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1775826c | 1 | /****************************************************************************** |
1775826c JF |
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 | |
080e2be7 DK |
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. | |
1775826c JF |
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 | #include <linux/kernel.h> | |
1775826c JF |
40 | #include <linux/sched.h> |
41 | #include <linux/errno.h> | |
72ee5112 | 42 | #include <linux/module.h> |
1775826c JF |
43 | #include <linux/mm.h> |
44 | #include <linux/bootmem.h> | |
45 | #include <linux/pagemap.h> | |
46 | #include <linux/highmem.h> | |
47 | #include <linux/mutex.h> | |
1775826c | 48 | #include <linux/list.h> |
5a0e3ad6 | 49 | #include <linux/gfp.h> |
080e2be7 DK |
50 | #include <linux/notifier.h> |
51 | #include <linux/memory.h> | |
52 | #include <linux/memory_hotplug.h> | |
1775826c | 53 | |
1775826c JF |
54 | #include <asm/page.h> |
55 | #include <asm/pgalloc.h> | |
56 | #include <asm/pgtable.h> | |
1775826c | 57 | #include <asm/tlb.h> |
66946f67 | 58 | #include <asm/e820.h> |
1775826c | 59 | |
ecbf29cd JF |
60 | #include <asm/xen/hypervisor.h> |
61 | #include <asm/xen/hypercall.h> | |
1ccbf534 JF |
62 | |
63 | #include <xen/xen.h> | |
ecbf29cd | 64 | #include <xen/interface/xen.h> |
1775826c | 65 | #include <xen/interface/memory.h> |
803eb047 | 66 | #include <xen/balloon.h> |
1775826c JF |
67 | #include <xen/features.h> |
68 | #include <xen/page.h> | |
69 | ||
95d2ac4a DK |
70 | /* |
71 | * balloon_process() state: | |
72 | * | |
73 | * BP_DONE: done or nothing to do, | |
74 | * BP_EAGAIN: error, go to sleep, | |
75 | * BP_ECANCELED: error, balloon operation canceled. | |
76 | */ | |
1775826c | 77 | |
95d2ac4a DK |
78 | enum bp_state { |
79 | BP_DONE, | |
80 | BP_EAGAIN, | |
81 | BP_ECANCELED | |
1775826c JF |
82 | }; |
83 | ||
1775826c | 84 | |
1775826c | 85 | static DEFINE_MUTEX(balloon_mutex); |
1775826c | 86 | |
803eb047 DDG |
87 | struct balloon_stats balloon_stats; |
88 | EXPORT_SYMBOL_GPL(balloon_stats); | |
1775826c JF |
89 | |
90 | /* We increase/decrease in batches which fit in a page */ | |
91 | static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)]; | |
92 | ||
1775826c | 93 | #ifdef CONFIG_HIGHMEM |
1775826c JF |
94 | #define inc_totalhigh_pages() (totalhigh_pages++) |
95 | #define dec_totalhigh_pages() (totalhigh_pages--) | |
96 | #else | |
e882dc9c RP |
97 | #define inc_totalhigh_pages() do {} while (0) |
98 | #define dec_totalhigh_pages() do {} while (0) | |
1775826c JF |
99 | #endif |
100 | ||
101 | /* List of ballooned pages, threaded through the mem_map array. */ | |
102 | static LIST_HEAD(ballooned_pages); | |
103 | ||
104 | /* Main work function, always executed in process context. */ | |
105 | static void balloon_process(struct work_struct *work); | |
95170b2e | 106 | static DECLARE_DELAYED_WORK(balloon_worker, balloon_process); |
1775826c JF |
107 | |
108 | /* When ballooning out (allocating memory to return to Xen) we don't really | |
109 | want the kernel to try too hard since that can trigger the oom killer. */ | |
110 | #define GFP_BALLOON \ | |
111 | (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) | |
112 | ||
113 | static void scrub_page(struct page *page) | |
114 | { | |
115 | #ifdef CONFIG_XEN_SCRUB_PAGES | |
26a3e991 | 116 | clear_highpage(page); |
1775826c JF |
117 | #endif |
118 | } | |
119 | ||
120 | /* balloon_append: add the given page to the balloon. */ | |
9be4d457 | 121 | static void __balloon_append(struct page *page) |
1775826c JF |
122 | { |
123 | /* Lowmem is re-populated first, so highmem pages go at list tail. */ | |
