1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Collaborative memory management interface. 4 * 5 * Copyright (C) 2008 IBM Corporation 6 * Author(s): Brian King (brking@linux.vnet.ibm.com), 7 */ 8 9 #include <linux/ctype.h> 10 #include <linux/delay.h> 11 #include <linux/errno.h> 12 #include <linux/fs.h> 13 #include <linux/gfp.h> 14 #include <linux/kthread.h> 15 #include <linux/module.h> 16 #include <linux/oom.h> 17 #include <linux/reboot.h> 18 #include <linux/sched.h> 19 #include <linux/stringify.h> 20 #include <linux/swap.h> 21 #include <linux/device.h> 22 #include <linux/balloon.h> 23 #include <asm/firmware.h> 24 #include <asm/hvcall.h> 25 #include <asm/mmu.h> 26 #include <linux/uaccess.h> 27 #include <linux/memory.h> 28 #include <asm/plpar_wrappers.h> 29 30 #include "pseries.h" 31 32 #define CMM_DRIVER_VERSION "1.0.0" 33 #define CMM_DEFAULT_DELAY 1 34 #define CMM_HOTPLUG_DELAY 5 35 #define CMM_DEBUG 0 36 #define CMM_DISABLE 0 37 #define CMM_OOM_KB 1024 38 #define CMM_MIN_MEM_MB 256 39 #define KB2PAGES(_p) ((_p)>>(PAGE_SHIFT-10)) 40 #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) 41 42 #define CMM_MEM_HOTPLUG_PRI 1 43 44 static unsigned int delay = CMM_DEFAULT_DELAY; 45 static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY; 46 static unsigned int oom_kb = CMM_OOM_KB; 47 static unsigned int cmm_debug = CMM_DEBUG; 48 static unsigned int cmm_disabled = CMM_DISABLE; 49 static unsigned long min_mem_mb = CMM_MIN_MEM_MB; 50 static bool __read_mostly simulate; 51 static unsigned long simulate_loan_target_kb; 52 static struct device cmm_dev; 53 54 MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>"); 55 MODULE_DESCRIPTION("IBM System p Collaborative Memory Manager"); 56 MODULE_LICENSE("GPL"); 57 MODULE_VERSION(CMM_DRIVER_VERSION); 58 59 module_param_named(delay, delay, uint, 0644); 60 MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. " 61 "[Default=" __stringify(CMM_DEFAULT_DELAY) "]"); 62 module_param_named(hotplug_delay, hotplug_delay, uint, 0644); 63 MODULE_PARM_DESC(hotplug_delay, "Delay (in seconds) after memory hotplug remove " 64 "before loaning resumes. " 65 "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]"); 66 module_param_named(oom_kb, oom_kb, uint, 0644); 67 MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. " 68 "[Default=" __stringify(CMM_OOM_KB) "]"); 69 module_param_named(min_mem_mb, min_mem_mb, ulong, 0644); 70 MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. " 71 "[Default=" __stringify(CMM_MIN_MEM_MB) "]"); 72 module_param_named(debug, cmm_debug, uint, 0644); 73 MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. " 74 "[Default=" __stringify(CMM_DEBUG) "]"); 75 module_param_named(simulate, simulate, bool, 0444); 76 MODULE_PARM_DESC(simulate, "Enable simulation mode (no communication with hw)."); 77 78 #define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); } 79 80 static atomic_long_t loaned_pages; 81 static unsigned long loaned_pages_target; 82 static unsigned long oom_freed_pages; 83 84 static DEFINE_MUTEX(hotplug_mutex); 85 static int hotplug_occurred; /* protected by the hotplug mutex */ 86 87 static struct task_struct *cmm_thread_ptr; 88 static struct balloon_dev_info b_dev_info; 89 90 static long plpar_page_set_loaned(struct page *page) 91 { 92 const unsigned long vpa = page_to_phys(page); 93 unsigned long cmo_page_sz = cmo_get_page_size(); 94 long rc = 0; 95 int i; 96 97 if (unlikely(simulate)) 98 return 