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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
76static int xen_hotplug_unpopulated;
77
78#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
79
80static 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
93static struct ctl_table balloon_root[] = {
94 {
95 .procname = "balloon",
96 .mode = 0555,
97 .child = balloon_table,
98 },
99 { }
100};
101
102static 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
115
116
117#define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
118
119
120
121
122
123
124
125
126
127
128enum bp_state {
129 BP_DONE,
130 BP_WAIT,
131 BP_EAGAIN,
132 BP_ECANCELED
133};
134
135
136static DEFINE_MUTEX(balloon_mutex);
137
138struct balloon_stats balloon_stats;
139EXPORT_SYMBOL_GPL(balloon_stats);
140
141
142static xen_pfn_t frame_list[PAGE_SIZE / sizeof(xen_pfn_t)];
143
144
145
146static LIST_HEAD(ballooned_pages);
147static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
148
149
150static void balloon_process(struct work_struct *work);
151static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
152
153
154
155#define GFP_BALLOON \
156 (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
157
158
159static void balloon_append(struct page *page)
160{
161 __SetPageOffline(page);
162
163
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
175static 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
196static 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
204static 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
236static void release_memory_resource(struct resource *resource)
237{
238 if (!resource)
239 return;
240
241
242
243
244
245 release_resource(resource);
246 kfree(resource);
247}
248
249static 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
287static 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
299
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
315
316
317 BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
318
319
320
321
322
323
324
325
326
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
343
344
345
346
347 mutex_unlock(&balloon_mutex);
348
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
367static 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
383static 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
391static struct notifier_block xen_memory_nb = {
392 .notifier_call = xen_memory_notifier,
393 .priority = 0
394};
395#else
396static enum bp_state reserve_additional_memory(void)
397{
398 balloon_stats.target_pages = balloon_stats.current_pages;
399 return BP_ECANCELED;
400}
401#endif
402
403static long current_credit(void)
404{
405 return balloon_stats.target_pages - balloon_stats.current_pages;
406}
407
408static bool balloon_is_inflated(void)
409{
410 return balloon_stats.balloon_low || balloon_stats.balloon_high;
411}
412
413static enum bp_state increase_reservation(unsigned long nr_pages)
414{
415 int rc;
416 unsigned long i;
417 struct page *page;
418
419 if (nr_pages > ARRAY_SIZE(frame_list))
420 nr_pages = ARRAY_SIZE(frame_list);
421
422 page = list_first_entry_or_null(&ballooned_pages, struct page, lru);
423 for (i = 0; i < nr_pages; i++) {
424 if (!page) {
425 nr_pages = i;
426 break;
427 }
428
429 frame_list[i] = page_to_xen_pfn(page);
430 page = balloon_next_page(page);
431 }
432
433 rc = xenmem_reservation_increase(nr_pages, frame_list);
434 if (rc <= 0)
435 return BP_EAGAIN;
436
437 for (i = 0; i < rc; i++) {
438 page = balloon_retrieve(false);
439 BUG_ON(page == NULL);
440
441 xenmem_reservation_va_mapping_update(1, &page, &frame_list[i]);
442
443
444 free_reserved_page(page);
445 }
446
447 balloon_stats.current_pages += rc;
448
449 return BP_DONE;
450}
451
452static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
453{
454 enum bp_state state = BP_DONE;
455 unsigned long i;
456 struct page *page, *tmp;
457 int ret;
458 LIST_HEAD(pages);
459
460 if (nr_pages > ARRAY_SIZE(frame_list))
461 nr_pages = ARRAY_SIZE(frame_list);
462
463 for (i = 0; i < nr_pages; i++) {
464 page = alloc_page(gfp);
465 if (page == NULL) {
466 nr_pages = i;
467 state = BP_EAGAIN;
468 break;
469 }
470 adjust_managed_page_count(page, -1);
471 xenmem_reservation_scrub_page(page);
472 list_add(&page->lru, &pages);
473 }
474
475
476
477
478
479
480
481
482 kmap_flush_unused();
483
484
485
486
487
488 i = 0;
489 list_for_each_entry_safe(page, tmp, &pages, lru) {
490 frame_list[i++] = xen_page_to_gfn(page);
491
492 xenmem_reservation_va_mapping_reset(1, &page);
493
494 list_del(&page->lru);
495
496 balloon_append(page);
497 }
498
499 flush_tlb_all();
500
501 ret = xenmem_reservation_decrease(nr_pages, frame_list);
502 BUG_ON(ret != nr_pages);
503
504 balloon_stats.current_pages -= nr_pages;
505
506 return state;