124 | if (PageHighMem(page)) { | |
125 | list_add_tail(&page->lru, &ballooned_pages); | |
126 | balloon_stats.balloon_high++; | |
1775826c JF |
127 | } else { |
128 | list_add(&page->lru, &ballooned_pages); | |
129 | balloon_stats.balloon_low++; | |
130 | } | |
9be4d457 | 131 | } |
3d65c948 | 132 | |
9be4d457 JF |
133 | static void balloon_append(struct page *page) |
134 | { | |
135 | __balloon_append(page); | |
09ca132a DK |
136 | if (PageHighMem(page)) |
137 | dec_totalhigh_pages(); | |
3d65c948 | 138 | totalram_pages--; |
1775826c JF |
139 | } |
140 | ||
141 | /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ | |
b6f30679 | 142 | static struct page *balloon_retrieve(bool prefer_highmem) |
1775826c JF |
143 | { |
144 | struct page *page; | |
145 | ||
146 | if (list_empty(&ballooned_pages)) | |
147 | return NULL; | |
148 | ||
b6f30679 KRW |
149 | if (prefer_highmem) |
150 | page = list_entry(ballooned_pages.prev, struct page, lru); | |
151 | else | |
152 | page = list_entry(ballooned_pages.next, struct page, lru); | |
1775826c JF |
153 | list_del(&page->lru); |
154 | ||
155 | if (PageHighMem(page)) { | |
156 | balloon_stats.balloon_high--; | |
157 | inc_totalhigh_pages(); | |
e882dc9c | 158 | } else |
1775826c JF |
159 | balloon_stats.balloon_low--; |
160 | ||
3d65c948 GG |
161 | totalram_pages++; |
162 | ||
1775826c JF |
163 | return page; |
164 | } | |
165 | ||
166 | static struct page *balloon_first_page(void) | |
167 | { | |
168 | if (list_empty(&ballooned_pages)) | |
169 | return NULL; | |
170 | return list_entry(ballooned_pages.next, struct page, lru); | |
171 | } | |
172 | ||
173 | static struct page *balloon_next_page(struct page *page) | |
174 | { | |
175 | struct list_head *next = page->lru.next; | |
176 | if (next == &ballooned_pages) | |
177 | return NULL; | |
178 | return list_entry(next, struct page, lru); | |
179 | } | |
180 | ||
95d2ac4a | 181 | static enum bp_state update_schedule(enum bp_state state) |
1775826c | 182 | { |
95d2ac4a DK |
183 | if (state == BP_DONE) { |
184 | balloon_stats.schedule_delay = 1; | |
185 | balloon_stats.retry_count = 1; | |
186 | return BP_DONE; | |
187 | } | |
188 | ||
95d2ac4a DK |
189 | ++balloon_stats.retry_count; |
190 | ||
191 | if (balloon_stats.max_retry_count != RETRY_UNLIMITED && | |
192 | balloon_stats.retry_count > balloon_stats.max_retry_count) { | |
95d2ac4a DK |
193 | balloon_stats.schedule_delay = 1; |
194 | balloon_stats.retry_count = 1; | |
195 | return BP_ECANCELED; | |
196 | } | |
197 | ||
198 | balloon_stats.schedule_delay <<= 1; | |
199 | ||
200 | if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay) | |
201 | balloon_stats.schedule_delay = balloon_stats.max_schedule_delay; | |
202 | ||
203 | return BP_EAGAIN; | |
1775826c JF |
204 | } |
205 | ||
080e2be7 DK |
206 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
207 | static long current_credit(void) | |
208 | { | |
209 | return balloon_stats.target_pages - balloon_stats.current_pages - | |
210 | balloon_stats.hotplug_pages; | |
211 | } | |
212 | ||
213 | static bool balloon_is_inflated(void) | |
214 | { | |
215 | if (balloon_stats.balloon_low || balloon_stats.balloon_high || | |
216 | balloon_stats.balloon_hotplug) | |
217 | return true; | |
218 | else | |
219 | return false; | |
220 | } | |
221 | ||
222 | /* | |
223 | * reserve_additional_memory() adds memory region of size >= credit above | |
224 | * max_pfn. New region is section aligned and size is modified to be multiple | |
225 | * of section size. Those features allow optimal use of address space and | |
226 | * establish proper alignment when this function is called first time after | |
