Merge tag 'powerpc-5.4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc...
[linux-2.6-block.git] / drivers / xen / balloon.c
CommitLineData
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 43#include <linux/sched.h>
5b825c3a 44#include <linux/cred.h>
1775826c
JF
45#include <linux/errno.h>
46#include <linux/mm.h>
57c8a661 47#include <linux/memblock.h>
1775826c
JF
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>
55b3da98 57#include <linux/slab.h>
1cf6a6c8 58#include <linux/sysctl.h>
1775826c 59
1775826c
JF
60#include <asm/page.h>
61#include <asm/pgalloc.h>
62#include <asm/pgtable.h>
1775826c
JF
63#include <asm/tlb.h>
64
ecbf29cd
JF
65#include <asm/xen/hypervisor.h>
66#include <asm/xen/hypercall.h>
1ccbf534
JF
67
68#include <xen/xen.h>
ecbf29cd 69#include <xen/interface/xen.h>
1775826c 70#include <xen/interface/memory.h>
803eb047 71#include <xen/balloon.h>
1775826c
JF
72#include <xen/features.h>
73#include <xen/page.h>
ae4c51a5 74#include <xen/mem-reservation.h>
1775826c 75
1cf6a6c8
DV
76static int xen_hotplug_unpopulated;
77
78#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
79
1cf6a6c8
DV
80static struct ctl_table balloon_table[] = {
81 {
82 .procname = "hotplug_unpopulated",
83 .data = &xen_hotplug_unpopulated,
84 .maxlen = sizeof(int),
85 .mode = 0644,
86 .proc_handler = proc_dointvec_minmax,
eec4844f
MC
87 .extra1 = SYSCTL_ZERO,
88 .extra2 = SYSCTL_ONE,
1cf6a6c8
DV
89 },
90 { }
91};
92
93static struct ctl_table balloon_root[] = {
94 {
95 .procname = "balloon",
96 .mode = 0555,
97 .child = balloon_table,
98 },
99 { }
100};
101
102static struct ctl_table xen_root[] = {
103 {
104 .procname = "xen",
105 .mode = 0555,
106 .child = balloon_root,
107 },
108 { }
109};
110
111#endif
112
30756c62
JG
113/*
114 * Use one extent per PAGE_SIZE to avoid to break down the page into
115 * multiple frame.
116 */
117#define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
118
95d2ac4a
DK
119/*
120 * balloon_process() state:
121 *
122 * BP_DONE: done or nothing to do,
b2ac6aa8 123 * BP_WAIT: wait to be rescheduled,
95d2ac4a
DK
124 * BP_EAGAIN: error, go to sleep,
125 * BP_ECANCELED: error, balloon operation canceled.
126 */
1775826c 127
95d2ac4a
DK
128enum bp_state {
129 BP_DONE,
b2ac6aa8 130 BP_WAIT,
95d2ac4a
DK
131 BP_EAGAIN,
132 BP_ECANCELED
1775826c
JF
133};
134
1775826c 135
1775826c 136static DEFINE_MUTEX(balloon_mutex);
1775826c 137
803eb047
DDG
138struct balloon_stats balloon_stats;
139EXPORT_SYMBOL_GPL(balloon_stats);
1775826c
JF
140
141/* We increase/decrease in batches which fit in a page */
3990dd27 142static xen_pfn_t frame_list[PAGE_SIZE / sizeof(xen_pfn_t)];
cd9151e2 143
1775826c 144
1775826c
JF
145/* List of ballooned pages, threaded through the mem_map array. */
146static LIST_HEAD(ballooned_pages);
1cf6a6c8 147static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
1775826c
JF
148
149/* Main work function, always executed in process context. */
150static void balloon_process(struct work_struct *work);
95170b2e 151static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
1775826c
JF
152
153/* When ballooning out (allocating memory to return to Xen) we don't really
154 want the kernel to try too hard since that can trigger the oom killer. */
155#define GFP_BALLOON \
156 (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
157
1775826c 158/* balloon_append: add the given page to the balloon. */
dde3285f 159static void balloon_append(struct page *page)
1775826c 160{
59b52f10
DH
161 __SetPageOffline(page);
162
1775826c
JF
163 /* Lowmem is re-populated first, so highmem pages go at list tail. */
164 if (PageHighMem(page)) {
165 list_add_tail(&page->lru, &ballooned_pages);
166 balloon_stats.balloon_high++;
1775826c
JF
167 } else {
