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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/errno.h> | |
45 | #include <linux/mm.h> | |
46 | #include <linux/bootmem.h> | |
47 | #include <linux/pagemap.h> | |
48 | #include <linux/highmem.h> | |
49 | #include <linux/mutex.h> | |
50 | #include <linux/list.h> | |
51 | #include <linux/gfp.h> | |
52 | #include <linux/notifier.h> | |
53 | #include <linux/memory.h> | |
54 | #include <linux/memory_hotplug.h> | |
55 | #include <linux/percpu-defs.h> | |
56 | #include <linux/slab.h> | |
57 | #include <linux/sysctl.h> | |
58 | ||
59 | #include <asm/page.h> | |
60 | #include <asm/pgalloc.h> | |
61 | #include <asm/pgtable.h> | |
62 | #include <asm/tlb.h> | |
63 | ||
64 | #include <asm/xen/hypervisor.h> | |
65 | #include <asm/xen/hypercall.h> | |
66 | ||
67 | #include <xen/xen.h> | |
68 | #include <xen/interface/xen.h> | |
69 | #include <xen/interface/memory.h> | |
70 | #include <xen/balloon.h> | |
71 | #include <xen/features.h> | |
72 | #include <xen/page.h> | |
73 | ||
74 | static int xen_hotplug_unpopulated; | |
75 | ||
76 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG | |
77 | ||
78 | static int zero; | |
79 | static int one = 1; | |
80 | ||
81 | static struct ctl_table balloon_table[] = { | |
82 | { | |
83 | .procname = "hotplug_unpopulated", | |
84 | .data = &xen_hotplug_unpopulated, | |
85 | .maxlen = sizeof(int), | |
86 | .mode = 0644, | |
87 | .proc_handler = proc_dointvec_minmax, | |
88 | .extra1 = &zero, | |
89 | .extra2 = &one, | |
90 | }, | |
91 | { } | |
92 | }; | |
93 | ||
94 | static struct ctl_table balloon_root[] = { | |
95 | { | |
96 | .procname = "balloon", | |
97 | .mode = 0555, | |
98 | .child = balloon_table, | |
99 | }, | |
100 | { } | |
101 | }; | |
102 | ||
103 | static struct ctl_table xen_root[] = { | |
104 | { | |
105 | .procname = "xen", | |
106 | .mode = 0555, | |
107 | .child = balloon_root, | |
108 | }, | |
109 | { } | |
110 | }; | |
111 | ||
112 | #endif | |
113 | ||
114 | /* | |
115 | * Use one extent per PAGE_SIZE to avoid to break down the page into | |
116 | * multiple frame. | |
117 | */ | |
118 | #define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1) | |
119 | ||
120 | /* | |
121 | * balloon_process() state: | |
122 | * | |
123 | * BP_DONE: done or nothing to do, | |
124 | * BP_WAIT: wait to be rescheduled, | |
125 | * BP_EAGAIN: error, go to sleep, | |
126 | * BP_ECANCELED: error, balloon operation canceled. | |
127 | */ | |
128 | ||
129 | enum bp_state { | |
130 | BP_DONE, | |
131 | BP_WAIT, | |
132 | BP_EAGAIN, | |
133 | BP_ECANCELED | |
134 | }; | |
135 | ||
136 | ||
137 | static DEFINE_MUTEX(balloon_mutex); | |
138 | ||
139 | struct balloon_stats balloon_stats; | |
140 | EXPORT_SYMBOL_GPL(balloon_stats); | |
141 | ||
142 | /* We increase/decrease in batches which fit in a page */ | |
143 | static xen_pfn_t frame_list[PAGE_SIZE / sizeof(xen_pfn_t)]; | |
144 | ||
145 | ||
146 | /* List of ballooned pages, threaded through the mem_map array. */ | |
147 | static LIST_HEAD(ballooned_pages); | |
148 | static DECLARE_WAIT_QUEUE_HEAD(balloon_wq); | |
149 | ||
150 | /* Main work function, always executed in process context. */ | |
151 | static void balloon_process(struct work_struct *work); | |
