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/freezer.h>
47 #include <linux/kthread.h>
48 #include <linux/mm.h>
49 #include <linux/memblock.h>
50 #include <linux/pagemap.h>
51 #include <linux/highmem.h>
52 #include <linux/mutex.h>
53 #include <linux/list.h>
54 #include <linux/gfp.h>
55 #include <linux/notifier.h>
56 #include <linux/memory.h>
57 #include <linux/memory_hotplug.h>
58 #include <linux/percpu-defs.h>
59 #include <linux/slab.h>
60 #include <linux/sysctl.h>
61 #include <linux/moduleparam.h>
62
63 #include <asm/page.h>
64 #include <asm/tlb.h>
65
66 #include <asm/xen/hypervisor.h>
67 #include <asm/xen/hypercall.h>
68
69 #include <xen/xen.h>
70 #include <xen/interface/xen.h>
71 #include <xen/interface/memory.h>
72 #include <xen/balloon.h>
73 #include <xen/features.h>
74 #include <xen/page.h>
75 #include <xen/mem-reservation.h>
76
77 #undef MODULE_PARAM_PREFIX
78 #define MODULE_PARAM_PREFIX "xen."
79
80 static uint __read_mostly balloon_boot_timeout = 180;
81 module_param(balloon_boot_timeout, uint, 0444);
82
83 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
84 static int xen_hotplug_unpopulated;
85
86 static struct ctl_table balloon_table[] = {
87 {
88 .procname = "hotplug_unpopulated",
89 .data = &xen_hotplug_unpopulated,
90 .maxlen = sizeof(int),
91 .mode = 0644,
92 .proc_handler = proc_dointvec_minmax,
93 .extra1 = SYSCTL_ZERO,
94 .extra2 = SYSCTL_ONE,
95 },
96 { }
97 };
98
99 static struct ctl_table balloon_root[] = {
100 {
101 .procname = "balloon",
102 .mode = 0555,
103 .child = balloon_table,
104 },
105 { }
106 };
107
108 static struct ctl_table xen_root[] = {
109 {
110 .procname = "xen",
111 .mode = 0555,
112 .child = balloon_root,
113 },
114 { }
115 };
116
117 #else
118 #define xen_hotplug_unpopulated 0
119 #endif
120
121 /*
122 * Use one extent per PAGE_SIZE to avoid to break down the page into
123 * multiple frame.
124 */
125 #define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
126
127 /*
128 * balloon_thread() state:
129 *
130 * BP_DONE: done or nothing to do,
131 * BP_WAIT: wait to be rescheduled,
132 * BP_EAGAIN: error, go to sleep,
133 * BP_ECANCELED: error, balloon operation canceled.
134 */
135
136 static enum bp_state {
137 BP_DONE,
138 BP_WAIT,
139 BP_EAGAIN,
140 BP_ECANCELED
141 } balloon_state = BP_DONE;
142
143 /* Main waiting point for xen-balloon thread. */
144 static DECLARE_WAIT_QUEUE_HEAD(balloon_thread_wq);
145
146 static DEFINE_MUTEX(balloon_mutex);
147
148 struct balloon_stats balloon_stats;
149 EXPORT_SYMBOL_GPL(balloon_stats);
150
151 /* We increase/decrease in batches which fit in a page */
152 static xen_pfn_t frame_list[PAGE_SIZE / sizeof(xen_pfn_t)];
153
154
155 /* List of ballooned pages, threaded through the mem_map array. */
156 static LIST_HEAD(ballooned_pages);
157 static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
158
159 /* When ballooning out (allocating memory to return to Xen) we don't really
160 want the kernel to try too hard since that can trigger the oom killer. */
161 #define GFP_BALLOON \
162 (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
163
164 /* balloon_append: add the given page to the balloon. */
balloon_append(struct page * page)165 static void balloon_append(struct page *page)
166 {
167 __SetPageOffline(page);
168
169 /* Lowmem is re-populated first, so highmem pages go at list tail. */
170 if (PageHighMem(page)) {
171 list_add_tail(&page->lru, &ballooned_pages);
172 balloon_stats.balloon_high++;
173 } else {
174 list_add(&page->lru, &ballooned_pages);
