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