Loading...
1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * (C) Copyright 2020 Hewlett Packard Enterprise Development LP
7 * Copyright (c) 2004-2009 Silicon Graphics, Inc. All Rights Reserved.
8 */
9
10/*
11 * Cross Partition Communication (XPC) support - standard version.
12 *
13 * XPC provides a message passing capability that crosses partition
14 * boundaries. This module is made up of two parts:
15 *
16 * partition This part detects the presence/absence of other
17 * partitions. It provides a heartbeat and monitors
18 * the heartbeats of other partitions.
19 *
20 * channel This part manages the channels and sends/receives
21 * messages across them to/from other partitions.
22 *
23 * There are a couple of additional functions residing in XP, which
24 * provide an interface to XPC for its users.
25 *
26 *
27 * Caveats:
28 *
29 * . Currently on sn2, we have no way to determine which nasid an IRQ
30 * came from. Thus, xpc_send_IRQ_sn2() does a remote amo write
31 * followed by an IPI. The amo indicates where data is to be pulled
32 * from, so after the IPI arrives, the remote partition checks the amo
33 * word. The IPI can actually arrive before the amo however, so other
34 * code must periodically check for this case. Also, remote amo
35 * operations do not reliably time out. Thus we do a remote PIO read
36 * solely to know whether the remote partition is down and whether we
37 * should stop sending IPIs to it. This remote PIO read operation is
38 * set up in a special nofault region so SAL knows to ignore (and
39 * cleanup) any errors due to the remote amo write, PIO read, and/or
40 * PIO write operations.
41 *
42 * If/when new hardware solves this IPI problem, we should abandon
43 * the current approach.
44 *
45 */
46
47#include <linux/module.h>
48#include <linux/slab.h>
49#include <linux/sysctl.h>
50#include <linux/device.h>
51#include <linux/delay.h>
52#include <linux/reboot.h>
53#include <linux/kdebug.h>
54#include <linux/kthread.h>
55#include "xpc.h"
56
57#ifdef CONFIG_X86_64
58#include <asm/traps.h>
59#endif
60
61/* define two XPC debug device structures to be used with dev_dbg() et al */
62
63static struct device_driver xpc_dbg_name = {
64 .name = "xpc"
65};
66
67static struct device xpc_part_dbg_subname = {
68 .init_name = "", /* set to "part" at xpc_init() time */
69 .driver = &xpc_dbg_name
70};
71
72static struct device xpc_chan_dbg_subname = {
73 .init_name = "", /* set to "chan" at xpc_init() time */
74 .driver = &xpc_dbg_name
75};
76
77struct device *xpc_part = &xpc_part_dbg_subname;
78struct device *xpc_chan = &xpc_chan_dbg_subname;
79
80static int xpc_kdebug_ignore;
81
82/* systune related variables for /proc/sys directories */
83
84static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
85static int xpc_hb_min_interval = 1;
86static int xpc_hb_max_interval = 10;
87
88static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
89static int xpc_hb_check_min_interval = 10;
90static int xpc_hb_check_max_interval = 120;
91
92int xpc_disengage_timelimit = XPC_DISENGAGE_DEFAULT_TIMELIMIT;
93static int xpc_disengage_min_timelimit; /* = 0 */
94static int xpc_disengage_max_timelimit = 120;
95
96static struct ctl_table xpc_sys_xpc_hb[] = {
97 {
98 .procname = "hb_interval",
99 .data = &xpc_hb_interval,
100 .maxlen = sizeof(int),
101 .mode = 0644,
102 .proc_handler = proc_dointvec_minmax,
103 .extra1 = &xpc_hb_min_interval,
104 .extra2 = &xpc_hb_max_interval},
105 {
106 .procname = "hb_check_interval",
107 .data = &xpc_hb_check_interval,
108 .maxlen = sizeof(int),
109 .mode = 0644,
110 .proc_handler = proc_dointvec_minmax,
111 .extra1 = &xpc_hb_check_min_interval,
112 .extra2 = &xpc_hb_check_max_interval},
113};
114static struct ctl_table xpc_sys_xpc[] = {
115 {
116 .procname = "disengage_timelimit",
117 .data = &xpc_disengage_timelimit,
118 .maxlen = sizeof(int),
119 .mode = 0644,
120 .proc_handler = proc_dointvec_minmax,
121 .extra1 = &xpc_disengage_min_timelimit,
122 .extra2 = &xpc_disengage_max_timelimit},
123};
124
125static struct ctl_table_header *xpc_sysctl;
126static struct ctl_table_header *xpc_sysctl_hb;
127
128/* non-zero if any remote partition disengage was timed out */
129int xpc_disengage_timedout;
130
131/* #of activate IRQs received and not yet processed */
132int xpc_activate_IRQ_rcvd;
133DEFINE_SPINLOCK(xpc_activate_IRQ_rcvd_lock);
134
135/* IRQ handler notifies this wait queue on receipt of an IRQ */
136DECLARE_WAIT_QUEUE_HEAD(xpc_activate_IRQ_wq);
137
138static unsigned long xpc_hb_check_timeout;
139static struct timer_list xpc_hb_timer;
140
141/* notification that the xpc_hb_checker thread has exited */
142static DECLARE_COMPLETION(xpc_hb_checker_exited);
143
144/* notification that the xpc_discovery thread has exited */
145static DECLARE_COMPLETION(xpc_discovery_exited);
146
147static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
148
149static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
150static struct notifier_block xpc_reboot_notifier = {
151 .notifier_call = xpc_system_reboot,
152};
153
154static int xpc_system_die(struct notifier_block *, unsigned long, void *);
155static struct notifier_block xpc_die_notifier = {
156 .notifier_call = xpc_system_die,
157};
158
159struct xpc_arch_operations xpc_arch_ops;
160
161/*
162 * Timer function to enforce the timelimit on the partition disengage.
163 */
164static void
165xpc_timeout_partition_disengage(struct timer_list *t)
166{
167 struct xpc_partition *part = from_timer(part, t, disengage_timer);
168
169 DBUG_ON(time_is_after_jiffies(part->disengage_timeout));
170
171 xpc_partition_disengaged_from_timer(part);
172
173 DBUG_ON(part->disengage_timeout != 0);
174 DBUG_ON(xpc_arch_ops.partition_engaged(XPC_PARTID(part)));
175}
176
177/*
178 * Timer to produce the heartbeat. The timer structures function is
179 * already set when this is initially called. A tunable is used to
180 * specify when the next timeout should occur.
181 */
182static void
183xpc_hb_beater(struct timer_list *unused)
184{
185 xpc_arch_ops.increment_heartbeat();
186
187 if (time_is_before_eq_jiffies(xpc_hb_check_timeout))
188 wake_up_interruptible(&xpc_activate_IRQ_wq);
189
190 xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
191 add_timer(&xpc_hb_timer);
192}
193
194static void
195xpc_start_hb_beater(void)
196{
197 xpc_arch_ops.heartbeat_init();
198 timer_setup(&xpc_hb_timer, xpc_hb_beater, 0);
199 xpc_hb_beater(NULL);
200}
201
202static void
203xpc_stop_hb_beater(void)
204{
205 del_timer_sync(&xpc_hb_timer);
206 xpc_arch_ops.heartbeat_exit();
207}
208
209/*
210 * At periodic intervals, scan through all active partitions and ensure
211 * their heartbeat is still active. If not, the partition is deactivated.
212 */
213static void
214xpc_check_remote_hb(void)
215{
216 struct xpc_partition *part;
217 short partid;
218 enum xp_retval ret;
219
220 for (partid = 0; partid < xp_max_npartitions; partid++) {
221
222 if (xpc_exiting)
223 break;
224
225 if (partid == xp_partition_id)
226 continue;
227
228 part = &xpc_partitions[partid];
229
230 if (part->act_state == XPC_P_AS_INACTIVE ||
231 part->act_state == XPC_P_AS_DEACTIVATING) {
232 continue;
233 }
234
235 ret = xpc_arch_ops.get_remote_heartbeat(part);
236 if (ret != xpSuccess)
237 XPC_DEACTIVATE_PARTITION(part, ret);
238 }
239}
240
241/*
242 * This thread is responsible for nearly all of the partition
243 * activation/deactivation.
244 */
245static int
246xpc_hb_checker(void *ignore)
247{
248 int force_IRQ = 0;
249
250 /* this thread was marked active by xpc_hb_init() */
251
252 set_cpus_allowed_ptr(current, cpumask_of(XPC_HB_CHECK_CPU));
253
254 /* set our heartbeating to other partitions into motion */
255 xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
256 xpc_start_hb_beater();
257
258 while (!xpc_exiting) {
259
260 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
261 "been received\n",
262 (int)(xpc_hb_check_timeout - jiffies),
263 xpc_activate_IRQ_rcvd);
264
265 /* checking of remote heartbeats is skewed by IRQ handling */
266 if (time_is_before_eq_jiffies(xpc_hb_check_timeout)) {
267 xpc_hb_check_timeout = jiffies +
268 (xpc_hb_check_interval * HZ);
269
270 dev_dbg(xpc_part, "checking remote heartbeats\n");
271 xpc_check_remote_hb();
272 }
273
274 /* check for outstanding IRQs */
275 if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) {
276 force_IRQ = 0;
277 dev_dbg(xpc_part, "processing activate IRQs "
278 "received\n");
279 xpc_arch_ops.process_activate_IRQ_rcvd();
280 }
281
282 /* wait for IRQ or timeout */
283 (void)wait_event_interruptible(xpc_activate_IRQ_wq,
284 (time_is_before_eq_jiffies(
285 xpc_hb_check_timeout) ||
286 xpc_activate_IRQ_rcvd > 0 ||
287 xpc_exiting));
288 }
289
290 xpc_stop_hb_beater();
291
292 dev_dbg(xpc_part, "heartbeat checker is exiting\n");
293
294 /* mark this thread as having exited */
295 complete(&xpc_hb_checker_exited);
296 return 0;
297}
298
299/*
300 * This thread will attempt to discover other partitions to activate
301 * based on info provided by SAL. This new thread is short lived and
302 * will exit once discovery is complete.
303 */
304static int
305xpc_initiate_discovery(void *ignore)
306{
307 xpc_discovery();
308
309 dev_dbg(xpc_part, "discovery thread is exiting\n");
310
311 /* mark this thread as having exited */
312 complete(&xpc_discovery_exited);
313 return 0;
314}
315
316/*
317 * The first kthread assigned to a newly activated partition is the one
318 * created by XPC HB with which it calls xpc_activating(). XPC hangs on to
319 * that kthread until the partition is brought down, at which time that kthread
320 * returns back to XPC HB. (The return of that kthread will signify to XPC HB
321 * that XPC has dismantled all communication infrastructure for the associated
322 * partition.) This kthread becomes the channel manager for that partition.