175 balloon_stats.balloon_low++;
176 }
177 wake_up(&balloon_wq);
178 }
179
180 /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
balloon_retrieve(bool require_lowmem)181 static struct page *balloon_retrieve(bool require_lowmem)
182 {
183 struct page *page;
184
185 if (list_empty(&ballooned_pages))
186 return NULL;
187
188 page = list_entry(ballooned_pages.next, struct page, lru);
189 if (require_lowmem && PageHighMem(page))
190 return NULL;
191 list_del(&page->lru);
192
193 if (PageHighMem(page))
194 balloon_stats.balloon_high--;
195 else
196 balloon_stats.balloon_low--;
197
198 __ClearPageOffline(page);
199 return page;
200 }
201
balloon_next_page(struct page * page)202 static struct page *balloon_next_page(struct page *page)
203 {
204 struct list_head *next = page->lru.next;
205 if (next == &ballooned_pages)
206 return NULL;
207 return list_entry(next, struct page, lru);
208 }
209
update_schedule(void)210 static void update_schedule(void)
211 {
212 if (balloon_state == BP_WAIT || balloon_state == BP_ECANCELED)
213 return;
214
215 if (balloon_state == BP_DONE) {
216 balloon_stats.schedule_delay = 1;
217 balloon_stats.retry_count = 1;
218 return;
219 }
220
221 ++balloon_stats.retry_count;
222
223 if (balloon_stats.max_retry_count != RETRY_UNLIMITED &&
224 balloon_stats.retry_count > balloon_stats.max_retry_count) {
225 balloon_stats.schedule_delay = 1;
226 balloon_stats.retry_count = 1;
227 balloon_state = BP_ECANCELED;
228 return;
229 }
230
231 balloon_stats.schedule_delay <<= 1;
232
233 if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay)
234 balloon_stats.schedule_delay = balloon_stats.max_schedule_delay;
235
236 balloon_state = BP_EAGAIN;
237 }
238
239 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
release_memory_resource(struct resource * resource)240 static void release_memory_resource(struct resource *resource)
241 {
242 if (!resource)
243 return;
244
245 /*
246 * No need to reset region to identity mapped since we now
247 * know that no I/O can be in this region
248 */
249 release_resource(resource);
250 kfree(resource);
251 }
252
additional_memory_resource(phys_addr_t size)253 static struct resource *additional_memory_resource(phys_addr_t size)
254 {
255 struct resource *res;
256 int ret;
257
258 res = kzalloc(sizeof(*res), GFP_KERNEL);
259 if (!res)
260 return NULL;
261
262 res->name = "System RAM";
263 res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
264
265 ret = allocate_resource(&iomem_resource, res,
266 size, 0, -1,
267 PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
268 if (ret < 0) {
269 pr_err("Cannot allocate new System RAM resource\n");
270 kfree(res);
271 return NULL;
272 }
273
274 return res;
275 }
276
reserve_additional_memory(void)277 static enum bp_state reserve_additional_memory(void)
278 {
279 long credit;
280 struct resource *resource;
281 int nid, rc;
282 unsigned long balloon_hotplug;
283
284 credit = balloon_stats.target_pages + balloon_stats.target_unpopulated
285 - balloon_stats.total_pages;
286
287 /*
288 * Already hotplugged enough pages? Wait for them to be
289 * onlined.
290 */
291 if (credit <= 0)
292 return BP_WAIT;
293
294 balloon_hotplug = round_up(credit, PAGES_PER_SECTION);
295
296 resource = additional_memory_resource(balloon_hotplug * PAGE_SIZE);
297 if (!resource)
298 goto err;
299
300 nid = memory_add_physaddr_to_nid(resource->start);
301
302 #ifdef CONFIG_XEN_HAVE_PVMMU
303 /*
304 * We don't support PV MMU when Linux and Xen is using
305 * different page granularity.