152 | static DECLARE_DELAYED_WORK(balloon_worker, balloon_process); | |
153 | ||
154 | /* When ballooning out (allocating memory to return to Xen) we don't really | |
155 | want the kernel to try too hard since that can trigger the oom killer. */ | |
156 | #define GFP_BALLOON \ | |
157 | (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) | |
158 | ||
159 | static void scrub_page(struct page *page) | |
160 | { | |
161 | #ifdef CONFIG_XEN_SCRUB_PAGES | |
162 | clear_highpage(page); | |
163 | #endif | |
164 | } | |
165 | ||
166 | /* balloon_append: add the given page to the balloon. */ | |
167 | static void __balloon_append(struct page *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 | static void balloon_append(struct page *page) | |
181 | { | |
182 | __balloon_append(page); | |
183 | } | |
184 | ||
185 | /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ | |
186 | static struct page *balloon_retrieve(bool require_lowmem) | |
187 | { | |
188 | struct page *page; | |
189 | ||
190 | if (list_empty(&ballooned_pages)) | |
191 | return NULL; | |
192 | ||
193 | page = list_entry(ballooned_pages.next, struct page, lru); | |
194 | if (require_lowmem && PageHighMem(page)) | |
195 | return NULL; | |
196 | list_del(&page->lru); | |
197 | ||
198 | if (PageHighMem(page)) | |
199 | balloon_stats.balloon_high--; | |
200 | else | |
201 | balloon_stats.balloon_low--; | |
202 | ||
203 | return page; | |
204 | } | |
205 | ||
206 | static struct page *balloon_next_page(struct page *page) | |
207 | { | |
208 | struct list_head *next = page->lru.next; | |
209 | if (next == &ballooned_pages) | |
210 | return NULL; | |
211 | return list_entry(next, struct page, lru); | |
212 | } | |
213 | ||
214 | static enum bp_state update_schedule(enum bp_state state) | |
215 | { | |
216 | if (state == BP_WAIT) | |
217 | return BP_WAIT; | |
218 | ||
219 | if (state == BP_ECANCELED) | |
220 | return BP_ECANCELED; | |
221 | ||
222 | if (state == BP_DONE) { | |
223 | balloon_stats.schedule_delay = 1; | |
224 | balloon_stats.retry_count = 1; | |
225 | return BP_DONE; | |
226 | } | |
227 | ||
228 | ++balloon_stats.retry_count; | |
229 | ||
230 | if (balloon_stats.max_retry_count != RETRY_UNLIMITED && | |
231 | balloon_stats.retry_count > balloon_stats.max_retry_count) { | |
232 | balloon_stats.schedule_delay = 1; | |
233 | balloon_stats.retry_count = 1; | |
234 | return BP_ECANCELED; | |
235 | } | |
236 | ||
237 | balloon_stats.schedule_delay <<= 1; | |
238 | ||
239 | if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay) | |
240 | balloon_stats.schedule_delay = balloon_stats.max_schedule_delay; | |
241 | ||
242 | return BP_EAGAIN; | |
243 | } | |
244 | ||
245 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG | |
246 | static void release_memory_resource(struct resource *resource) | |
247 | { | |
248 | if (!resource) | |
249 | return; | |
250 | ||
251 | /* | |
252 | * No need to reset region to identity mapped since we now | |
253 | * know that no I/O can be in this region | |
254 | */ | |
255 | release_resource(resource); | |
256 | kfree(resource); | |
257 | } | |
258 | ||
259 | static struct resource *additional_memory_resource(phys_addr_t size) | |
260 | { | |
261 | struct resource *res; | |
262 | int ret; | |
263 | ||
264 | res = kzalloc(sizeof(*res), GFP_KERNEL); | |