168 list_add(&page->lru, &ballooned_pages);
169 balloon_stats.balloon_low++;
170 }
1cf6a6c8 171 wake_up(&balloon_wq);
9be4d457 172}
3d65c948 173
1775826c 174/* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
81b286e0 175static struct page *balloon_retrieve(bool require_lowmem)
1775826c
JF
176{
177 struct page *page;
178
179 if (list_empty(&ballooned_pages))
180 return NULL;
181
81b286e0
DV
182 page = list_entry(ballooned_pages.next, struct page, lru);
183 if (require_lowmem && PageHighMem(page))
184 return NULL;
1775826c
JF
185 list_del(&page->lru);
186
3dcc0571 187 if (PageHighMem(page))
1775826c 188 balloon_stats.balloon_high--;
3dcc0571 189 else
1775826c
JF
190 balloon_stats.balloon_low--;
191
04ccbdc3 192 __ClearPageOffline(page);
1775826c
JF
193 return page;
194}
195
1775826c
JF
196static struct page *balloon_next_page(struct page *page)
197{
198 struct list_head *next = page->lru.next;
199 if (next == &ballooned_pages)
200 return NULL;
201 return list_entry(next, struct page, lru);
202}
203
95d2ac4a 204static enum bp_state update_schedule(enum bp_state state)
1775826c 205{
b2ac6aa8
DV
206 if (state == BP_WAIT)
207 return BP_WAIT;
208
fd8b7951
BO
209 if (state == BP_ECANCELED)
210 return BP_ECANCELED;
211
95d2ac4a
DK
212 if (state == BP_DONE) {
213 balloon_stats.schedule_delay = 1;
214 balloon_stats.retry_count = 1;
215 return BP_DONE;
216 }
217
95d2ac4a
DK
218 ++balloon_stats.retry_count;
219
220 if (balloon_stats.max_retry_count != RETRY_UNLIMITED &&
221 balloon_stats.retry_count > balloon_stats.max_retry_count) {
95d2ac4a
DK
222 balloon_stats.schedule_delay = 1;
223 balloon_stats.retry_count = 1;
224 return BP_ECANCELED;
225 }
226
227 balloon_stats.schedule_delay <<= 1;
228
229 if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay)
230 balloon_stats.schedule_delay = balloon_stats.max_schedule_delay;
231
232 return BP_EAGAIN;
1775826c
JF
233}
234
080e2be7 235#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
842775f1
RL
236static void release_memory_resource(struct resource *resource)
237{
238 if (!resource)
239 return;
240
241 /*
242 * No need to reset region to identity mapped since we now
243 * know that no I/O can be in this region
244 */
245 release_resource(resource);
246 kfree(resource);
247}
248
55b3da98
DV
249static struct resource *additional_memory_resource(phys_addr_t size)
250{
12366410
ID
251 struct resource *res;
252 int ret;
55b3da98
DV
253
254 res = kzalloc(sizeof(*res), GFP_KERNEL);
255 if (!res)
256 return NULL;
257
258 res->name = "System RAM";
782b8664 259 res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
55b3da98 260
12366410
ID
261 ret = allocate_resource(&iomem_resource, res,
262 size, 0, -1,
263 PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
264 if (ret < 0) {
265 pr_err("Cannot allocate new System RAM resource\n");
266 kfree(res);
267 return NULL;
55b3da98
DV
268 }
269
dfd74a1e
RL
270#ifdef CONFIG_SPARSEMEM
271 {
272 unsigned long limit = 1UL << (MAX_PHYSMEM_BITS - PAGE_SHIFT);
273 unsigned long pfn = res->start >> PAGE_SHIFT;
274
275 if (pfn > limit) {
276 pr_err("New System RAM resource outside addressable RAM (%lu > %lu)\n",
277 pfn, limit);
278 release_memory_resource(res);
279 return NULL;
280 }
281 }
282#endif
283
55b3da98
DV
284 return res;
285}
286
b2ac6aa8 287static enum bp_state reserve_additional_memory(void)
080e2be7 288{
b2ac6aa8 289 long credit;
55b3da98 290 struct resource *resource;
080e2be7 291 int nid, rc;
55b3da98 292 unsigned long balloon_hotplug;
080e2be7 293
1cf6a6c8
DV
294 credit = balloon_stats.target_pages + balloon_stats.target_unpopulated
295 - balloon_stats.total_pages;
b2ac6aa8
DV
296
297 /*
298 * Already hotplugged enough pages? Wait for them to be
299 * onlined.
