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Jeremy Fitzhardinge17758262008-04-02 10:54:13 -07001/******************************************************************************
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -07002 * 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
Daniel Kiper080e2be2011-07-25 17:12:06 -07007 * 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.
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070013 *
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>
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070040#include <linux/sched.h>
41#include <linux/errno.h>
Paul Gortmaker72ee5112011-07-03 16:20:57 -040042#include <linux/module.h>
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070043#include <linux/mm.h>
44#include <linux/bootmem.h>
45#include <linux/pagemap.h>
46#include <linux/highmem.h>
47#include <linux/mutex.h>
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070048#include <linux/list.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090049#include <linux/gfp.h>
Daniel Kiper080e2be2011-07-25 17:12:06 -070050#include <linux/notifier.h>
51#include <linux/memory.h>
52#include <linux/memory_hotplug.h>
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070053
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070054#include <asm/page.h>
55#include <asm/pgalloc.h>
56#include <asm/pgtable.h>
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070057#include <asm/tlb.h>
Jeremy Fitzhardinge66946f62010-09-14 10:32:32 -070058#include <asm/e820.h>
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070059
Jeremy Fitzhardingeecbf29c2008-12-16 12:37:07 -080060#include <asm/xen/hypervisor.h>
61#include <asm/xen/hypercall.h>
Jeremy Fitzhardinge1ccbf532009-10-06 15:11:14 -070062
63#include <xen/xen.h>
Jeremy Fitzhardingeecbf29c2008-12-16 12:37:07 -080064#include <xen/interface/xen.h>
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070065#include <xen/interface/memory.h>
Daniel De Graaf803eb042011-03-14 11:29:37 -040066#include <xen/balloon.h>
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070067#include <xen/features.h>
68#include <xen/page.h>
69
Daniel Kiper95d2ac42011-03-08 22:48:24 +010070/*
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 */
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070077
Daniel Kiper95d2ac42011-03-08 22:48:24 +010078enum bp_state {
79 BP_DONE,
80 BP_EAGAIN,
81 BP_ECANCELED
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070082};
83
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070084
85static DEFINE_MUTEX(balloon_mutex);
86
Daniel De Graaf803eb042011-03-14 11:29:37 -040087struct balloon_stats balloon_stats;
88EXPORT_SYMBOL_GPL(balloon_stats);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070089
90/* We increase/decrease in batches which fit in a page */
91static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)];
92
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070093#ifdef CONFIG_HIGHMEM
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070094#define inc_totalhigh_pages() (totalhigh_pages++)
95#define dec_totalhigh_pages() (totalhigh_pages--)
96#else
Ruslan Pisareve882dc92011-07-26 14:15:59 +030097#define inc_totalhigh_pages() do {} while (0)
98#define dec_totalhigh_pages() do {} while (0)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -070099#endif
100
101/* List of ballooned pages, threaded through the mem_map array. */
102static LIST_HEAD(ballooned_pages);
103
104/* Main work function, always executed in process context. */
105static void balloon_process(struct work_struct *work);
Daniel Kiper95170b22011-03-08 22:47:39 +0100106static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700107
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
113static void scrub_page(struct page *page)
114{
115#ifdef CONFIG_XEN_SCRUB_PAGES
Jeremy Fitzhardinge26a3e992008-11-17 09:35:00 -0800116 clear_highpage(page);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700117#endif
118}
119
120/* balloon_append: add the given page to the balloon. */
Jeremy Fitzhardinge9be4d452010-08-31 15:01:16 -0700121static void __balloon_append(struct page *page)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700122{
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++;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700127 } else {
128 list_add(&page->lru, &ballooned_pages);
129 balloon_stats.balloon_low++;
130 }
Jeremy Fitzhardinge9be4d452010-08-31 15:01:16 -0700131}
Gianluca Guida3d65c942009-07-30 22:54:36 +0100132
Jeremy Fitzhardinge9be4d452010-08-31 15:01:16 -0700133static void balloon_append(struct page *page)
134{
135 __balloon_append(page);
Daniel Kiper09ca1322011-03-28 11:35:59 +0200136 if (PageHighMem(page))
137 dec_totalhigh_pages();
Gianluca Guida3d65c942009-07-30 22:54:36 +0100138 totalram_pages--;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700139}
140
141/* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400142static struct page *balloon_retrieve(bool prefer_highmem)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700143{
144 struct page *page;
145
146 if (list_empty(&ballooned_pages))