265 | if (!res) | |
266 | return NULL; | |
267 | ||
268 | res->name = "System RAM"; | |
269 | res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; | |
270 | ||
271 | ret = allocate_resource(&iomem_resource, res, | |
272 | size, 0, -1, | |
273 | PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL); | |
274 | if (ret < 0) { | |
275 | pr_err("Cannot allocate new System RAM resource\n"); | |
276 | kfree(res); | |
277 | return NULL; | |
278 | } | |
279 | ||
280 | #ifdef CONFIG_SPARSEMEM | |
281 | { | |
282 | unsigned long limit = 1UL << (MAX_PHYSMEM_BITS - PAGE_SHIFT); | |
283 | unsigned long pfn = res->start >> PAGE_SHIFT; | |
284 | ||
285 | if (pfn > limit) { | |
286 | pr_err("New System RAM resource outside addressable RAM (%lu > %lu)\n", | |
287 | pfn, limit); | |
288 | release_memory_resource(res); | |
289 | return NULL; | |
290 | } | |
291 | } | |
292 | #endif | |
293 | ||
294 | return res; | |
295 | } | |
296 | ||
297 | static enum bp_state reserve_additional_memory(void) | |
298 | { | |
299 | long credit; | |
300 | struct resource *resource; | |
301 | int nid, rc; | |
302 | unsigned long balloon_hotplug; | |
303 | ||
304 | credit = balloon_stats.target_pages + balloon_stats.target_unpopulated | |
305 | - balloon_stats.total_pages; | |
306 | ||
307 | /* | |
308 | * Already hotplugged enough pages? Wait for them to be | |
309 | * onlined. | |
310 | */ | |
311 | if (credit <= 0) | |
312 | return BP_WAIT; | |
313 | ||
314 | balloon_hotplug = round_up(credit, PAGES_PER_SECTION); | |
315 | ||
316 | resource = additional_memory_resource(balloon_hotplug * PAGE_SIZE); | |
317 | if (!resource) | |
318 | goto err; | |
319 | ||
320 | nid = memory_add_physaddr_to_nid(resource->start); | |
321 | ||
322 | #ifdef CONFIG_XEN_HAVE_PVMMU | |
323 | /* | |
324 | * We don't support PV MMU when Linux and Xen is using | |
325 | * different page granularity. | |
326 | */ | |
327 | BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); | |
328 | ||
329 | /* | |
330 | * add_memory() will build page tables for the new memory so | |
331 | * the p2m must contain invalid entries so the correct | |
332 | * non-present PTEs will be written. | |
333 | * | |
334 | * If a failure occurs, the original (identity) p2m entries | |
335 | * are not restored since this region is now known not to | |
336 | * conflict with any devices. | |
337 | */ | |
338 | if (!xen_feature(XENFEAT_auto_translated_physmap)) { | |
339 | unsigned long pfn, i; | |
340 | ||
341 | pfn = PFN_DOWN(resource->start); | |
342 | for (i = 0; i < balloon_hotplug; i++) { | |
343 | if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) { | |
344 | pr_warn("set_phys_to_machine() failed, no memory added\n"); | |
345 | goto err; | |
346 | } | |
347 | } | |
348 | } | |
349 | #endif | |
350 | ||
351 | /* | |
352 | * add_memory_resource() will call online_pages() which in its turn | |
353 | * will call xen_online_page() callback causing deadlock if we don't | |
354 | * release balloon_mutex here. Unlocking here is safe because the | |
355 | * callers drop the mutex before trying again. | |
356 | */ | |
357 | mutex_unlock(&balloon_mutex); | |
358 | rc = add_memory_resource(nid, resource, memhp_auto_online); | |
359 | mutex_lock(&balloon_mutex); | |
360 | ||
361 | if (rc) { | |