306 */
307 BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
308
309 /*
310 * add_memory() will build page tables for the new memory so
311 * the p2m must contain invalid entries so the correct
312 * non-present PTEs will be written.
313 *
314 * If a failure occurs, the original (identity) p2m entries
315 * are not restored since this region is now known not to
316 * conflict with any devices.
317 */
318 if (!xen_feature(XENFEAT_auto_translated_physmap)) {
319 unsigned long pfn, i;
320
321 pfn = PFN_DOWN(resource->start);
322 for (i = 0; i < balloon_hotplug; i++) {
323 if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
324 pr_warn("set_phys_to_machine() failed, no memory added\n");
325 goto err;
326 }
327 }
328 }
329 #endif
330
331 /*
332 * add_memory_resource() will call online_pages() which in its turn
333 * will call xen_online_page() callback causing deadlock if we don't
334 * release balloon_mutex here. Unlocking here is safe because the
335 * callers drop the mutex before trying again.
336 */
337 mutex_unlock(&balloon_mutex);
338 /* add_memory_resource() requires the device_hotplug lock */
339 lock_device_hotplug();
340 rc = add_memory_resource(nid, resource, MHP_MERGE_RESOURCE);
341 unlock_device_hotplug();
342 mutex_lock(&balloon_mutex);
343
344 if (rc) {
345 pr_warn("Cannot add additional memory (%i)\n", rc);
346 goto err;
347 }
348
349 balloon_stats.total_pages += balloon_hotplug;
350
351 return BP_WAIT;
352 err:
353 release_memory_resource(resource);
354 return BP_ECANCELED;
355 }
356
xen_online_page(struct page * page,unsigned int order)357 static void xen_online_page(struct page *page, unsigned int order)
358 {
359 unsigned long i, size = (1 << order);
360 unsigned long start_pfn = page_to_pfn(page);
361 struct page *p;
362
363 pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn);
364 mutex_lock(&balloon_mutex);
365 for (i = 0; i < size; i++) {
366 p = pfn_to_page(start_pfn + i);
367 balloon_append(p);
368 }
369 mutex_unlock(&balloon_mutex);
370 }
371
xen_memory_notifier(struct notifier_block * nb,unsigned long val,void * v)372 static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v)
373 {
374 if (val == MEM_ONLINE)
375 wake_up(&balloon_thread_wq);
376
377 return NOTIFY_OK;
378 }
379
380 static struct notifier_block xen_memory_nb = {
381 .notifier_call = xen_memory_notifier,
382 .priority = 0
383 };
384 #else
reserve_additional_memory(void)385 static enum bp_state reserve_additional_memory(void)
386 {
387 balloon_stats.target_pages = balloon_stats.current_pages +
388 balloon_stats.target_unpopulated;
389 return BP_ECANCELED;
390 }
391 #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
392
current_credit(void)393 static long current_credit(void)
394 {
395 return balloon_stats.target_pages - balloon_stats.current_pages;
396 }
397
balloon_is_inflated(void)398 static bool balloon_is_inflated(void)
399 {
400 return balloon_stats.balloon_low || balloon_stats.balloon_high;
401 }
402
increase_reservation(unsigned long nr_pages)403 static enum bp_state increase_reservation(unsigned long nr_pages)
404 {
405 int rc;
406 unsigned long i;
407 struct page *page;
408
409 if (nr_pages > ARRAY_SIZE(frame_list))
410 nr_pages = ARRAY_SIZE(frame_list);
411
412 page = list_first_entry_or_null(&ballooned_pages, struct page, lru);
413 for (i = 0; i < nr_pages; i++) {
414 if (!page) {
415 nr_pages = i;
416 break;
417 }
418
419 frame_list[i] = page_to_xen_pfn(page);
420 page = balloon_next_page(page);
421 }
422
423 rc = xenmem_reservation_increase(nr_pages, frame_list);
424 if (rc <= 0)
425 return BP_EAGAIN;
426
427 for (i = 0; i < rc; i++) {
428 page = balloon_retrieve(false);
429 BUG_ON(page == NULL);
430
431 xenmem_reservation_va_mapping_update(1, &page, &frame_list[i]);
432
433 /* Relinquish the page back to the allocator. */
434 free_reserved_page(page);
435 }
436
437 balloon_stats.current_pages += rc;
438
439 return BP_DONE;
440 }
441
decrease_reservation(unsigned long nr_pages,gfp_t gfp)442 static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
443 {
444 enum bp_state state = BP_DONE;
445 unsigned long i;
446 struct page *page, *tmp;
447 int ret;
448 LIST_HEAD(pages);
449
450 if (nr_pages > ARRAY_SIZE(frame_list))
451 nr_pages = ARRAY_SIZE(frame_list);
452
453 for (i = 0; i < nr_pages; i++) {
454 page = alloc_page(gfp);
455 if (page == NULL) {
456 nr_pages = i;
457 state = BP_EAGAIN;
458 break;
459 }
460 adjust_managed_page_count(page, -1);
461 xenmem_reservation_scrub_page(page);
462 list_add(&page->lru, &pages);
463 }
464
465 /*
466 * Ensure that ballooned highmem pages don't have kmaps.
