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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 | ||
283c0972 JP |
39 | #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt |
40 | ||
cd9151e2 | 41 | #include <linux/cpu.h> |
1775826c | 42 | #include <linux/kernel.h> |
1775826c JF |
43 | #include <linux/sched.h> |
44 | #include <linux/errno.h> | |
72ee5112 | 45 | #include <linux/module.h> |
1775826c JF |
46 | #include <linux/mm.h> |
47 | #include <linux/bootmem.h> | |
48 | #include <linux/pagemap.h> | |
49 | #include <linux/highmem.h> | |
50 | #include <linux/mutex.h> | |
1775826c | 51 | #include <linux/list.h> |
5a0e3ad6 | 52 | #include <linux/gfp.h> |
080e2be7 DK |
53 | #include <linux/notifier.h> |
54 | #include <linux/memory.h> | |
55 | #include <linux/memory_hotplug.h> | |
cd9151e2 | 56 | #include <linux/percpu-defs.h> |
1775826c | 57 | |
1775826c JF |
58 | #include <asm/page.h> |
59 | #include <asm/pgalloc.h> | |
60 | #include <asm/pgtable.h> | |
1775826c JF |
61 | #include <asm/tlb.h> |
62 | ||
ecbf29cd JF |
63 | #include <asm/xen/hypervisor.h> |
64 | #include <asm/xen/hypercall.h> | |
1ccbf534 JF |
65 | |
66 | #include <xen/xen.h> | |
ecbf29cd | 67 | #include <xen/interface/xen.h> |
1775826c | 68 | #include <xen/interface/memory.h> |
803eb047 | 69 | #include <xen/balloon.h> |
1775826c JF |
70 | #include <xen/features.h> |
71 | #include <xen/page.h> | |
72 | ||
95d2ac4a DK |
73 | /* |
74 | * balloon_process() state: | |
75 | * | |
76 | * BP_DONE: done or nothing to do, | |
77 | * BP_EAGAIN: error, go to sleep, | |
78 | * BP_ECANCELED: error, balloon operation canceled. | |
79 | */ | |
1775826c | 80 | |
95d2ac4a DK |
81 | enum bp_state { |
82 | BP_DONE, | |
83 | BP_EAGAIN, | |
84 | BP_ECANCELED | |
1775826c JF |
85 | }; |
86 | ||
1775826c | 87 | |
1775826c | 88 | static DEFINE_MUTEX(balloon_mutex); |
1775826c | 89 | |
803eb047 DDG |
90 | struct balloon_stats balloon_stats; |
91 | EXPORT_SYMBOL_GPL(balloon_stats); | |
1775826c JF |
92 | |
93 | /* We increase/decrease in batches which fit in a page */ | |
965c0aaa | 94 | static xen_pfn_t frame_list[PAGE_SIZE / sizeof(unsigned long)]; |
cd9151e2 SS |
95 | static DEFINE_PER_CPU(struct page *, balloon_scratch_page); |
96 | ||
1775826c | 97 | |
1775826c JF |
98 | /* List of ballooned pages, threaded through the mem_map array. */ |
99 | static LIST_HEAD(ballooned_pages); | |
100 | ||
101 | /* Main work function, always executed in process context. */ | |
102 | static void balloon_process(struct work_struct *work); | |
95170b2e | 103 | static DECLARE_DELAYED_WORK(balloon_worker, balloon_process); |
1775826c JF |
104 | |
105 | /* When ballooning out (allocating memory to return to Xen) we don't really | |
106 | want the kernel to try too hard since that can trigger the oom killer. */ | |
107 | #define GFP_BALLOON \ | |
108 | (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) | |
109 | ||
110 | static void scrub_page(struct page *page) | |
111 | { | |
112 | #ifdef CONFIG_XEN_SCRUB_PAGES | |
26a3e991 | 113 | clear_highpage(page); |
1775826c JF |
114 | #endif |
115 | } | |
116 | ||
117 | /* balloon_append: add the given page to the balloon. */ | |
9be4d457 | 118 | static void __balloon_append(struct page *page) |
1775826c JF |
119 | { |
120 | /* Lowmem is re-populated first, so highmem pages go at list tail. */ | |
121 | if (PageHighMem(page)) { | |
122 | list_add_tail(&page->lru, &ballooned_pages); | |