300 */
301 if (credit <= 0)
302 return BP_WAIT;
303
55b3da98
DV
304 balloon_hotplug = round_up(credit, PAGES_PER_SECTION);
305
306 resource = additional_memory_resource(balloon_hotplug * PAGE_SIZE);
307 if (!resource)
308 goto err;
309
310 nid = memory_add_physaddr_to_nid(resource->start);
080e2be7 311
3c56b3a1 312#ifdef CONFIG_XEN_HAVE_PVMMU
30756c62
JG
313 /*
314 * We don't support PV MMU when Linux and Xen is using
315 * different page granularity.
316 */
317 BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
318
3c56b3a1
JG
319 /*
320 * add_memory() will build page tables for the new memory so
321 * the p2m must contain invalid entries so the correct
322 * non-present PTEs will be written.
323 *
324 * If a failure occurs, the original (identity) p2m entries
325 * are not restored since this region is now known not to
326 * conflict with any devices.
327 */
328 if (!xen_feature(XENFEAT_auto_translated_physmap)) {
329 unsigned long pfn, i;
330
55b3da98 331 pfn = PFN_DOWN(resource->start);
3c56b3a1
JG
332 for (i = 0; i < balloon_hotplug; i++) {
333 if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
334 pr_warn("set_phys_to_machine() failed, no memory added\n");
55b3da98 335 goto err;
3c56b3a1
JG
336 }
337 }
338 }
339#endif
340
703fc13a
VK
341 /*
342 * add_memory_resource() will call online_pages() which in its turn
343 * will call xen_online_page() callback causing deadlock if we don't
344 * release balloon_mutex here. Unlocking here is safe because the
345 * callers drop the mutex before trying again.
346 */
347 mutex_unlock(&balloon_mutex);
8df1d0e4
DH
348 /* add_memory_resource() requires the device_hotplug lock */
349 lock_device_hotplug();
f29d8e9c 350 rc = add_memory_resource(nid, resource);
8df1d0e4 351 unlock_device_hotplug();
703fc13a
VK
352 mutex_lock(&balloon_mutex);
353
080e2be7 354 if (rc) {
3dcf6367 355 pr_warn("Cannot add additional memory (%i)\n", rc);
55b3da98 356 goto err;
080e2be7
DK
357 }
358
de5a77d8 359 balloon_stats.total_pages += balloon_hotplug;
080e2be7 360
b2ac6aa8 361 return BP_WAIT;
55b3da98
DV
362 err:
363 release_memory_resource(resource);
364 return BP_ECANCELED;
080e2be7
DK
365}
366
a9cd410a 367static void xen_online_page(struct page *page, unsigned int order)
080e2be7 368{
a9cd410a
AK
369 unsigned long i, size = (1 << order);
370 unsigned long start_pfn = page_to_pfn(page);
371 struct page *p;
080e2be7 372
a9cd410a 373 pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn);
080e2be7 374 mutex_lock(&balloon_mutex);
a9cd410a
AK
375 for (i = 0; i < size; i++) {
376 p = pfn_to_page(start_pfn + i);
377 __online_page_set_limits(p);
dde3285f 378 balloon_append(p);
a9cd410a 379 }
080e2be7
DK
380 mutex_unlock(&balloon_mutex);
381}
382
383static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v)
384{
385 if (val == MEM_ONLINE)
386 schedule_delayed_work(&balloon_worker, 0);
387
388 return NOTIFY_OK;
389}
390
391static struct notifier_block xen_memory_nb = {
392 .notifier_call = xen_memory_notifier,
393 .priority = 0
394};
395#else
b2ac6aa8 396static enum bp_state reserve_additional_memory(void)
1775826c 397{
de5a77d8 398 balloon_stats.target_pages = balloon_stats.current_pages;
1cf6a6c8 399 return BP_ECANCELED;
1775826c 400}
de5a77d8 401#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
1775826c 402
de5a77d8 403static long current_credit(void)
080e2be7 404{