507}
508
509
510
511
512
513
514
515static void balloon_process(struct work_struct *work)
516{
517 enum bp_state state = BP_DONE;
518 long credit;
519
520
521 do {
522 mutex_lock(&balloon_mutex);
523
524 credit = current_credit();
525
526 if (credit > 0) {
527 if (balloon_is_inflated())
528 state = increase_reservation(credit);
529 else
530 state = reserve_additional_memory();
531 }
532
533 if (credit < 0) {
534 long n_pages;
535
536 n_pages = min(-credit, si_mem_available());
537 state = decrease_reservation(n_pages, GFP_BALLOON);
538 if (state == BP_DONE && n_pages != -credit &&
539 n_pages < totalreserve_pages)
540 state = BP_EAGAIN;
541 }
542
543 state = update_schedule(state);
544
545 mutex_unlock(&balloon_mutex);
546
547 cond_resched();
548
549 } while (credit && state == BP_DONE);
550
551
552 if (state == BP_EAGAIN)
553 schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ);
554}
555
556
557void balloon_set_new_target(unsigned long target)
558{
559
560 balloon_stats.target_pages = target;
561 schedule_delayed_work(&balloon_worker, 0);
562}
563EXPORT_SYMBOL_GPL(balloon_set_new_target);
564
565static int add_ballooned_pages(int nr_pages)
566{
567 enum bp_state st;
568
569 if (xen_hotplug_unpopulated) {
570 st = reserve_additional_memory();
571 if (st != BP_ECANCELED) {
572 mutex_unlock(&balloon_mutex);
573 wait_event(balloon_wq,
574 !list_empty(&ballooned_pages));
575 mutex_lock(&balloon_mutex);
576 return 0;
577 }
578 }
579
580 if (si_mem_available() < nr_pages)
581 return -ENOMEM;
582
583 st = decrease_reservation(nr_pages, GFP_USER);
584 if (st != BP_DONE)
585 return -ENOMEM;
586
587 return 0;
588}
589
590
591
592
593
594
595
596int alloc_xenballooned_pages(int nr_pages, struct page **pages)
597{
598 int pgno = 0;
599 struct page *page;
600 int ret;
601
602 mutex_lock(&balloon_mutex);
603
604 balloon_stats.target_unpopulated += nr_pages;
605
606 while (pgno < nr_pages) {
607 page = balloon_retrieve(true);
608 if (page) {
609 pages[pgno++] = page;
610#ifdef CONFIG_XEN_HAVE_PVMMU
611
612
613
614
615 BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
616
617 if (!xen_feature(XENFEAT_auto_translated_physmap)) {
618 ret = xen_alloc_p2m_entry(page_to_pfn(page));
619 if (ret < 0)
620 goto out_undo;
621 }
622#endif
623 } else {
624 ret = add_ballooned_pages(nr_pages - pgno);
625 if (ret < 0)
626 goto out_undo;
627 }
628 }
629 mutex_unlock(&balloon_mutex);
630 return 0;
631 out_undo:
632 mutex_unlock(&balloon_mutex);
633 free_xenballooned_pages(pgno, pages);
634 return ret;
635}
636EXPORT_SYMBOL(alloc_xenballooned_pages);
637
638
639
640
641
642
643void free_xenballooned_pages(int nr_pages, struct page **pages)
644{
645 int i;
646
647 mutex_lock(&balloon_mutex);
648
649 for (i = 0; i < nr_pages; i++) {
650 if (pages[i])
651 balloon_append(pages[i]);
652 }
653
654 balloon_stats.target_unpopulated -= nr_pages;
655
656
657 if (current_credit())
658 schedule_delayed_work(&balloon_worker, 0);
659
660 mutex_unlock(&balloon_mutex);
661}
662EXPORT_SYMBOL(free_xenballooned_pages);
663
664#ifdef CONFIG_XEN_PV
665static void __init balloon_add_region(unsigned long start_pfn,
666 unsigned long pages)
667{
668 unsigned long pfn, extra_pfn_end;
669
670
671
672
673
674
675 extra_pfn_end = min(max_pfn, start_pfn + pages);
676
677 for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) {
678
679
680
681 balloon_append(pfn_to_page(pfn));
682 }
683
684 balloon_stats.total_pages += extra_pfn_end - start_pfn;
685}
686#endif
687
688static int __init balloon_init(void)
689{
690 if (!xen_domain())
691 return -ENODEV;
692
693 pr_info("Initialising balloon driver\n");
694
695#ifdef CONFIG_XEN_PV
696 balloon_stats.current_pages = xen_pv_domain()
697 ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn)
698 : get_num_physpages();
699#else
700 balloon_stats.current_pages = get_num_physpages();
701#endif
702 balloon_stats.target_pages = balloon_stats.current_pages;
703 balloon_stats.balloon_low = 0;
704 balloon_stats.balloon_high = 0;
705 balloon_stats.total_pages = balloon_stats.current_pages;
706
707 balloon_stats.schedule_delay = 1;
708 balloon_stats.max_schedule_delay = 32;
709 balloon_stats.retry_count = 1;
710 balloon_stats.max_retry_count = 4;
711
712#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
713 set_online_page_callback(&xen_online_page);
714 register_memory_notifier(&xen_memory_nb);
715 register_sysctl_table(xen_root);
716#endif
717
718#ifdef CONFIG_XEN_PV
719 {
720 int i;
721
722
723
724
725
726 for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++)
727 if (xen_extra_mem[i].n_pfns)
728 balloon_add_region(xen_extra_mem[i].start_pfn,
729 xen_extra_mem[i].n_pfns);
730 }
731#endif
732
733
734 xen_balloon_init();
735
736 return 0;
737}
738subsys_initcall(balloon_init);
739