arch/powerpc/platforms/pseries/cmm.c

   1 /*
   2  * Collaborative memory management interface.
   3  *
   4  * Copyright (C) 2008 IBM Corporation
   5  * Author(s): Brian King (brking@linux.vnet.ibm.com),
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  *
  21  */
  22
  23 #include <linux/ctype.h>
  24 #include <linux/delay.h>
  25 #include <linux/errno.h>
  26 #include <linux/fs.h>
  27 #include <linux/gfp.h>
  28 #include <linux/kthread.h>
  29 #include <linux/module.h>
  30 #include <linux/oom.h>
  31 #include <linux/reboot.h>
  32 #include <linux/sched.h>
  33 #include <linux/stringify.h>
  34 #include <linux/swap.h>
  35 #include <linux/device.h>
  36 #include <asm/firmware.h>
  37 #include <asm/hvcall.h>
  38 #include <asm/mmu.h>
  39 #include <asm/pgalloc.h>
  40 #include <linux/uaccess.h>
  41 #include <linux/memory.h>
  42 #include <asm/plpar_wrappers.h>
  43
  44 #include "pseries.h"
  45
  46 #define CMM_DRIVER_VERSION      "1.0.0"
  47 #define CMM_DEFAULT_DELAY       1
  48 #define CMM_HOTPLUG_DELAY       5
  49 #define CMM_DEBUG                       0
  50 #define CMM_DISABLE             0
  51 #define CMM_OOM_KB              1024
  52 #define CMM_MIN_MEM_MB          256
  53 #define KB2PAGES(_p)            ((_p)>>(PAGE_SHIFT-10))
  54 #define PAGES2KB(_p)            ((_p)<<(PAGE_SHIFT-10))
  55 /*
  56  * The priority level tries to ensure that this notifier is called as
  57  * late as possible to reduce thrashing in the shared memory pool.
  58  */
  59 #define CMM_MEM_HOTPLUG_PRI     1
  60 #define CMM_MEM_ISOLATE_PRI     15
  61
  62 static unsigned int delay = CMM_DEFAULT_DELAY;
  63 static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY;
  64 static unsigned int oom_kb = CMM_OOM_KB;
  65 static unsigned int cmm_debug = CMM_DEBUG;
  66 static unsigned int cmm_disabled = CMM_DISABLE;
  67 static unsigned long min_mem_mb = CMM_MIN_MEM_MB;
  68 static struct device cmm_dev;
  69
  70 MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>");
  71 MODULE_DESCRIPTION("IBM System p Collaborative Memory Manager");
  72 MODULE_LICENSE("GPL");
  73 MODULE_VERSION(CMM_DRIVER_VERSION);
  74
  75 module_param_named(delay, delay, uint, 0644);
  76 MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. "
  77                  "[Default=" __stringify(CMM_DEFAULT_DELAY) "]");
  78 module_param_named(hotplug_delay, hotplug_delay, uint, 0644);
  79 MODULE_PARM_DESC(hotplug_delay, "Delay (in seconds) after memory hotplug remove "
  80                  "before loaning resumes. "
  81                  "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]");
  82 module_param_named(oom_kb, oom_kb, uint, 0644);
  83 MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. "
  84                  "[Default=" __stringify(CMM_OOM_KB) "]");
  85 module_param_named(min_mem_mb, min_mem_mb, ulong, 0644);
  86 MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. "
  87                  "[Default=" __stringify(CMM_MIN_MEM_MB) "]");
  88 module_param_named(debug, cmm_debug, uint, 0644);
  89 MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. "
  90                  "[Default=" __stringify(CMM_DEBUG) "]");
  91
  92 #define CMM_NR_PAGES ((PAGE_SIZE - sizeof(void *) - sizeof(unsigned long)) / sizeof(unsigned long))
  93
  94 #define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); }
  95
  96 struct cmm_page_array {
  97         struct cmm_page_array *next;
  98         unsigned long index;
  99         unsigned long page[CMM_NR_PAGES];
 100 };
 101
 102 static unsigned long loaned_pages;
 103 static unsigned long loaned_pages_target;
 104 static unsigned long oom_freed_pages;
 105
 106 static struct cmm_page_array *cmm_page_list;
 107 static DEFINE_SPINLOCK(cmm_lock);
 108
 109 static DEFINE_MUTEX(hotplug_mutex);
 110 static int hotplug_occurred; /* protected by the hotplug mutex */
 111
 112 static struct task_struct *cmm_thread_ptr;
 113
 114 static long plpar_page_set_loaned(unsigned long vpa)
 115 {
 116         unsigned long cmo_page_sz = cmo_get_page_size();
