drivers/xen/balloon.c

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This source file includes following definitions.
balloon_append
balloon_retrieve
balloon_next_page
update_schedule
release_memory_resource
additional_memory_resource
reserve_additional_memory
xen_online_page
xen_memory_notifier
reserve_additional_memory
current_credit
balloon_is_inflated
increase_reservation
decrease_reservation
balloon_process
balloon_set_new_target
add_ballooned_pages
alloc_xenballooned_pages
free_xenballooned_pages
balloon_add_region
balloon_init
   1 /******************************************************************************
   2  * Xen balloon driver - enables returning/claiming memory to/from Xen.
   3  *
   4  * Copyright (c) 2003, B Dragovic
   5  * Copyright (c) 2003-2004, M Williamson, K Fraser
   6  * Copyright (c) 2005 Dan M. Smith, IBM Corporation
   7  * Copyright (c) 2010 Daniel Kiper
   8  *
   9  * Memory hotplug support was written by Daniel Kiper. Work on
  10  * it was sponsored by Google under Google Summer of Code 2010
  11  * program. Jeremy Fitzhardinge from Citrix was the mentor for
  12  * this project.
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License version 2
  16  * as published by the Free Software Foundation; or, when distributed
  17  * separately from the Linux kernel or incorporated into other
  18  * software packages, subject to the following license:
  19  *
  20  * Permission is hereby granted, free of charge, to any person obtaining a copy
  21  * of this source file (the "Software"), to deal in the Software without
  22  * restriction, including without limitation the rights to use, copy, modify,
  23  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  24  * and to permit persons to whom the Software is furnished to do so, subject to
  25  * the following conditions:
  26  *
  27  * The above copyright notice and this permission notice shall be included in
  28  * all copies or substantial portions of the Software.
  29  *
  30  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  31  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  32  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  33  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  34  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  35  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  36  * IN THE SOFTWARE.
  37  */
  38 
  39 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  40 
  41 #include <linux/cpu.h>
  42 #include <linux/kernel.h>
  43 #include <linux/sched.h>
  44 #include <linux/cred.h>
  45 #include <linux/errno.h>
  46 #include <linux/mm.h>
  47 #include <linux/memblock.h>
  48 #include <linux/pagemap.h>
  49 #include <linux/highmem.h>
  50 #include <linux/mutex.h>
  51 #include <linux/list.h>
  52 #include <linux/gfp.h>
  53 #include <linux/notifier.h>
  54 #include <linux/memory.h>
  55 #include <linux/memory_hotplug.h>
  56 #include <linux/percpu-defs.h>
  57 #include <linux/slab.h>
  58 #include <linux/sysctl.h>
  59 
  60 #include <asm/page.h>
  61 #include <asm/pgalloc.h>
  62 #include <asm/pgtable.h>
  63 #include <asm/tlb.h>
  64 
  65 #include <asm/xen/hypervisor.h>
  66 #include <asm/xen/hypercall.h>
  67 
  68 #include <xen/xen.h>
  69 #include <xen/interface/xen.h>
  70 #include <xen/interface/memory.h>
  71 #include <xen/balloon.h>
  72 #include <xen/features.h>
  73 #include <xen/page.h>
  74 #include <xen/mem-reservation.h>
  75 
  76 static int xen_hotplug_unpopulated;
  77 
  78 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
  79 
  80 static struct ctl_table balloon_table[] = {
  81         {
  82                 .procname       = "hotplug_unpopulated",
  83                 .data           = &xen_hotplug_unpopulated,
  84                 .maxlen         = sizeof(int),
  85                 .mode           = 0644,
  86                 .proc_handler   = proc_dointvec_minmax,
  87                 .extra1         = SYSCTL_ZERO,
  88                 .extra2         = SYSCTL_ONE,
  89         },
  90         { }
  91 };
  92 
  93 static struct ctl_table balloon_root[] = {
  94         {
  95                 .procname       = "balloon",
  96                 .mode           = 0555,
  97                 .child          = balloon_table,
  98         },
  99         { }
 100 };
 101 
 102 static struct ctl_table xen_root[] = {
 103         {
 104                 .procname       = "xen",
 105                 .mode           = 0555,
 106                 .child          = balloon_root,
 107         },
 108         { }
 109 };
 110 
 111 #endif
 112 
 113 /*
 114  * Use one extent per PAGE_SIZE to avoid to break down the page into
 115  * multiple frame.