362 | pr_warn("Cannot add additional memory (%i)\n", rc); | |
363 | goto err; | |
364 | } | |
365 | ||
366 | balloon_stats.total_pages += balloon_hotplug; | |
367 | ||
368 | return BP_WAIT; | |
369 | err: | |
370 | release_memory_resource(resource); | |
371 | return BP_ECANCELED; | |
372 | } | |
373 | ||
374 | static void xen_online_page(struct page *page) | |
375 | { | |
376 | __online_page_set_limits(page); | |
377 | ||
378 | mutex_lock(&balloon_mutex); | |
379 | ||
380 | __balloon_append(page); | |
381 | ||
382 | mutex_unlock(&balloon_mutex); | |
383 | } | |
384 | ||
385 | static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v) | |
386 | { | |
387 | if (val == MEM_ONLINE) | |
388 | schedule_delayed_work(&balloon_worker, 0); | |
389 | ||
390 | return NOTIFY_OK; | |
391 | } | |
392 | ||
393 | static struct notifier_block xen_memory_nb = { | |
394 | .notifier_call = xen_memory_notifier, | |
395 | .priority = 0 | |
396 | }; | |
397 | #else | |
398 | static enum bp_state reserve_additional_memory(void) | |
399 | { | |
400 | balloon_stats.target_pages = balloon_stats.current_pages; | |
401 | return BP_ECANCELED; | |
402 | } | |
403 | #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */ | |
404 | ||
405 | static long current_credit(void) | |
406 | { | |
407 | return balloon_stats.target_pages - balloon_stats.current_pages; | |
408 | } | |
409 | ||
410 | static bool balloon_is_inflated(void) | |
411 | { | |
412 | return balloon_stats.balloon_low || balloon_stats.balloon_high; | |
413 | } | |
414 | ||
415 | static enum bp_state increase_reservation(unsigned long nr_pages) | |
416 | { | |
417 | int rc; | |
418 | unsigned long i; | |
419 | struct page *page; | |
420 | struct xen_memory_reservation reservation = { | |
421 | .address_bits = 0, | |
422 | .extent_order = EXTENT_ORDER, | |
423 | .domid = DOMID_SELF | |
424 | }; | |
425 | ||
426 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
427 | nr_pages = ARRAY_SIZE(frame_list); | |
428 | ||
429 | page = list_first_entry_or_null(&ballooned_pages, struct page, lru); | |
430 | for (i = 0; i < nr_pages; i++) { | |
431 | if (!page) { | |
432 | nr_pages = i; | |
433 | break; | |
434 | } | |
435 | ||
436 | /* XENMEM_populate_physmap requires a PFN based on Xen | |
437 | * granularity. | |
438 | */ | |
439 | frame_list[i] = page_to_xen_pfn(page); | |
440 | page = balloon_next_page(page); | |
441 | } | |
442 | ||
443 | set_xen_guest_handle(reservation.extent_start, frame_list); | |
444 | reservation.nr_extents = nr_pages; | |
445 | rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); | |
446 | if (rc <= 0) | |
447 | return BP_EAGAIN; | |
448 | ||
449 | for (i = 0; i < rc; i++) { | |
450 | page = balloon_retrieve(false); | |
451 | BUG_ON(page == NULL); | |
452 | ||
453 | #ifdef CONFIG_XEN_HAVE_PVMMU | |
454 | /* | |
455 | * We don't support PV MMU when Linux and Xen is using | |
456 | * different page granularity. | |
457 | */ | |
458 | BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); | |
459 | ||
460 | if (!xen_feature(XENFEAT_auto_translated_physmap)) { | |
461 | unsigned long pfn = page_to_pfn(page); | |
462 | ||
463 | set_phys_to_machine(pfn, frame_list[i]); | |
464 | ||
465 | /* Link back into the page tables if not highmem. */ | |
466 | if (!PageHighMem(page)) { | |