227 | * boot (last section not fully populated at boot time contains unused memory | |
228 | * pages with PG_reserved bit not set; online_pages_range() does not allow page | |
229 | * onlining in whole range if first onlined page does not have PG_reserved | |
230 | * bit set). Real size of added memory is established at page onlining stage. | |
231 | */ | |
232 | ||
233 | static enum bp_state reserve_additional_memory(long credit) | |
234 | { | |
235 | int nid, rc; | |
236 | u64 hotplug_start_paddr; | |
237 | unsigned long balloon_hotplug = credit; | |
238 | ||
239 | hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn)); | |
240 | balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION); | |
241 | nid = memory_add_physaddr_to_nid(hotplug_start_paddr); | |
242 | ||
243 | rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug << PAGE_SHIFT); | |
244 | ||
245 | if (rc) { | |
246 | pr_info("xen_balloon: %s: add_memory() failed: %i\n", __func__, rc); | |
247 | return BP_EAGAIN; | |
248 | } | |
249 | ||
250 | balloon_hotplug -= credit; | |
251 | ||
252 | balloon_stats.hotplug_pages += credit; | |
253 | balloon_stats.balloon_hotplug = balloon_hotplug; | |
254 | ||
255 | return BP_DONE; | |
256 | } | |
257 | ||
258 | static void xen_online_page(struct page *page) | |
259 | { | |
260 | __online_page_set_limits(page); | |
261 | ||
262 | mutex_lock(&balloon_mutex); | |
263 | ||
264 | __balloon_append(page); | |
265 | ||
266 | if (balloon_stats.hotplug_pages) | |
267 | --balloon_stats.hotplug_pages; | |
268 | else | |
269 | --balloon_stats.balloon_hotplug; | |
270 | ||
271 | mutex_unlock(&balloon_mutex); | |
272 | } | |
273 | ||
274 | static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v) | |
275 | { | |
276 | if (val == MEM_ONLINE) | |
277 | schedule_delayed_work(&balloon_worker, 0); | |
278 | ||
279 | return NOTIFY_OK; | |
280 | } | |
281 | ||
282 | static struct notifier_block xen_memory_nb = { | |
283 | .notifier_call = xen_memory_notifier, | |
284 | .priority = 0 | |
285 | }; | |
286 | #else | |
83be7e52 | 287 | static long current_credit(void) |
1775826c | 288 | { |
bc2c0303 | 289 | unsigned long target = balloon_stats.target_pages; |
1775826c JF |
290 | |
291 | target = min(target, | |
292 | balloon_stats.current_pages + | |
293 | balloon_stats.balloon_low + | |
294 | balloon_stats.balloon_high); | |
295 | ||
83be7e52 | 296 | return target - balloon_stats.current_pages; |
1775826c JF |
297 | } |
298 | ||
080e2be7 DK |
299 | static bool balloon_is_inflated(void) |
300 | { | |
301 | if (balloon_stats.balloon_low || balloon_stats.balloon_high) | |
302 | return true; | |
303 | else | |
304 | return false; | |
305 | } | |
306 | ||
307 | static enum bp_state reserve_additional_memory(long credit) | |
308 | { | |
309 | balloon_stats.target_pages = balloon_stats.current_pages; | |
310 | return BP_DONE; | |
311 | } | |
312 | #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */ | |
313 | ||
95d2ac4a | 314 | static enum bp_state increase_reservation(unsigned long nr_pages) |
1775826c | 315 | { |
95d2ac4a | 316 | int rc; |
2f70e0ac | 317 | unsigned long pfn, i; |
1775826c | 318 | struct page *page; |
1775826c JF |
319 | struct xen_memory_reservation reservation = { |
320 | .address_bits = 0, | |
321 | .extent_order = 0, | |
322 | .domid = DOMID_SELF | |
323 | }; | |
324 | ||
080e2be7 DK |
325 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
326 | if (!balloon_stats.balloon_low && !balloon_stats.balloon_high) { | |
327 | nr_pages = min(nr_pages, balloon_stats.balloon_hotplug); | |
328 | balloon_stats.hotplug_pages += nr_pages; | |
329 | balloon_stats.balloon_hotplug -= nr_pages; | |
330 | return BP_DONE; | |
331 | } | |