 117         long rc = 0;
 118         int i;
 119
 120         for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
 121                 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, vpa + i, 0);
 122
 123         for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz)
 124                 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE,
 125                                    vpa + i - cmo_page_sz, 0);
 126
 127         return rc;
 128 }
 129
 130 static long plpar_page_set_active(unsigned long vpa)
 131 {
 132         unsigned long cmo_page_sz = cmo_get_page_size();
 133         long rc = 0;
 134         int i;
 135
 136         for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
 137                 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, vpa + i, 0);
 138
 139         for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz)
 140                 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED,
 141                                    vpa + i - cmo_page_sz, 0);
 142
 143         return rc;
 144 }
 145
 146 /**
 147  * cmm_alloc_pages - Allocate pages and mark them as loaned
 148  * @nr: number of pages to allocate
 149  *
 150  * Return value:
 151  *      number of pages requested to be allocated which were not
 152  **/
 153 static long cmm_alloc_pages(long nr)
 154 {
 155         struct cmm_page_array *pa, *npa;
 156         unsigned long addr;
 157         long rc;
 158
 159         cmm_dbg("Begin request for %ld pages\n", nr);
 160
 161         while (nr) {
 162                 /* Exit if a hotplug operation is in progress or occurred */
 163                 if (mutex_trylock(&hotplug_mutex)) {
 164                         if (hotplug_occurred) {
 165                                 mutex_unlock(&hotplug_mutex);
 166                                 break;
 167                         }
 168                         mutex_unlock(&hotplug_mutex);
 169                 } else {
 170                         break;
 171                 }
 172
 173                 addr = __get_free_page(GFP_NOIO | __GFP_NOWARN |
 174                                        __GFP_NORETRY | __GFP_NOMEMALLOC);
 175                 if (!addr)
 176                         break;
 177                 spin_lock(&cmm_lock);
 178                 pa = cmm_page_list;
 179                 if (!pa || pa->index >= CMM_NR_PAGES) {
 180                         /* Need a new page for the page list. */
 181                         spin_unlock(&cmm_lock);
 182                         npa = (struct cmm_page_array *)__get_free_page(
 183                                         GFP_NOIO | __GFP_NOWARN |
 184                                         __GFP_NORETRY | __GFP_NOMEMALLOC);
 185                         if (!npa) {
 186                                 pr_info("%s: Can not allocate new page list\n", __func__);
 187                                 free_page(addr);
 188                                 break;
 189                         }
 190                         spin_lock(&cmm_lock);
 191                         pa = cmm_page_list;
 192
 193                         if (!pa || pa->index >= CMM_NR_PAGES) {
 194                                 npa->next = pa;
 195                                 npa->index = 0;
 196                                 pa = npa;
 197                                 cmm_page_list = pa;
 198                         } else
 199                                 free_page((unsigned long) npa);
 200                 }
 201
 202                 if ((rc = plpar_page_set_loaned(__pa(addr)))) {
 203                         pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc);
 204                         spin_unlock(&cmm_lock);
 205                         free_page(addr);
 206                         break;
 207                 }
 208
 209                 pa->page[pa->index++] = addr;
 210                 loaned_pages++;
 211                 totalram_pages--;
 212                 spin_unlock(&cmm_lock);