467 | int ret; | |
468 | ret = HYPERVISOR_update_va_mapping( | |
469 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
470 | mfn_pte(frame_list[i], PAGE_KERNEL), | |
471 | 0); | |
472 | BUG_ON(ret); | |
473 | } | |
474 | } | |
475 | #endif | |
476 | ||
477 | /* Relinquish the page back to the allocator. */ | |
478 | free_reserved_page(page); | |
479 | } | |
480 | ||
481 | balloon_stats.current_pages += rc; | |
482 | ||
483 | return BP_DONE; | |
484 | } | |
485 | ||
486 | static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) | |
487 | { | |
488 | enum bp_state state = BP_DONE; | |
489 | unsigned long i; | |
490 | struct page *page, *tmp; | |
491 | int ret; | |
492 | struct xen_memory_reservation reservation = { | |
493 | .address_bits = 0, | |
494 | .extent_order = EXTENT_ORDER, | |
495 | .domid = DOMID_SELF | |
496 | }; | |
497 | LIST_HEAD(pages); | |
498 | ||
499 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
500 | nr_pages = ARRAY_SIZE(frame_list); | |
501 | ||
502 | for (i = 0; i < nr_pages; i++) { | |
503 | page = alloc_page(gfp); | |
504 | if (page == NULL) { | |
505 | nr_pages = i; | |
506 | state = BP_EAGAIN; | |
507 | break; | |
508 | } | |
509 | adjust_managed_page_count(page, -1); | |
510 | scrub_page(page); | |
511 | list_add(&page->lru, &pages); | |
512 | } | |
513 | ||
514 | /* | |
515 | * Ensure that ballooned highmem pages don't have kmaps. | |
516 | * | |
517 | * Do this before changing the p2m as kmap_flush_unused() | |
518 | * reads PTEs to obtain pages (and hence needs the original | |
519 | * p2m entry). | |
520 | */ | |
521 | kmap_flush_unused(); | |
522 | ||
523 | /* | |
524 | * Setup the frame, update direct mapping, invalidate P2M, | |
525 | * and add to balloon. | |
526 | */ | |
527 | i = 0; | |
528 | list_for_each_entry_safe(page, tmp, &pages, lru) { | |
529 | /* XENMEM_decrease_reservation requires a GFN */ | |
530 | frame_list[i++] = xen_page_to_gfn(page); | |
531 | ||
532 | #ifdef CONFIG_XEN_HAVE_PVMMU | |
533 | /* | |
534 | * We don't support PV MMU when Linux and Xen is using | |
535 | * different page granularity. | |
536 | */ | |
537 | BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); | |
538 | ||
539 | if (!xen_feature(XENFEAT_auto_translated_physmap)) { | |
540 | unsigned long pfn = page_to_pfn(page); | |
541 | ||
542 | if (!PageHighMem(page)) { | |
543 | ret = HYPERVISOR_update_va_mapping( | |
544 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
545 | __pte_ma(0), 0); | |
546 | BUG_ON(ret); | |
547 | } | |
548 | __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); | |
549 | } | |
550 | #endif | |
551 | list_del(&page->lru); | |
552 | ||
553 | balloon_append(page); | |
554 | } | |
555 | ||
556 | flush_tlb_all(); | |
557 | ||
558 | set_xen_guest_handle(reservation.extent_start, frame_list); | |
559 | reservation.nr_extents = nr_pages; | |
560 | ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); | |
561 | BUG_ON(ret != nr_pages); | |
562 | ||
563 | balloon_stats.current_pages -= nr_pages; | |
564 | ||
565 | return state; | |
566 | } | |
567 | ||
568 | /* | |
569 | * As this is a work item it is guaranteed to run as a single instance only. | |
570 | * We may of course race updates of the target counts (which are protected | |
