cpu_probe = dlpar_cpu_probe;
	ppc_md.cpu_release = dlpar_cpu_release;
#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */

	rtas_stop_self_token = rtas_token("stop-self");
	qcss_tok = rtas_token("query-cpu-stopped-state");

	if (rtas_stop_self_token == RTAS_UNKNOWN_SERVICE ||
			qcss_tok == RTAS_UNKNOWN_SERVICE) {
		printk(KERN_INFO "CPU Hotplug not supported by firmware "
				"- disabling.\n");
		return 0;
	}

	ppc_md.cpu_die = pseries_mach_cpu_die;
	smp_ops->cpu_disable = pseries_cpu_disable;
	smp_ops->cpu_die = pseries_cpu_die;

	/* Processors can be added/removed only on LPAR */
	if (firmware_has_feature(FW_FEATURE_LPAR)) {
		of_reconfig_notifier_register(&pseries_smp_nb);
		cpu_maps_update_begin();
		if (cede_offline_enabled && parse_cede_parameters() == 0) {
			default_offline_state = CPU_STATE_INACTIVE;
			for_each_online_cpu(cpu)
				set_default_offline_state(cpu);
		}
		cpu_maps_update_done();
	}

	return 0;
}
machine_arch_initcall(pseries, pseries_cpu_hotplug_init);