467 *
468 * Do this before changing the p2m as kmap_flush_unused()
469 * reads PTEs to obtain pages (and hence needs the original
470 * p2m entry).
471 */
472 kmap_flush_unused();
473
474 /*
475 * Setup the frame, update direct mapping, invalidate P2M,
476 * and add to balloon.
477 */
478 i = 0;
479 list_for_each_entry_safe(page, tmp, &pages, lru) {
480 frame_list[i++] = xen_page_to_gfn(page);
481
482 xenmem_reservation_va_mapping_reset(1, &page);
483
484 list_del(&page->lru);
485
486 balloon_append(page);
487 }
488
489 flush_tlb_all();
490
491 ret = xenmem_reservation_decrease(nr_pages, frame_list);
492 BUG_ON(ret != nr_pages);
493
494 balloon_stats.current_pages -= nr_pages;
495
496 return state;
497 }
498
499 /*
500 * Stop waiting if either state is BP_DONE and ballooning action is
501 * needed, or if the credit has changed while state is not BP_DONE.
502 */
balloon_thread_cond(long credit)503 static bool balloon_thread_cond(long credit)
504 {
505 if (balloon_state == BP_DONE)
506 credit = 0;
507
508 return current_credit() != credit || kthread_should_stop();
509 }
510
511 /*
512 * As this is a kthread it is guaranteed to run as a single instance only.
513 * We may of course race updates of the target counts (which are protected
514 * by the balloon lock), or with changes to the Xen hard limit, but we will
515 * recover from these in time.
516 */
balloon_thread(void * unused)517 static int balloon_thread(void *unused)
518 {
519 long credit;
520 unsigned long timeout;
521
522 set_freezable();
523 for (;;) {
524 switch (balloon_state) {
525 case BP_DONE:
526 case BP_ECANCELED:
527 timeout = 3600 * HZ;
528 break;
529 case BP_EAGAIN:
530 timeout = balloon_stats.schedule_delay * HZ;
531 break;
532 case BP_WAIT:
533 timeout = HZ;
534 break;
535 }
536
537 credit = current_credit();
538
539 wait_event_freezable_timeout(balloon_thread_wq,
540 balloon_thread_cond(credit), timeout);
541
542 if (kthread_should_stop())
543 return 0;
544
545 mutex_lock(&balloon_mutex);
546
547 credit = current_credit();
548
549 if (credit > 0) {
550 if (balloon_is_inflated())
551 balloon_state = increase_reservation(credit);
552 else
553 balloon_state = reserve_additional_memory();
554 }
555
556 if (credit < 0) {
557 long n_pages;
558
559 n_pages = min(-credit, si_mem_available());
560 balloon_state = decrease_reservation(n_pages,
561 GFP_BALLOON);
562 if (balloon_state == BP_DONE && n_pages != -credit &&
563 n_pages < totalreserve_pages)
564 balloon_state = BP_EAGAIN;
565 }
566
567 update_schedule();
568
569 mutex_unlock(&balloon_mutex);
570
571 cond_resched();
572 }
573 }
574
575 /* Resets the Xen limit, sets new target, and kicks off processing. */
balloon_set_new_target(unsigned long target)576 void balloon_set_new_target(unsigned long target)
577 {
578 /* No need for lock. Not read-modify-write updates. */
579 balloon_stats.target_pages = target;
580 wake_up(&balloon_thread_wq);
581 }
582 EXPORT_SYMBOL_GPL(balloon_set_new_target);
583
584 #ifndef CONFIG_XEN_UNPOPULATED_ALLOC
add_ballooned_pages(unsigned int nr_pages)585 static int add_ballooned_pages(unsigned int nr_pages)
586 {
587 enum bp_state st;
588
589 if (xen_hotplug_unpopulated) {