de5a77d8 405 return balloon_stats.target_pages - balloon_stats.current_pages;
080e2be7
DK
406}
407
de5a77d8 408static bool balloon_is_inflated(void)
080e2be7 409{
de5a77d8 410 return balloon_stats.balloon_low || balloon_stats.balloon_high;
080e2be7 411}
080e2be7 412
95d2ac4a 413static enum bp_state increase_reservation(unsigned long nr_pages)
1775826c 414{
95d2ac4a 415 int rc;
30756c62 416 unsigned long i;
1775826c 417 struct page *page;
1775826c
JF
418
419 if (nr_pages > ARRAY_SIZE(frame_list))
420 nr_pages = ARRAY_SIZE(frame_list);
421
9346c2a8 422 page = list_first_entry_or_null(&ballooned_pages, struct page, lru);
1775826c 423 for (i = 0; i < nr_pages; i++) {
95d2ac4a
DK
424 if (!page) {
425 nr_pages = i;
426 break;
427 }
30756c62 428
30756c62 429 frame_list[i] = page_to_xen_pfn(page);
1775826c
JF
430 page = balloon_next_page(page);
431 }
432
ae4c51a5 433 rc = xenmem_reservation_increase(nr_pages, frame_list);
40095de1 434 if (rc <= 0)
95d2ac4a 435 return BP_EAGAIN;
1775826c 436
bc2c0303 437 for (i = 0; i < rc; i++) {
b6f30679 438 page = balloon_retrieve(false);
1775826c
JF
439 BUG_ON(page == NULL);
440
ae4c51a5 441 xenmem_reservation_va_mapping_update(1, &page, &frame_list[i]);
1775826c
JF
442
443 /* Relinquish the page back to the allocator. */
709613ad 444 free_reserved_page(page);
1775826c
JF
445 }
446
bc2c0303 447 balloon_stats.current_pages += rc;
1775826c 448
95d2ac4a 449 return BP_DONE;
1775826c
JF
450}
451
b6f30679 452static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
1775826c 453{
95d2ac4a 454 enum bp_state state = BP_DONE;
30756c62
JG
455 unsigned long i;
456 struct page *page, *tmp;
1775826c 457 int ret;
30756c62 458 LIST_HEAD(pages);
1775826c
JF
459
460 if (nr_pages > ARRAY_SIZE(frame_list))
461 nr_pages = ARRAY_SIZE(frame_list);
462
463 for (i = 0; i < nr_pages; i++) {
fce92683
LN
464 page = alloc_page(gfp);
465 if (page == NULL) {
1775826c 466 nr_pages = i;
95d2ac4a 467 state = BP_EAGAIN;
1775826c
JF
468 break;
469 }
709613ad 470 adjust_managed_page_count(page, -1);
ae4c51a5 471 xenmem_reservation_scrub_page(page);
30756c62 472 list_add(&page->lru, &pages);
09ed3d5b 473 }
1775826c 474
09ed3d5b
WL
475 /*
476 * Ensure that ballooned highmem pages don't have kmaps.
477 *
478 * Do this before changing the p2m as kmap_flush_unused()
479 * reads PTEs to obtain pages (and hence needs the original
480 * p2m entry).
481 */
482 kmap_flush_unused();
483
30756c62
JG
484 /*
485 * Setup the frame, update direct mapping, invalidate P2M,
486 * and add to balloon.
487 */
488 i = 0;
489 list_for_each_entry_safe(page, tmp, &pages, lru) {
30756c62 490 frame_list[i++] = xen_page_to_gfn(page);
1058a75f 491
ae4c51a5 492 xenmem_reservation_va_mapping_reset(1, &page);
30756c62 493
30756c62 494 list_del(&page->lru);
24f69373 495
09ed3d5b 496 balloon_append(page);
1775826c
JF
497 }
498
24f69373 499 flush_tlb_all();
2bad07ce 500
ae4c51a5 501 ret = xenmem_reservation_decrease(nr_pages, frame_list);
1775826c
JF
502 BUG_ON(ret != nr_pages);
503
504 balloon_stats.current_pages -= nr_pages;
1775826c 505
95d2ac4a 506 return state;
1775826c
JF
507}
508
509/*
929423fa 510 * As this is a work item it is guaranteed to run as a single instance only.
1775826c
JF
511 * We may of course race updates of the target counts (which are protected
512 * by the balloon lock), or with changes to the Xen hard limit, but we will
513 * recover from these in time.