123 | balloon_stats.balloon_high++; | |
1775826c JF |
124 | } else { |
125 | list_add(&page->lru, &ballooned_pages); | |
126 | balloon_stats.balloon_low++; | |
127 | } | |
9be4d457 | 128 | } |
3d65c948 | 129 | |
9be4d457 JF |
130 | static void balloon_append(struct page *page) |
131 | { | |
132 | __balloon_append(page); | |
3dcc0571 | 133 | adjust_managed_page_count(page, -1); |
1775826c JF |
134 | } |
135 | ||
136 | /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ | |
b6f30679 | 137 | static struct page *balloon_retrieve(bool prefer_highmem) |
1775826c JF |
138 | { |
139 | struct page *page; | |
140 | ||
141 | if (list_empty(&ballooned_pages)) | |
142 | return NULL; | |
143 | ||
b6f30679 KRW |
144 | if (prefer_highmem) |
145 | page = list_entry(ballooned_pages.prev, struct page, lru); | |
146 | else | |
147 | page = list_entry(ballooned_pages.next, struct page, lru); | |
1775826c JF |
148 | list_del(&page->lru); |
149 | ||
3dcc0571 | 150 | if (PageHighMem(page)) |
1775826c | 151 | balloon_stats.balloon_high--; |
3dcc0571 | 152 | else |
1775826c JF |
153 | balloon_stats.balloon_low--; |
154 | ||
3dcc0571 | 155 | adjust_managed_page_count(page, 1); |
3d65c948 | 156 | |
1775826c JF |
157 | return page; |
158 | } | |
159 | ||
160 | static struct page *balloon_first_page(void) | |
161 | { | |
162 | if (list_empty(&ballooned_pages)) | |
163 | return NULL; | |
164 | return list_entry(ballooned_pages.next, struct page, lru); | |
165 | } | |
166 | ||
167 | static struct page *balloon_next_page(struct page *page) | |
168 | { | |
169 | struct list_head *next = page->lru.next; | |
170 | if (next == &ballooned_pages) | |
171 | return NULL; | |
172 | return list_entry(next, struct page, lru); | |
173 | } | |
174 | ||
95d2ac4a | 175 | static enum bp_state update_schedule(enum bp_state state) |
1775826c | 176 | { |
95d2ac4a DK |
177 | if (state == BP_DONE) { |
178 | balloon_stats.schedule_delay = 1; | |
179 | balloon_stats.retry_count = 1; | |
180 | return BP_DONE; | |
181 | } | |
182 | ||
95d2ac4a DK |
183 | ++balloon_stats.retry_count; |
184 | ||
185 | if (balloon_stats.max_retry_count != RETRY_UNLIMITED && | |
186 | balloon_stats.retry_count > balloon_stats.max_retry_count) { | |
95d2ac4a DK |
187 | balloon_stats.schedule_delay = 1; |
188 | balloon_stats.retry_count = 1; | |
189 | return BP_ECANCELED; | |
190 | } | |
191 | ||
192 | balloon_stats.schedule_delay <<= 1; | |
193 | ||
194 | if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay) | |
195 | balloon_stats.schedule_delay = balloon_stats.max_schedule_delay; | |
196 | ||
197 | return BP_EAGAIN; | |
1775826c JF |
198 | } |
199 | ||
080e2be7 DK |
200 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
201 | static long current_credit(void) | |
202 | { | |
203 | return balloon_stats.target_pages - balloon_stats.current_pages - | |
204 | balloon_stats.hotplug_pages; | |
205 | } | |
206 | ||
207 | static bool balloon_is_inflated(void) | |
208 | { | |
209 | if (balloon_stats.balloon_low || balloon_stats.balloon_high || | |
210 | balloon_stats.balloon_hotplug) | |
211 | return true; | |
212 | else | |
213 | return false; | |
214 | } | |
215 | ||
216 | /* | |
217 | * reserve_additional_memory() adds memory region of size >= credit above | |
218 | * max_pfn. New region is section aligned and size is modified to be multiple | |
219 | * of section size. Those features allow optimal use of address space and | |