332 | #endif | |
333 | ||
1775826c JF |
334 | if (nr_pages > ARRAY_SIZE(frame_list)) |
335 | nr_pages = ARRAY_SIZE(frame_list); | |
336 | ||
1775826c JF |
337 | page = balloon_first_page(); |
338 | for (i = 0; i < nr_pages; i++) { | |
95d2ac4a DK |
339 | if (!page) { |
340 | nr_pages = i; | |
341 | break; | |
342 | } | |
a419aef8 | 343 | frame_list[i] = page_to_pfn(page); |
1775826c JF |
344 | page = balloon_next_page(page); |
345 | } | |
346 | ||
a90971eb | 347 | set_xen_guest_handle(reservation.extent_start, frame_list); |
fde28e8f JF |
348 | reservation.nr_extents = nr_pages; |
349 | rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); | |
40095de1 | 350 | if (rc <= 0) |
95d2ac4a | 351 | return BP_EAGAIN; |
1775826c | 352 | |
bc2c0303 | 353 | for (i = 0; i < rc; i++) { |
b6f30679 | 354 | page = balloon_retrieve(false); |
1775826c JF |
355 | BUG_ON(page == NULL); |
356 | ||
357 | pfn = page_to_pfn(page); | |
358 | BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) && | |
359 | phys_to_machine_mapping_valid(pfn)); | |
360 | ||
361 | set_phys_to_machine(pfn, frame_list[i]); | |
362 | ||
363 | /* Link back into the page tables if not highmem. */ | |
4dfe22f5 | 364 | if (xen_pv_domain() && !PageHighMem(page)) { |
1775826c JF |
365 | int ret; |
366 | ret = HYPERVISOR_update_va_mapping( | |
367 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
368 | mfn_pte(frame_list[i], PAGE_KERNEL), | |
369 | 0); | |
370 | BUG_ON(ret); | |
371 | } | |
372 | ||
373 | /* Relinquish the page back to the allocator. */ | |
374 | ClearPageReserved(page); | |
375 | init_page_count(page); | |
376 | __free_page(page); | |
377 | } | |
378 | ||
bc2c0303 | 379 | balloon_stats.current_pages += rc; |
1775826c | 380 | |
95d2ac4a | 381 | return BP_DONE; |
1775826c JF |
382 | } |
383 | ||
b6f30679 | 384 | static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) |
1775826c | 385 | { |
95d2ac4a | 386 | enum bp_state state = BP_DONE; |
2f70e0ac | 387 | unsigned long pfn, i; |
1775826c | 388 | struct page *page; |
1775826c JF |
389 | int ret; |
390 | struct xen_memory_reservation reservation = { | |
391 | .address_bits = 0, | |
392 | .extent_order = 0, | |
393 | .domid = DOMID_SELF | |
394 | }; | |
395 | ||
080e2be7 DK |
396 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
397 | if (balloon_stats.hotplug_pages) { | |
398 | nr_pages = min(nr_pages, balloon_stats.hotplug_pages); | |
399 | balloon_stats.hotplug_pages -= nr_pages; | |
400 | balloon_stats.balloon_hotplug += nr_pages; | |
401 | return BP_DONE; | |
402 | } | |
403 | #endif | |
404 | ||
1775826c JF |
405 | if (nr_pages > ARRAY_SIZE(frame_list)) |
406 | nr_pages = ARRAY_SIZE(frame_list); | |
407 | ||
408 | for (i = 0; i < nr_pages; i++) { | |
b6f30679 | 409 | if ((page = alloc_page(gfp)) == NULL) { |
1775826c | 410 | nr_pages = i; |
95d2ac4a | 411 | state = BP_EAGAIN; |
1775826c JF |
412 | break; |
413 | } | |
414 | ||
415 | pfn = page_to_pfn(page); | |
416 | frame_list[i] = pfn_to_mfn(pfn); | |
417 | ||
418 | scrub_page(page); | |
1058a75f | 419 | |
4dfe22f5 | 420 | if (xen_pv_domain() && !PageHighMem(page)) { |
ff4ce8c3 IC |
421 | ret = HYPERVISOR_update_va_mapping( |
422 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
423 | __pte_ma(0), 0); | |
424 | BUG_ON(ret); | |
e882dc9c | 425 | } |
ff4ce8c3 | 426 | |
1775826c JF |
427 | } |
428 | ||
429 | /* Ensure that ballooned highmem pages don't have kmaps. */ | |
430 | kmap_flush_unused(); | |
431 | flush_tlb_all(); | |
432 | ||
1775826c JF |
433 | /* No more mappings: invalidate P2M and add to balloon. */ |
434 | for (i = 0; i < nr_pages; i++) { | |
435 | pfn = mfn_to_pfn(frame_list[i]); | |