323 *
324 * Each active partition has a channel manager, who, besides connecting and
325 * disconnecting channels, will ensure that each of the partition's connected
326 * channels has the required number of assigned kthreads to get the work done.
327 */
328static void
329xpc_channel_mgr(struct xpc_partition *part)
330{
331 while (part->act_state != XPC_P_AS_DEACTIVATING ||
332 atomic_read(&part->nchannels_active) > 0 ||
333 !xpc_partition_disengaged(part)) {
334
335 xpc_process_sent_chctl_flags(part);
336
337 /*
338 * Wait until we've been requested to activate kthreads or
339 * all of the channel's message queues have been torn down or
340 * a signal is pending.
341 *
342 * The channel_mgr_requests is set to 1 after being awakened,
343 * This is done to prevent the channel mgr from making one pass
344 * through the loop for each request, since he will
345 * be servicing all the requests in one pass. The reason it's
346 * set to 1 instead of 0 is so that other kthreads will know
347 * that the channel mgr is running and won't bother trying to
348 * wake him up.
349 */
350 atomic_dec(&part->channel_mgr_requests);
351 (void)wait_event_interruptible(part->channel_mgr_wq,
352 (atomic_read(&part->channel_mgr_requests) > 0 ||
353 part->chctl.all_flags != 0 ||
354 (part->act_state == XPC_P_AS_DEACTIVATING &&
355 atomic_read(&part->nchannels_active) == 0 &&
356 xpc_partition_disengaged(part))));
357 atomic_set(&part->channel_mgr_requests, 1);
358 }
359}
360
361/*
362 * Guarantee that the kzalloc'd memory is cacheline aligned.
363 */
364void *
365xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
366{
367 /* see if kzalloc will give us cachline aligned memory by default */
368 *base = kzalloc(size, flags);
369 if (*base == NULL)
370 return NULL;
371
372 if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
373 return *base;
374
375 kfree(*base);
376
377 /* nope, we'll have to do it ourselves */
378 *base = kzalloc(size + L1_CACHE_BYTES, flags);
379 if (*base == NULL)
380 return NULL;
381
382 return (void *)L1_CACHE_ALIGN((u64)*base);
383}
384
385/*
386 * Setup the channel structures necessary to support XPartition Communication
387 * between the specified remote partition and the local one.
388 */
389static enum xp_retval
390xpc_setup_ch_structures(struct xpc_partition *part)
391{
392 enum xp_retval ret;
393 int ch_number;
394 struct xpc_channel *ch;
395 short partid = XPC_PARTID(part);
396
397 /*
398 * Allocate all of the channel structures as a contiguous chunk of
399 * memory.
400 */
401 DBUG_ON(part->channels != NULL);
402 part->channels = kcalloc(XPC_MAX_NCHANNELS,
403 sizeof(struct xpc_channel),
404 GFP_KERNEL);
405 if (part->channels == NULL) {
406 dev_err(xpc_chan, "can't get memory for channels\n");
407 return xpNoMemory;
408 }
409
410 /* allocate the remote open and close args */
411
412 part->remote_openclose_args =
413 xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
414 GFP_KERNEL, &part->
415 remote_openclose_args_base);
416 if (part->remote_openclose_args == NULL) {
417 dev_err(xpc_chan, "can't get memory for remote connect args\n");
418 ret = xpNoMemory;
419 goto out_1;
420 }
421
422 part->chctl.all_flags = 0;
423 spin_lock_init(&part->chctl_lock);
424
425 atomic_set(&part->channel_mgr_requests, 1);
426 init_waitqueue_head(&part->channel_mgr_wq);
427
428 part->nchannels = XPC_MAX_NCHANNELS;
429
430 atomic_set(&part->nchannels_active, 0);
431 atomic_set(&part->nchannels_engaged, 0);
432
433 for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
434 ch = &part->channels[ch_number];
435
436 ch->partid = partid;
437 ch->number = ch_number;
438 ch->flags = XPC_C_DISCONNECTED;
439
440 atomic_set(&ch->kthreads_assigned, 0);
441 atomic_set(&ch->kthreads_idle, 0);
442 atomic_set(&ch->kthreads_active, 0);
443
444 atomic_set(&ch->references, 0);
445 atomic_set(&ch->n_to_notify, 0);
446
447 spin_lock_init(&ch->lock);
448 init_completion(&ch->wdisconnect_wait);
449
450 atomic_set(&ch->n_on_msg_allocate_wq, 0);
451 init_waitqueue_head(&ch->msg_allocate_wq);
452 init_waitqueue_head(&ch->idle_wq);
453 }
454
455 ret = xpc_arch_ops.setup_ch_structures(part);
456 if (ret != xpSuccess)
457 goto out_2;
458
459 /*
460 * With the setting of the partition setup_state to XPC_P_SS_SETUP,
461 * we're declaring that this partition is ready to go.
462 */
463 part->setup_state = XPC_P_SS_SETUP;
464
465 return xpSuccess;
466
467 /* setup of ch structures failed */
468out_2:
469 kfree(part->remote_openclose_args_base);
470 part->remote_openclose_args = NULL;
471out_1:
472 kfree(part->channels);
473 part->channels = NULL;
474 return ret;
475}
476
477/*
478 * Teardown the channel structures necessary to support XPartition Communication
479 * between the specified remote partition and the local one.
480 */
481static void
482xpc_teardown_ch_structures(struct xpc_partition *part)
483{
484 DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
485 DBUG_ON(atomic_read(&part->nchannels_active) != 0);
486
487 /*
488 * Make this partition inaccessible to local processes by marking it
489 * as no longer setup. Then wait before proceeding with the teardown
490 * until all existing references cease.
491 */
492 DBUG_ON(part->setup_state != XPC_P_SS_SETUP);
493 part->setup_state = XPC_P_SS_WTEARDOWN;
494
495 wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
496
497 /* now we can begin tearing down the infrastructure */
498
499 xpc_arch_ops.teardown_ch_structures(part);
500
501 kfree(part->remote_openclose_args_base);
502 part->remote_openclose_args = NULL;
503 kfree(part->channels);
504 part->channels = NULL;
505
506 part->setup_state = XPC_P_SS_TORNDOWN;
507}
508
509/*
510 * When XPC HB determines that a partition has come up, it will create a new
511 * kthread and that kthread will call this function to attempt to set up the
512 * basic infrastructure used for Cross Partition Communication with the newly
513 * upped partition.
514 *
515 * The kthread that was created by XPC HB and which setup the XPC
516 * infrastructure will remain assigned to the partition becoming the channel
517 * manager for that partition until the partition is deactivating, at which
518 * time the kthread will teardown the XPC infrastructure and then exit.
519 */
520static int
521xpc_activating(void *__partid)
522{
523 short partid = (u64)__partid;
524 struct xpc_partition *part = &xpc_partitions[partid];
525 unsigned long irq_flags;
526
527 DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
528
529 spin_lock_irqsave(&part->act_lock, irq_flags);
530
531 if (part->act_state == XPC_P_AS_DEACTIVATING) {
532 part->act_state = XPC_P_AS_INACTIVE;
533 spin_unlock_irqrestore(&part->act_lock, irq_flags);
534 part->remote_rp_pa = 0;
535 return 0;
536 }
537
538 /* indicate the thread is activating */
539 DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ);
540 part->act_state = XPC_P_AS_ACTIVATING;
541
542 XPC_SET_REASON(part, 0, 0);
543 spin_unlock_irqrestore(&part->act_lock, irq_flags);
544
545 dev_dbg(xpc_part, "activating partition %d\n", partid);
546
547 xpc_arch_ops.allow_hb(partid);
548
549 if (xpc_setup_ch_structures(part) == xpSuccess) {
550 (void)xpc_part_ref(part); /* this will always succeed */
551
552 if (xpc_arch_ops.make_first_contact(part) == xpSuccess) {
553 xpc_mark_partition_active(part);
554 xpc_channel_mgr(part);
555 /* won't return until partition is deactivating */
556 }
557
558 xpc_part_deref(part);
559 xpc_teardown_ch_structures(part);
560 }
561
562 xpc_arch_ops.disallow_hb(partid);
563 xpc_mark_partition_inactive(part);
564
565 if (part->reason == xpReactivating) {
566 /* interrupting ourselves results in activating partition */
567 xpc_arch_ops.request_partition_reactivation(part);
568 }
569
570 return 0;
571}
572
573void
574xpc_activate_partition(struct xpc_partition *part)
575{
576 short partid = XPC_PARTID(part);
577 unsigned long irq_flags;
578 struct task_struct *kthread;
579
580 spin_lock_irqsave(&part->act_lock, irq_flags);
581
582 DBUG_ON(part->act_state != XPC_P_AS_INACTIVE);
583
584 part->act_state = XPC_P_AS_ACTIVATION_REQ;
585 XPC_SET_REASON(part, xpCloneKThread, __LINE__);
586
587 spin_unlock_irqrestore(&part->act_lock, irq_flags);
588
589 kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
590 partid);
591 if (IS_ERR(kthread)) {
592 spin_lock_irqsave(&part->act_lock, irq_flags);
593 part->act_state = XPC_P_AS_INACTIVE;
594 XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
595 spin_unlock_irqrestore(&part->act_lock, irq_flags);
596 }
597}
598
599void
600xpc_activate_kthreads(struct xpc_channel *ch, int needed)
601{
602 int idle = atomic_read(&ch->kthreads_idle);
603 int assigned = atomic_read(&ch->kthreads_assigned);
604 int wakeup;
605
606 DBUG_ON(needed <= 0);
607
608 if (idle > 0) {
609 wakeup = (needed > idle) ? idle : needed;
610 needed -= wakeup;
611
612 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
613 "channel=%d\n", wakeup, ch->partid, ch->number);
614
615 /* only wakeup the requested number of kthreads */
616 wake_up_nr(&ch->idle_wq, wakeup);
617 }
618
619 if (needed <= 0)
620 return;
621
622 if (needed + assigned > ch->kthreads_assigned_limit) {
623 needed = ch->kthreads_assigned_limit - assigned;
624 if (needed <= 0)
625 return;
626 }
627
628 dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
629 needed, ch->partid, ch->number);
630
631 xpc_create_kthreads(ch, needed, 0);
632}
633
634/*
635 * This function is where XPC's kthreads wait for messages to deliver.