590 st = reserve_additional_memory();
591 if (st != BP_ECANCELED) {
592 int rc;
593
594 mutex_unlock(&balloon_mutex);
595 rc = wait_event_interruptible(balloon_wq,
596 !list_empty(&ballooned_pages));
597 mutex_lock(&balloon_mutex);
598 return rc ? -ENOMEM : 0;
599 }
600 }
601
602 if (si_mem_available() < nr_pages)
603 return -ENOMEM;
604
605 st = decrease_reservation(nr_pages, GFP_USER);
606 if (st != BP_DONE)
607 return -ENOMEM;
608
609 return 0;
610 }
611
612 /**
613 * xen_alloc_unpopulated_pages - get pages that have been ballooned out
614 * @nr_pages: Number of pages to get
615 * @pages: pages returned
616 * @return 0 on success, error otherwise
617 */
xen_alloc_unpopulated_pages(unsigned int nr_pages,struct page ** pages)618 int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
619 {
620 unsigned int pgno = 0;
621 struct page *page;
622 int ret;
623
624 mutex_lock(&balloon_mutex);
625
626 balloon_stats.target_unpopulated += nr_pages;
627
628 while (pgno < nr_pages) {
629 page = balloon_retrieve(true);
630 if (page) {
631 pages[pgno++] = page;
632 #ifdef CONFIG_XEN_HAVE_PVMMU
633 /*
634 * We don't support PV MMU when Linux and Xen is using
635 * different page granularity.
636 */
637 BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
638
639 if (!xen_feature(XENFEAT_auto_translated_physmap)) {
640 ret = xen_alloc_p2m_entry(page_to_pfn(page));
641 if (ret < 0)
642 goto out_undo;
643 }
644 #endif
645 } else {
646 ret = add_ballooned_pages(nr_pages - pgno);
647 if (ret < 0)
648 goto out_undo;
649 }
650 }
651 mutex_unlock(&balloon_mutex);
652 return 0;
653 out_undo:
654 mutex_unlock(&balloon_mutex);
655 xen_free_unpopulated_pages(pgno, pages);
656 /*
657 * NB: free_xenballooned_pages will only subtract pgno pages, but since
658 * target_unpopulated is incremented with nr_pages at the start we need
659 * to remove the remaining ones also, or accounting will be screwed.
660 */
661 balloon_stats.target_unpopulated -= nr_pages - pgno;
662 return ret;
663 }
664 EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
665
666 /**
667 * xen_free_unpopulated_pages - return pages retrieved with get_ballooned_pages
668 * @nr_pages: Number of pages
669 * @pages: pages to return
670 */
xen_free_unpopulated_pages(unsigned int nr_pages,struct page ** pages)671 void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
672 {
673 unsigned int i;
674
675 mutex_lock(&balloon_mutex);
676
677 for (i = 0; i < nr_pages; i++) {
678 if (pages[i])
679 balloon_append(pages[i]);
680 }
681
682 balloon_stats.target_unpopulated -= nr_pages;
683
684 /* The balloon may be too large now. Shrink it if needed. */
685 if (current_credit())
686 wake_up(&balloon_thread_wq);
687
688 mutex_unlock(&balloon_mutex);
689 }
690 EXPORT_SYMBOL(xen_free_unpopulated_pages);
691
692 #if defined(CONFIG_XEN_PV)
balloon_add_region(unsigned long start_pfn,unsigned long pages)693 static void __init balloon_add_region(unsigned long start_pfn,
694 unsigned long pages)
695 {
696 unsigned long pfn, extra_pfn_end;
697
698 /*
699 * If the amount of usable memory has been limited (e.g., with
700 * the 'mem' command line parameter), don't add pages beyond
701 * this limit.