514 */
515static void balloon_process(struct work_struct *work)
516{
95d2ac4a 517 enum bp_state state = BP_DONE;
1775826c
JF
518 long credit;
519
1775826c
JF
520
521 do {
929423fa
JG
522 mutex_lock(&balloon_mutex);
523
83be7e52 524 credit = current_credit();
95d2ac4a 525
080e2be7
DK
526 if (credit > 0) {
527 if (balloon_is_inflated())
528 state = increase_reservation(credit);
529 else
b2ac6aa8 530 state = reserve_additional_memory();
080e2be7 531 }
95d2ac4a 532
a1078e82
JG
533 if (credit < 0) {
534 long n_pages;
535
536 n_pages = min(-credit, si_mem_available());
537 state = decrease_reservation(n_pages, GFP_BALLOON);
538 if (state == BP_DONE && n_pages != -credit &&
539 n_pages < totalreserve_pages)
540 state = BP_EAGAIN;
541 }
95d2ac4a
DK
542
543 state = update_schedule(state);
1775826c 544
929423fa
JG
545 mutex_unlock(&balloon_mutex);
546
547 cond_resched();
548
95d2ac4a 549 } while (credit && state == BP_DONE);
1775826c
JF
550
551 /* Schedule more work if there is some still to be done. */
95d2ac4a
DK
552 if (state == BP_EAGAIN)
553 schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ);
1775826c
JF
554}
555
556/* Resets the Xen limit, sets new target, and kicks off processing. */
803eb047 557void balloon_set_new_target(unsigned long target)
1775826c
JF
558{
559 /* No need for lock. Not read-modify-write updates. */
1775826c 560 balloon_stats.target_pages = target;
95170b2e 561 schedule_delayed_work(&balloon_worker, 0);
1775826c 562}
803eb047 563EXPORT_SYMBOL_GPL(balloon_set_new_target);
1775826c 564
1cf6a6c8
DV
565static int add_ballooned_pages(int nr_pages)
566{
567 enum bp_state st;
568
569 if (xen_hotplug_unpopulated) {
570 st = reserve_additional_memory();
571 if (st != BP_ECANCELED) {
572 mutex_unlock(&balloon_mutex);
573 wait_event(balloon_wq,
574 !list_empty(&ballooned_pages));
575 mutex_lock(&balloon_mutex);
576 return 0;
577 }
578 }
579
a1078e82
JG
580 if (si_mem_available() < nr_pages)
581 return -ENOMEM;
582
1cf6a6c8
DV
583 st = decrease_reservation(nr_pages, GFP_USER);
584 if (st != BP_DONE)
585 return -ENOMEM;
586
587 return 0;
588}
589
b6f30679
KRW
590/**
591 * alloc_xenballooned_pages - get pages that have been ballooned out
592 * @nr_pages: Number of pages to get
593 * @pages: pages returned
594 * @return 0 on success, error otherwise
595 */
81b286e0 596int alloc_xenballooned_pages(int nr_pages, struct page **pages)
1775826c 597{
b6f30679 598 int pgno = 0;
e882dc9c 599 struct page *page;
1cf6a6c8
DV
600 int ret;
601
b6f30679 602 mutex_lock(&balloon_mutex);
1cf6a6c8
DV
603
604 balloon_stats.target_unpopulated += nr_pages;
605
b6f30679 606 while (pgno < nr_pages) {
81b286e0
DV
607 page = balloon_retrieve(true);
608 if (page) {
b6f30679 609 pages[pgno++] = page;
4a69c909 610#ifdef CONFIG_XEN_HAVE_PVMMU
30756c62
JG
611 /*
612 * We don't support PV MMU when Linux and Xen is using
613 * different page granularity.