636 */
637static void
638xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
639{
640 int (*n_of_deliverable_payloads) (struct xpc_channel *) =
641 xpc_arch_ops.n_of_deliverable_payloads;
642
643 do {
644 /* deliver messages to their intended recipients */
645
646 while (n_of_deliverable_payloads(ch) > 0 &&
647 !(ch->flags & XPC_C_DISCONNECTING)) {
648 xpc_deliver_payload(ch);
649 }
650
651 if (atomic_inc_return(&ch->kthreads_idle) >
652 ch->kthreads_idle_limit) {
653 /* too many idle kthreads on this channel */
654 atomic_dec(&ch->kthreads_idle);
655 break;
656 }
657
658 dev_dbg(xpc_chan, "idle kthread calling "
659 "wait_event_interruptible_exclusive()\n");
660
661 (void)wait_event_interruptible_exclusive(ch->idle_wq,
662 (n_of_deliverable_payloads(ch) > 0 ||
663 (ch->flags & XPC_C_DISCONNECTING)));
664
665 atomic_dec(&ch->kthreads_idle);
666
667 } while (!(ch->flags & XPC_C_DISCONNECTING));
668}
669
670static int
671xpc_kthread_start(void *args)
672{
673 short partid = XPC_UNPACK_ARG1(args);
674 u16 ch_number = XPC_UNPACK_ARG2(args);
675 struct xpc_partition *part = &xpc_partitions[partid];
676 struct xpc_channel *ch;
677 int n_needed;
678 unsigned long irq_flags;
679 int (*n_of_deliverable_payloads) (struct xpc_channel *) =
680 xpc_arch_ops.n_of_deliverable_payloads;
681
682 dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
683 partid, ch_number);
684
685 ch = &part->channels[ch_number];
686
687 if (!(ch->flags & XPC_C_DISCONNECTING)) {
688
689 /* let registerer know that connection has been established */
690
691 spin_lock_irqsave(&ch->lock, irq_flags);
692 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
693 ch->flags |= XPC_C_CONNECTEDCALLOUT;
694 spin_unlock_irqrestore(&ch->lock, irq_flags);
695
696 xpc_connected_callout(ch);
697
698 spin_lock_irqsave(&ch->lock, irq_flags);
699 ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
700 spin_unlock_irqrestore(&ch->lock, irq_flags);
701
702 /*
703 * It is possible that while the callout was being
704 * made that the remote partition sent some messages.
705 * If that is the case, we may need to activate
706 * additional kthreads to help deliver them. We only
707 * need one less than total #of messages to deliver.
708 */
709 n_needed = n_of_deliverable_payloads(ch) - 1;
710 if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
711 xpc_activate_kthreads(ch, n_needed);
712
713 } else {
714 spin_unlock_irqrestore(&ch->lock, irq_flags);
715 }
716
717 xpc_kthread_waitmsgs(part, ch);
718 }
719
720 /* let registerer know that connection is disconnecting */
721
722 spin_lock_irqsave(&ch->lock, irq_flags);
723 if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
724 !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
725 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
726 spin_unlock_irqrestore(&ch->lock, irq_flags);
727
728 xpc_disconnect_callout(ch, xpDisconnecting);
729
730 spin_lock_irqsave(&ch->lock, irq_flags);
731 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
732 }
733 spin_unlock_irqrestore(&ch->lock, irq_flags);
734
735 if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
736 atomic_dec_return(&part->nchannels_engaged) == 0) {
737 xpc_arch_ops.indicate_partition_disengaged(part);
738 }
739
740 xpc_msgqueue_deref(ch);
741
742 dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
743 partid, ch_number);
744
745 xpc_part_deref(part);
746 return 0;
747}
748
749/*
750 * For each partition that XPC has established communications with, there is
751 * a minimum of one kernel thread assigned to perform any operation that
752 * may potentially sleep or block (basically the callouts to the asynchronous
753 * functions registered via xpc_connect()).
754 *
755 * Additional kthreads are created and destroyed by XPC as the workload
756 * demands.
757 *
758 * A kthread is assigned to one of the active channels that exists for a given
759 * partition.
760 */
761void
762xpc_create_kthreads(struct xpc_channel *ch, int needed,
763 int ignore_disconnecting)
764{
765 unsigned long irq_flags;
766 u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
767 struct xpc_partition *part = &xpc_partitions[ch->partid];
768 struct task_struct *kthread;
769 void (*indicate_partition_disengaged) (struct xpc_partition *) =
770 xpc_arch_ops.indicate_partition_disengaged;
771
772 while (needed-- > 0) {
773
774 /*
775 * The following is done on behalf of the newly created
776 * kthread. That kthread is responsible for doing the
777 * counterpart to the following before it exits.
778 */
779 if (ignore_disconnecting) {
780 if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
781 /* kthreads assigned had gone to zero */
782 BUG_ON(!(ch->flags &
783 XPC_C_DISCONNECTINGCALLOUT_MADE));
784 break;
785 }
786
787 } else if (ch->flags & XPC_C_DISCONNECTING) {
788 break;
789
790 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
791 atomic_inc_return(&part->nchannels_engaged) == 1) {
792 xpc_arch_ops.indicate_partition_engaged(part);
793 }
794 (void)xpc_part_ref(part);
795 xpc_msgqueue_ref(ch);
796
797 kthread = kthread_run(xpc_kthread_start, (void *)args,
798 "xpc%02dc%d", ch->partid, ch->number);
799 if (IS_ERR(kthread)) {
800 /* the fork failed */
801
802 /*
803 * NOTE: if (ignore_disconnecting &&
804 * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
805 * then we'll deadlock if all other kthreads assigned
806 * to this channel are blocked in the channel's
807 * registerer, because the only thing that will unblock
808 * them is the xpDisconnecting callout that this
809 * failed kthread_run() would have made.
810 */
811
812 if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
813 atomic_dec_return(&part->nchannels_engaged) == 0) {
814 indicate_partition_disengaged(part);
815 }
816 xpc_msgqueue_deref(ch);
817 xpc_part_deref(part);
818
819 if (atomic_read(&ch->kthreads_assigned) <
820 ch->kthreads_idle_limit) {
821 /*
822 * Flag this as an error only if we have an
823 * insufficient #of kthreads for the channel
824 * to function.
825 */
826 spin_lock_irqsave(&ch->lock, irq_flags);
827 XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
828 &irq_flags);
829 spin_unlock_irqrestore(&ch->lock, irq_flags);
830 }
831 break;
832 }
833 }
834}
835
836void
837xpc_disconnect_wait(int ch_number)
838{
839 unsigned long irq_flags;
840 short partid;
841 struct xpc_partition *part;
842 struct xpc_channel *ch;
843 int wakeup_channel_mgr;
844
845 /* now wait for all callouts to the caller's function to cease */
846 for (partid = 0; partid < xp_max_npartitions; partid++) {
847 part = &xpc_partitions[partid];
848
849 if (!xpc_part_ref(part))
850 continue;
851
852 ch = &part->channels[ch_number];
853
854 if (!(ch->flags & XPC_C_WDISCONNECT)) {
855 xpc_part_deref(part);
856 continue;
857 }
858
859 wait_for_completion(&ch->wdisconnect_wait);
860
861 spin_lock_irqsave(&ch->lock, irq_flags);
862 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
863 wakeup_channel_mgr = 0;
864
865 if (ch->delayed_chctl_flags) {
866 if (part->act_state != XPC_P_AS_DEACTIVATING) {
867 spin_lock(&part->chctl_lock);
868 part->chctl.flags[ch->number] |=
869 ch->delayed_chctl_flags;
870 spin_unlock(&part->chctl_lock);
871 wakeup_channel_mgr = 1;
872 }
873 ch->delayed_chctl_flags = 0;
874 }
875
876 ch->flags &= ~XPC_C_WDISCONNECT;
877 spin_unlock_irqrestore(&ch->lock, irq_flags);
878
879 if (wakeup_channel_mgr)
880 xpc_wakeup_channel_mgr(part);
881
882 xpc_part_deref(part);
883 }
884}
885
886static int
887xpc_setup_partitions(void)
888{
889 short partid;
890 struct xpc_partition *part;
891
892 xpc_partitions = kcalloc(xp_max_npartitions,
893 sizeof(struct xpc_partition),
894 GFP_KERNEL);
895 if (xpc_partitions == NULL) {
896 dev_err(xpc_part, "can't get memory for partition structure\n");
897 return -ENOMEM;
898 }
899
900 /*
901 * The first few fields of each entry of xpc_partitions[] need to
902 * be initialized now so that calls to xpc_connect() and
903 * xpc_disconnect() can be made prior to the activation of any remote
904 * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
905 * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
906 * PARTITION HAS BEEN ACTIVATED.
907 */
908 for (partid = 0; partid < xp_max_npartitions; partid++) {
909 part = &xpc_partitions[partid];
910
911 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
912
913 part->activate_IRQ_rcvd = 0;
914 spin_lock_init(&part->act_lock);
915 part->act_state = XPC_P_AS_INACTIVE;
916 XPC_SET_REASON(part, 0, 0);
917
918 timer_setup(&part->disengage_timer,
919 xpc_timeout_partition_disengage, 0);
920
921 part->setup_state = XPC_P_SS_UNSET;
922 init_waitqueue_head(&part->teardown_wq);
923 atomic_set(&part->references, 0);
924 }
925
926 return xpc_arch_ops.setup_partitions();
927}
928
929static void
930xpc_teardown_partitions(void)
931{
932 xpc_arch_ops.teardown_partitions();
933 kfree(xpc_partitions);
934}
935
936static void
937xpc_do_exit(enum xp_retval reason)
938{
939 short partid;
940 int active_part_count, printed_waiting_msg = 0;
941 struct xpc_partition *part;
942 unsigned long printmsg_time, disengage_timeout = 0;
943
944 /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
945 DBUG_ON(xpc_exiting == 1);
946
947 /*
948 * Let the heartbeat checker thread and the discovery thread
949 * (if one is running) know that they should exit. Also wake up
950 * the heartbeat checker thread in case it's sleeping.