702 */
703 extra_pfn_end = min(max_pfn, start_pfn + pages);
704
705 for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) {
706 /* totalram_pages and totalhigh_pages do not
707 include the boot-time balloon extension, so
708 don't subtract from it. */
709 balloon_append(pfn_to_page(pfn));
710 }
711
712 balloon_stats.total_pages += extra_pfn_end - start_pfn;
713 }
714 #endif
715 #endif
716
balloon_init(void)717 static int __init balloon_init(void)
718 {
719 struct task_struct *task;
720
721 if (!xen_domain())
722 return -ENODEV;
723
724 pr_info("Initialising balloon driver\n");
725
726 #ifdef CONFIG_XEN_PV
727 balloon_stats.current_pages = xen_pv_domain()
728 ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn)
729 : get_num_physpages();
730 #else
731 balloon_stats.current_pages = get_num_physpages();
732 #endif
733 balloon_stats.target_pages = balloon_stats.current_pages;
734 balloon_stats.balloon_low = 0;
735 balloon_stats.balloon_high = 0;
736 balloon_stats.total_pages = balloon_stats.current_pages;
737
738 balloon_stats.schedule_delay = 1;
739 balloon_stats.max_schedule_delay = 32;
740 balloon_stats.retry_count = 1;
741 balloon_stats.max_retry_count = 4;
742
743 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
744 set_online_page_callback(&xen_online_page);
745 register_memory_notifier(&xen_memory_nb);
746 register_sysctl_table(xen_root);
747 #endif
748
749 #if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC)
750 {
751 int i;
752
753 /*
754 * Initialize the balloon with pages from the extra memory
755 * regions (see arch/x86/xen/setup.c).
756 */
757 for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++)
758 if (xen_extra_mem[i].n_pfns)
759 balloon_add_region(xen_extra_mem[i].start_pfn,
760 xen_extra_mem[i].n_pfns);
761 }
762 #endif
763
764 task = kthread_run(balloon_thread, NULL, "xen-balloon");
765 if (IS_ERR(task)) {
766 pr_err("xen-balloon thread could not be started, ballooning will not work!\n");
767 return PTR_ERR(task);
768 }
769
770 /* Init the xen-balloon driver. */
771 xen_balloon_init();
772
773 return 0;
774 }
775 subsys_initcall(balloon_init);
776
balloon_wait_finish(void)777 static int __init balloon_wait_finish(void)
778 {
779 long credit, last_credit = 0;
780 unsigned long last_changed = 0;
781
782 if (!xen_domain())
783 return -ENODEV;
784
785 /* PV guests don't need to wait. */
786 if (xen_pv_domain() || !current_credit())
787 return 0;
788
789 pr_notice("Waiting for initial ballooning down having finished.\n");
790
791 while ((credit = current_credit()) < 0) {
792 if (credit != last_credit) {
793 last_changed = jiffies;
794 last_credit = credit;
795 }
796 if (balloon_state == BP_ECANCELED) {
797 pr_warn_once("Initial ballooning failed, %ld pages need to be freed.\n",
798 -credit);
799 if (jiffies - last_changed >= HZ * balloon_boot_timeout)
800 panic("Initial ballooning failed!\n");
801 }
802
803 schedule_timeout_interruptible(HZ / 10);
804 }
805
806 pr_notice("Initial ballooning down finished.\n");
807
808 return 0;
809 }
810 late_initcall_sync(balloon_wait_finish);
811