0; 99 100 for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz) 101 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, vpa + i, 0); 102 103 for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz) 104 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, 105 vpa + i - cmo_page_sz, 0); 106 107 return rc; 108 } 109 110 static long plpar_page_set_active(struct page *page) 111 { 112 const unsigned long vpa = page_to_phys(page); 113 unsigned long cmo_page_sz = cmo_get_page_size(); 114 long rc = 0; 115 int i; 116 117 if (unlikely(simulate)) 118 return 0; 119 120 for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz) 121 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, 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_LOANED, 125 vpa + i - cmo_page_sz, 0); 126 127 return rc; 128 } 129 130 /** 131 * cmm_alloc_pages - Allocate pages and mark them as loaned 132 * @nr: number of pages to allocate 133 * 134 * Return value: 135 * number of pages requested to be allocated which were not 136 **/ 137 static long cmm_alloc_pages(long nr) 138 { 139 struct page *page; 140 long rc; 141 142 cmm_dbg("Begin request for %ld pages\n", nr); 143 144 while (nr) { 145 /* Exit if a hotplug operation is in progress or occurred */ 146 if (mutex_trylock(&hotplug_mutex)) { 147 if (hotplug_occurred) { 148 mutex_unlock(&hotplug_mutex); 149 break; 150 } 151 mutex_unlock(&hotplug_mutex); 152 } else { 153 break; 154 } 155 156 page = balloon_page_alloc(); 157 if (!page) 158 break; 159 rc = plpar_page_set_loaned(page); 160 if (rc) { 161 pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc); 162 __free_page(page); 163 break; 164 } 165 166 balloon_page_enqueue(&b_dev_info, page); 167 atomic_long_inc(&loaned_pages); 168 nr--; 169 } 170 171 cmm_dbg("End request with %ld pages unfulfilled\n", nr); 172 return nr; 173 } 174 175 /** 176 * cmm_free_pages - Free pages and mark them as active 177 * @nr: number of pages to free 178 * 179 * Return value: 180 * number of pages requested to be freed which were not 181 **/ 182 static long cmm_free_pages(long nr) 183 { 184 struct page *page; 185 186 cmm_dbg("Begin free of %ld pages.\n", nr); 187 while (nr) { 188 page = balloon_page_dequeue(&b_dev_info); 189 if (!page) 190 break; 191 plpar_page_set_active(page); 192 __free_page(page); 193 atomic_long_dec(&loaned_pages); 194 nr--; 195 } 196 cmm_dbg("End request with %ld pages unfulfilled\n", nr); 197 return nr; 198 } 199 200 /** 201 * cmm_oom_notify - OOM notifier 202 * @self: notifier block struct 203 * @dummy: not used 204 * @parm: returned - number of pages freed 205 * 206 * Return value: 207 * NOTIFY_OK 208 **/ 209 static int cmm_oom_notify(struct notifier_block *self, 210 unsigned long dummy, void *parm) 211 { 212 unsigned long *freed = parm; 213 long nr = KB2PAGES(oom_kb); 214 215 cmm_dbg("OOM processing started\n"); 216 nr = cmm_free_pages(nr); 217 loaned_pages_target = atomic_long_read(&loaned_pages); 218 *freed += KB2PAGES(oom_kb) - nr; 219 oom_freed_pages += KB2PAGES(oom_kb) - nr; 220 cmm_dbg("OOM processing complete\n"); 221 return NOTIFY_OK; 222 } 223 224 /** 225 * cmm_get_mpp - Read memory performance parameters 226 * 227 * Makes hcall to query the current page loan request from the hypervisor. 