linux/arch/powerpc/platforms/pseries/cmm.c
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   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
  62static unsigned int delay = CMM_DEFAULT_DELAY;
  63static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY;
  64static unsigned int oom_kb = CMM_OOM_KB;
  65static unsigned int cmm_debug = CMM_DEBUG;
  66static unsigned int cmm_disabled = CMM_DISABLE;
  67static unsigned long min_mem_mb = CMM_MIN_MEM_MB;
  68static struct device cmm_dev;
  69
  70MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>");
  71MODULE_DESCRIPTION("IBM System p Collaborative Memory Manager");
  72MODULE_LICENSE("GPL");
  73MODULE_VERSION(CMM_DRIVER_VERSION);
  74
  75module_param_named(delay, delay, uint, 0644);
  76MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. "
  77                 "[Default=" __stringify(CMM_DEFAULT_DELAY) "]");
  78module_param_named(hotplug_delay, hotplug_delay, uint, 0644);
  79MODULE_PARM_DESC(hotplug_delay, "Delay (in seconds) after memory hotplug remove "
  80                 "before loaning resumes. "
  81                 "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]");
  82module_param_named(oom_kb, oom_kb, uint, 0644);
  83MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. "
  84                 "[Default=" __stringify(CMM_OOM_KB) "]");
  85module_param_named(min_mem_mb, min_mem_mb, ulong, 0644);
  86MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. "
  87                 "[Default=" __stringify(CMM_MIN_MEM_MB) "]");
  88module_param_named(debug, cmm_debug, uint, 0644);
  89MODULE_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
  96struct cmm_page_array {
  97        struct cmm_page_array *next;
  98        unsigned long index;
  99        unsigned long page[CMM_NR_PAGES];
 100};
 101
 102static unsigned long loaned_pages;
 103static unsigned long loaned_pages_target;
 104static unsigned long oom_freed_pages;
 105
 106static struct cmm_page_array *cmm_page_list;
 107static DEFINE_SPINLOCK(cmm_lock);
 108
 109static DEFINE_MUTEX(hotplug_mutex);
 110static int hotplug_occurred; /* protected by the hotplug mutex */
 111
 112static struct task_struct *cmm_thread_ptr;
 113
 114static 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
 130static 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 **/
 153static 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 **/
 227static 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 **/
 266static 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 **/
 289static 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
 328static 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 **/
 339static 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
 390CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));
 391CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
 392
 393static 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
 399static 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
 414static DEVICE_ATTR(oom_freed_kb, 0644,
 415                   show_oom_pages, store_oom_pages);
 416
 417static struct device_attribute *cmm_attrs[] = {
 418        &dev_attr_loaned_kb,
 419        &dev_attr_loaned_target_kb,
 420        &dev_attr_oom_freed_kb,
 421};
 422
 423static struct bus_type cmm_subsys = {
 424        .name = "cmm",
 425        .dev_name = "cmm",
 426};
 427
 428/**
 429 * cmm_sysfs_register - Register with sysfs
 430 *
 431 * Return value:
 432 *      0 on success / other on failure
 433 **/
 434static int cmm_sysfs_register(struct device *dev)
 435{
 436        int i, rc;
 437
 438        if ((rc = subsys_system_register(&cmm_subsys, NULL)))
 439                return rc;
 440
 441        dev->id = 0;
 442        dev->bus = &cmm_subsys;
 443
 444        if ((rc = device_register(dev)))
 445                goto subsys_unregister;
 446
 447        for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) {
 448                if ((rc = device_create_file(dev, cmm_attrs[i])))
 449                        goto fail;
 450        }
 451
 452        return 0;
 453
 454fail:
 455        while (--i >= 0)
 456                device_remove_file(dev, cmm_attrs[i]);
 457        device_unregister(dev);
 458subsys_unregister:
 459        bus_unregister(&cmm_subsys);
 460        return rc;
 461}
 462
 463/**
 464 * cmm_unregister_sysfs - Unregister from sysfs
 465 *
 466 **/
 467static void cmm_unregister_sysfs(struct device *dev)
 468{
 469        int i;
 470
 471        for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++)
 472                device_remove_file(dev, cmm_attrs[i]);
 473        device_unregister(dev);
 474        bus_unregister(&cmm_subsys);
 475}
 476
 477/**
 478 * cmm_reboot_notifier - Make sure pages are not still marked as "loaned"
 479 *
 480 **/
 481static int cmm_reboot_notifier(struct notifier_block *nb,
 482                               unsigned long action, void *unused)
 483{
 484        if (action == SYS_RESTART) {
 485                if (cmm_thread_ptr)
 486                        kthread_stop(cmm_thread_ptr);
 487                cmm_thread_ptr = NULL;
 488                cmm_free_pages(loaned_pages);
 489        }
 490        return NOTIFY_DONE;
 491}
 492
 493static struct notifier_block cmm_reboot_nb = {
 494        .notifier_call = cmm_reboot_notifier,
 495};
 496
 497/**
 498 * cmm_count_pages - Count the number of pages loaned in a particular range.