147 return NULL;
148
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400149 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);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700153 list_del(&page->lru);
154
155 if (PageHighMem(page)) {
156 balloon_stats.balloon_high--;
157 inc_totalhigh_pages();
Ruslan Pisareve882dc92011-07-26 14:15:59 +0300158 } else
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700159 balloon_stats.balloon_low--;
160
Gianluca Guida3d65c942009-07-30 22:54:36 +0100161 totalram_pages++;
162
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700163 return page;
164}
165
166static 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
173static 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
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100181static enum bp_state update_schedule(enum bp_state state)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700182{
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100183 if (state == BP_DONE) {
184 balloon_stats.schedule_delay = 1;
185 balloon_stats.retry_count = 1;
186 return BP_DONE;
187 }
188
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100189 ++balloon_stats.retry_count;
190
191 if (balloon_stats.max_retry_count != RETRY_UNLIMITED &&
192 balloon_stats.retry_count > balloon_stats.max_retry_count) {
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100193 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;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700204}
205
Daniel Kiper080e2be2011-07-25 17:12:06 -0700206#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
207static long current_credit(void)
208{
209 return balloon_stats.target_pages - balloon_stats.current_pages -
210 balloon_stats.hotplug_pages;
211}
212
213static 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
233static 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
258static 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
274static 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
282static struct notifier_block xen_memory_nb = {
283 .notifier_call = xen_memory_notifier,
284 .priority = 0
285};
286#else
Daniel Kiper83be7e52011-03-28 11:34:10 +0200287static long current_credit(void)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700288{
Ian Campbellbc2c0302009-06-05 11:58:37 +0100289 unsigned long target = balloon_stats.target_pages;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700290
291 target = min(target,
292 balloon_stats.current_pages +
293 balloon_stats.balloon_low +
294 balloon_stats.balloon_high);
295
Daniel Kiper83be7e52011-03-28 11:34:10 +0200296 return target - balloon_stats.current_pages;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700297}
298
Daniel Kiper080e2be2011-07-25 17:12:06 -0700299static 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
307static 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
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100314static enum bp_state increase_reservation(unsigned long nr_pages)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700315{
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100316 int rc;
Jeremy Fitzhardinge2f70e0a2010-09-02 23:11:17 -0700317 unsigned long pfn, i;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700318 struct page *page;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700319 struct xen_memory_reservation reservation = {
320 .address_bits = 0,
321 .extent_order = 0,
322 .domid = DOMID_SELF
323 };
324
Daniel Kiper080e2be2011-07-25 17:12:06 -0700325#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
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700334 if (nr_pages > ARRAY_SIZE(frame_list))
335 nr_pages = ARRAY_SIZE(frame_list);
336
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700337 page = balloon_first_page();
338 for (i = 0; i < nr_pages; i++) {
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100339 if (!page) {
340 nr_pages = i;
341 break;
342 }
Joe Perchesa419aef2009-08-18 11:18:35 -0700343 frame_list[i] = page_to_pfn(page);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700344 page = balloon_next_page(page);
345 }
346
Isaku Yamahataa90971e2008-05-26 23:31:14 +0100347 set_xen_guest_handle(reservation.extent_start, frame_list);
Jeremy Fitzhardingefde28e82008-07-24 16:28:00 -0700348 reservation.nr_extents = nr_pages;
349 rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
Konrad Rzeszutek Wilk40095de2011-03-14 11:42:40 -0400350 if (rc <= 0)
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100351 return BP_EAGAIN;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700352
Ian Campbellbc2c0302009-06-05 11:58:37 +0100353 for (i = 0; i < rc; i++) {
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400354 page = balloon_retrieve(false);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700355 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. */
Daniel Kiper4dfe22f2011-03-28 11:33:18 +0200364 if (xen_pv_domain() && !PageHighMem(page)) {
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700365 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