228 * 229 * Return value: 230 * nothing 231 **/ 232 static void cmm_get_mpp(void) 233 { 234 const long __loaned_pages = atomic_long_read(&loaned_pages); 235 const long total_pages = totalram_pages() + __loaned_pages; 236 int rc; 237 struct hvcall_mpp_data mpp_data; 238 signed long active_pages_target, page_loan_request, target; 239 signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE; 240 241 if (likely(!simulate)) { 242 rc = h_get_mpp(&mpp_data); 243 if (rc != H_SUCCESS) 244 return; 245 page_loan_request = div_s64((s64)mpp_data.loan_request, 246 PAGE_SIZE); 247 target = page_loan_request + __loaned_pages; 248 } else { 249 target = KB2PAGES(simulate_loan_target_kb); 250 page_loan_request = target - __loaned_pages; 251 } 252 253 if (target < 0 || total_pages < min_mem_pages) 254 target = 0; 255 256 if (target > oom_freed_pages) 257 target -= oom_freed_pages; 258 else 259 target = 0; 260 261 active_pages_target = total_pages - target; 262 263 if (min_mem_pages > active_pages_target) 264 target = total_pages - min_mem_pages; 265 266 if (target < 0) 267 target = 0; 268 269 loaned_pages_target = target; 270 271 cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n", 272 page_loan_request, __loaned_pages, loaned_pages_target, 273 oom_freed_pages, totalram_pages()); 274 } 275 276 static struct notifier_block cmm_oom_nb = { 277 .notifier_call = cmm_oom_notify 278 }; 279 280 /** 281 * cmm_thread - CMM task thread 282 * @dummy: not used 283 * 284 * Return value: 285 * 0 286 **/ 287 static int cmm_thread(void *dummy) 288 { 289 unsigned long timeleft; 290 long __loaned_pages; 291 292 while (1) { 293 timeleft = msleep_interruptible(delay * 1000); 294 295 if (kthread_should_stop() || timeleft) 296 break; 297 298 if (mutex_trylock(&hotplug_mutex)) { 299 if (hotplug_occurred) { 300 hotplug_occurred = 0; 301 mutex_unlock(&hotplug_mutex); 302 cmm_dbg("Hotplug operation has occurred, " 303 "loaning activity suspended " 304 "for %d seconds.\n", 305 hotplug_delay); 306 timeleft = msleep_interruptible(hotplug_delay * 307 1000); 308 if (kthread_should_stop() || timeleft) 309 break; 310 continue; 311 } 312 mutex_unlock(&hotplug_mutex); 313 } else { 314 cmm_dbg("Hotplug operation in progress, activity " 315 "suspended\n"); 316 continue; 317 } 318 319 cmm_get_mpp(); 320 321 __loaned_pages = atomic_long_read(&loaned_pages); 322 if (loaned_pages_target > __loaned_pages) { 323 if (cmm_alloc_pages(loaned_pages_target - __loaned_pages)) 324 loaned_pages_target = __loaned_pages; 325 } else if (loaned_pages_target < __loaned_pages) 326 cmm_free_pages(__loaned_pages - loaned_pages_target); 327 } 328 return 0; 329 } 330 331 #define CMM_SHOW(name, format, args...) \ 332 static ssize_t show_##name(struct device *dev, \ 333 struct device_attribute *attr, \ 334 char *buf) \ 335 { \ 336 return sprintf(buf, format, ##args); \ 337 } \ 338 static DEVICE_ATTR(name, 0444, show_##name, NULL) 339 340 CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(atomic_long_read(&loaned_pages))); 341 CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target)); 342 343 static ssize_t show_oom_pages(struct device *dev, 344 struct device_attribute *attr, char *buf) 345 { 346 return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages)); 347 } 348 349 static ssize_t store_oom_pages(struct device *dev, 350 struct device_attribute *attr, 351 const char *buf, size_t count) 352 { 353 unsigned long val = simple_strtoul (buf, NULL, 10); 354 355 if (!capable(CAP_SYS_ADMIN)) 356 return -EPERM; 357 if (val != 0) 358 return -EBADMSG; 359 360 oom_freed_pages = 0; 361 return count; 362 } 363 364 static DEVICE_ATTR(oom_freed_kb, 0644, 