220 | * establish proper alignment when this function is called first time after | |
221 | * boot (last section not fully populated at boot time contains unused memory | |
222 | * pages with PG_reserved bit not set; online_pages_range() does not allow page | |
223 | * onlining in whole range if first onlined page does not have PG_reserved | |
224 | * bit set). Real size of added memory is established at page onlining stage. | |
225 | */ | |
226 | ||
227 | static enum bp_state reserve_additional_memory(long credit) | |
228 | { | |
229 | int nid, rc; | |
230 | u64 hotplug_start_paddr; | |
231 | unsigned long balloon_hotplug = credit; | |
232 | ||
233 | hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn)); | |
234 | balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION); | |
235 | nid = memory_add_physaddr_to_nid(hotplug_start_paddr); | |
236 | ||
237 | rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug << PAGE_SHIFT); | |
238 | ||
239 | if (rc) { | |
283c0972 | 240 | pr_info("%s: add_memory() failed: %i\n", __func__, rc); |
080e2be7 DK |
241 | return BP_EAGAIN; |
242 | } | |
243 | ||
244 | balloon_hotplug -= credit; | |
245 | ||
246 | balloon_stats.hotplug_pages += credit; | |
247 | balloon_stats.balloon_hotplug = balloon_hotplug; | |
248 | ||
249 | return BP_DONE; | |
250 | } | |
251 | ||
252 | static void xen_online_page(struct page *page) | |
253 | { | |
254 | __online_page_set_limits(page); | |
255 | ||
256 | mutex_lock(&balloon_mutex); | |
257 | ||
258 | __balloon_append(page); | |
259 | ||
260 | if (balloon_stats.hotplug_pages) | |
261 | --balloon_stats.hotplug_pages; | |
262 | else | |
263 | --balloon_stats.balloon_hotplug; | |
264 | ||
265 | mutex_unlock(&balloon_mutex); | |
266 | } | |
267 | ||
268 | static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v) | |
269 | { | |
270 | if (val == MEM_ONLINE) | |
271 | schedule_delayed_work(&balloon_worker, 0); | |
272 | ||
273 | return NOTIFY_OK; | |
274 | } | |
275 | ||
276 | static struct notifier_block xen_memory_nb = { | |
277 | .notifier_call = xen_memory_notifier, | |
278 | .priority = 0 | |
279 | }; | |
280 | #else | |
83be7e52 | 281 | static long current_credit(void) |
1775826c | 282 | { |
bc2c0303 | 283 | unsigned long target = balloon_stats.target_pages; |
1775826c JF |
284 | |
285 | target = min(target, | |
286 | balloon_stats.current_pages + | |
287 | balloon_stats.balloon_low + | |
288 | balloon_stats.balloon_high); | |
289 | ||
83be7e52 | 290 | return target - balloon_stats.current_pages; |
1775826c JF |
291 | } |
292 | ||
080e2be7 DK |
293 | static bool balloon_is_inflated(void) |
294 | { | |
295 | if (balloon_stats.balloon_low || balloon_stats.balloon_high) | |
296 | return true; | |
297 | else | |
298 | return false; | |
299 | } | |
300 | ||
301 | static enum bp_state reserve_additional_memory(long credit) | |
302 | { | |
303 | balloon_stats.target_pages = balloon_stats.current_pages; | |
304 | return BP_DONE; | |
305 | } | |
306 | #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */ | |
307 | ||
95d2ac4a | 308 | static enum bp_state increase_reservation(unsigned long nr_pages) |
1775826c | 309 | { |
95d2ac4a | 310 | int rc; |
2f70e0ac | 311 | unsigned long pfn, i; |
1775826c | 312 | struct page *page; |
1775826c JF |
313 | struct xen_memory_reservation reservation = { |
314 | .address_bits = 0, | |
315 | .extent_order = 0, | |
316 | .domid = DOMID_SELF | |
317 | }; | |
318 | ||