614 */
615 BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
616
b194da25
BO
617 if (!xen_feature(XENFEAT_auto_translated_physmap)) {
618 ret = xen_alloc_p2m_entry(page_to_pfn(page));
619 if (ret < 0)
620 goto out_undo;
621 }
4a69c909 622#endif
b6f30679 623 } else {
1cf6a6c8
DV
624 ret = add_ballooned_pages(nr_pages - pgno);
625 if (ret < 0)
b6f30679
KRW
626 goto out_undo;
627 }
1775826c 628 }
b6f30679
KRW
629 mutex_unlock(&balloon_mutex);
630 return 0;
631 out_undo:
b6f30679 632 mutex_unlock(&balloon_mutex);
1cf6a6c8
DV
633 free_xenballooned_pages(pgno, pages);
634 return ret;
1775826c 635}
b6f30679 636EXPORT_SYMBOL(alloc_xenballooned_pages);
1775826c 637
b6f30679
KRW
638/**
639 * free_xenballooned_pages - return pages retrieved with get_ballooned_pages
640 * @nr_pages: Number of pages
641 * @pages: pages to return
642 */
e882dc9c 643void free_xenballooned_pages(int nr_pages, struct page **pages)
1775826c 644{
b6f30679 645 int i;
1775826c 646
b6f30679 647 mutex_lock(&balloon_mutex);
1775826c 648
b6f30679 649 for (i = 0; i < nr_pages; i++) {
59b52f10 650 if (pages[i])
b6f30679
KRW
651 balloon_append(pages[i]);
652 }
653
1cf6a6c8
DV
654 balloon_stats.target_unpopulated -= nr_pages;
655
b6f30679 656 /* The balloon may be too large now. Shrink it if needed. */
83be7e52 657 if (current_credit())
b6f30679 658 schedule_delayed_work(&balloon_worker, 0);
1775826c 659
b6f30679
KRW
660 mutex_unlock(&balloon_mutex);
661}
662EXPORT_SYMBOL(free_xenballooned_pages);
1775826c 663
4fee9ad8 664#ifdef CONFIG_XEN_PV
8b5d44a5
DV
665static void __init balloon_add_region(unsigned long start_pfn,
666 unsigned long pages)
1775826c 667{
4dfe22f5 668 unsigned long pfn, extra_pfn_end;
1775826c 669
8b5d44a5
DV
670 /*
671 * If the amount of usable memory has been limited (e.g., with
672 * the 'mem' command line parameter), don't add pages beyond
673 * this limit.
674 */
675 extra_pfn_end = min(max_pfn, start_pfn + pages);
676
677 for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) {
8b5d44a5
DV
678 /* totalram_pages and totalhigh_pages do not
679 include the boot-time balloon extension, so
680 don't subtract from it. */
59b52f10 681 balloon_append(pfn_to_page(pfn));
8b5d44a5 682 }
de5a77d8
DV
683
684 balloon_stats.total_pages += extra_pfn_end - start_pfn;
8b5d44a5 685}
4fee9ad8 686#endif
8b5d44a5
DV
687
688static int __init balloon_init(void)
689{
53d5522c 690 if (!xen_domain())
1775826c
JF
691 return -ENODEV;
692
283c0972 693 pr_info("Initialising balloon driver\n");
1775826c 694
4fee9ad8 695#ifdef CONFIG_XEN_PV
aa24411b
DV
696 balloon_stats.current_pages = xen_pv_domain()
697 ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn)
c275a57f 698 : get_num_physpages();
4fee9ad8
VK
699#else
700 balloon_stats.current_pages = get_num_physpages();
701#endif
1775826c
JF
702 balloon_stats.target_pages = balloon_stats.current_pages;
703 balloon_stats.balloon_low = 0;
704 balloon_stats.balloon_high = 0;
de5a77d8 705 balloon_stats.total_pages = balloon_stats.current_pages;
1775826c 706
95d2ac4a
DK
707 balloon_stats.schedule_delay = 1;
708 balloon_stats.max_schedule_delay = 32;
709 balloon_stats.retry_count = 1;
a1078e82 710 balloon_stats.max_retry_count = 4;
1775826c 711
080e2be7 712#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
080e2be7
DK
713 set_online_page_callback(&xen_online_page);
714 register_memory_notifier(&xen_memory_nb);
1cf6a6c8 715 register_sysctl_table(xen_root);
080e2be7
DK
716#endif
717
4fee9ad8
VK
718#ifdef CONFIG_XEN_PV
719 {
720 int i;
721
722 /*
723 * Initialize the balloon with pages from the extra memory
724 * regions (see arch/x86/xen/setup.c).
725 */
726 for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++)
727 if (xen_extra_mem[i].n_pfns)
728 balloon_add_region(xen_extra_mem[i].start_pfn,
729 xen_extra_mem[i].n_pfns);
730 }
731#endif
1775826c 732
96edd61d
JG
733 /* Init the xen-balloon driver. */
734 xen_balloon_init();
735
1775826c
JF
736 return 0;
737}
1775826c 738subsys_initcall(balloon_init);