 499 *
 500 * @arg: memory_isolate_notify structure with address range and count
 501 *
 502 * Return value:
 503 *      0 on success
 504 **/
 505static unsigned long cmm_count_pages(void *arg)
 506{
 507        struct memory_isolate_notify *marg = arg;
 508        struct cmm_page_array *pa;
 509        unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn);
 510        unsigned long end = start + (marg->nr_pages << PAGE_SHIFT);
 511        unsigned long idx;
 512
 513        spin_lock(&cmm_lock);
 514        pa = cmm_page_list;
 515        while (pa) {
 516                if ((unsigned long)pa >= start && (unsigned long)pa < end)
 517                        marg->pages_found++;
 518                for (idx = 0; idx < pa->index; idx++)
 519                        if (pa->page[idx] >= start && pa->page[idx] < end)
 520                                marg->pages_found++;
 521                pa = pa->next;
 522        }
 523        spin_unlock(&cmm_lock);
 524        return 0;
 525}
 526
 527/**
 528 * cmm_memory_isolate_cb - Handle memory isolation notifier calls
 529 * @self:       notifier block struct
 530 * @action:     action to take
 531 * @arg:        struct memory_isolate_notify data for handler
 532 *
 533 * Return value:
 534 *      NOTIFY_OK or notifier error based on subfunction return value
 535 **/
 536static int cmm_memory_isolate_cb(struct notifier_block *self,
 537                                 unsigned long action, void *arg)
 538{
 539        int ret = 0;
 540
 541        if (action == MEM_ISOLATE_COUNT)
 542                ret = cmm_count_pages(arg);
 543
 544        return notifier_from_errno(ret);
 545}
 546
 547static struct notifier_block cmm_mem_isolate_nb = {
 548        .notifier_call = cmm_memory_isolate_cb,
 549        .priority = CMM_MEM_ISOLATE_PRI
 550};
 551
 552/**
 553 * cmm_mem_going_offline - Unloan pages where memory is to be removed
 554 * @arg: memory_notify structure with page range to be offlined
 555 *
 556 * Return value:
 557 *      0 on success
 558 **/
 559static int cmm_mem_going_offline(void *arg)
 560{
 561        struct memory_notify *marg = arg;
 562        unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn);
 563        unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT);
 564        struct cmm_page_array *pa_curr, *pa_last, *npa;
 565        unsigned long idx;
 566        unsigned long freed = 0;
 567
 568        cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n",
 569                        start_page, marg->nr_pages);
 570        spin_lock(&cmm_lock);
 571
 572        /* Search the page list for pages in the range to be offlined */
 573        pa_last = pa_curr = cmm_page_list;
 574        while (pa_curr) {
 575                for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) {
 576                        if ((pa_curr->page[idx] < start_page) ||
 577                            (pa_curr->page[idx] >= end_page))
 578                                continue;
 579
 580                        plpar_page_set_active(__pa(pa_curr->page[idx]));
 581                        free_page(pa_curr->page[idx]);
 582                        freed++;
 583                        loaned_pages--;
 584                        totalram_pages++;
 585                        pa_curr->page[idx] = pa_last->page[--pa_last->index];
 586                        if (pa_last->index == 0) {
 587                                if (pa_curr == pa_last)
 588                                        pa_curr = pa_last->next;
 589                                pa_last = pa_last->next;
 590                                free_page((unsigned long)cmm_page_list);
 591                                cmm_page_list = pa_last;
 592                        }
 593                }
 594                pa_curr = pa_curr->next;
 595        }
 596
 597        /* Search for page list structures in the range to be offlined */
 598        pa_last = NULL;
 599        pa_curr = cmm_page_list;
 600        while (pa_curr) {
 601                if (((unsigned long)pa_curr >= start_page) &&
 602                                ((unsigned long)pa_curr < end_page)) {
 603                        npa = (struct cmm_page_array *)__get_free_page(
 604                                        GFP_NOIO | __GFP_NOWARN |
 605                                        __GFP_NORETRY | __GFP_NOMEMALLOC);
 606                        if (!npa) {
 607                                spin_unlock(&cmm_lock);
 608                                cmm_dbg("Failed to allocate memory for list "
 609                                                "management. Memory hotplug "
 610                                                "failed.\n");
 611                                return -ENOMEM;
 612                        }
 613                        memcpy(npa, pa_curr, PAGE_SIZE);
 614                        if (pa_curr == cmm_page_list)
 615                                cmm_page_list = npa;
 616                        if (pa_last)