951 */
952 xpc_exiting = 1;
953 wake_up_interruptible(&xpc_activate_IRQ_wq);
954
955 /* wait for the discovery thread to exit */
956 wait_for_completion(&xpc_discovery_exited);
957
958 /* wait for the heartbeat checker thread to exit */
959 wait_for_completion(&xpc_hb_checker_exited);
960
961 /* sleep for a 1/3 of a second or so */
962 (void)msleep_interruptible(300);
963
964 /* wait for all partitions to become inactive */
965
966 printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
967 xpc_disengage_timedout = 0;
968
969 do {
970 active_part_count = 0;
971
972 for (partid = 0; partid < xp_max_npartitions; partid++) {
973 part = &xpc_partitions[partid];
974
975 if (xpc_partition_disengaged(part) &&
976 part->act_state == XPC_P_AS_INACTIVE) {
977 continue;
978 }
979
980 active_part_count++;
981
982 XPC_DEACTIVATE_PARTITION(part, reason);
983
984 if (part->disengage_timeout > disengage_timeout)
985 disengage_timeout = part->disengage_timeout;
986 }
987
988 if (xpc_arch_ops.any_partition_engaged()) {
989 if (time_is_before_jiffies(printmsg_time)) {
990 dev_info(xpc_part, "waiting for remote "
991 "partitions to deactivate, timeout in "
992 "%ld seconds\n", (disengage_timeout -
993 jiffies) / HZ);
994 printmsg_time = jiffies +
995 (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
996 printed_waiting_msg = 1;
997 }
998
999 } else if (active_part_count > 0) {
1000 if (printed_waiting_msg) {
1001 dev_info(xpc_part, "waiting for local partition"
1002 " to deactivate\n");
1003 printed_waiting_msg = 0;
1004 }
1005
1006 } else {
1007 if (!xpc_disengage_timedout) {
1008 dev_info(xpc_part, "all partitions have "
1009 "deactivated\n");
1010 }
1011 break;
1012 }
1013
1014 /* sleep for a 1/3 of a second or so */
1015 (void)msleep_interruptible(300);
1016
1017 } while (1);
1018
1019 DBUG_ON(xpc_arch_ops.any_partition_engaged());
1020
1021 xpc_teardown_rsvd_page();
1022
1023 if (reason == xpUnloading) {
1024 (void)unregister_die_notifier(&xpc_die_notifier);
1025 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1026 }
1027
1028 /* clear the interface to XPC's functions */
1029 xpc_clear_interface();
1030
1031 if (xpc_sysctl)
1032 unregister_sysctl_table(xpc_sysctl);
1033 if (xpc_sysctl_hb)
1034 unregister_sysctl_table(xpc_sysctl_hb);
1035
1036 xpc_teardown_partitions();
1037
1038 if (is_uv_system())
1039 xpc_exit_uv();
1040}
1041
1042/*
1043 * This function is called when the system is being rebooted.
1044 */
1045static int
1046xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1047{
1048 enum xp_retval reason;
1049
1050 switch (event) {
1051 case SYS_RESTART:
1052 reason = xpSystemReboot;
1053 break;
1054 case SYS_HALT:
1055 reason = xpSystemHalt;
1056 break;
1057 case SYS_POWER_OFF:
1058 reason = xpSystemPoweroff;
1059 break;
1060 default:
1061 reason = xpSystemGoingDown;
1062 }
1063
1064 xpc_do_exit(reason);
1065 return NOTIFY_DONE;
1066}
1067
1068/* Used to only allow one cpu to complete disconnect */
1069static unsigned int xpc_die_disconnecting;
1070
1071/*
1072 * Notify other partitions to deactivate from us by first disengaging from all
1073 * references to our memory.
1074 */
1075static void
1076xpc_die_deactivate(void)
1077{
1078 struct xpc_partition *part;
1079 short partid;
1080 int any_engaged;
1081 long keep_waiting;
1082 long wait_to_print;
1083
1084 if (cmpxchg(&xpc_die_disconnecting, 0, 1))
1085 return;
1086
1087 /* keep xpc_hb_checker thread from doing anything (just in case) */
1088 xpc_exiting = 1;
1089
1090 xpc_arch_ops.disallow_all_hbs(); /*indicate we're deactivated */
1091
1092 for (partid = 0; partid < xp_max_npartitions; partid++) {
1093 part = &xpc_partitions[partid];
1094
1095 if (xpc_arch_ops.partition_engaged(partid) ||
1096 part->act_state != XPC_P_AS_INACTIVE) {
1097 xpc_arch_ops.request_partition_deactivation(part);
1098 xpc_arch_ops.indicate_partition_disengaged(part);
1099 }
1100 }
1101
1102 /*
1103 * Though we requested that all other partitions deactivate from us,
1104 * we only wait until they've all disengaged or we've reached the
1105 * defined timelimit.
1106 *
1107 * Given that one iteration through the following while-loop takes
1108 * approximately 200 microseconds, calculate the #of loops to take
1109 * before bailing and the #of loops before printing a waiting message.
1110 */
1111 keep_waiting = xpc_disengage_timelimit * 1000 * 5;
1112 wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5;
1113
1114 while (1) {
1115 any_engaged = xpc_arch_ops.any_partition_engaged();
1116 if (!any_engaged) {
1117 dev_info(xpc_part, "all partitions have deactivated\n");
1118 break;
1119 }
1120
1121 if (!keep_waiting--) {
1122 for (partid = 0; partid < xp_max_npartitions;
1123 partid++) {
1124 if (xpc_arch_ops.partition_engaged(partid)) {
1125 dev_info(xpc_part, "deactivate from "
1126 "remote partition %d timed "
1127 "out\n", partid);
1128 }
1129 }
1130 break;
1131 }
1132
1133 if (!wait_to_print--) {
1134 dev_info(xpc_part, "waiting for remote partitions to "
1135 "deactivate, timeout in %ld seconds\n",
1136 keep_waiting / (1000 * 5));
1137 wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL *
1138 1000 * 5;
1139 }
1140
1141 udelay(200);
1142 }
1143}
1144
1145/*
1146 * This function is called when the system is being restarted or halted due
1147 * to some sort of system failure. If this is the case we need to notify the
1148 * other partitions to disengage from all references to our memory.
1149 * This function can also be called when our heartbeater could be offlined
1150 * for a time. In this case we need to notify other partitions to not worry
1151 * about the lack of a heartbeat.
1152 */
1153static int
1154xpc_system_die(struct notifier_block *nb, unsigned long event, void *_die_args)
1155{
1156 struct die_args *die_args = _die_args;
1157
1158 switch (event) {
1159 case DIE_TRAP:
1160 if (die_args->trapnr == X86_TRAP_DF)
1161 xpc_die_deactivate();
1162
1163 if (((die_args->trapnr == X86_TRAP_MF) ||
1164 (die_args->trapnr == X86_TRAP_XF)) &&
1165 !user_mode(die_args->regs))
1166 xpc_die_deactivate();
1167
1168 break;
1169 case DIE_INT3:
1170 case DIE_DEBUG:
1171 break;
1172 case DIE_OOPS:
1173 case DIE_GPF:
1174 default:
1175 xpc_die_deactivate();
1176 }
1177
1178 return NOTIFY_DONE;
1179}
1180
1181static int __init
1182xpc_init(void)
1183{
1184 int ret;
1185 struct task_struct *kthread;
1186
1187 dev_set_name(xpc_part, "part");
1188 dev_set_name(xpc_chan, "chan");
1189
1190 if (is_uv_system()) {
1191 ret = xpc_init_uv();
1192
1193 } else {
1194 ret = -ENODEV;
1195 }
1196
1197 if (ret != 0)
1198 return ret;
1199
1200 ret = xpc_setup_partitions();
1201 if (ret != 0) {
1202 dev_err(xpc_part, "can't get memory for partition structure\n");
1203 goto out_1;
1204 }
1205
1206 xpc_sysctl = register_sysctl("xpc", xpc_sys_xpc);
1207 xpc_sysctl_hb = register_sysctl("xpc/hb", xpc_sys_xpc_hb);
1208
1209 /*
1210 * Fill the partition reserved page with the information needed by
1211 * other partitions to discover we are alive and establish initial
1212 * communications.
1213 */
1214 ret = xpc_setup_rsvd_page();
1215 if (ret != 0) {
1216 dev_err(xpc_part, "can't setup our reserved page\n");
1217 goto out_2;
1218 }
1219
1220 /* add ourselves to the reboot_notifier_list */
1221 ret = register_reboot_notifier(&xpc_reboot_notifier);
1222 if (ret != 0)
1223 dev_warn(xpc_part, "can't register reboot notifier\n");
1224
1225 /* add ourselves to the die_notifier list */
1226 ret = register_die_notifier(&xpc_die_notifier);
1227 if (ret != 0)
1228 dev_warn(xpc_part, "can't register die notifier\n");
1229
1230 /*
1231 * The real work-horse behind xpc. This processes incoming
1232 * interrupts and monitors remote heartbeats.
1233 */
1234 kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1235 if (IS_ERR(kthread)) {
1236 dev_err(xpc_part, "failed while forking hb check thread\n");
1237 ret = -EBUSY;
1238 goto out_3;
1239 }
1240
1241 /*
1242 * Startup a thread that will attempt to discover other partitions to
1243 * activate based on info provided by SAL. This new thread is short
1244 * lived and will exit once discovery is complete.
1245 */
1246 kthread = kthread_run(xpc_initiate_discovery, NULL,
1247 XPC_DISCOVERY_THREAD_NAME);
1248 if (IS_ERR(kthread)) {
1249 dev_err(xpc_part, "failed while forking discovery thread\n");
1250
1251 /* mark this new thread as a non-starter */
1252 complete(&xpc_discovery_exited);
1253
1254 xpc_do_exit(xpUnloading);
1255 return -EBUSY;
1256 }
1257
1258 /* set the interface to point at XPC's functions */
1259 xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1260 xpc_initiate_send, xpc_initiate_send_notify,
1261 xpc_initiate_received, xpc_initiate_partid_to_nasids);
1262
1263 return 0;
1264
1265 /* initialization was not successful */
1266out_3:
1267 xpc_teardown_rsvd_page();
1268
1269 (void)unregister_die_notifier(&xpc_die_notifier);
1270 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1271out_2:
1272 if (xpc_sysctl_hb)
1273 unregister_sysctl_table(xpc_sysctl_hb);
1274 if (xpc_sysctl)
1275 unregister_sysctl_table(xpc_sysctl);
1276
1277 xpc_teardown_partitions();
1278out_1:
1279 if (is_uv_system())
1280 xpc_exit_uv();
1281 return ret;
1282}
1283
1284module_init(xpc_init);
1285
1286static void __exit
1287xpc_exit(void)
1288{
1289 xpc_do_exit(xpUnloading);
1290}
1291
1292module_exit(xpc_exit);
1293
1294MODULE_AUTHOR("Silicon Graphics, Inc.");
1295MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1296MODULE_LICENSE("GPL");
1297
1298module_param(xpc_hb_interval, int, 0);
1299MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1300 "heartbeat increments.");
1301
1302module_param(xpc_hb_check_interval, int, 0);
1303MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1304 "heartbeat checks.");
1305
1306module_param(xpc_disengage_timelimit, int, 0);
1307MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait "
1308 "for disengage to complete.");
1309
1310module_param(xpc_kdebug_ignore, int, 0);
1311MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1312 "other partitions when dropping into kdebug.");
1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * (C) Copyright 2020 Hewlett Packard Enterprise Development LP
7 * Copyright (c) 2004-2009 Silicon Graphics, Inc. All Rights Reserved.
8 */
9
10/*
11 * Cross Partition Communication (XPC) support - standard version.
12 *
13 * XPC provides a message passing capability that crosses partition
14 * boundaries. This module is made up of two parts:
15 *
16 * partition This part detects the presence/absence of other
17 * partitions. It provides a heartbeat and monitors
18 * the heartbeats of other partitions.