080e2be7 DK |
319 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
320 | if (!balloon_stats.balloon_low && !balloon_stats.balloon_high) { | |
321 | nr_pages = min(nr_pages, balloon_stats.balloon_hotplug); | |
322 | balloon_stats.hotplug_pages += nr_pages; | |
323 | balloon_stats.balloon_hotplug -= nr_pages; | |
324 | return BP_DONE; | |
325 | } | |
326 | #endif | |
327 | ||
1775826c JF |
328 | if (nr_pages > ARRAY_SIZE(frame_list)) |
329 | nr_pages = ARRAY_SIZE(frame_list); | |
330 | ||
1775826c JF |
331 | page = balloon_first_page(); |
332 | for (i = 0; i < nr_pages; i++) { | |
95d2ac4a DK |
333 | if (!page) { |
334 | nr_pages = i; | |
335 | break; | |
336 | } | |
a419aef8 | 337 | frame_list[i] = page_to_pfn(page); |
1775826c JF |
338 | page = balloon_next_page(page); |
339 | } | |
340 | ||
a90971eb | 341 | set_xen_guest_handle(reservation.extent_start, frame_list); |
fde28e8f JF |
342 | reservation.nr_extents = nr_pages; |
343 | rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); | |
40095de1 | 344 | if (rc <= 0) |
95d2ac4a | 345 | return BP_EAGAIN; |
1775826c | 346 | |
bc2c0303 | 347 | for (i = 0; i < rc; i++) { |
b6f30679 | 348 | page = balloon_retrieve(false); |
1775826c JF |
349 | BUG_ON(page == NULL); |
350 | ||
351 | pfn = page_to_pfn(page); | |
1775826c JF |
352 | |
353 | set_phys_to_machine(pfn, frame_list[i]); | |
354 | ||
c2374bf5 | 355 | #ifdef CONFIG_XEN_HAVE_PVMMU |
1775826c | 356 | /* Link back into the page tables if not highmem. */ |
4dfe22f5 | 357 | if (xen_pv_domain() && !PageHighMem(page)) { |
1775826c JF |
358 | int ret; |
359 | ret = HYPERVISOR_update_va_mapping( | |
360 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
361 | mfn_pte(frame_list[i], PAGE_KERNEL), | |
362 | 0); | |
363 | BUG_ON(ret); | |
364 | } | |
c2374bf5 | 365 | #endif |
1775826c JF |
366 | |
367 | /* Relinquish the page back to the allocator. */ | |
3dcc0571 | 368 | __free_reserved_page(page); |
1775826c JF |
369 | } |
370 | ||
bc2c0303 | 371 | balloon_stats.current_pages += rc; |
1775826c | 372 | |
95d2ac4a | 373 | return BP_DONE; |
1775826c JF |
374 | } |
375 | ||
b6f30679 | 376 | static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) |
1775826c | 377 | { |
95d2ac4a | 378 | enum bp_state state = BP_DONE; |
2f70e0ac | 379 | unsigned long pfn, i; |
1775826c | 380 | struct page *page; |
2bad07ce | 381 | struct page *scratch_page; |
1775826c JF |
382 | int ret; |
383 | struct xen_memory_reservation reservation = { | |
384 | .address_bits = 0, | |
385 | .extent_order = 0, | |
386 | .domid = DOMID_SELF | |
387 | }; | |
388 | ||
080e2be7 DK |
389 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
390 | if (balloon_stats.hotplug_pages) { | |
391 | nr_pages = min(nr_pages, balloon_stats.hotplug_pages); | |
392 | balloon_stats.hotplug_pages -= nr_pages; | |
393 | balloon_stats.balloon_hotplug += nr_pages; | |
394 | return BP_DONE; | |
395 | } | |
396 | #endif | |
397 | ||
1775826c JF |
398 | if (nr_pages > ARRAY_SIZE(frame_list)) |
399 | nr_pages = ARRAY_SIZE(frame_list); | |
400 | ||
2bad07ce DV |
401 | scratch_page = get_balloon_scratch_page(); |
402 | ||
1775826c | 403 | for (i = 0; i < nr_pages; i++) { |
fce92683 LN |
404 | page = alloc_page(gfp); |
405 | if (page == NULL) { | |
1775826c | 406 | nr_pages = i; |
95d2ac4a | 407 | state = BP_EAGAIN; |
1775826c JF |
408 | break; |
409 | } | |
410 | ||
411 | pfn = page_to_pfn(page); | |