365 show_oom_pages, store_oom_pages); 366 367 static struct device_attribute *cmm_attrs[] = { 368 &dev_attr_loaned_kb, 369 &dev_attr_loaned_target_kb, 370 &dev_attr_oom_freed_kb, 371 }; 372 373 static DEVICE_ULONG_ATTR(simulate_loan_target_kb, 0644, 374 simulate_loan_target_kb); 375 376 static const struct bus_type cmm_subsys = { 377 .name = "cmm", 378 .dev_name = "cmm", 379 }; 380 381 static void cmm_release_device(struct device *dev) 382 { 383 } 384 385 /** 386 * cmm_sysfs_register - Register with sysfs 387 * 388 * Return value: 389 * 0 on success / other on failure 390 **/ 391 static int cmm_sysfs_register(struct device *dev) 392 { 393 int i, rc; 394 395 if ((rc = subsys_system_register(&cmm_subsys, NULL))) 396 return rc; 397 398 dev->id = 0; 399 dev->bus = &cmm_subsys; 400 dev->release = cmm_release_device; 401 402 if ((rc = device_register(dev))) 403 goto subsys_unregister; 404 405 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) { 406 if ((rc = device_create_file(dev, cmm_attrs[i]))) 407 goto fail; 408 } 409 410 if (!simulate) 411 return 0; 412 rc = device_create_file(dev, &dev_attr_simulate_loan_target_kb.attr); 413 if (rc) 414 goto fail; 415 return 0; 416 417 fail: 418 while (--i >= 0) 419 device_remove_file(dev, cmm_attrs[i]); 420 device_unregister(dev); 421 subsys_unregister: 422 bus_unregister(&cmm_subsys); 423 return rc; 424 } 425 426 /** 427 * cmm_unregister_sysfs - Unregister from sysfs 428 * 429 **/ 430 static void cmm_unregister_sysfs(struct device *dev) 431 { 432 int i; 433 434 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) 435 device_remove_file(dev, cmm_attrs[i]); 436 device_unregister(dev); 437 bus_unregister(&cmm_subsys); 438 } 439 440 /** 441 * cmm_reboot_notifier - Make sure pages are not still marked as "loaned" 442 * 443 **/ 444 static int cmm_reboot_notifier(struct notifier_block *nb, 445 unsigned long action, void *unused) 446 { 447 if (action == SYS_RESTART) { 448 if (cmm_thread_ptr) 449 kthread_stop(cmm_thread_ptr); 450 cmm_thread_ptr = NULL; 451 cmm_free_pages(atomic_long_read(&loaned_pages)); 452 } 453 return NOTIFY_DONE; 454 } 455 456 static struct notifier_block cmm_reboot_nb = { 457 .notifier_call = cmm_reboot_notifier, 458 }; 459 460 /** 461 * cmm_memory_cb - Handle memory hotplug notifier calls 462 * @self: notifier block struct 463 * @action: action to take 464 * @arg: struct memory_notify data for handler 465 * 466 * Return value: 467 * NOTIFY_OK or notifier error based on subfunction return value 468 * 469 **/ 470 static int cmm_memory_cb(struct notifier_block *self, 471 unsigned long action, void *arg) 472 { 473 switch (action) { 474 case MEM_GOING_OFFLINE: 475 mutex_lock(&hotplug_mutex); 476 hotplug_occurred = 1; 477 break; 478 case MEM_OFFLINE: 479 case MEM_CANCEL_OFFLINE: 480 mutex_unlock(&hotplug_mutex); 481 cmm_dbg("Memory offline operation complete.\n"); 482 break; 483 case MEM_GOING_ONLINE: 484 case MEM_ONLINE: 485 case MEM_CANCEL_ONLINE: 486 break; 487 } 488 489 return NOTIFY_OK; 490 } 491 492 static struct notifier_block cmm_mem_nb = { 493 .notifier_call = cmm_memory_cb, 494 .priority = CMM_MEM_HOTPLUG_PRI 495 }; 496 497 #ifdef CONFIG_BALLOON_MIGRATION 498 static int cmm_migratepage(struct balloon_dev_info *b_dev_info, 499 struct page *newpage, struct page *page, 500 enum migrate_mode mode) 501 { 502 /* 503 * loan/"inflate" the newpage first. 