 617                                pa_last->next = npa;
 618                        free_page((unsigned long) pa_curr);
 619                        freed++;
 620                        pa_curr = npa;
 621                }
 622
 623                pa_last = pa_curr;
 624                pa_curr = pa_curr->next;
 625        }
 626
 627        spin_unlock(&cmm_lock);
 628        cmm_dbg("Released %ld pages in the search range.\n", freed);
 629
 630        return 0;
 631}
 632
 633/**
 634 * cmm_memory_cb - Handle memory hotplug notifier calls
 635 * @self:       notifier block struct
 636 * @action:     action to take
 637 * @arg:        struct memory_notify data for handler
 638 *
 639 * Return value:
 640 *      NOTIFY_OK or notifier error based on subfunction return value
 641 *
 642 **/
 643static int cmm_memory_cb(struct notifier_block *self,
 644                        unsigned long action, void *arg)
 645{
 646        int ret = 0;
 647
 648        switch (action) {
 649        case MEM_GOING_OFFLINE:
 650                mutex_lock(&hotplug_mutex);
 651                hotplug_occurred = 1;
 652                ret = cmm_mem_going_offline(arg);
 653                break;
 654        case MEM_OFFLINE:
 655        case MEM_CANCEL_OFFLINE:
 656                mutex_unlock(&hotplug_mutex);
 657                cmm_dbg("Memory offline operation complete.\n");
 658                break;
 659        case MEM_GOING_ONLINE:
 660        case MEM_ONLINE:
 661        case MEM_CANCEL_ONLINE:
 662                break;
 663        }
 664
 665        return notifier_from_errno(ret);
 666}
 667
 668static struct notifier_block cmm_mem_nb = {
 669        .notifier_call = cmm_memory_cb,
 670        .priority = CMM_MEM_HOTPLUG_PRI
 671};
 672
 673/**
 674 * cmm_init - Module initialization
 675 *
 676 * Return value:
 677 *      0 on success / other on failure
 678 **/
 679static int cmm_init(void)
 680{
 681        int rc = -ENOMEM;
 682
 683        if (!firmware_has_feature(FW_FEATURE_CMO))
 684                return -EOPNOTSUPP;
 685
 686        if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0)
 687                return rc;
 688
 689        if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
 690                goto out_oom_notifier;
 691
 692        if ((rc = cmm_sysfs_register(&cmm_dev)))
 693                goto out_reboot_notifier;
 694
 695        if (register_memory_notifier(&cmm_mem_nb) ||
 696            register_memory_isolate_notifier(&cmm_mem_isolate_nb))
 697                goto out_unregister_notifier;
 698
 699        if (cmm_disabled)
 700                return rc;
 701
 702        cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
 703        if (IS_ERR(cmm_thread_ptr)) {
 704                rc = PTR_ERR(cmm_thread_ptr);
 705                goto out_unregister_notifier;
 706        }
 707
 708        return rc;
 709
 710out_unregister_notifier:
 711        unregister_memory_notifier(&cmm_mem_nb);
 712        unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
 713        cmm_unregister_sysfs(&cmm_dev);
 714out_reboot_notifier:
 715        unregister_reboot_notifier(&cmm_reboot_nb);
 716out_oom_notifier:
 717        unregister_oom_notifier(&cmm_oom_nb);
 718        return rc;
 719}
 720
 721/**
 722 * cmm_exit - Module exit
 723 *
 724 * Return value:
 725 *      nothing
 726 **/
 727static void cmm_exit(void)
 728{
 729        if (cmm_thread_ptr)
 730                kthread_stop(cmm_thread_ptr);
 731        unregister_oom_notifier(&cmm_oom_nb);
 732        unregister_reboot_notifier(&cmm_reboot_nb);
 733        unregister_memory_notifier(&cmm_mem_nb);
 734        unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
 735        cmm_free_pages(loaned_pages);
 736        cmm_unregister_sysfs(&cmm_dev);
 737}
 738
 739/**
 740 * cmm_set_disable - Disable/Enable CMM
 741 *
 742 * Return value:
 743 *      0 on success / other on failure
 744 **/
 745static int cmm_set_disable(const char *val, const struct kernel_param *kp)
 746{
 747        int disable = simple_strtoul(val, NULL, 10);
 748
 749        if (disable != 0 && disable != 1)
 750                return -EINVAL;
 751
 752        if (disable && !cmm_disabled) {
 753                if (cmm_thread_ptr)
 754                        kthread_stop(cmm_thread_ptr);
 755                cmm_thread_ptr = NULL;
 756                cmm_free_pages(loaned_pages);
 757        } else if (!disable && cmm_disabled) {
 758                cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
 759                if (IS_ERR(cmm_thread_ptr))
 760                        return PTR_ERR(cmm_thread_ptr);
 761        }
 762
 763        cmm_disabled = disable;
 764        return 0;
 765}
 766
 767module_param_call(disable, cmm_set_disable, param_get_uint,
 768                  &cmm_disabled, 0644);
 769MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
 770                 "[Default=" __stringify(CMM_DISABLE) "]");
 771
 772module_init(cmm_init);
 773module_exit(cmm_exit);
 774