 116  */
 117 #define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
 118 
 119 /*
 120  * balloon_process() state:
 121  *
 122  * BP_DONE: done or nothing to do,
 123  * BP_WAIT: wait to be rescheduled,
 124  * BP_EAGAIN: error, go to sleep,
 125  * BP_ECANCELED: error, balloon operation canceled.
 126  */
 127 
 128 enum bp_state {
 129         BP_DONE,
 130         BP_WAIT,
 131         BP_EAGAIN,
 132         BP_ECANCELED
 133 };
 134 
 135 
 136 static DEFINE_MUTEX(balloon_mutex);
 137 
 138 struct balloon_stats balloon_stats;
 139 EXPORT_SYMBOL_GPL(balloon_stats);
 140 
 141 /* We increase/decrease in batches which fit in a page */
 142 static xen_pfn_t frame_list[PAGE_SIZE / sizeof(xen_pfn_t)];
 143 
 144 
 145 /* List of ballooned pages, threaded through the mem_map array. */
 146 static LIST_HEAD(ballooned_pages);
 147 static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
 148 
 149 /* Main work function, always executed in process context. */
 150 static void balloon_process(struct work_struct *work);
 151 static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
 152 
 153 /* When ballooning out (allocating memory to return to Xen) we don't really
 154    want the kernel to try too hard since that can trigger the oom killer. */
 155 #define GFP_BALLOON \
 156         (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
 157 
 158 /* balloon_append: add the given page to the balloon. */
 159 static void balloon_append(struct page *page)
 160 {
 161         __SetPageOffline(page);
 162 
 163         /* Lowmem is re-populated first, so highmem pages go at list tail. */
 164         if (PageHighMem(page)) {
 165                 list_add_tail(&page->lru, &ballooned_pages);
 166                 balloon_stats.balloon_high++;
 167         } else {
 168                 list_add(&page->lru, &ballooned_pages);
 169                 balloon_stats.balloon_low++;
 170         }
 171         wake_up(&balloon_wq);
 172 }
 173 
 174 /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
 175 static struct page *balloon_retrieve(bool require_lowmem)
 176 {
 177         struct page *page;
 178 
 179         if (list_empty(&ballooned_pages))
 180                 return NULL;
 181 
 182         page = list_entry(ballooned_pages.next, struct page, lru);
 183         if (require_lowmem && PageHighMem(page))
 184                 return NULL;
 185         list_del(&page->lru);
 186 
 187         if (PageHighMem(page))
 188                 balloon_stats.balloon_high--;
 189         else
 190                 balloon_stats.balloon_low--;
 191 
 192         __ClearPageOffline(page);
 193         return page;
 194 }
 195 
 196 static struct page *balloon_next_page(struct page *page)
 197 {
 198         struct list_head *next = page->lru.next;
 199         if (next == &ballooned_pages)
 200                 return NULL;
 201         return list_entry(next, struct page, lru);
 202 }
 203 
 204 static enum bp_state update_schedule(enum bp_state state)
 205 {
 206         if (state == BP_WAIT)
 207                 return BP_WAIT;
 208 
 209         if (state == BP_ECANCELED)
 210                 return BP_ECANCELED;
 211 
 212         if (state == BP_DONE) {
 213                 balloon_stats.schedule_delay = 1;
 214                 balloon_stats.retry_count = 1;
 215                 return BP_DONE;
 216         }
 217 
 218         ++balloon_stats.retry_count;
 219 
 220         if (balloon_stats.max_retry_count != RETRY_UNLIMITED &&
 221                         balloon_stats.retry_count > balloon_stats.max_retry_count) {
 222                 balloon_stats.schedule_delay = 1;
 223                 balloon_stats.retry_count = 1;
 224                 return BP_ECANCELED;
 225         }
 226 
 227         balloon_stats.schedule_delay <<= 1;
 228 
 229         if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay)
 230                 balloon_stats.schedule_delay = balloon_stats.max_schedule_delay;
 231 
 232         return BP_EAGAIN;
 233 }
 234 
 235 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