504 * 505 * We might race against the cmm_thread who might discover after our 506 * loan request that another page is to be unloaned. However, once 507 * the cmm_thread runs again later, this error will automatically 508 * be corrected. 509 */ 510 if (plpar_page_set_loaned(newpage)) { 511 /* Unlikely, but possible. Tell the caller not to retry now. */ 512 pr_err_ratelimited("%s: Cannot set page to loaned.", __func__); 513 return -EBUSY; 514 } 515 516 /* 517 * activate/"deflate" the old page. We ignore any errors just like the 518 * other callers. 519 */ 520 plpar_page_set_active(page); 521 return 0; 522 } 523 #else /* CONFIG_BALLOON_MIGRATION */ 524 int cmm_migratepage(struct balloon_dev_info *b_dev_info, struct page *newpage, 525 struct page *page, enum migrate_mode mode); 526 #endif /* CONFIG_BALLOON_MIGRATION */ 527 528 /** 529 * cmm_init - Module initialization 530 * 531 * Return value: 532 * 0 on success / other on failure 533 **/ 534 static int cmm_init(void) 535 { 536 int rc; 537 538 if (!firmware_has_feature(FW_FEATURE_CMO) && !simulate) 539 return -EOPNOTSUPP; 540 541 balloon_devinfo_init(&b_dev_info); 542 b_dev_info.adjust_managed_page_count = true; 543 if (IS_ENABLED(CONFIG_BALLOON_MIGRATION)) 544 b_dev_info.migratepage = cmm_migratepage; 545 546 rc = register_oom_notifier(&cmm_oom_nb); 547 if (rc < 0) 548 return rc; 549 550 if ((rc = register_reboot_notifier(&cmm_reboot_nb))) 551 goto out_oom_notifier; 552 553 if ((rc = cmm_sysfs_register(&cmm_dev))) 554 goto out_reboot_notifier; 555 556 rc = register_memory_notifier(&cmm_mem_nb); 557 if (rc) 558 goto out_unregister_notifier; 559 560 if (cmm_disabled) 561 return 0; 562 563 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); 564 if (IS_ERR(cmm_thread_ptr)) { 565 rc = PTR_ERR(cmm_thread_ptr); 566 goto out_unregister_notifier; 567 } 568 569 return 0; 570 out_unregister_notifier: 571 unregister_memory_notifier(&cmm_mem_nb); 572 cmm_unregister_sysfs(&cmm_dev); 573 out_reboot_notifier: 574 unregister_reboot_notifier(&cmm_reboot_nb); 575 out_oom_notifier: 576 unregister_oom_notifier(&cmm_oom_nb); 577 return rc; 578 } 579 580 /** 581 * cmm_exit - Module exit 582 * 583 * Return value: 584 * nothing 585 **/ 586 static void cmm_exit(void) 587 { 588 if (cmm_thread_ptr) 589 kthread_stop(cmm_thread_ptr); 590 unregister_oom_notifier(&cmm_oom_nb); 591 unregister_reboot_notifier(&cmm_reboot_nb); 592 unregister_memory_notifier(&cmm_mem_nb); 593 cmm_free_pages(atomic_long_read(&loaned_pages)); 594 cmm_unregister_sysfs(&cmm_dev); 595 } 596 597 /** 598 * cmm_set_disable - Disable/Enable CMM 599 * 600 * Return value: 601 * 0 on success / other on failure 602 **/ 603 static int cmm_set_disable(const char *val, const struct kernel_param *kp) 604 { 605 int disable = simple_strtoul(val, NULL, 10); 606 607 if (disable != 0 && disable != 1) 608 return -EINVAL; 609 610 if (disable && !cmm_disabled) { 611 if (cmm_thread_ptr) 612 kthread_stop(cmm_thread_ptr); 613 cmm_thread_ptr = NULL; 614 cmm_free_pages(atomic_long_read(&loaned_pages)); 615 } else if (!disable && cmm_disabled) { 616 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); 617 if (IS_ERR(cmm_thread_ptr)) 618 return PTR_ERR(cmm_thread_ptr); 619 } 620 621 cmm_disabled = disable; 622 return 0; 623 } 624 625 module_param_call(disable, cmm_set_disable, param_get_uint, 626 &cmm_disabled, 0644); 627 MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. " 628 "[Default=" __stringify(CMM_DISABLE) "]"); 629 630 module_init(cmm_init); 631 module_exit(cmm_exit); 632