19 *
20 * channel This part manages the channels and sends/receives
21 * messages across them to/from other partitions.
22 *
23 * There are a couple of additional functions residing in XP, which
24 * provide an interface to XPC for its users.
25 *
26 *
27 * Caveats:
28 *
29 * . Currently on sn2, we have no way to determine which nasid an IRQ
30 * came from. Thus, xpc_send_IRQ_sn2() does a remote amo write
31 * followed by an IPI. The amo indicates where data is to be pulled
32 * from, so after the IPI arrives, the remote partition checks the amo
33 * word. The IPI can actually arrive before the amo however, so other
34 * code must periodically check for this case. Also, remote amo
35 * operations do not reliably time out. Thus we do a remote PIO read
36 * solely to know whether the remote partition is down and whether we
37 * should stop sending IPIs to it. This remote PIO read operation is
38 * set up in a special nofault region so SAL knows to ignore (and
39 * cleanup) any errors due to the remote amo write, PIO read, and/or
40 * PIO write operations.
41 *
42 * If/when new hardware solves this IPI problem, we should abandon
43 * the current approach.
44 *
45 */
46
47#include <linux/module.h>
48#include <linux/slab.h>
49#include <linux/sysctl.h>
50#include <linux/device.h>
51#include <linux/delay.h>
52#include <linux/reboot.h>
53#include <linux/kdebug.h>
54#include <linux/kthread.h>
55#include "xpc.h"
56
57#ifdef CONFIG_X86_64
58#include <asm/traps.h>
59#endif
60
61/* define two XPC debug device structures to be used with dev_dbg() et al */
62
63static struct device_driver xpc_dbg_name = {
64 .name = "xpc"
65};
66
67static struct device xpc_part_dbg_subname = {
68 .init_name = "", /* set to "part" at xpc_init() time */
69 .driver = &xpc_dbg_name
70};
71
72static struct device xpc_chan_dbg_subname = {
73 .init_name = "", /* set to "chan" at xpc_init() time */
74 .driver = &xpc_dbg_name
75};
76
77struct device *xpc_part = &xpc_part_dbg_subname;
78struct device *xpc_chan = &xpc_chan_dbg_subname;
79
80static int xpc_kdebug_ignore;
81
82/* systune related variables for /proc/sys directories */
83
84static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
85static int xpc_hb_min_interval = 1;
86static int xpc_hb_max_interval = 10;
87
88static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
89static int xpc_hb_check_min_interval = 10;
90static int xpc_hb_check_max_interval = 120;
91
92int xpc_disengage_timelimit = XPC_DISENGAGE_DEFAULT_TIMELIMIT;
93static int xpc_disengage_min_timelimit; /* = 0 */
94static int xpc_disengage_max_timelimit = 120;
95
96static struct ctl_table xpc_sys_xpc_hb_dir[] = {
97 {
98 .procname = "hb_interval",
99 .data = &xpc_hb_interval,
100 .maxlen = sizeof(int),
101 .mode = 0644,
102 .proc_handler = proc_dointvec_minmax,
103 .extra1 = &xpc_hb_min_interval,
104 .extra2 = &xpc_hb_max_interval},
105 {
106 .procname = "hb_check_interval",
107 .data = &xpc_hb_check_interval,
108 .maxlen = sizeof(int),
109 .mode = 0644,
110 .proc_handler = proc_dointvec_minmax,
111 .extra1 = &xpc_hb_check_min_interval,
112 .extra2 = &xpc_hb_check_max_interval},
113 {}
114};
115static struct ctl_table xpc_sys_xpc_dir[] = {
116 {
117 .procname = "hb",
118 .mode = 0555,
119 .child = xpc_sys_xpc_hb_dir},
120 {
121 .procname = "disengage_timelimit",
122 .data = &xpc_disengage_timelimit,
123 .maxlen = sizeof(int),
124 .mode = 0644,
125 .proc_handler = proc_dointvec_minmax,
126 .extra1 = &xpc_disengage_min_timelimit,
127 .extra2 = &xpc_disengage_max_timelimit},
128 {}
129};
130static struct ctl_table xpc_sys_dir[] = {
131 {
132 .procname = "xpc",
133 .mode = 0555,
134 .child = xpc_sys_xpc_dir},
135 {}
136};
137static struct ctl_table_header *xpc_sysctl;
138
139/* non-zero if any remote partition disengage was timed out */
140int xpc_disengage_timedout;
141
142/* #of activate IRQs received and not yet processed */
143int xpc_activate_IRQ_rcvd;
144DEFINE_SPINLOCK(xpc_activate_IRQ_rcvd_lock);
145
146/* IRQ handler notifies this wait queue on receipt of an IRQ */
147DECLARE_WAIT_QUEUE_HEAD(xpc_activate_IRQ_wq);
148
149static unsigned long xpc_hb_check_timeout;
150static struct timer_list xpc_hb_timer;
151
152/* notification that the xpc_hb_checker thread has exited */
153static DECLARE_COMPLETION(xpc_hb_checker_exited);
154
155/* notification that the xpc_discovery thread has exited */
156static DECLARE_COMPLETION(xpc_discovery_exited);
157
158static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
159
160static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
161static struct notifier_block xpc_reboot_notifier = {
162 .notifier_call = xpc_system_reboot,
163};
164
165static int xpc_system_die(struct notifier_block *, unsigned long, void *);
166static struct notifier_block xpc_die_notifier = {
167 .notifier_call = xpc_system_die,
168};
169
170struct xpc_arch_operations xpc_arch_ops;
171
172/*
173 * Timer function to enforce the timelimit on the partition disengage.
174 */
175static void
176xpc_timeout_partition_disengage(struct timer_list *t)
177{
178 struct xpc_partition *part = from_timer(part, t, disengage_timer);
179
180 DBUG_ON(time_is_after_jiffies(part->disengage_timeout));
181
182 xpc_partition_disengaged_from_timer(part);
183
184 DBUG_ON(part->disengage_timeout != 0);
185 DBUG_ON(xpc_arch_ops.partition_engaged(XPC_PARTID(part)));
186}
187
188/*
189 * Timer to produce the heartbeat. The timer structures function is
190 * already set when this is initially called. A tunable is used to
191 * specify when the next timeout should occur.
192 */
193static void
194xpc_hb_beater(struct timer_list *unused)
195{
196 xpc_arch_ops.increment_heartbeat();
197
198 if (time_is_before_eq_jiffies(xpc_hb_check_timeout))
199 wake_up_interruptible(&xpc_activate_IRQ_wq);
200
201 xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
202 add_timer(&xpc_hb_timer);
203}
204
205static void
206xpc_start_hb_beater(void)
207{
208 xpc_arch_ops.heartbeat_init();
209 timer_setup(&xpc_hb_timer, xpc_hb_beater, 0);
210 xpc_hb_beater(NULL);
211}
212
213static void
214xpc_stop_hb_beater(void)
215{
216 del_timer_sync(&xpc_hb_timer);
217 xpc_arch_ops.heartbeat_exit();
218}
219
220/*
221 * At periodic intervals, scan through all active partitions and ensure
222 * their heartbeat is still active. If not, the partition is deactivated.
223 */
224static void
225xpc_check_remote_hb(void)
226{
227 struct xpc_partition *part;
228 short partid;
229 enum xp_retval ret;
230
231 for (partid = 0; partid < xp_max_npartitions; partid++) {
232
233 if (xpc_exiting)
234 break;
235
236 if (partid == xp_partition_id)
237 continue;
238
239 part = &xpc_partitions[partid];
240
241 if (part->act_state == XPC_P_AS_INACTIVE ||
242 part->act_state == XPC_P_AS_DEACTIVATING) {
243 continue;
244 }
245
246 ret = xpc_arch_ops.get_remote_heartbeat(part);
247 if (ret != xpSuccess)
248 XPC_DEACTIVATE_PARTITION(part, ret);
249 }
250}
251
252/*
253 * This thread is responsible for nearly all of the partition
254 * activation/deactivation.
255 */
256static int
257xpc_hb_checker(void *ignore)
258{
259 int force_IRQ = 0;
260
261 /* this thread was marked active by xpc_hb_init() */
262
263 set_cpus_allowed_ptr(current, cpumask_of(XPC_HB_CHECK_CPU));
264
265 /* set our heartbeating to other partitions into motion */
266 xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
267 xpc_start_hb_beater();
268
269 while (!xpc_exiting) {
270
271 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
272 "been received\n",
273 (int)(xpc_hb_check_timeout - jiffies),
274 xpc_activate_IRQ_rcvd);
275
276 /* checking of remote heartbeats is skewed by IRQ handling */
277 if (time_is_before_eq_jiffies(xpc_hb_check_timeout)) {
278 xpc_hb_check_timeout = jiffies +
279 (xpc_hb_check_interval * HZ);
280
281 dev_dbg(xpc_part, "checking remote heartbeats\n");
282 xpc_check_remote_hb();
283 }
284
285 /* check for outstanding IRQs */
286 if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) {
287 force_IRQ = 0;
288 dev_dbg(xpc_part, "processing activate IRQs "
289 "received\n");
290 xpc_arch_ops.process_activate_IRQ_rcvd();
291 }
292
293 /* wait for IRQ or timeout */
294 (void)wait_event_interruptible(xpc_activate_IRQ_wq,
295 (time_is_before_eq_jiffies(
296 xpc_hb_check_timeout) ||
297 xpc_activate_IRQ_rcvd > 0 ||
298 xpc_exiting));
299 }
300
301 xpc_stop_hb_beater();
302
303 dev_dbg(xpc_part, "heartbeat checker is exiting\n");
304
305 /* mark this thread as having exited */
306 complete(&xpc_hb_checker_exited);
307 return 0;
308}
309
310/*
311 * This thread will attempt to discover other partitions to activate
312 * based on info provided by SAL. This new thread is short lived and
313 * will exit once discovery is complete.
314 */
315static int
316xpc_initiate_discovery(void *ignore)
317{
318 xpc_discovery();
319
320 dev_dbg(xpc_part, "discovery thread is exiting\n");
321
322 /* mark this thread as having exited */
323 complete(&xpc_discovery_exited);
324 return 0;
325}
326
327/*
328 * The first kthread assigned to a newly activated partition is the one
329 * created by XPC HB with which it calls xpc_activating(). XPC hangs on to
330 * that kthread until the partition is brought down, at which time that kthread
331 * returns back to XPC HB. (The return of that kthread will signify to XPC HB
332 * that XPC has dismantled all communication infrastructure for the associated
333 * partition.) This kthread becomes the channel manager for that partition.
334 *
335 * Each active partition has a channel manager, who, besides connecting and
336 * disconnecting channels, will ensure that each of the partition's connected
337 * channels has the required number of assigned kthreads to get the work done.