 213                 nr--;
 214         }
 215
 216         cmm_dbg("End request with %ld pages unfulfilled\n", nr);
 217         return nr;
 218 }
 219
 220 /**
 221  * cmm_free_pages - Free pages and mark them as active
 222  * @nr: number of pages to free
 223  *
 224  * Return value:
 225  *      number of pages requested to be freed which were not
 226  **/
 227 static long cmm_free_pages(long nr)
 228 {
 229         struct cmm_page_array *pa;
 230         unsigned long addr;
 231
 232         cmm_dbg("Begin free of %ld pages.\n", nr);
 233         spin_lock(&cmm_lock);
 234         pa = cmm_page_list;
 235         while (nr) {
 236                 if (!pa || pa->index <= 0)
 237                         break;
 238                 addr = pa->page[--pa->index];
 239
 240                 if (pa->index == 0) {
 241                         pa = pa->next;
 242                         free_page((unsigned long) cmm_page_list);
 243                         cmm_page_list = pa;
 244                 }
 245
 246                 plpar_page_set_active(__pa(addr));
 247                 free_page(addr);
 248                 loaned_pages--;
 249                 nr--;
 250                 totalram_pages++;
 251         }
 252         spin_unlock(&cmm_lock);
 253         cmm_dbg("End request with %ld pages unfulfilled\n", nr);
 254         return nr;
 255 }
 256
 257 /**
 258  * cmm_oom_notify - OOM notifier
 259  * @self:       notifier block struct
 260  * @dummy:      not used
 261  * @parm:       returned - number of pages freed
 262  *
 263  * Return value:
 264  *      NOTIFY_OK
 265  **/
 266 static int cmm_oom_notify(struct notifier_block *self,
 267                           unsigned long dummy, void *parm)
 268 {
 269         unsigned long *freed = parm;
 270         long nr = KB2PAGES(oom_kb);
 271
 272         cmm_dbg("OOM processing started\n");
 273         nr = cmm_free_pages(nr);
 274         loaned_pages_target = loaned_pages;
 275         *freed += KB2PAGES(oom_kb) - nr;
 276         oom_freed_pages += KB2PAGES(oom_kb) - nr;
 277         cmm_dbg("OOM processing complete\n");
 278         return NOTIFY_OK;
 279 }
 280
 281 /**
 282  * cmm_get_mpp - Read memory performance parameters
 283  *
 284  * Makes hcall to query the current page loan request from the hypervisor.
 285  *
 286  * Return value:
 287  *      nothing
 288  **/
 289 static void cmm_get_mpp(void)
 290 {
 291         int rc;
 292         struct hvcall_mpp_data mpp_data;
 293         signed long active_pages_target, page_loan_request, target;
 294         signed long total_pages = totalram_pages + loaned_pages;
 295         signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE;
 296
 297         rc = h_get_mpp(&mpp_data);
 298
 299         if (rc != H_SUCCESS)
 300                 return;
 301
 302         page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE);
 303         target = page_loan_request + (signed long)loaned_pages;
 304
 305         if (target < 0 || total_pages < min_mem_pages)
 306                 target = 0;
 307
 308         if (target > oom_freed_pages)
 309                 target -= oom_freed_pages;
 310         else
 311                 target = 0;
 312
 313         active_pages_target = total_pages - target;
 314
 315         if (min_mem_pages > active_pages_target)
 316                 target = total_pages - min_mem_pages;
 317
 318         if (target < 0)
 319                 target = 0;
 320
 321         loaned_pages_target = target;
 322
 323         cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n",
 324                 page_loan_request, loaned_pages, loaned_pages_target,
 325                 oom_freed_pages, totalram_pages);
 326 }
 327
 328 static struct notifier_block cmm_oom_nb = {
 329         .notifier_call = cmm_oom_notify
 330 };
 331
 332 /**
 333  * cmm_thread - CMM task thread
 334  * @dummy:      not used
 335  *
 336  * Return value:
 337  *      0
 338  **/
 339 static int cmm_thread(void *dummy)
 340 {
 341         unsigned long timeleft;
 342