Ian Campbellbc2c0302009-06-05 11:58:37 +0100379 balloon_stats.current_pages += rc;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700380
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100381 return BP_DONE;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700382}
383
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400384static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700385{
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100386 enum bp_state state = BP_DONE;
Jeremy Fitzhardinge2f70e0a2010-09-02 23:11:17 -0700387 unsigned long pfn, i;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700388 struct page *page;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700389 int ret;
390 struct xen_memory_reservation reservation = {
391 .address_bits = 0,
392 .extent_order = 0,
393 .domid = DOMID_SELF
394 };
395
Daniel Kiper080e2be2011-07-25 17:12:06 -0700396#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
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700405 if (nr_pages > ARRAY_SIZE(frame_list))
406 nr_pages = ARRAY_SIZE(frame_list);
407
408 for (i = 0; i < nr_pages; i++) {
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400409 if ((page = alloc_page(gfp)) == NULL) {
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700410 nr_pages = i;
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100411 state = BP_EAGAIN;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700412 break;
413 }
414
415 pfn = page_to_pfn(page);
416 frame_list[i] = pfn_to_mfn(pfn);
417
418 scrub_page(page);
Dan Magenheimer1058a752009-01-22 14:36:08 -0800419
Daniel Kiper4dfe22f2011-03-28 11:33:18 +0200420 if (xen_pv_domain() && !PageHighMem(page)) {
Ian Campbellff4ce8c2009-01-23 16:26:21 +0000421 ret = HYPERVISOR_update_va_mapping(
422 (unsigned long)__va(pfn << PAGE_SHIFT),
423 __pte_ma(0), 0);
424 BUG_ON(ret);
Ruslan Pisareve882dc92011-07-26 14:15:59 +0300425 }
Ian Campbellff4ce8c2009-01-23 16:26:21 +0000426
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700427 }
428
429 /* Ensure that ballooned highmem pages don't have kmaps. */
430 kmap_flush_unused();
431 flush_tlb_all();
432
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700433 /* 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]);
Konrad Rzeszutek Wilk6eaa4122011-01-18 20:09:41 -0500436 __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700437 balloon_append(pfn_to_page(pfn));
438 }
439
Isaku Yamahataa90971e2008-05-26 23:31:14 +0100440 set_xen_guest_handle(reservation.extent_start, frame_list);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700441 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;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700446
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100447 return state;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700448}
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 */
456static void balloon_process(struct work_struct *work)
457{
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100458 enum bp_state state = BP_DONE;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700459 long credit;
460
461 mutex_lock(&balloon_mutex);
462
463 do {
Daniel Kiper83be7e52011-03-28 11:34:10 +0200464 credit = current_credit();
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100465
Daniel Kiper080e2be2011-07-25 17:12:06 -0700466 if (credit > 0) {
467 if (balloon_is_inflated())
468 state = increase_reservation(credit);
469 else
470 state = reserve_additional_memory(credit);
471 }
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100472
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700473 if (credit < 0)
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400474 state = decrease_reservation(-credit, GFP_BALLOON);
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100475
476 state = update_schedule(state);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700477
478#ifndef CONFIG_PREEMPT
479 if (need_resched())
480 schedule();
481#endif
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100482 } while (credit && state == BP_DONE);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700483
484 /* Schedule more work if there is some still to be done. */
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100485 if (state == BP_EAGAIN)
486 schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700487
488 mutex_unlock(&balloon_mutex);
489}
490
491/* Resets the Xen limit, sets new target, and kicks off processing. */
Daniel De Graaf803eb042011-03-14 11:29:37 -0400492void balloon_set_new_target(unsigned long target)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700493{
494 /* No need for lock. Not read-modify-write updates. */
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700495 balloon_stats.target_pages = target;
Daniel Kiper95170b22011-03-08 22:47:39 +0100496 schedule_delayed_work(&balloon_worker, 0);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700497}
Daniel De Graaf803eb042011-03-14 11:29:37 -0400498EXPORT_SYMBOL_GPL(balloon_set_new_target);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700499
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400500/**
501 * alloc_xenballooned_pages - get pages that have been ballooned out