6eaa412f | 436 | __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); |
1775826c JF |
437 | balloon_append(pfn_to_page(pfn)); |
438 | } | |
439 | ||
a90971eb | 440 | set_xen_guest_handle(reservation.extent_start, frame_list); |
1775826c JF |
441 | reservation.nr_extents = nr_pages; |
442 | ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); | |
443 | BUG_ON(ret != nr_pages); | |
444 | ||
445 | balloon_stats.current_pages -= nr_pages; | |
1775826c | 446 | |
95d2ac4a | 447 | return state; |
1775826c JF |
448 | } |
449 | ||
450 | /* | |
451 | * We avoid multiple worker processes conflicting via the balloon mutex. | |
452 | * We may of course race updates of the target counts (which are protected | |
453 | * by the balloon lock), or with changes to the Xen hard limit, but we will | |
454 | * recover from these in time. | |
455 | */ | |
456 | static void balloon_process(struct work_struct *work) | |
457 | { | |
95d2ac4a | 458 | enum bp_state state = BP_DONE; |
1775826c JF |
459 | long credit; |
460 | ||
461 | mutex_lock(&balloon_mutex); | |
462 | ||
463 | do { | |
83be7e52 | 464 | credit = current_credit(); |
95d2ac4a | 465 | |
080e2be7 DK |
466 | if (credit > 0) { |
467 | if (balloon_is_inflated()) | |
468 | state = increase_reservation(credit); | |
469 | else | |
470 | state = reserve_additional_memory(credit); | |
471 | } | |
95d2ac4a | 472 | |
1775826c | 473 | if (credit < 0) |
b6f30679 | 474 | state = decrease_reservation(-credit, GFP_BALLOON); |
95d2ac4a DK |
475 | |
476 | state = update_schedule(state); | |
1775826c JF |
477 | |
478 | #ifndef CONFIG_PREEMPT | |
479 | if (need_resched()) | |
480 | schedule(); | |
481 | #endif | |
95d2ac4a | 482 | } while (credit && state == BP_DONE); |
1775826c JF |
483 | |
484 | /* Schedule more work if there is some still to be done. */ | |
95d2ac4a DK |
485 | if (state == BP_EAGAIN) |
486 | schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ); | |
1775826c JF |
487 | |
488 | mutex_unlock(&balloon_mutex); | |
489 | } | |
490 | ||
491 | /* Resets the Xen limit, sets new target, and kicks off processing. */ | |
803eb047 | 492 | void balloon_set_new_target(unsigned long target) |
1775826c JF |
493 | { |
494 | /* No need for lock. Not read-modify-write updates. */ | |
1775826c | 495 | balloon_stats.target_pages = target; |
95170b2e | 496 | schedule_delayed_work(&balloon_worker, 0); |
1775826c | 497 | } |
803eb047 | 498 | EXPORT_SYMBOL_GPL(balloon_set_new_target); |
1775826c | 499 | |
b6f30679 KRW |
500 | /** |
501 | * alloc_xenballooned_pages - get pages that have been ballooned out | |
502 | * @nr_pages: Number of pages to get | |
503 | * @pages: pages returned | |
72e9cf2a | 504 | * @highmem: allow highmem pages |
b6f30679 KRW |
505 | * @return 0 on success, error otherwise |
506 | */ | |
693394b8 | 507 | int alloc_xenballooned_pages(int nr_pages, struct page **pages, bool highmem) |
1775826c | 508 | { |
b6f30679 | 509 | int pgno = 0; |
e882dc9c | 510 | struct page *page; |
b6f30679 KRW |
511 | mutex_lock(&balloon_mutex); |
512 | while (pgno < nr_pages) { | |
693394b8 | 513 | page = balloon_retrieve(highmem); |
72e9cf2a | 514 | if (page && (highmem || !PageHighMem(page))) { |
b6f30679 KRW |
515 | pages[pgno++] = page; |
516 | } else { | |
517 | enum bp_state st; | |
693394b8 SS |
518 | if (page) |
519 | balloon_append(page); | |
520 | st = decrease_reservation(nr_pages - pgno, | |
521 | highmem ? GFP_HIGHUSER : GFP_USER); | |
b6f30679 KRW |
522 | if (st != BP_DONE) |
523 | goto out_undo; | |
524 | } | |
1775826c | 525 | } |
b6f30679 KRW |
526 | mutex_unlock(&balloon_mutex); |
527 | return 0; | |
528 | out_undo: | |
529 | while (pgno) | |
530 | balloon_append(pages[--pgno]); | |
