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1/*2 * This file is subject to the terms and conditions of the GNU General Public3 * License. See the file "COPYING" in the main directory of this archive4 * for more details.5 *6 * (C) Copyright 2020 Hewlett Packard Enterprise Development LP7 * 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 partition14 * boundaries. This module is made up of two parts:15 *16 * partition This part detects the presence/absence of other17 * partitions. It provides a heartbeat and monitors18 * the heartbeats of other partitions.19 *20 * channel This part manages the channels and sends/receives21 * messages across them to/from other partitions.22 *23 * There are a couple of additional functions residing in XP, which24 * 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 IRQ30 * came from. Thus, xpc_send_IRQ_sn2() does a remote amo write31 * followed by an IPI. The amo indicates where data is to be pulled32 * from, so after the IPI arrives, the remote partition checks the amo33 * word. The IPI can actually arrive before the amo however, so other34 * code must periodically check for this case. Also, remote amo35 * operations do not reliably time out. Thus we do a remote PIO read36 * solely to know whether the remote partition is down and whether we37 * should stop sending IPIs to it. This remote PIO read operation is38 * set up in a special nofault region so SAL knows to ignore (and39 * cleanup) any errors due to the remote amo write, PIO read, and/or40 * PIO write operations.41 *42 * If/when new hardware solves this IPI problem, we should abandon43 * 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_6458#include <asm/traps.h>59#endif60 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_name70};71 72static struct device xpc_chan_dbg_subname = {73 .init_name = "", /* set to "chan" at xpc_init() time */74 .driver = &xpc_dbg_name75};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 void165xpc_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 is179 * already set when this is initially called. A tunable is used to180 * specify when the next timeout should occur.181 */182static void183xpc_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 void195xpc_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 void203xpc_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 ensure211 * their heartbeat is still active. If not, the partition is deactivated.212 */213static void214xpc_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 partition243 * activation/deactivation.244 */245static int246xpc_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 activate301 * based on info provided by SAL. This new thread is short lived and302 * will exit once discovery is complete.303 */304static int305xpc_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 one318 * created by XPC HB with which it calls xpc_activating(). XPC hangs on to319 * that kthread until the partition is brought down, at which time that kthread320 * returns back to XPC HB. (The return of that kthread will signify to XPC HB321 * that XPC has dismantled all communication infrastructure for the associated322 * partition.) This kthread becomes the channel manager for that partition.323 *324 * Each active partition has a channel manager, who, besides connecting and325 * disconnecting channels, will ensure that each of the partition's connected326 * channels has the required number of assigned kthreads to get the work done.327 */328static void329xpc_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 or339 * all of the channel's message queues have been torn down or340 * 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 pass344 * through the loop for each request, since he will345 * be servicing all the requests in one pass. The reason it's346 * set to 1 instead of 0 is so that other kthreads will know347 * that the channel mgr is running and won't bother trying to348 * 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 Communication387 * between the specified remote partition and the local one.388 */389static enum xp_retval390xpc_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 of399 * 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 Communication479 * between the specified remote partition and the local one.480 */481static void482xpc_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 it489 * as no longer setup. Then wait before proceeding with the teardown490 * 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 new511 * kthread and that kthread will call this function to attempt to set up the512 * basic infrastructure used for Cross Partition Communication with the newly513 * upped partition.514 *515 * The kthread that was created by XPC HB and which setup the XPC516 * infrastructure will remain assigned to the partition becoming the channel517 * manager for that partition until the partition is deactivating, at which518 * time the kthread will teardown the XPC infrastructure and then exit.519 */520static int521xpc_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 573void574xpc_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 599void600xpc_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 void638xpc_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 int671xpc_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 being704 * made that the remote partition sent some messages.705 * If that is the case, we may need to activate706 * additional kthreads to help deliver them. We only707 * 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 is751 * a minimum of one kernel thread assigned to perform any operation that752 * may potentially sleep or block (basically the callouts to the asynchronous753 * functions registered via xpc_connect()).754 *755 * Additional kthreads are created and destroyed by XPC as the workload756 * demands.757 *758 * A kthread is assigned to one of the active channels that exists for a given759 * partition.760 */761void762xpc_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 created776 * kthread. That kthread is responsible for doing the777 * 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 assigned806 * to this channel are blocked in the channel's807 * registerer, because the only thing that will unblock808 * them is the xpDisconnecting callout that this809 * 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 an823 * insufficient #of kthreads for the channel824 * 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 836void837xpc_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 int887xpc_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 to902 * be initialized now so that calls to xpc_connect() and903 * xpc_disconnect() can be made prior to the activation of any remote904 * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE905 * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING906 * 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 void930xpc_teardown_partitions(void)931{932 xpc_arch_ops.teardown_partitions();933 kfree(xpc_partitions);934}935 936static void937xpc_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 thread949 * (if one is running) know that they should exit. Also wake up950 * 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 int1046xpc_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 all1073 * references to our memory.1074 */1075static void1076xpc_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 the1105 * defined timelimit.1106 *1107 * Given that one iteration through the following while-loop takes1108 * approximately 200 microseconds, calculate the #of loops to take1109 * 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 due1147 * to some sort of system failure. If this is the case we need to notify the1148 * other partitions to disengage from all references to our memory.1149 * This function can also be called when our heartbeater could be offlined1150 * for a time. In this case we need to notify other partitions to not worry1151 * about the lack of a heartbeat.1152 */1153static int1154xpc_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 __init1182xpc_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 by1211 * other partitions to discover we are alive and establish initial1212 * 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 incoming1232 * 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 to1243 * activate based on info provided by SAL. This new thread is short1244 * 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 __exit1287xpc_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.");1313