338 */
339static void
340xpc_channel_mgr(struct xpc_partition *part)
341{
342 while (part->act_state != XPC_P_AS_DEACTIVATING ||
343 atomic_read(&part->nchannels_active) > 0 ||
344 !xpc_partition_disengaged(part)) {
345
346 xpc_process_sent_chctl_flags(part);
347
348 /*
349 * Wait until we've been requested to activate kthreads or
350 * all of the channel's message queues have been torn down or
351 * a signal is pending.
352 *
353 * The channel_mgr_requests is set to 1 after being awakened,
354 * This is done to prevent the channel mgr from making one pass
355 * through the loop for each request, since he will
356 * be servicing all the requests in one pass. The reason it's
357 * set to 1 instead of 0 is so that other kthreads will know
358 * that the channel mgr is running and won't bother trying to
359 * wake him up.
360 */
361 atomic_dec(&part->channel_mgr_requests);
362 (void)wait_event_interruptible(part->channel_mgr_wq,
363 (atomic_read(&part->channel_mgr_requests) > 0 ||
364 part->chctl.all_flags != 0 ||
365 (part->act_state == XPC_P_AS_DEACTIVATING &&
366 atomic_read(&part->nchannels_active) == 0 &&
367 xpc_partition_disengaged(part))));
368 atomic_set(&part->channel_mgr_requests, 1);
369 }
370}
371
372/*
373 * Guarantee that the kzalloc'd memory is cacheline aligned.
374 */
375void *
376xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
377{
378 /* see if kzalloc will give us cachline aligned memory by default */
379 *base = kzalloc(size, flags);
380 if (*base == NULL)
381 return NULL;
382
383 if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
384 return *base;
385
386 kfree(*base);
387
388 /* nope, we'll have to do it ourselves */
389 *base = kzalloc(size + L1_CACHE_BYTES, flags);
390 if (*base == NULL)
391 return NULL;
392
393 return (void *)L1_CACHE_ALIGN((u64)*base);
394}
395
396/*
397 * Setup the channel structures necessary to support XPartition Communication
398 * between the specified remote partition and the local one.
399 */
400static enum xp_retval
401xpc_setup_ch_structures(struct xpc_partition *part)
402{
403 enum xp_retval ret;
404 int ch_number;
405 struct xpc_channel *ch;
406 short partid = XPC_PARTID(part);
407
408 /*
409 * Allocate all of the channel structures as a contiguous chunk of
410 * memory.
411 */
412 DBUG_ON(part->channels != NULL);
413 part->channels = kcalloc(XPC_MAX_NCHANNELS,
414 sizeof(struct xpc_channel),
415 GFP_KERNEL);
416 if (part->channels == NULL) {
417 dev_err(xpc_chan, "can't get memory for channels\n");
418 return xpNoMemory;
419 }
420
421 /* allocate the remote open and close args */
422
423 part->remote_openclose_args =
424 xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
425 GFP_KERNEL, &part->
426 remote_openclose_args_base);
427 if (part->remote_openclose_args == NULL) {
428 dev_err(xpc_chan, "can't get memory for remote connect args\n");
429 ret = xpNoMemory;
430 goto out_1;
431 }
432
433 part->chctl.all_flags = 0;
434 spin_lock_init(&part->chctl_lock);
435
436 atomic_set(&part->channel_mgr_requests, 1);
437 init_waitqueue_head(&part->channel_mgr_wq);
438
439 part->nchannels = XPC_MAX_NCHANNELS;
440
441 atomic_set(&part->nchannels_active, 0);
442 atomic_set(&part->nchannels_engaged, 0);
443
444 for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
445 ch = &part->channels[ch_number];
446
447 ch->partid = partid;
448 ch->number = ch_number;
449 ch->flags = XPC_C_DISCONNECTED;
450
451 atomic_set(&ch->kthreads_assigned, 0);
452 atomic_set(&ch->kthreads_idle, 0);
453 atomic_set(&ch->kthreads_active, 0);
454
455 atomic_set(&ch->references, 0);
456 atomic_set(&ch->n_to_notify, 0);
457
458 spin_lock_init(&ch->lock);
459 init_completion(&ch->wdisconnect_wait);
460
461 atomic_set(&ch->n_on_msg_allocate_wq, 0);
462 init_waitqueue_head(&ch->msg_allocate_wq);
463 init_waitqueue_head(&ch->idle_wq);
464 }
465
466 ret = xpc_arch_ops.setup_ch_structures(part);
467 if (ret != xpSuccess)
468 goto out_2;
469
470 /*
471 * With the setting of the partition setup_state to XPC_P_SS_SETUP,
472 * we're declaring that this partition is ready to go.
473 */
474 part->setup_state = XPC_P_SS_SETUP;
475
476 return xpSuccess;
477
478 /* setup of ch structures failed */
479out_2:
480 kfree(part->remote_openclose_args_base);
481 part->remote_openclose_args = NULL;
482out_1:
483 kfree(part->channels);
484 part->channels = NULL;
485 return ret;
486}
487
488/*
489 * Teardown the channel structures necessary to support XPartition Communication
490 * between the specified remote partition and the local one.
491 */
492static void
493xpc_teardown_ch_structures(struct xpc_partition *part)
494{
495 DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
496 DBUG_ON(atomic_read(&part->nchannels_active) != 0);
497
498 /*
499 * Make this partition inaccessible to local processes by marking it
500 * as no longer setup. Then wait before proceeding with the teardown
501 * until all existing references cease.
502 */
503 DBUG_ON(part->setup_state != XPC_P_SS_SETUP);
504 part->setup_state = XPC_P_SS_WTEARDOWN;
505
506 wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
507
508 /* now we can begin tearing down the infrastructure */
509
510 xpc_arch_ops.teardown_ch_structures(part);
511
512 kfree(part->remote_openclose_args_base);
513 part->remote_openclose_args = NULL;
514 kfree(part->channels);
515 part->channels = NULL;
516
517 part->setup_state = XPC_P_SS_TORNDOWN;
518}
519
520/*
521 * When XPC HB determines that a partition has come up, it will create a new
522 * kthread and that kthread will call this function to attempt to set up the
523 * basic infrastructure used for Cross Partition Communication with the newly
524 * upped partition.
525 *
526 * The kthread that was created by XPC HB and which setup the XPC
527 * infrastructure will remain assigned to the partition becoming the channel
528 * manager for that partition until the partition is deactivating, at which
529 * time the kthread will teardown the XPC infrastructure and then exit.
530 */
531static int
532xpc_activating(void *__partid)
533{
534 short partid = (u64)__partid;
535 struct xpc_partition *part = &xpc_partitions[partid];
536 unsigned long irq_flags;
537
538 DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
539
540 spin_lock_irqsave(&part->act_lock, irq_flags);
541
542 if (part->act_state == XPC_P_AS_DEACTIVATING) {
543 part->act_state = XPC_P_AS_INACTIVE;
544 spin_unlock_irqrestore(&part->act_lock, irq_flags);
545 part->remote_rp_pa = 0;
546 return 0;
547 }
548
549 /* indicate the thread is activating */
550 DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ);
551 part->act_state = XPC_P_AS_ACTIVATING;
552
553 XPC_SET_REASON(part, 0, 0);
554 spin_unlock_irqrestore(&part->act_lock, irq_flags);
555
556 dev_dbg(xpc_part, "activating partition %d\n", partid);
557
558 xpc_arch_ops.allow_hb(partid);
559
560 if (xpc_setup_ch_structures(part) == xpSuccess) {
561 (void)xpc_part_ref(part); /* this will always succeed */
562
563 if (xpc_arch_ops.make_first_contact(part) == xpSuccess) {
564 xpc_mark_partition_active(part);
565 xpc_channel_mgr(part);
566 /* won't return until partition is deactivating */
567 }
568
569 xpc_part_deref(part);
570 xpc_teardown_ch_structures(part);
571 }
572
573 xpc_arch_ops.disallow_hb(partid);
574 xpc_mark_partition_inactive(part);
575
576 if (part->reason == xpReactivating) {
577 /* interrupting ourselves results in activating partition */
578 xpc_arch_ops.request_partition_reactivation(part);
579 }
580
581 return 0;
582}
583
584void
585xpc_activate_partition(struct xpc_partition *part)
586{
587 short partid = XPC_PARTID(part);
588 unsigned long irq_flags;
589 struct task_struct *kthread;
590
591 spin_lock_irqsave(&part->act_lock, irq_flags);
592
593 DBUG_ON(part->act_state != XPC_P_AS_INACTIVE);
594
595 part->act_state = XPC_P_AS_ACTIVATION_REQ;
596 XPC_SET_REASON(part, xpCloneKThread, __LINE__);
597
598 spin_unlock_irqrestore(&part->act_lock, irq_flags);
599
600 kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
601 partid);
602 if (IS_ERR(kthread)) {
603 spin_lock_irqsave(&part->act_lock, irq_flags);
604 part->act_state = XPC_P_AS_INACTIVE;
605 XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
606 spin_unlock_irqrestore(&part->act_lock, irq_flags);
607 }
608}
609
610void
611xpc_activate_kthreads(struct xpc_channel *ch, int needed)
612{
613 int idle = atomic_read(&ch->kthreads_idle);
614 int assigned = atomic_read(&ch->kthreads_assigned);
615 int wakeup;
616
617 DBUG_ON(needed <= 0);
618
619 if (idle > 0) {
620 wakeup = (needed > idle) ? idle : needed;
621 needed -= wakeup;
622
623 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
624 "channel=%d\n", wakeup, ch->partid, ch->number);
625
626 /* only wakeup the requested number of kthreads */
627 wake_up_nr(&ch->idle_wq, wakeup);
628 }
629
630 if (needed <= 0)
631 return;
632
633 if (needed + assigned > ch->kthreads_assigned_limit) {
634 needed = ch->kthreads_assigned_limit - assigned;
635 if (needed <= 0)
636 return;
637 }
638
639 dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
640 needed, ch->partid, ch->number);
641
642 xpc_create_kthreads(ch, needed, 0);
643}
644
645/*
646 * This function is where XPC's kthreads wait for messages to deliver.