 343         while (1) {
 344                 timeleft = msleep_interruptible(delay * 1000);
 345
 346                 if (kthread_should_stop() || timeleft)
 347                         break;
 348
 349                 if (mutex_trylock(&hotplug_mutex)) {
 350                         if (hotplug_occurred) {
 351                                 hotplug_occurred = 0;
 352                                 mutex_unlock(&hotplug_mutex);
 353                                 cmm_dbg("Hotplug operation has occurred, "
 354                                                 "loaning activity suspended "
 355                                                 "for %d seconds.\n",
 356                                                 hotplug_delay);
 357                                 timeleft = msleep_interruptible(hotplug_delay *
 358                                                 1000);
 359                                 if (kthread_should_stop() || timeleft)
 360                                         break;
 361                                 continue;
 362                         }
 363                         mutex_unlock(&hotplug_mutex);
 364                 } else {
 365                         cmm_dbg("Hotplug operation in progress, activity "
 366                                         "suspended\n");
 367                         continue;
 368                 }
 369
 370                 cmm_get_mpp();
 371
 372                 if (loaned_pages_target > loaned_pages) {
 373                         if (cmm_alloc_pages(loaned_pages_target - loaned_pages))
 374                                 loaned_pages_target = loaned_pages;
 375                 } else if (loaned_pages_target < loaned_pages)
 376                         cmm_free_pages(loaned_pages - loaned_pages_target);
 377         }
 378         return 0;
 379 }
 380
 381 #define CMM_SHOW(name, format, args...)                 \
 382         static ssize_t show_##name(struct device *dev,  \
 383                                    struct device_attribute *attr,       \
 384                                    char *buf)                   \
 385         {                                                       \
 386                 return sprintf(buf, format, ##args);            \
 387         }                                                       \
 388         static DEVICE_ATTR(name, 0444, show_##name, NULL)
 389
 390 CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));
 391 CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
 392
 393 static ssize_t show_oom_pages(struct device *dev,
 394                               struct device_attribute *attr, char *buf)
 395 {
 396         return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages));
 397 }
 398
 399 static ssize_t store_oom_pages(struct device *dev,
 400                                struct device_attribute *attr,
 401                                const char *buf, size_t count)
 402 {
 403         unsigned long val = simple_strtoul (buf, NULL, 10);
 404
 405         if (!capable(CAP_SYS_ADMIN))
 406                 return -EPERM;
 407         if (val != 0)
 408                 return -EBADMSG;
 409
 410         oom_freed_pages = 0;
 411         return count;
 412 }
 413
 414 static DEVICE_ATTR(oom_freed_kb, 0644,
 415                    show_oom_pages, store_oom_pages);
 416
 417 static struct device_attribute *cmm_attrs[] = {
 418         &dev_attr_loaned_kb,
 419         &dev_attr_loaned_target_kb,
 420         &dev_attr_oom_freed_kb,
 421 };
 422
 423 static struct bus_type cmm_subsys = {
 424         .name = "cmm",
 425         .dev_name = "cmm",
 426 };
 427
 428 static void cmm_release_device(struct device *dev)
 429 {
 430 }
 431
 432 /**
 433  * cmm_sysfs_register - Register with sysfs
 434  *
 435  * Return value:
 436  *      0 on success / other on failure
 437  **/
 438 static int cmm_sysfs_register(struct device *dev)
 439 {
 440         int i, rc;
 441
 442         if ((rc = subsys_system_register(&cmm_subsys, NULL)))