531 | /* Free the memory back to the kernel soon */ | |
532 | schedule_delayed_work(&balloon_worker, 0); | |
533 | mutex_unlock(&balloon_mutex); | |
534 | return -ENOMEM; | |
1775826c | 535 | } |
b6f30679 | 536 | EXPORT_SYMBOL(alloc_xenballooned_pages); |
1775826c | 537 | |
b6f30679 KRW |
538 | /** |
539 | * free_xenballooned_pages - return pages retrieved with get_ballooned_pages | |
540 | * @nr_pages: Number of pages | |
541 | * @pages: pages to return | |
542 | */ | |
e882dc9c | 543 | void free_xenballooned_pages(int nr_pages, struct page **pages) |
1775826c | 544 | { |
b6f30679 | 545 | int i; |
1775826c | 546 | |
b6f30679 | 547 | mutex_lock(&balloon_mutex); |
1775826c | 548 | |
b6f30679 KRW |
549 | for (i = 0; i < nr_pages; i++) { |
550 | if (pages[i]) | |
551 | balloon_append(pages[i]); | |
552 | } | |
553 | ||
554 | /* The balloon may be too large now. Shrink it if needed. */ | |
83be7e52 | 555 | if (current_credit()) |
b6f30679 | 556 | schedule_delayed_work(&balloon_worker, 0); |
1775826c | 557 | |
b6f30679 KRW |
558 | mutex_unlock(&balloon_mutex); |
559 | } | |
560 | EXPORT_SYMBOL(free_xenballooned_pages); | |
1775826c | 561 | |
8b5d44a5 DV |
562 | static void __init balloon_add_region(unsigned long start_pfn, |
563 | unsigned long pages) | |
1775826c | 564 | { |
4dfe22f5 | 565 | unsigned long pfn, extra_pfn_end; |
1775826c JF |
566 | struct page *page; |
567 | ||
8b5d44a5 DV |
568 | /* |
569 | * If the amount of usable memory has been limited (e.g., with | |
570 | * the 'mem' command line parameter), don't add pages beyond | |
571 | * this limit. | |
572 | */ | |
573 | extra_pfn_end = min(max_pfn, start_pfn + pages); | |
574 | ||
575 | for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) { | |
576 | page = pfn_to_page(pfn); | |
577 | /* totalram_pages and totalhigh_pages do not | |
578 | include the boot-time balloon extension, so | |
579 | don't subtract from it. */ | |
580 | __balloon_append(page); | |
581 | } | |
582 | } | |
583 | ||
584 | static int __init balloon_init(void) | |
585 | { | |
586 | int i; | |
587 | ||
53d5522c | 588 | if (!xen_domain()) |
1775826c JF |
589 | return -ENODEV; |
590 | ||
803eb047 | 591 | pr_info("xen/balloon: Initialising balloon driver.\n"); |
1775826c | 592 | |
aa24411b DV |
593 | balloon_stats.current_pages = xen_pv_domain() |
594 | ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn) | |
595 | : max_pfn; | |
1775826c JF |
596 | balloon_stats.target_pages = balloon_stats.current_pages; |
597 | balloon_stats.balloon_low = 0; | |
598 | balloon_stats.balloon_high = 0; | |
1775826c | 599 | |
95d2ac4a DK |
600 | balloon_stats.schedule_delay = 1; |
601 | balloon_stats.max_schedule_delay = 32; | |
602 | balloon_stats.retry_count = 1; | |
40095de1 | 603 | balloon_stats.max_retry_count = RETRY_UNLIMITED; |
1775826c | 604 | |
080e2be7 DK |
605 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
606 | balloon_stats.hotplug_pages = 0; | |
607 | balloon_stats.balloon_hotplug = 0; | |
608 | ||
609 | set_online_page_callback(&xen_online_page); | |
610 | register_memory_notifier(&xen_memory_nb); | |
611 | #endif | |
612 | ||
2a4c92fa | 613 | /* |
b1cbf9b1 | 614 | * Initialize the balloon with pages from the extra memory |
8b5d44a5 | 615 | * regions (see arch/x86/xen/setup.c). |
2a4c92fa | 616 | */ |
8b5d44a5 DV |
617 | for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) |
618 | if (xen_extra_mem[i].size) | |
619 | balloon_add_region(PFN_UP(xen_extra_mem[i].start), | |
620 | PFN_DOWN(xen_extra_mem[i].size)); | |
1775826c | 621 | |
1775826c JF |
622 | return 0; |
623 | } | |
624 | ||
625 | subsys_initcall(balloon_init); | |
626 | ||
1775826c | 627 | MODULE_LICENSE("GPL"); |