571 | * by the balloon lock), or with changes to the Xen hard limit, but we will | |
572 | * recover from these in time. | |
573 | */ | |
574 | static void balloon_process(struct work_struct *work) | |
575 | { | |
576 | enum bp_state state = BP_DONE; | |
577 | long credit; | |
578 | ||
579 | ||
580 | do { | |
581 | mutex_lock(&balloon_mutex); | |
582 | ||
583 | credit = current_credit(); | |
584 | ||
585 | if (credit > 0) { | |
586 | if (balloon_is_inflated()) | |
587 | state = increase_reservation(credit); | |
588 | else | |
589 | state = reserve_additional_memory(); | |
590 | } | |
591 | ||
592 | if (credit < 0) | |
593 | state = decrease_reservation(-credit, GFP_BALLOON); | |
594 | ||
595 | state = update_schedule(state); | |
596 | ||
597 | mutex_unlock(&balloon_mutex); | |
598 | ||
599 | cond_resched(); | |
600 | ||
601 | } while (credit && state == BP_DONE); | |
602 | ||
603 | /* Schedule more work if there is some still to be done. */ | |
604 | if (state == BP_EAGAIN) | |
605 | schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ); | |
606 | } | |
607 | ||
608 | /* Resets the Xen limit, sets new target, and kicks off processing. */ | |
609 | void balloon_set_new_target(unsigned long target) | |
610 | { | |
611 | /* No need for lock. Not read-modify-write updates. */ | |
612 | balloon_stats.target_pages = target; | |
613 | schedule_delayed_work(&balloon_worker, 0); | |
614 | } | |
615 | EXPORT_SYMBOL_GPL(balloon_set_new_target); | |
616 | ||
617 | static int add_ballooned_pages(int nr_pages) | |
618 | { | |
619 | enum bp_state st; | |
620 | ||
621 | if (xen_hotplug_unpopulated) { | |
622 | st = reserve_additional_memory(); | |
623 | if (st != BP_ECANCELED) { | |
624 | mutex_unlock(&balloon_mutex); | |
625 | wait_event(balloon_wq, | |
626 | !list_empty(&ballooned_pages)); | |
627 | mutex_lock(&balloon_mutex); | |
628 | return 0; | |
629 | } | |
630 | } | |
631 | ||
632 | st = decrease_reservation(nr_pages, GFP_USER); | |
633 | if (st != BP_DONE) | |
634 | return -ENOMEM; | |
635 | ||
636 | return 0; | |
637 | } | |
638 | ||
639 | /** | |
640 | * alloc_xenballooned_pages - get pages that have been ballooned out | |
641 | * @nr_pages: Number of pages to get | |
642 | * @pages: pages returned | |
643 | * @return 0 on success, error otherwise | |
644 | */ | |
645 | int alloc_xenballooned_pages(int nr_pages, struct page **pages) | |
646 | { | |
647 | int pgno = 0; | |
648 | struct page *page; | |
649 | int ret; | |
650 | ||
651 | mutex_lock(&balloon_mutex); | |
652 | ||
653 | balloon_stats.target_unpopulated += nr_pages; | |
654 | ||
655 | while (pgno < nr_pages) { | |
656 | page = balloon_retrieve(true); | |
657 | if (page) { | |
658 | pages[pgno++] = page; | |
659 | #ifdef CONFIG_XEN_HAVE_PVMMU | |
660 | /* | |
661 | * We don't support PV MMU when Linux and Xen is using | |
662 | * different page granularity. | |
663 | */ | |
664 | BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); | |
665 | ||
666 | ret = xen_alloc_p2m_entry(page_to_pfn(page)); | |
667 | if (ret < 0) | |
668 | goto out_undo; | |
669 | #endif | |
670 | } else { | |
671 | ret = add_ballooned_pages(nr_pages - pgno); | |
672 | if (ret < 0) | |
673 | goto out_undo; | |
674 | } | |
675 | } | |
676 | mutex_unlock(&balloon_mutex); | |
677 | return 0; | |
678 | out_undo: | |