 236 static void release_memory_resource(struct resource *resource)
 237 {
 238         if (!resource)
 239                 return;
 240 
 241         /*
 242          * No need to reset region to identity mapped since we now
 243          * know that no I/O can be in this region
 244          */
 245         release_resource(resource);
 246         kfree(resource);
 247 }
 248 
 249 static struct resource *additional_memory_resource(phys_addr_t size)
 250 {
 251         struct resource *res;
 252         int ret;
 253 
 254         res = kzalloc(sizeof(*res), GFP_KERNEL);
 255         if (!res)
 256                 return NULL;
 257 
 258         res->name = "System RAM";
 259         res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
 260 
 261         ret = allocate_resource(&iomem_resource, res,
 262                                 size, 0, -1,
 263                                 PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
 264         if (ret < 0) {
 265                 pr_err("Cannot allocate new System RAM resource\n");
 266                 kfree(res);
 267                 return NULL;
 268         }
 269 
 270 #ifdef CONFIG_SPARSEMEM
 271         {
 272                 unsigned long limit = 1UL << (MAX_PHYSMEM_BITS - PAGE_SHIFT);
 273                 unsigned long pfn = res->start >> PAGE_SHIFT;
 274 
 275                 if (pfn > limit) {
 276                         pr_err("New System RAM resource outside addressable RAM (%lu > %lu)\n",
 277                                pfn, limit);
 278                         release_memory_resource(res);
 279                         return NULL;
 280                 }
 281         }
 282 #endif
 283 
 284         return res;
 285 }
 286 
 287 static enum bp_state reserve_additional_memory(void)
 288 {
 289         long credit;
 290         struct resource *resource;
 291         int nid, rc;
 292         unsigned long balloon_hotplug;
 293 
 294         credit = balloon_stats.target_pages + balloon_stats.target_unpopulated
 295                 - balloon_stats.total_pages;
 296 
 297         /*
 298          * Already hotplugged enough pages?  Wait for them to be
 299          * onlined.
 300          */
 301         if (credit <= 0)
 302                 return BP_WAIT;
 303 
 304         balloon_hotplug = round_up(credit, PAGES_PER_SECTION);
 305 
 306         resource = additional_memory_resource(balloon_hotplug * PAGE_SIZE);
 307         if (!resource)
 308                 goto err;
 309 
 310         nid = memory_add_physaddr_to_nid(resource->start);
 311 
 312 #ifdef CONFIG_XEN_HAVE_PVMMU
 313         /*
 314          * We don't support PV MMU when Linux and Xen is using
 315          * different page granularity.
 316          */
 317         BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
 318 
 319         /*
 320          * add_memory() will build page tables for the new memory so
 321          * the p2m must contain invalid entries so the correct
 322          * non-present PTEs will be written.
 323          *
 324          * If a failure occurs, the original (identity) p2m entries
 325          * are not restored since this region is now known not to
 326          * conflict with any devices.
 327          */ 
 328         if (!xen_feature(XENFEAT_auto_translated_physmap)) {
 329                 unsigned long pfn, i;
 330 
 331                 pfn = PFN_DOWN(resource->start);
 332                 for (i = 0; i < balloon_hotplug; i++) {
 333                         if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
 334                                 pr_warn("set_phys_to_machine() failed, no memory added\n");
 335                                 goto err;
 336                         }
 337                 }
 338         }
 339 #endif
 340 
 341         /*
 342          * add_memory_resource() will call online_pages() which in its turn
 343          * will call xen_online_page() callback causing deadlock if we don't
 344          * release balloon_mutex here. Unlocking here is safe because the
 345          * callers drop the mutex before trying again.