 443                 return rc;
 444
 445         dev->id = 0;
 446         dev->bus = &cmm_subsys;
 447         dev->release = cmm_release_device;
 448
 449         if ((rc = device_register(dev)))
 450                 goto subsys_unregister;
 451
 452         for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) {
 453                 if ((rc = device_create_file(dev, cmm_attrs[i])))
 454                         goto fail;
 455         }
 456
 457         return 0;
 458
 459 fail:
 460         while (--i >= 0)
 461                 device_remove_file(dev, cmm_attrs[i]);
 462         device_unregister(dev);
 463 subsys_unregister:
 464         bus_unregister(&cmm_subsys);
 465         return rc;
 466 }
 467
 468 /**
 469  * cmm_unregister_sysfs - Unregister from sysfs
 470  *
 471  **/
 472 static void cmm_unregister_sysfs(struct device *dev)
 473 {
 474         int i;
 475
 476         for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++)
 477                 device_remove_file(dev, cmm_attrs[i]);
 478         device_unregister(dev);
 479         bus_unregister(&cmm_subsys);
 480 }
 481
 482 /**
 483  * cmm_reboot_notifier - Make sure pages are not still marked as "loaned"
 484  *
 485  **/
 486 static int cmm_reboot_notifier(struct notifier_block *nb,
 487                                unsigned long action, void *unused)
 488 {
 489         if (action == SYS_RESTART) {
 490                 if (cmm_thread_ptr)
 491                         kthread_stop(cmm_thread_ptr);
 492                 cmm_thread_ptr = NULL;
 493                 cmm_free_pages(loaned_pages);
 494         }
 495         return NOTIFY_DONE;
 496 }
 497
 498 static struct notifier_block cmm_reboot_nb = {
 499         .notifier_call = cmm_reboot_notifier,
 500 };
 501
 502 /**
 503  * cmm_count_pages - Count the number of pages loaned in a particular range.
 504  *
 505  * @arg: memory_isolate_notify structure with address range and count
 506  *
 507  * Return value:
 508  *      0 on success
 509  **/
 510 static unsigned long cmm_count_pages(void *arg)
 511 {
 512         struct memory_isolate_notify *marg = arg;
 513         struct cmm_page_array *pa;
 514         unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn);
 515         unsigned long end = start + (marg->nr_pages << PAGE_SHIFT);
 516         unsigned long idx;
 517
 518         spin_lock(&cmm_lock);
 519         pa = cmm_page_list;
 520         while (pa) {
 521                 if ((unsigned long)pa >= start && (unsigned long)pa < end)
 522                         marg->pages_found++;
 523                 for (idx = 0; idx < pa->index; idx++)
 524                         if (pa->page[idx] >= start && pa->page[idx] < end)
 525                                 marg->pages_found++;
 526                 pa = pa->next;
 527         }
 528         spin_unlock(&cmm_lock);
 529         return 0;
 530 }
 531
 532 /**
 533  * cmm_memory_isolate_cb - Handle memory isolation notifier calls
 534  * @self:       notifier block struct
 535  * @action:     action to take
 536  * @arg:        struct memory_isolate_notify data for handler
 537  *
 538  * Return value:
 539  *      NOTIFY_OK or notifier error based on subfunction return value
 540  **/
 541 static int cmm_memory_isolate_cb(struct notifier_block *self,
 542                                  unsigned long action, void *arg)
 543 {
 544         int ret = 0;
 545
 546         if (action == MEM_ISOLATE_COUNT)
 547                 ret = cmm_count_pages(arg);
 548
 549         return notifier_from_errno(ret);
 550 }
 551
 552 static struct notifier_block cmm_mem_isolate_nb = {
 553         .notifier_call = cmm_memory_isolate_cb,
 554         .priority = CMM_MEM_ISOLATE_PRI
 555 };
 556
 557 /**
 558  * cmm_mem_going_offline - Unloan pages where memory is to be removed
 559  * @arg: memory_notify structure with page range to be offlined
 560  *
 561  * Return value:
 562  *      0 on success
 563  **/
 564 static int cmm_mem_going_offline(void *arg)
 565 {
 566         struct memory_notify *marg = arg;
