]> Git Repo - linux.git/blob - drivers/xen/balloon.c
platform/x86: amd-pmc: Move to later in the suspend process
[linux.git] / drivers / xen / balloon.c
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. */
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. */
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
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
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
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
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
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
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
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
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
393 static long current_credit(void)
394 {
395         return balloon_stats.target_pages - balloon_stats.current_pages;
396 }
397
398 static bool balloon_is_inflated(void)
399 {
400         return balloon_stats.balloon_low || balloon_stats.balloon_high;
401 }
402
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
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  */
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  */
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. */
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 static int add_ballooned_pages(unsigned int nr_pages)
585 {
586         enum bp_state st;
587
588         if (xen_hotplug_unpopulated) {
589                 st = reserve_additional_memory();
590                 if (st != BP_ECANCELED) {
591                         int rc;
592
593                         mutex_unlock(&balloon_mutex);
594                         rc = wait_event_interruptible(balloon_wq,
595                                    !list_empty(&ballooned_pages));
596                         mutex_lock(&balloon_mutex);
597                         return rc ? -ENOMEM : 0;
598                 }
599         }
600
601         if (si_mem_available() < nr_pages)
602                 return -ENOMEM;
603
604         st = decrease_reservation(nr_pages, GFP_USER);
605         if (st != BP_DONE)
606                 return -ENOMEM;
607
608         return 0;
609 }
610
611 /**
612  * xen_alloc_ballooned_pages - get pages that have been ballooned out
613  * @nr_pages: Number of pages to get
614  * @pages: pages returned
615  * @return 0 on success, error otherwise
616  */
617 int xen_alloc_ballooned_pages(unsigned int nr_pages, struct page **pages)
618 {
619         unsigned int pgno = 0;
620         struct page *page;
621         int ret;
622
623         mutex_lock(&balloon_mutex);
624
625         balloon_stats.target_unpopulated += nr_pages;
626
627         while (pgno < nr_pages) {
628                 page = balloon_retrieve(true);
629                 if (page) {
630                         pages[pgno++] = page;
631 #ifdef CONFIG_XEN_HAVE_PVMMU
632                         /*
633                          * We don't support PV MMU when Linux and Xen is using
634                          * different page granularity.
635                          */
636                         BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
637
638                         if (!xen_feature(XENFEAT_auto_translated_physmap)) {
639                                 ret = xen_alloc_p2m_entry(page_to_pfn(page));
640                                 if (ret < 0)
641                                         goto out_undo;
642                         }
643 #endif
644                 } else {
645                         ret = add_ballooned_pages(nr_pages - pgno);
646                         if (ret < 0)
647                                 goto out_undo;
648                 }
649         }
650         mutex_unlock(&balloon_mutex);
651         return 0;
652  out_undo:
653         mutex_unlock(&balloon_mutex);
654         xen_free_ballooned_pages(pgno, pages);
655         /*
656          * NB: xen_free_ballooned_pages will only subtract pgno pages, but since
657          * target_unpopulated is incremented with nr_pages at the start we need
658          * to remove the remaining ones also, or accounting will be screwed.
659          */
660         balloon_stats.target_unpopulated -= nr_pages - pgno;
661         return ret;
662 }
663 EXPORT_SYMBOL(xen_alloc_ballooned_pages);
664
665 /**
666  * xen_free_ballooned_pages - return pages retrieved with get_ballooned_pages
667  * @nr_pages: Number of pages
668  * @pages: pages to return
669  */
670 void xen_free_ballooned_pages(unsigned int nr_pages, struct page **pages)
671 {
672         unsigned int i;
673
674         mutex_lock(&balloon_mutex);
675
676         for (i = 0; i < nr_pages; i++) {
677                 if (pages[i])
678                         balloon_append(pages[i]);
679         }
680
681         balloon_stats.target_unpopulated -= nr_pages;
682
683         /* The balloon may be too large now. Shrink it if needed. */
684         if (current_credit())
685                 wake_up(&balloon_thread_wq);
686
687         mutex_unlock(&balloon_mutex);
688 }
689 EXPORT_SYMBOL(xen_free_ballooned_pages);
690
691 #if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC)
692 static void __init balloon_add_region(unsigned long start_pfn,
693                                       unsigned long pages)
694 {
695         unsigned long pfn, extra_pfn_end;
696
697         /*
698          * If the amount of usable memory has been limited (e.g., with
699          * the 'mem' command line parameter), don't add pages beyond
700          * this limit.