679 | mutex_unlock(&balloon_mutex); | |
680 | free_xenballooned_pages(pgno, pages); | |
681 | return ret; | |
682 | } | |
683 | EXPORT_SYMBOL(alloc_xenballooned_pages); | |
684 | ||
685 | /** | |
686 | * free_xenballooned_pages - return pages retrieved with get_ballooned_pages | |
687 | * @nr_pages: Number of pages | |
688 | * @pages: pages to return | |
689 | */ | |
690 | void free_xenballooned_pages(int nr_pages, struct page **pages) | |
691 | { | |
692 | int i; | |
693 | ||
694 | mutex_lock(&balloon_mutex); | |
695 | ||
696 | for (i = 0; i < nr_pages; i++) { | |
697 | if (pages[i]) | |
698 | balloon_append(pages[i]); | |
699 | } | |
700 | ||
701 | balloon_stats.target_unpopulated -= nr_pages; | |
702 | ||
703 | /* The balloon may be too large now. Shrink it if needed. */ | |
704 | if (current_credit()) | |
705 | schedule_delayed_work(&balloon_worker, 0); | |
706 | ||
707 | mutex_unlock(&balloon_mutex); | |
708 | } | |
709 | EXPORT_SYMBOL(free_xenballooned_pages); | |
710 | ||
711 | static void __init balloon_add_region(unsigned long start_pfn, | |
712 | unsigned long pages) | |
713 | { | |
714 | unsigned long pfn, extra_pfn_end; | |
715 | struct page *page; | |
716 | ||
717 | /* | |
718 | * If the amount of usable memory has been limited (e.g., with | |
719 | * the 'mem' command line parameter), don't add pages beyond | |
720 | * this limit. | |
721 | */ | |
722 | extra_pfn_end = min(max_pfn, start_pfn + pages); | |
723 | ||
724 | for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) { | |
725 | page = pfn_to_page(pfn); | |
726 | /* totalram_pages and totalhigh_pages do not | |
727 | include the boot-time balloon extension, so | |
728 | don't subtract from it. */ | |
729 | __balloon_append(page); | |
730 | } | |
731 | ||
732 | balloon_stats.total_pages += extra_pfn_end - start_pfn; | |
733 | } | |
734 | ||
735 | static int __init balloon_init(void) | |
736 | { | |
737 | int i; | |
738 | ||
739 | if (!xen_domain()) | |
740 | return -ENODEV; | |
741 | ||
742 | pr_info("Initialising balloon driver\n"); | |
743 | ||
744 | balloon_stats.current_pages = xen_pv_domain() | |
745 | ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn) | |
746 | : get_num_physpages(); | |
747 | balloon_stats.target_pages = balloon_stats.current_pages; | |
748 | balloon_stats.balloon_low = 0; | |
749 | balloon_stats.balloon_high = 0; | |
750 | balloon_stats.total_pages = balloon_stats.current_pages; | |
751 | ||
752 | balloon_stats.schedule_delay = 1; | |
753 | balloon_stats.max_schedule_delay = 32; | |
754 | balloon_stats.retry_count = 1; | |
755 | balloon_stats.max_retry_count = RETRY_UNLIMITED; | |
756 | ||
757 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG | |
758 | set_online_page_callback(&xen_online_page); | |
759 | register_memory_notifier(&xen_memory_nb); | |
760 | register_sysctl_table(xen_root); | |
761 | #endif | |
762 | ||
763 | /* | |
764 | * Initialize the balloon with pages from the extra memory | |
765 | * regions (see arch/x86/xen/setup.c). | |
766 | */ | |
767 | for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) | |
768 | if (xen_extra_mem[i].n_pfns) | |
769 | balloon_add_region(xen_extra_mem[i].start_pfn, | |
770 | xen_extra_mem[i].n_pfns); | |
771 | ||
772 | return 0; | |
773 | } | |
774 | subsys_initcall(balloon_init); |