 346          */
 347         mutex_unlock(&balloon_mutex);
 348         /* add_memory_resource() requires the device_hotplug lock */
 349         lock_device_hotplug();
 350         rc = add_memory_resource(nid, resource);
 351         unlock_device_hotplug();
 352         mutex_lock(&balloon_mutex);
 353 
 354         if (rc) {
 355                 pr_warn("Cannot add additional memory (%i)\n", rc);
 356                 goto err;
 357         }
 358 
 359         balloon_stats.total_pages += balloon_hotplug;
 360 
 361         return BP_WAIT;
 362   err:
 363         release_memory_resource(resource);
 364         return BP_ECANCELED;
 365 }
 366 
 367 static void xen_online_page(struct page *page, unsigned int order)
 368 {
 369         unsigned long i, size = (1 << order);
 370         unsigned long start_pfn = page_to_pfn(page);
 371         struct page *p;
 372 
 373         pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn);
 374         mutex_lock(&balloon_mutex);
 375         for (i = 0; i < size; i++) {
 376                 p = pfn_to_page(start_pfn + i);
 377                 __online_page_set_limits(p);
 378                 balloon_append(p);
 379         }
 380         mutex_unlock(&balloon_mutex);
 381 }
 382 
 383 static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v)
 384 {
 385         if (val == MEM_ONLINE)
 386                 schedule_delayed_work(&balloon_worker, 0);
 387 
 388         return NOTIFY_OK;
 389 }
 390 
 391 static struct notifier_block xen_memory_nb = {
 392         .notifier_call = xen_memory_notifier,
 393         .priority = 0
 394 };
 395 #else
 396 static enum bp_state reserve_additional_memory(void)
 397 {
 398         balloon_stats.target_pages = balloon_stats.current_pages +
 399                                      balloon_stats.target_unpopulated;
 400         return BP_ECANCELED;
 401 }
 402 #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
 403 
 404 static long current_credit(void)
 405 {
 406         return balloon_stats.target_pages - balloon_stats.current_pages;
 407 }
 408 
 409 static bool balloon_is_inflated(void)
 410 {
 411         return balloon_stats.balloon_low || balloon_stats.balloon_high;
 412 }
 413 
 414 static enum bp_state increase_reservation(unsigned long nr_pages)
 415 {
 416         int rc;
 417         unsigned long i;
 418         struct page   *page;
 419 
 420         if (nr_pages > ARRAY_SIZE(frame_list))
 421                 nr_pages = ARRAY_SIZE(frame_list);
 422 
 423         page = list_first_entry_or_null(&ballooned_pages, struct page, lru);
 424         for (i = 0; i < nr_pages; i++) {
 425                 if (!page) {
 426                         nr_pages = i;
 427                         break;
 428                 }
 429 
 430                 frame_list[i] = page_to_xen_pfn(page);
 431                 page = balloon_next_page(page);
 432         }
 433 
 434         rc = xenmem_reservation_increase(nr_pages, frame_list);
 435         if (rc <= 0)
 436                 return BP_EAGAIN;
 437 
 438         for (i = 0; i < rc; i++) {
 439                 page = balloon_retrieve(false);
 440                 BUG_ON(page == NULL);
 441 
 442                 xenmem_reservation_va_mapping_update(1, &page, &frame_list[i]);
 443 
 444                 /* Relinquish the page back to the allocator. */
 445                 free_reserved_page(page);
 446         }
 447 
 448         balloon_stats.current_pages += rc;
 449 
 450         return BP_DONE;
 451 }
 452 
 453 static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 454 {
 455         enum bp_state state = BP_DONE;
 456         unsigned long i;
 457         struct page *page, *tmp;
 458         int ret;
 459         LIST_HEAD(pages);
 460 
 461         if (nr_pages > ARRAY_SIZE(frame_list))
 462                 nr_pages = ARRAY_SIZE(frame_list);
 463 
 464         for (i = 0; i < nr_pages; i++) {
 465                 page = alloc_page(gfp);
 466                 if (page == NULL) {
 467                         nr_pages = i;
 468                         state = BP_EAGAIN;
 469                         break;
 470                 }
 471                 adjust_managed_page_count(page, -1);
 472                 xenmem_reservation_scrub_page(page);
 473                 list_add(&page->lru, &pages);
 474         }
 475 
 476         /*
 477          * Ensure that ballooned highmem pages don't have kmaps.
 478          *
 479          * Do this before changing the p2m as kmap_flush_unused()
 480          * reads PTEs to obtain pages (and hence needs the original
 481          * p2m entry).
 482          */
 483         kmap_flush_unused();
 484 
 485         /*
 486          * Setup the frame, update direct mapping, invalidate P2M,
 487          * and add to balloon.