701          */
702         extra_pfn_end = min(max_pfn, start_pfn + pages);
703
704         for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) {
705                 /* totalram_pages and totalhigh_pages do not
706                    include the boot-time balloon extension, so
707                    don't subtract from it. */
708                 balloon_append(pfn_to_page(pfn));
709         }
710
711         balloon_stats.total_pages += extra_pfn_end - start_pfn;
712 }
713 #endif
714
715 static int __init balloon_init(void)
716 {
717         struct task_struct *task;
718
719         if (!xen_domain())
720                 return -ENODEV;
721
722         pr_info("Initialising balloon driver\n");
723
724 #ifdef CONFIG_XEN_PV
725         balloon_stats.current_pages = xen_pv_domain()
726                 ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn)
727                 : get_num_physpages();
728 #else
729         balloon_stats.current_pages = get_num_physpages();
730 #endif
731         balloon_stats.target_pages  = balloon_stats.current_pages;
732         balloon_stats.balloon_low   = 0;
733         balloon_stats.balloon_high  = 0;
734         balloon_stats.total_pages   = balloon_stats.current_pages;
735
736         balloon_stats.schedule_delay = 1;
737         balloon_stats.max_schedule_delay = 32;
738         balloon_stats.retry_count = 1;
739         balloon_stats.max_retry_count = 4;
740
741 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
742         set_online_page_callback(&xen_online_page);
743         register_memory_notifier(&xen_memory_nb);
744         register_sysctl_table(xen_root);
745 #endif
746
747 #if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC)
748         {
749                 int i;
750
751                 /*
752                  * Initialize the balloon with pages from the extra memory
753                  * regions (see arch/x86/xen/setup.c).
754                  */
755                 for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++)
756                         if (xen_extra_mem[i].n_pfns)
757                                 balloon_add_region(xen_extra_mem[i].start_pfn,
758                                                    xen_extra_mem[i].n_pfns);
759         }
760 #endif
761
762         task = kthread_run(balloon_thread, NULL, "xen-balloon");
763         if (IS_ERR(task)) {
764                 pr_err("xen-balloon thread could not be started, ballooning will not work!\n");
765                 return PTR_ERR(task);
766         }
767
768         /* Init the xen-balloon driver. */
769         xen_balloon_init();
770
771         return 0;
772 }
773 subsys_initcall(balloon_init);
774
775 static int __init balloon_wait_finish(void)
776 {
777         long credit, last_credit = 0;
778         unsigned long last_changed = 0;
779
780         if (!xen_domain())
781                 return -ENODEV;
782
783         /* PV guests don't need to wait. */
784         if (xen_pv_domain() || !current_credit())
785                 return 0;
786
787         pr_notice("Waiting for initial ballooning down having finished.\n");
788
789         while ((credit = current_credit()) < 0) {
790                 if (credit != last_credit) {
791                         last_changed = jiffies;
792                         last_credit = credit;
793                 }
794                 if (balloon_state == BP_ECANCELED) {
795                         pr_warn_once("Initial ballooning failed, %ld pages need to be freed.\n",
796                                      -credit);
797                         if (jiffies - last_changed >= HZ * balloon_boot_timeout)
798                                 panic("Initial ballooning failed!\n");
799                 }
800
801                 schedule_timeout_interruptible(HZ / 10);
802         }
803
804         pr_notice("Initial ballooning down finished.\n");
805
806         return 0;
807 }
808 late_initcall_sync(balloon_wait_finish);
This page took 0.082222 seconds and 4 git commands to generate.