 567         unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn);
 568         unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT);
 569         struct cmm_page_array *pa_curr, *pa_last, *npa;
 570         unsigned long idx;
 571         unsigned long freed = 0;
 572
 573         cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n",
 574                         start_page, marg->nr_pages);
 575         spin_lock(&cmm_lock);
 576
 577         /* Search the page list for pages in the range to be offlined */
 578         pa_last = pa_curr = cmm_page_list;
 579         while (pa_curr) {
 580                 for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) {
 581                         if ((pa_curr->page[idx] < start_page) ||
 582                             (pa_curr->page[idx] >= end_page))
 583                                 continue;
 584
 585                         plpar_page_set_active(__pa(pa_curr->page[idx]));
 586                         free_page(pa_curr->page[idx]);
 587                         freed++;
 588                         loaned_pages--;
 589                         totalram_pages++;
 590                         pa_curr->page[idx] = pa_last->page[--pa_last->index];
 591                         if (pa_last->index == 0) {
 592                                 if (pa_curr == pa_last)
 593                                         pa_curr = pa_last->next;
 594                                 pa_last = pa_last->next;
 595                                 free_page((unsigned long)cmm_page_list);
 596                                 cmm_page_list = pa_last;
 597                         }
 598                 }
 599                 pa_curr = pa_curr->next;
 600         }
 601
 602         /* Search for page list structures in the range to be offlined */
 603         pa_last = NULL;
 604         pa_curr = cmm_page_list;
 605         while (pa_curr) {
 606                 if (((unsigned long)pa_curr >= start_page) &&
 607                                 ((unsigned long)pa_curr < end_page)) {
 608                         npa = (struct cmm_page_array *)__get_free_page(
 609                                         GFP_NOIO | __GFP_NOWARN |
 610                                         __GFP_NORETRY | __GFP_NOMEMALLOC);
 611                         if (!npa) {
 612                                 spin_unlock(&cmm_lock);
 613                                 cmm_dbg("Failed to allocate memory for list "
 614                                                 "management. Memory hotplug "
 615                                                 "failed.\n");
 616                                 return -ENOMEM;
 617                         }
 618                         memcpy(npa, pa_curr, PAGE_SIZE);
 619                         if (pa_curr == cmm_page_list)
 620                                 cmm_page_list = npa;
 621                         if (pa_last)
 622                                 pa_last->next = npa;
 623                         free_page((unsigned long) pa_curr);
 624                         freed++;
 625                         pa_curr = npa;
 626                 }
 627
 628                 pa_last = pa_curr;
 629                 pa_curr = pa_curr->next;
 630         }
 631
 632         spin_unlock(&cmm_lock);
 633         cmm_dbg("Released %ld pages in the search range.\n", freed);
 634
 635         return 0;
 636 }
 637
 638 /**
 639  * cmm_memory_cb - Handle memory hotplug notifier calls
 640  * @self:       notifier block struct
 641  * @action:     action to take
 642  * @arg:        struct memory_notify data for handler
 643  *
 644  * Return value:
 645  *      NOTIFY_OK or notifier error based on subfunction return value
 646  *
 647  **/
 648 static int cmm_memory_cb(struct notifier_block *self,
 649                         unsigned long action, void *arg)
 650 {
 651         int ret = 0;
 652
 653         switch (action) {
 654         case MEM_GOING_OFFLINE:
 655                 mutex_lock(&hotplug_mutex);