 488          */
 489         i = 0;
 490         list_for_each_entry_safe(page, tmp, &pages, lru) {
 491                 frame_list[i++] = xen_page_to_gfn(page);
 492 
 493                 xenmem_reservation_va_mapping_reset(1, &page);
 494 
 495                 list_del(&page->lru);
 496 
 497                 balloon_append(page);
 498         }
 499 
 500         flush_tlb_all();
 501 
 502         ret = xenmem_reservation_decrease(nr_pages, frame_list);
 503         BUG_ON(ret != nr_pages);
 504 
 505         balloon_stats.current_pages -= nr_pages;
 506 
 507         return state;
 508 }
 509 
 510 /*
 511  * As this is a work item it is guaranteed to run as a single instance only.
 512  * We may of course race updates of the target counts (which are protected
 513  * by the balloon lock), or with changes to the Xen hard limit, but we will
 514  * recover from these in time.
 515  */
 516 static void balloon_process(struct work_struct *work)
 517 {
 518         enum bp_state state = BP_DONE;
 519         long credit;
 520 
 521 
 522         do {
 523                 mutex_lock(&balloon_mutex);
 524 
 525                 credit = current_credit();
 526 
 527                 if (credit > 0) {
 528                         if (balloon_is_inflated())
 529                                 state = increase_reservation(credit);
 530                         else
 531                                 state = reserve_additional_memory();
 532                 }
 533 
 534                 if (credit < 0) {
 535                         long n_pages;
 536 
 537                         n_pages = min(-credit, si_mem_available());
 538                         state = decrease_reservation(n_pages, GFP_BALLOON);
 539                         if (state == BP_DONE && n_pages != -credit &&
 540                             n_pages < totalreserve_pages)
 541                                 state = BP_EAGAIN;
 542                 }
 543 
 544                 state = update_schedule(state);
 545 
 546                 mutex_unlock(&balloon_mutex);
 547 
 548                 cond_resched();
 549 
 550         } while (credit && state == BP_DONE);
 551 
 552         /* Schedule more work if there is some still to be done. */
 553         if (state == BP_EAGAIN)
 554                 schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ);
 555 }
 556 
 557 /* Resets the Xen limit, sets new target, and kicks off processing. */
 558 void balloon_set_new_target(unsigned long target)
 559 {
 560         /* No need for lock. Not read-modify-write updates. */
 561         balloon_stats.target_pages = target;
 562         schedule_delayed_work(&balloon_worker, 0);
 563 }
 564 EXPORT_SYMBOL_GPL(balloon_set_new_target);
 565 
 566 static int add_ballooned_pages(int nr_pages)
 567 {
 568         enum bp_state st;
 569 
 570         if (xen_hotplug_unpopulated) {
 571                 st = reserve_additional_memory();
 572                 if (st != BP_ECANCELED) {
 573                         mutex_unlock(&balloon_mutex);
 574                         wait_event(balloon_wq,
 575                                    !list_empty(&ballooned_pages));
 576                         mutex_lock(&balloon_mutex);
 577                         return 0;
 578                 }
 579         }
 580 
 581         if (si_mem_available() < nr_pages)
 582                 return -ENOMEM;
 583 
 584         st = decrease_reservation(nr_pages, GFP_USER);
 585         if (st != BP_DONE)
 586                 return -ENOMEM;
 587 
 588         return 0;
 589 }
 590 
 591 /**
 592  * alloc_xenballooned_pages - get pages that have been ballooned out
 593  * @nr_pages: Number of pages to get
 594  * @pages: pages returned
 595  * @return 0 on success, error otherwise
 596  */
 597 int alloc_xenballooned_pages(int nr_pages, struct page **pages)
 598 {
 599         int pgno = 0;
 600         struct page *page;
 601         int ret;
 602 
 603         mutex_lock(&balloon_mutex);
 604 
 605         balloon_stats.target_unpopulated += nr_pages;
 606 
 607         while (pgno < nr_pages) {
 608                 page = balloon_retrieve(true);
 609                 if (page) {
 610                         pages[pgno++] = page;
 611 #ifdef CONFIG_XEN_HAVE_PVMMU
 612                         /*
 613                          * We don't support PV MMU when Linux and Xen is using
 614                          * different page granularity.