502 * @nr_pages: Number of pages to get
503 * @pages: pages returned
Daniel De Graaf72e9cf22011-10-19 17:59:37 -0400504 * @highmem: allow highmem pages
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400505 * @return 0 on success, error otherwise
506 */
Stefano Stabellini693394b2011-09-29 11:57:55 +0100507int alloc_xenballooned_pages(int nr_pages, struct page **pages, bool highmem)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700508{
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400509 int pgno = 0;
Ruslan Pisareve882dc92011-07-26 14:15:59 +0300510 struct page *page;
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400511 mutex_lock(&balloon_mutex);
512 while (pgno < nr_pages) {
Stefano Stabellini693394b2011-09-29 11:57:55 +0100513 page = balloon_retrieve(highmem);
Daniel De Graaf72e9cf22011-10-19 17:59:37 -0400514 if (page && (highmem || !PageHighMem(page))) {
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400515 pages[pgno++] = page;
516 } else {
517 enum bp_state st;
Stefano Stabellini693394b2011-09-29 11:57:55 +0100518 if (page)
519 balloon_append(page);
520 st = decrease_reservation(nr_pages - pgno,
521 highmem ? GFP_HIGHUSER : GFP_USER);
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400522 if (st != BP_DONE)
523 goto out_undo;
524 }
525 }
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;
535}
536EXPORT_SYMBOL(alloc_xenballooned_pages);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700537
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400538/**
539 * free_xenballooned_pages - return pages retrieved with get_ballooned_pages
540 * @nr_pages: Number of pages
541 * @pages: pages to return
542 */
Ruslan Pisareve882dc92011-07-26 14:15:59 +0300543void free_xenballooned_pages(int nr_pages, struct page **pages)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700544{
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400545 int i;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700546
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400547 mutex_lock(&balloon_mutex);
548
549 for (i = 0; i < nr_pages; i++) {
550 if (pages[i])
551 balloon_append(pages[i]);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700552 }
553
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400554 /* The balloon may be too large now. Shrink it if needed. */
Daniel Kiper83be7e52011-03-28 11:34:10 +0200555 if (current_credit())
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400556 schedule_delayed_work(&balloon_worker, 0);
557
558 mutex_unlock(&balloon_mutex);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700559}
Konrad Rzeszutek Wilkb6f30672011-03-15 10:23:57 -0400560EXPORT_SYMBOL(free_xenballooned_pages);
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700561
David Vrabel8b5d44a2011-09-28 17:46:34 +0100562static void __init balloon_add_region(unsigned long start_pfn,
563 unsigned long pages)
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700564{
Daniel Kiper4dfe22f2011-03-28 11:33:18 +0200565 unsigned long pfn, extra_pfn_end;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700566 struct page *page;
567
David Vrabel8b5d44a2011-09-28 17:46:34 +0100568 /*
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
584static int __init balloon_init(void)
585{
586 int i;
587
Stefano Stabellini53d55222010-12-02 17:55:05 +0000588 if (!xen_domain())
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700589 return -ENODEV;
590
Daniel De Graaf803eb042011-03-14 11:29:37 -0400591 pr_info("xen/balloon: Initialising balloon driver.\n");
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700592
David Vrabelaa244112011-09-28 17:46:32 +0100593 balloon_stats.current_pages = xen_pv_domain()
594 ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn)
595 : max_pfn;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700596 balloon_stats.target_pages = balloon_stats.current_pages;
597 balloon_stats.balloon_low = 0;
598 balloon_stats.balloon_high = 0;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700599
Daniel Kiper95d2ac42011-03-08 22:48:24 +0100600 balloon_stats.schedule_delay = 1;
601 balloon_stats.max_schedule_delay = 32;
602 balloon_stats.retry_count = 1;
Konrad Rzeszutek Wilk40095de2011-03-14 11:42:40 -0400603 balloon_stats.max_retry_count = RETRY_UNLIMITED;
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700604
Daniel Kiper080e2be2011-07-25 17:12:06 -0700605#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
Jeremy Fitzhardinge2a4c92f2010-12-02 15:30:06 -0800613 /*
David Vrabelb1cbf9b2011-09-28 17:46:33 +0100614 * Initialize the balloon with pages from the extra memory
David Vrabel8b5d44a2011-09-28 17:46:34 +0100615 * regions (see arch/x86/xen/setup.c).
Jeremy Fitzhardinge2a4c92f2010-12-02 15:30:06 -0800616 */
David Vrabel8b5d44a2011-09-28 17:46:34 +0100617 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));
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700621
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700622 return 0;
623}
624
625subsys_initcall(balloon_init);
626
Jeremy Fitzhardinge17758262008-04-02 10:54:13 -0700627MODULE_LICENSE("GPL");