 656                 hotplug_occurred = 1;
 657                 ret = cmm_mem_going_offline(arg);
 658                 break;
 659         case MEM_OFFLINE:
 660         case MEM_CANCEL_OFFLINE:
 661                 mutex_unlock(&hotplug_mutex);
 662                 cmm_dbg("Memory offline operation complete.\n");
 663                 break;
 664         case MEM_GOING_ONLINE:
 665         case MEM_ONLINE:
 666         case MEM_CANCEL_ONLINE:
 667                 break;
 668         }
 669
 670         return notifier_from_errno(ret);
 671 }
 672
 673 static struct notifier_block cmm_mem_nb = {
 674         .notifier_call = cmm_memory_cb,
 675         .priority = CMM_MEM_HOTPLUG_PRI
 676 };
 677
 678 /**
 679  * cmm_init - Module initialization
 680  *
 681  * Return value:
 682  *      0 on success / other on failure
 683  **/
 684 static int cmm_init(void)
 685 {
 686         int rc = -ENOMEM;
 687
 688         if (!firmware_has_feature(FW_FEATURE_CMO))
 689                 return -EOPNOTSUPP;
 690
 691         if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0)
 692                 return rc;
 693
 694         if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
 695                 goto out_oom_notifier;
 696
 697         if ((rc = cmm_sysfs_register(&cmm_dev)))
 698                 goto out_reboot_notifier;
 699
 700         if (register_memory_notifier(&cmm_mem_nb) ||
 701             register_memory_isolate_notifier(&cmm_mem_isolate_nb))
 702                 goto out_unregister_notifier;
 703
 704         if (cmm_disabled)
 705                 return rc;
 706
 707         cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
 708         if (IS_ERR(cmm_thread_ptr)) {
 709                 rc = PTR_ERR(cmm_thread_ptr);
 710                 goto out_unregister_notifier;
 711         }
 712
 713         return rc;
 714
 715 out_unregister_notifier:
 716         unregister_memory_notifier(&cmm_mem_nb);
 717         unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
 718         cmm_unregister_sysfs(&cmm_dev);
 719 out_reboot_notifier:
 720         unregister_reboot_notifier(&cmm_reboot_nb);
 721 out_oom_notifier:
 722         unregister_oom_notifier(&cmm_oom_nb);
 723         return rc;
 724 }
 725
 726 /**
 727  * cmm_exit - Module exit
 728  *
 729  * Return value:
 730  *      nothing
 731  **/
 732 static void cmm_exit(void)
 733 {
 734         if (cmm_thread_ptr)
 735                 kthread_stop(cmm_thread_ptr);
 736         unregister_oom_notifier(&cmm_oom_nb);
 737         unregister_reboot_notifier(&cmm_reboot_nb);
 738         unregister_memory_notifier(&cmm_mem_nb);
 739         unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
 740         cmm_free_pages(loaned_pages);
 741         cmm_unregister_sysfs(&cmm_dev);
 742 }
 743
 744 /**
 745  * cmm_set_disable - Disable/Enable CMM
 746  *
 747  * Return value:
 748  *      0 on success / other on failure
 749  **/
 750 static int cmm_set_disable(const char *val, const struct kernel_param *kp)
 751 {
 752         int disable = simple_strtoul(val, NULL, 10);
 753
 754         if (disable != 0 && disable != 1)
 755                 return -EINVAL;
 756
 757         if (disable && !cmm_disabled) {
 758                 if (cmm_thread_ptr)
 759                         kthread_stop(cmm_thread_ptr);
 760                 cmm_thread_ptr = NULL;
 761                 cmm_free_pages(loaned_pages);
 762         } else if (!disable && cmm_disabled) {
 763                 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
 764                 if (IS_ERR(cmm_thread_ptr))
 765                         return PTR_ERR(cmm_thread_ptr);
 766         }
 767
 768         cmm_disabled = disable;
 769         return 0;
 770 }
 771
 772 module_param_call(disable, cmm_set_disable, param_get_uint,
 773                   &cmm_disabled, 0644);
 774 MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
 775                  "[Default=" __stringify(CMM_DISABLE) "]");
 776
 777 module_init(cmm_init);
 778 module_exit(cmm_exit);