647 */
648static void
649xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
650{
651 int (*n_of_deliverable_payloads) (struct xpc_channel *) =
652 xpc_arch_ops.n_of_deliverable_payloads;
653
654 do {
655 /* deliver messages to their intended recipients */
656
657 while (n_of_deliverable_payloads(ch) > 0 &&
658 !(ch->flags & XPC_C_DISCONNECTING)) {
659 xpc_deliver_payload(ch);
660 }
661
662 if (atomic_inc_return(&ch->kthreads_idle) >
663 ch->kthreads_idle_limit) {
664 /* too many idle kthreads on this channel */
665 atomic_dec(&ch->kthreads_idle);
666 break;
667 }
668
669 dev_dbg(xpc_chan, "idle kthread calling "
670 "wait_event_interruptible_exclusive()\n");
671
672 (void)wait_event_interruptible_exclusive(ch->idle_wq,
673 (n_of_deliverable_payloads(ch) > 0 ||
674 (ch->flags & XPC_C_DISCONNECTING)));
675
676 atomic_dec(&ch->kthreads_idle);
677
678 } while (!(ch->flags & XPC_C_DISCONNECTING));
679}
680
681static int
682xpc_kthread_start(void *args)
683{
684 short partid = XPC_UNPACK_ARG1(args);
685 u16 ch_number = XPC_UNPACK_ARG2(args);
686 struct xpc_partition *part = &xpc_partitions[partid];
687 struct xpc_channel *ch;
688 int n_needed;
689 unsigned long irq_flags;
690 int (*n_of_deliverable_payloads) (struct xpc_channel *) =
691 xpc_arch_ops.n_of_deliverable_payloads;
692
693 dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
694 partid, ch_number);
695
696 ch = &part->channels[ch_number];
697
698 if (!(ch->flags & XPC_C_DISCONNECTING)) {
699
700 /* let registerer know that connection has been established */
701
702 spin_lock_irqsave(&ch->lock, irq_flags);
703 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
704 ch->flags |= XPC_C_CONNECTEDCALLOUT;
705 spin_unlock_irqrestore(&ch->lock, irq_flags);
706
707 xpc_connected_callout(ch);
708
709 spin_lock_irqsave(&ch->lock, irq_flags);
710 ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
711 spin_unlock_irqrestore(&ch->lock, irq_flags);
712
713 /*
714 * It is possible that while the callout was being
715 * made that the remote partition sent some messages.
716 * If that is the case, we may need to activate
717 * additional kthreads to help deliver them. We only
718 * need one less than total #of messages to deliver.
719 */
720 n_needed = n_of_deliverable_payloads(ch) - 1;
721 if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
722 xpc_activate_kthreads(ch, n_needed);
723
724 } else {
725 spin_unlock_irqrestore(&ch->lock, irq_flags);
726 }
727
728 xpc_kthread_waitmsgs(part, ch);
729 }
730
731 /* let registerer know that connection is disconnecting */
732
733 spin_lock_irqsave(&ch->lock, irq_flags);
734 if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
735 !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
736 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
737 spin_unlock_irqrestore(&ch->lock, irq_flags);
738
739 xpc_disconnect_callout(ch, xpDisconnecting);
740
741 spin_lock_irqsave(&ch->lock, irq_flags);
742 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
743 }
744 spin_unlock_irqrestore(&ch->lock, irq_flags);
745
746 if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
747 atomic_dec_return(&part->nchannels_engaged) == 0) {
748 xpc_arch_ops.indicate_partition_disengaged(part);
749 }
750
751 xpc_msgqueue_deref(ch);
752
753 dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
754 partid, ch_number);
755
756 xpc_part_deref(part);
757 return 0;
758}
759
760/*
761 * For each partition that XPC has established communications with, there is
762 * a minimum of one kernel thread assigned to perform any operation that
763 * may potentially sleep or block (basically the callouts to the asynchronous
764 * functions registered via xpc_connect()).
765 *
766 * Additional kthreads are created and destroyed by XPC as the workload
767 * demands.
768 *
769 * A kthread is assigned to one of the active channels that exists for a given
770 * partition.
771 */
772void
773xpc_create_kthreads(struct xpc_channel *ch, int needed,
774 int ignore_disconnecting)
775{
776 unsigned long irq_flags;
777 u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
778 struct xpc_partition *part = &xpc_partitions[ch->partid];
779 struct task_struct *kthread;
780 void (*indicate_partition_disengaged) (struct xpc_partition *) =
781 xpc_arch_ops.indicate_partition_disengaged;
782
783 while (needed-- > 0) {
784
785 /*
786 * The following is done on behalf of the newly created
787 * kthread. That kthread is responsible for doing the
788 * counterpart to the following before it exits.
789 */
790 if (ignore_disconnecting) {
791 if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
792 /* kthreads assigned had gone to zero */
793 BUG_ON(!(ch->flags &
794 XPC_C_DISCONNECTINGCALLOUT_MADE));
795 break;
796 }
797
798 } else if (ch->flags & XPC_C_DISCONNECTING) {
799 break;
800
801 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
802 atomic_inc_return(&part->nchannels_engaged) == 1) {
803 xpc_arch_ops.indicate_partition_engaged(part);
804 }
805 (void)xpc_part_ref(part);
806 xpc_msgqueue_ref(ch);
807
808 kthread = kthread_run(xpc_kthread_start, (void *)args,
809 "xpc%02dc%d", ch->partid, ch->number);
810 if (IS_ERR(kthread)) {
811 /* the fork failed */
812
813 /*
814 * NOTE: if (ignore_disconnecting &&
815 * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
816 * then we'll deadlock if all other kthreads assigned
817 * to this channel are blocked in the channel's
818 * registerer, because the only thing that will unblock
819 * them is the xpDisconnecting callout that this
820 * failed kthread_run() would have made.
821 */
822
823 if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
824 atomic_dec_return(&part->nchannels_engaged) == 0) {
825 indicate_partition_disengaged(part);
826 }
827 xpc_msgqueue_deref(ch);
828 xpc_part_deref(part);
829
830 if (atomic_read(&ch->kthreads_assigned) <
831 ch->kthreads_idle_limit) {
832 /*
833 * Flag this as an error only if we have an
834 * insufficient #of kthreads for the channel
835 * to function.
836 */
837 spin_lock_irqsave(&ch->lock, irq_flags);
838 XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
839 &irq_flags);
840 spin_unlock_irqrestore(&ch->lock, irq_flags);
841 }
842 break;
843 }
844 }
845}
846
847void
848xpc_disconnect_wait(int ch_number)
849{
850 unsigned long irq_flags;
851 short partid;
852 struct xpc_partition *part;
853 struct xpc_channel *ch;
854 int wakeup_channel_mgr;
855
856 /* now wait for all callouts to the caller's function to cease */
857 for (partid = 0; partid < xp_max_npartitions; partid++) {
858 part = &xpc_partitions[partid];
859
860 if (!xpc_part_ref(part))
861 continue;
862
863 ch = &part->channels[ch_number];
864
865 if (!(ch->flags & XPC_C_WDISCONNECT)) {
866 xpc_part_deref(part);
867 continue;
868 }
869
870 wait_for_completion(&ch->wdisconnect_wait);
871
872 spin_lock_irqsave(&ch->lock, irq_flags);
873 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
874 wakeup_channel_mgr = 0;
875
876 if (ch->delayed_chctl_flags) {
877 if (part->act_state != XPC_P_AS_DEACTIVATING) {
878 spin_lock(&part->chctl_lock);
879 part->chctl.flags[ch->number] |=
880 ch->delayed_chctl_flags;
881 spin_unlock(&part->chctl_lock);
882 wakeup_channel_mgr = 1;
883 }
884 ch->delayed_chctl_flags = 0;
885 }
886
887 ch->flags &= ~XPC_C_WDISCONNECT;
888 spin_unlock_irqrestore(&ch->lock, irq_flags);
889
890 if (wakeup_channel_mgr)
891 xpc_wakeup_channel_mgr(part);
892
893 xpc_part_deref(part);
894 }
895}
896
897static int
898xpc_setup_partitions(void)
899{
900 short partid;
901 struct xpc_partition *part;
902
903 xpc_partitions = kcalloc(xp_max_npartitions,
904 sizeof(struct xpc_partition),
905 GFP_KERNEL);
906 if (xpc_partitions == NULL) {
907 dev_err(xpc_part, "can't get memory for partition structure\n");
908 return -ENOMEM;
909 }
910
911 /*
912 * The first few fields of each entry of xpc_partitions[] need to
913 * be initialized now so that calls to xpc_connect() and
914 * xpc_disconnect() can be made prior to the activation of any remote
915 * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
916 * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
917 * PARTITION HAS BEEN ACTIVATED.
918 */
919 for (partid = 0; partid < xp_max_npartitions; partid++) {
920 part = &xpc_partitions[partid];
921
922 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
923
924 part->activate_IRQ_rcvd = 0;
925 spin_lock_init(&part->act_lock);
926 part->act_state = XPC_P_AS_INACTIVE;
927 XPC_SET_REASON(part, 0, 0);
928
929 timer_setup(&part->disengage_timer,
930 xpc_timeout_partition_disengage, 0);
931
932 part->setup_state = XPC_P_SS_UNSET;
933 init_waitqueue_head(&part->teardown_wq);
934 atomic_set(&part->references, 0);
935 }
936
937 return xpc_arch_ops.setup_partitions();
938}
939
940static void
941xpc_teardown_partitions(void)
942{
943 xpc_arch_ops.teardown_partitions();
944 kfree(xpc_partitions);
945}
946
947static void
948xpc_do_exit(enum xp_retval reason)
949{
950 short partid;
951 int active_part_count, printed_waiting_msg = 0;
952 struct xpc_partition *part;
953 unsigned long printmsg_time, disengage_timeout = 0;
954
955 /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
956 DBUG_ON(xpc_exiting == 1);
957
958 /*
959 * Let the heartbeat checker thread and the discovery thread
960 * (if one is running) know that they should exit. Also wake up
961 * the heartbeat checker thread in case it's sleeping.
962 */
963 xpc_exiting = 1;
964 wake_up_interruptible(&xpc_activate_IRQ_wq);
965
966 /* wait for the discovery thread to exit */
967 wait_for_completion(&xpc_discovery_exited);
968
969 /* wait for the heartbeat checker thread to exit */
970 wait_for_completion(&xpc_hb_checker_exited);
971
972 /* sleep for a 1/3 of a second or so */
973 (void)msleep_interruptible(300);
974
975 /* wait for all partitions to become inactive */
976
977 printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
978 xpc_disengage_timedout = 0;
979
980 do {
981 active_part_count = 0;
982
983 for (partid = 0; partid < xp_max_npartitions; partid++) {
984 part = &xpc_partitions[partid];
985
986 if (xpc_partition_disengaged(part) &&
987 part->act_state == XPC_P_AS_INACTIVE) {
988 continue;
989 }
990
991 active_part_count++;
992
993 XPC_DEACTIVATE_PARTITION(part, reason);
994
995 if (part->disengage_timeout > disengage_timeout)
996 disengage_timeout = part->disengage_timeout;
997 }
998
999 if (xpc_arch_ops.any_partition_engaged()) {
1000 if (time_is_before_jiffies(printmsg_time)) {
1001 dev_info(xpc_part, "waiting for remote "
1002 "partitions to deactivate, timeout in "
1003 "%ld seconds\n", (disengage_timeout -
1004 jiffies) / HZ);
1005 printmsg_time = jiffies +
1006 (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1007 printed_waiting_msg = 1;
1008 }
1009
1010 } else if (active_part_count > 0) {
1011 if (printed_waiting_msg) {
1012 dev_info(xpc_part, "waiting for local partition"
1013 " to deactivate\n");
1014 printed_waiting_msg = 0;
1015 }
1016
1017 } else {
1018 if (!xpc_disengage_timedout) {
1019 dev_info(xpc_part, "all partitions have "
1020 "deactivated\n");
1021 }
1022 break;
1023 }
1024
1025 /* sleep for a 1/3 of a second or so */
1026 (void)msleep_interruptible(300);
1027
1028 } while (1);
1029
1030 DBUG_ON(xpc_arch_ops.any_partition_engaged());
1031
1032 xpc_teardown_rsvd_page();
1033
1034 if (reason == xpUnloading) {
1035 (void)unregister_die_notifier(&xpc_die_notifier);
1036 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1037 }
1038
1039 /* clear the interface to XPC's functions */
1040 xpc_clear_interface();
1041
1042 if (xpc_sysctl)
1043 unregister_sysctl_table(xpc_sysctl);
1044
1045 xpc_teardown_partitions();
1046
1047 if (is_uv_system())
1048 xpc_exit_uv();
1049}
1050
1051/*
1052 * This function is called when the system is being rebooted.