 615                          */
 616                         BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
 617 
 618                         if (!xen_feature(XENFEAT_auto_translated_physmap)) {
 619                                 ret = xen_alloc_p2m_entry(page_to_pfn(page));
 620                                 if (ret < 0)
 621                                         goto out_undo;
 622                         }
 623 #endif
 624                 } else {
 625                         ret = add_ballooned_pages(nr_pages - pgno);
 626                         if (ret < 0)
 627                                 goto out_undo;
 628                 }
 629         }
 630         mutex_unlock(&balloon_mutex);
 631         return 0;
 632  out_undo:
 633         mutex_unlock(&balloon_mutex);
 634         free_xenballooned_pages(pgno, pages);
 635         return ret;
 636 }
 637 EXPORT_SYMBOL(alloc_xenballooned_pages);
 638 
 639 /**
 640  * free_xenballooned_pages - return pages retrieved with get_ballooned_pages
 641  * @nr_pages: Number of pages
 642  * @pages: pages to return
 643  */
 644 void free_xenballooned_pages(int nr_pages, struct page **pages)
 645 {
 646         int i;
 647 
 648         mutex_lock(&balloon_mutex);
 649 
 650         for (i = 0; i < nr_pages; i++) {
 651                 if (pages[i])
 652                         balloon_append(pages[i]);
 653         }
 654 
 655         balloon_stats.target_unpopulated -= nr_pages;
 656 
 657         /* The balloon may be too large now. Shrink it if needed. */
 658         if (current_credit())
 659                 schedule_delayed_work(&balloon_worker, 0);
 660 
 661         mutex_unlock(&balloon_mutex);
 662 }
 663 EXPORT_SYMBOL(free_xenballooned_pages);
 664 
 665 #ifdef CONFIG_XEN_PV
 666 static void __init balloon_add_region(unsigned long start_pfn,
 667                                       unsigned long pages)
 668 {
 669         unsigned long pfn, extra_pfn_end;
 670 
 671         /*
 672          * If the amount of usable memory has been limited (e.g., with
 673          * the 'mem' command line parameter), don't add pages beyond
 674          * this limit.
 675          */
 676         extra_pfn_end = min(max_pfn, start_pfn + pages);
 677 
 678         for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) {
 679                 /* totalram_pages and totalhigh_pages do not
 680                    include the boot-time balloon extension, so
 681                    don't subtract from it. */
 682                 balloon_append(pfn_to_page(pfn));
 683         }
 684 
 685         balloon_stats.total_pages += extra_pfn_end - start_pfn;
 686 }
 687 #endif
 688 
 689 static int __init balloon_init(void)
 690 {
 691         if (!xen_domain())
 692                 return -ENODEV;
 693 
 694         pr_info("Initialising balloon driver\n");
 695 
 696 #ifdef CONFIG_XEN_PV
 697         balloon_stats.current_pages = xen_pv_domain()
 698                 ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn)
 699                 : get_num_physpages();
 700 #else
 701         balloon_stats.current_pages = get_num_physpages();
 702 #endif
 703         balloon_stats.target_pages  = balloon_stats.current_pages;
 704         balloon_stats.balloon_low   = 0;
 705         balloon_stats.balloon_high  = 0;
 706         balloon_stats.total_pages   = balloon_stats.current_pages;
 707 
 708         balloon_stats.schedule_delay = 1;
 709         balloon_stats.max_schedule_delay = 32;
 710         balloon_stats.retry_count = 1;
 711         balloon_stats.max_retry_count = 4;
 712 
 713 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
 714         set_online_page_callback(&xen_online_page);
 715         register_memory_notifier(&xen_memory_nb);
 716         register_sysctl_table(xen_root);
 717 #endif
 718 
 719 #ifdef CONFIG_XEN_PV
 720         {
 721                 int i;
 722 
 723                 /*
 724                  * Initialize the balloon with pages from the extra memory
 725                  * regions (see arch/x86/xen/setup.c).
 726                  */
 727                 for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++)
 728                         if (xen_extra_mem[i].n_pfns)
 729                                 balloon_add_region(xen_extra_mem[i].start_pfn,
 730                                                    xen_extra_mem[i].n_pfns);
 731         }
 732 #endif
 733 
 734         /* Init the xen-balloon driver. */
 735         xen_balloon_init();
 736 
 737         return 0;
 738 }
 739 subsys_initcall(balloon_init);
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/xen/balloon.c

DEFINITIONS