412 | frame_list[i] = pfn_to_mfn(pfn); | |
413 | ||
414 | scrub_page(page); | |
1058a75f | 415 | |
c2374bf5 | 416 | #ifdef CONFIG_XEN_HAVE_PVMMU |
4dfe22f5 | 417 | if (xen_pv_domain() && !PageHighMem(page)) { |
ff4ce8c3 IC |
418 | ret = HYPERVISOR_update_va_mapping( |
419 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
2bad07ce | 420 | pfn_pte(page_to_pfn(scratch_page), |
cd9151e2 | 421 | PAGE_KERNEL_RO), 0); |
ff4ce8c3 | 422 | BUG_ON(ret); |
e882dc9c | 423 | } |
c2374bf5 | 424 | #endif |
1775826c JF |
425 | } |
426 | ||
427 | /* Ensure that ballooned highmem pages don't have kmaps. */ | |
428 | kmap_flush_unused(); | |
429 | flush_tlb_all(); | |
430 | ||
1775826c JF |
431 | /* No more mappings: invalidate P2M and add to balloon. */ |
432 | for (i = 0; i < nr_pages; i++) { | |
433 | pfn = mfn_to_pfn(frame_list[i]); | |
04660bb5 WL |
434 | if (!xen_feature(XENFEAT_auto_translated_physmap)) { |
435 | unsigned long p; | |
2bad07ce | 436 | p = page_to_pfn(scratch_page); |
04660bb5 WL |
437 | __set_phys_to_machine(pfn, pfn_to_mfn(p)); |
438 | } | |
1775826c JF |
439 | balloon_append(pfn_to_page(pfn)); |
440 | } | |
441 | ||
2bad07ce DV |
442 | put_balloon_scratch_page(); |
443 | ||
a90971eb | 444 | set_xen_guest_handle(reservation.extent_start, frame_list); |
1775826c JF |
445 | reservation.nr_extents = nr_pages; |
446 | ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); | |
447 | BUG_ON(ret != nr_pages); | |
448 | ||
449 | balloon_stats.current_pages -= nr_pages; | |
1775826c | 450 | |
95d2ac4a | 451 | return state; |
1775826c JF |
452 | } |
453 | ||
454 | /* | |
455 | * We avoid multiple worker processes conflicting via the balloon mutex. | |
456 | * We may of course race updates of the target counts (which are protected | |
457 | * by the balloon lock), or with changes to the Xen hard limit, but we will | |
458 | * recover from these in time. | |
459 | */ | |
460 | static void balloon_process(struct work_struct *work) | |
461 | { | |
95d2ac4a | 462 | enum bp_state state = BP_DONE; |
1775826c JF |
463 | long credit; |
464 | ||
465 | mutex_lock(&balloon_mutex); | |
466 | ||
467 | do { | |
83be7e52 | 468 | credit = current_credit(); |
95d2ac4a | 469 | |
080e2be7 DK |
470 | if (credit > 0) { |
471 | if (balloon_is_inflated()) | |
472 | state = increase_reservation(credit); | |
473 | else | |
474 | state = reserve_additional_memory(credit); | |
475 | } | |
95d2ac4a | 476 | |
1775826c | 477 | if (credit < 0) |
b6f30679 | 478 | state = decrease_reservation(-credit, GFP_BALLOON); |
95d2ac4a DK |
479 | |
480 | state = update_schedule(state); | |
1775826c JF |
481 | |
482 | #ifndef CONFIG_PREEMPT | |
483 | if (need_resched()) | |
484 | schedule(); | |
485 | #endif | |
95d2ac4a | 486 | } while (credit && state == BP_DONE); |
1775826c JF |
487 | |
488 | /* Schedule more work if there is some still to be done. */ | |
95d2ac4a DK |
489 | if (state == BP_EAGAIN) |
490 | schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ); | |
1775826c JF |
491 | |
492 | mutex_unlock(&balloon_mutex); | |
493 | } | |
494 | ||
cd9151e2 SS |
495 | struct page *get_balloon_scratch_page(void) |
496 | { | |
497 | struct page *ret = get_cpu_var(balloon_scratch_page); | |
498 | BUG_ON(ret == NULL); | |
499 | return ret; | |
500 | } | |
501 | ||
502 | void put_balloon_scratch_page(void) | |
503 | { | |
504 | put_cpu_var(balloon_scratch_page); | |
505 | } | |
506 | ||