1053 */
1054static int
1055xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1056{
1057 enum xp_retval reason;
1058
1059 switch (event) {
1060 case SYS_RESTART:
1061 reason = xpSystemReboot;
1062 break;
1063 case SYS_HALT:
1064 reason = xpSystemHalt;
1065 break;
1066 case SYS_POWER_OFF:
1067 reason = xpSystemPoweroff;
1068 break;
1069 default:
1070 reason = xpSystemGoingDown;
1071 }
1072
1073 xpc_do_exit(reason);
1074 return NOTIFY_DONE;
1075}
1076
1077/* Used to only allow one cpu to complete disconnect */
1078static unsigned int xpc_die_disconnecting;
1079
1080/*
1081 * Notify other partitions to deactivate from us by first disengaging from all
1082 * references to our memory.
1083 */
1084static void
1085xpc_die_deactivate(void)
1086{
1087 struct xpc_partition *part;
1088 short partid;
1089 int any_engaged;
1090 long keep_waiting;
1091 long wait_to_print;
1092
1093 if (cmpxchg(&xpc_die_disconnecting, 0, 1))
1094 return;
1095
1096 /* keep xpc_hb_checker thread from doing anything (just in case) */
1097 xpc_exiting = 1;
1098
1099 xpc_arch_ops.disallow_all_hbs(); /*indicate we're deactivated */
1100
1101 for (partid = 0; partid < xp_max_npartitions; partid++) {
1102 part = &xpc_partitions[partid];
1103
1104 if (xpc_arch_ops.partition_engaged(partid) ||
1105 part->act_state != XPC_P_AS_INACTIVE) {
1106 xpc_arch_ops.request_partition_deactivation(part);
1107 xpc_arch_ops.indicate_partition_disengaged(part);
1108 }
1109 }
1110
1111 /*
1112 * Though we requested that all other partitions deactivate from us,
1113 * we only wait until they've all disengaged or we've reached the
1114 * defined timelimit.
1115 *
1116 * Given that one iteration through the following while-loop takes
1117 * approximately 200 microseconds, calculate the #of loops to take
1118 * before bailing and the #of loops before printing a waiting message.
1119 */
1120 keep_waiting = xpc_disengage_timelimit * 1000 * 5;
1121 wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5;
1122
1123 while (1) {
1124 any_engaged = xpc_arch_ops.any_partition_engaged();
1125 if (!any_engaged) {
1126 dev_info(xpc_part, "all partitions have deactivated\n");
1127 break;
1128 }
1129
1130 if (!keep_waiting--) {
1131 for (partid = 0; partid < xp_max_npartitions;
1132 partid++) {
1133 if (xpc_arch_ops.partition_engaged(partid)) {
1134 dev_info(xpc_part, "deactivate from "
1135 "remote partition %d timed "
1136 "out\n", partid);
1137 }
1138 }
1139 break;
1140 }
1141
1142 if (!wait_to_print--) {
1143 dev_info(xpc_part, "waiting for remote partitions to "
1144 "deactivate, timeout in %ld seconds\n",
1145 keep_waiting / (1000 * 5));
1146 wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL *
1147 1000 * 5;
1148 }
1149
1150 udelay(200);
1151 }
1152}
1153
1154/*
1155 * This function is called when the system is being restarted or halted due
1156 * to some sort of system failure. If this is the case we need to notify the
1157 * other partitions to disengage from all references to our memory.
1158 * This function can also be called when our heartbeater could be offlined
1159 * for a time. In this case we need to notify other partitions to not worry
1160 * about the lack of a heartbeat.
1161 */
1162static int
1163xpc_system_die(struct notifier_block *nb, unsigned long event, void *_die_args)
1164{
1165#ifdef CONFIG_IA64 /* !!! temporary kludge */
1166 switch (event) {
1167 case DIE_MACHINE_RESTART:
1168 case DIE_MACHINE_HALT:
1169 xpc_die_deactivate();
1170 break;
1171
1172 case DIE_KDEBUG_ENTER:
1173 /* Should lack of heartbeat be ignored by other partitions? */
1174 if (!xpc_kdebug_ignore)
1175 break;
1176
1177 fallthrough;
1178 case DIE_MCA_MONARCH_ENTER:
1179 case DIE_INIT_MONARCH_ENTER:
1180 xpc_arch_ops.offline_heartbeat();
1181 break;
1182
1183 case DIE_KDEBUG_LEAVE:
1184 /* Is lack of heartbeat being ignored by other partitions? */
1185 if (!xpc_kdebug_ignore)
1186 break;
1187
1188 fallthrough;
1189 case DIE_MCA_MONARCH_LEAVE:
1190 case DIE_INIT_MONARCH_LEAVE:
1191 xpc_arch_ops.online_heartbeat();
1192 break;
1193 }
1194#else
1195 struct die_args *die_args = _die_args;
1196
1197 switch (event) {
1198 case DIE_TRAP:
1199 if (die_args->trapnr == X86_TRAP_DF)
1200 xpc_die_deactivate();
1201
1202 if (((die_args->trapnr == X86_TRAP_MF) ||
1203 (die_args->trapnr == X86_TRAP_XF)) &&
1204 !user_mode(die_args->regs))
1205 xpc_die_deactivate();
1206
1207 break;
1208 case DIE_INT3:
1209 case DIE_DEBUG:
1210 break;
1211 case DIE_OOPS:
1212 case DIE_GPF:
1213 default:
1214 xpc_die_deactivate();
1215 }
1216#endif
1217
1218 return NOTIFY_DONE;
1219}
1220
1221static int __init
1222xpc_init(void)
1223{
1224 int ret;
1225 struct task_struct *kthread;
1226
1227 dev_set_name(xpc_part, "part");
1228 dev_set_name(xpc_chan, "chan");
1229
1230 if (is_uv_system()) {
1231 ret = xpc_init_uv();
1232
1233 } else {
1234 ret = -ENODEV;
1235 }
1236
1237 if (ret != 0)
1238 return ret;
1239
1240 ret = xpc_setup_partitions();
1241 if (ret != 0) {
1242 dev_err(xpc_part, "can't get memory for partition structure\n");
1243 goto out_1;
1244 }
1245
1246 xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1247
1248 /*
1249 * Fill the partition reserved page with the information needed by
1250 * other partitions to discover we are alive and establish initial
1251 * communications.
1252 */
1253 ret = xpc_setup_rsvd_page();
1254 if (ret != 0) {
1255 dev_err(xpc_part, "can't setup our reserved page\n");
1256 goto out_2;
1257 }
1258
1259 /* add ourselves to the reboot_notifier_list */
1260 ret = register_reboot_notifier(&xpc_reboot_notifier);
1261 if (ret != 0)
1262 dev_warn(xpc_part, "can't register reboot notifier\n");
1263
1264 /* add ourselves to the die_notifier list */
1265 ret = register_die_notifier(&xpc_die_notifier);
1266 if (ret != 0)
1267 dev_warn(xpc_part, "can't register die notifier\n");
1268
1269 /*
1270 * The real work-horse behind xpc. This processes incoming
1271 * interrupts and monitors remote heartbeats.
1272 */
1273 kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1274 if (IS_ERR(kthread)) {
1275 dev_err(xpc_part, "failed while forking hb check thread\n");
1276 ret = -EBUSY;
1277 goto out_3;
1278 }
1279
1280 /*
1281 * Startup a thread that will attempt to discover other partitions to
1282 * activate based on info provided by SAL. This new thread is short
1283 * lived and will exit once discovery is complete.
1284 */
1285 kthread = kthread_run(xpc_initiate_discovery, NULL,
1286 XPC_DISCOVERY_THREAD_NAME);
1287 if (IS_ERR(kthread)) {
1288 dev_err(xpc_part, "failed while forking discovery thread\n");
1289
1290 /* mark this new thread as a non-starter */
1291 complete(&xpc_discovery_exited);
1292
1293 xpc_do_exit(xpUnloading);
1294 return -EBUSY;
1295 }
1296
1297 /* set the interface to point at XPC's functions */
1298 xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1299 xpc_initiate_send, xpc_initiate_send_notify,
1300 xpc_initiate_received, xpc_initiate_partid_to_nasids);
1301
1302 return 0;
1303
1304 /* initialization was not successful */
1305out_3:
1306 xpc_teardown_rsvd_page();
1307
1308 (void)unregister_die_notifier(&xpc_die_notifier);
1309 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1310out_2:
1311 if (xpc_sysctl)
1312 unregister_sysctl_table(xpc_sysctl);
1313
1314 xpc_teardown_partitions();
1315out_1:
1316 if (is_uv_system())
1317 xpc_exit_uv();
1318 return ret;
1319}
1320
1321module_init(xpc_init);
1322
1323static void __exit
1324xpc_exit(void)
1325{
1326 xpc_do_exit(xpUnloading);
1327}
1328
1329module_exit(xpc_exit);
1330
1331MODULE_AUTHOR("Silicon Graphics, Inc.");
1332MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1333MODULE_LICENSE("GPL");
1334
1335module_param(xpc_hb_interval, int, 0);
1336MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1337 "heartbeat increments.");
1338
1339module_param(xpc_hb_check_interval, int, 0);
1340MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1341 "heartbeat checks.");
1342
1343module_param(xpc_disengage_timelimit, int, 0);
1344MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait "
1345 "for disengage to complete.");
1346
1347module_param(xpc_kdebug_ignore, int, 0);
1348MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1349 "other partitions when dropping into kdebug.");