1775826c | 507 | /* Resets the Xen limit, sets new target, and kicks off processing. */ |
803eb047 | 508 | void balloon_set_new_target(unsigned long target) |
1775826c JF |
509 | { |
510 | /* No need for lock. Not read-modify-write updates. */ | |
1775826c | 511 | balloon_stats.target_pages = target; |
95170b2e | 512 | schedule_delayed_work(&balloon_worker, 0); |
1775826c | 513 | } |
803eb047 | 514 | EXPORT_SYMBOL_GPL(balloon_set_new_target); |
1775826c | 515 | |
b6f30679 KRW |
516 | /** |
517 | * alloc_xenballooned_pages - get pages that have been ballooned out | |
518 | * @nr_pages: Number of pages to get | |
519 | * @pages: pages returned | |
72e9cf2a | 520 | * @highmem: allow highmem pages |
b6f30679 KRW |
521 | * @return 0 on success, error otherwise |
522 | */ | |
693394b8 | 523 | int alloc_xenballooned_pages(int nr_pages, struct page **pages, bool highmem) |
1775826c | 524 | { |
b6f30679 | 525 | int pgno = 0; |
e882dc9c | 526 | struct page *page; |
b6f30679 KRW |
527 | mutex_lock(&balloon_mutex); |
528 | while (pgno < nr_pages) { | |
693394b8 | 529 | page = balloon_retrieve(highmem); |
72e9cf2a | 530 | if (page && (highmem || !PageHighMem(page))) { |
b6f30679 KRW |
531 | pages[pgno++] = page; |
532 | } else { | |
533 | enum bp_state st; | |
693394b8 SS |
534 | if (page) |
535 | balloon_append(page); | |
536 | st = decrease_reservation(nr_pages - pgno, | |
537 | highmem ? GFP_HIGHUSER : GFP_USER); | |
b6f30679 KRW |
538 | if (st != BP_DONE) |
539 | goto out_undo; | |
540 | } | |
1775826c | 541 | } |
b6f30679 KRW |
542 | mutex_unlock(&balloon_mutex); |
543 | return 0; | |
544 | out_undo: | |
545 | while (pgno) | |
546 | balloon_append(pages[--pgno]); | |
547 | /* Free the memory back to the kernel soon */ | |
548 | schedule_delayed_work(&balloon_worker, 0); | |
549 | mutex_unlock(&balloon_mutex); | |
550 | return -ENOMEM; | |
1775826c | 551 | } |
b6f30679 | 552 | EXPORT_SYMBOL(alloc_xenballooned_pages); |
1775826c | 553 | |
b6f30679 KRW |
554 | /** |
555 | * free_xenballooned_pages - return pages retrieved with get_ballooned_pages | |
556 | * @nr_pages: Number of pages | |
557 | * @pages: pages to return | |
558 | */ | |
e882dc9c | 559 | void free_xenballooned_pages(int nr_pages, struct page **pages) |
1775826c | 560 | { |
b6f30679 | 561 | int i; |
1775826c | 562 | |
b6f30679 | 563 | mutex_lock(&balloon_mutex); |
1775826c | 564 | |
b6f30679 KRW |
565 | for (i = 0; i < nr_pages; i++) { |
566 | if (pages[i]) | |
567 | balloon_append(pages[i]); | |
568 | } | |
569 | ||
570 | /* The balloon may be too large now. Shrink it if needed. */ | |
83be7e52 | 571 | if (current_credit()) |
b6f30679 | 572 | schedule_delayed_work(&balloon_worker, 0); |
1775826c | 573 | |
b6f30679 KRW |
574 | mutex_unlock(&balloon_mutex); |
575 | } | |
576 | EXPORT_SYMBOL(free_xenballooned_pages); | |
1775826c | 577 | |
8b5d44a5 DV |
578 | static void __init balloon_add_region(unsigned long start_pfn, |
579 | unsigned long pages) | |
1775826c | 580 | { |
4dfe22f5 | 581 | unsigned long pfn, extra_pfn_end; |
1775826c JF |
582 | struct page *page; |
583 | ||
8b5d44a5 DV |
584 | /* |
585 | * If the amount of usable memory has been limited (e.g., with | |
586 | * the 'mem' command line parameter), don't add pages beyond | |
587 | * this limit. | |
588 | */ | |
589 | extra_pfn_end = min(max_pfn, start_pfn + pages); | |
590 | ||
591 | for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) { | |
592 | page = pfn_to_page(pfn); | |
593 | /* totalram_pages and totalhigh_pages do not | |
594 | include the boot-time balloon extension, so | |
595 | don't subtract from it. */ | |
596 | __balloon_append(page); | |
597 | } | |
598 | } | |
599 | ||
cd9151e2 SS |
600 | static int __cpuinit balloon_cpu_notify(struct notifier_block *self, |
601 | unsigned long action, void *hcpu) | |
602 | { | |
603 | int cpu = (long)hcpu; | |
604 | switch (action) { | |
605 | case CPU_UP_PREPARE: | |
606 | if (per_cpu(balloon_scratch_page, cpu) != NULL) | |
607 | break; | |
608 | per_cpu(balloon_scratch_page, cpu) = alloc_page(GFP_KERNEL); | |
609 | if (per_cpu(balloon_scratch_page, cpu) == NULL) { | |
610 | pr_warn("Failed to allocate balloon_scratch_page for cpu %d\n", cpu); | |
611 | return NOTIFY_BAD; | |
612 | } | |
613 | break; | |
614 | default: | |
615 | break; | |
616 | } | |
617 | return NOTIFY_OK; | |
618 | } | |
619 | ||
620 | static struct notifier_block balloon_cpu_notifier __cpuinitdata = { | |
621 | .notifier_call = balloon_cpu_notify, | |
622 | }; | |
623 | ||
8b5d44a5 DV |
624 | static int __init balloon_init(void) |
625 | { | |
cd9151e2 | 626 | int i, cpu; |
8b5d44a5 | 627 | |
53d5522c | 628 | if (!xen_domain()) |
1775826c JF |
629 | return -ENODEV; |
630 | ||
cd9151e2 SS |
631 | for_each_online_cpu(cpu) |
632 | { | |
633 | per_cpu(balloon_scratch_page, cpu) = alloc_page(GFP_KERNEL); | |
634 | if (per_cpu(balloon_scratch_page, cpu) == NULL) { | |
635 | pr_warn("Failed to allocate balloon_scratch_page for cpu %d\n", cpu); | |
636 | return -ENOMEM; | |
637 | } | |
638 | } | |
639 | register_cpu_notifier(&balloon_cpu_notifier); | |
640 | ||
283c0972 | 641 | pr_info("Initialising balloon driver\n"); |
1775826c | 642 | |
aa24411b DV |
643 | balloon_stats.current_pages = xen_pv_domain() |
644 | ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn) | |
645 | : max_pfn; | |
1775826c JF |
646 | balloon_stats.target_pages = balloon_stats.current_pages; |
647 | balloon_stats.balloon_low = 0; | |
648 | balloon_stats.balloon_high = 0; | |
1775826c | 649 | |
95d2ac4a DK |
650 | balloon_stats.schedule_delay = 1; |
651 | balloon_stats.max_schedule_delay = 32; | |
652 | balloon_stats.retry_count = 1; | |
40095de1 | 653 | balloon_stats.max_retry_count = RETRY_UNLIMITED; |
1775826c | 654 | |
080e2be7 DK |
655 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
656 | balloon_stats.hotplug_pages = 0; | |
657 | balloon_stats.balloon_hotplug = 0; | |
658 | ||
659 | set_online_page_callback(&xen_online_page); | |
660 | register_memory_notifier(&xen_memory_nb); | |
661 | #endif | |
662 | ||
2a4c92fa | 663 | /* |
b1cbf9b1 | 664 | * Initialize the balloon with pages from the extra memory |
8b5d44a5 | 665 | * regions (see arch/x86/xen/setup.c). |
2a4c92fa | 666 | */ |
8b5d44a5 DV |
667 | for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) |
668 | if (xen_extra_mem[i].size) | |
669 | balloon_add_region(PFN_UP(xen_extra_mem[i].start), | |
670 | PFN_DOWN(xen_extra_mem[i].size)); | |
1775826c | 671 | |
1775826c JF |
672 | return 0; |
673 | } | |
674 | ||
675 | subsys_initcall(balloon_init); | |
676 | ||
cd9151e2 SS |
677 | static int __init balloon_clear(void) |
678 | { | |
679 | int cpu; | |
680 | ||
681 | for_each_possible_cpu(cpu) | |
682 | per_cpu(balloon_scratch_page, cpu) = NULL; | |
683 | ||
684 | return 0; | |
685 | } | |
686 | early_initcall(balloon_clear); | |
687 | ||
1775826c | 688 | MODULE_LICENSE("GPL"); |