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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 | 43 | #include <linux/sched.h> |
5b825c3a | 44 | #include <linux/cred.h> |
1775826c | 45 | #include <linux/errno.h> |
8480ed9c JG |
46 | #include <linux/freezer.h> |
47 | #include <linux/kthread.h> | |
1775826c | 48 | #include <linux/mm.h> |
57c8a661 | 49 | #include <linux/memblock.h> |
1775826c JF |
50 | #include <linux/pagemap.h> |
51 | #include <linux/highmem.h> | |
52 | #include <linux/mutex.h> | |
1775826c | 53 | #include <linux/list.h> |
5a0e3ad6 | 54 | #include <linux/gfp.h> |
080e2be7 DK |
55 | #include <linux/notifier.h> |
56 | #include <linux/memory.h> | |
57 | #include <linux/memory_hotplug.h> | |
cd9151e2 | 58 | #include <linux/percpu-defs.h> |
55b3da98 | 59 | #include <linux/slab.h> |
1cf6a6c8 | 60 | #include <linux/sysctl.h> |
e0af2c30 | 61 | #include <linux/moduleparam.h> |
1775826c | 62 | |
1775826c | 63 | #include <asm/page.h> |
1775826c JF |
64 | #include <asm/tlb.h> |
65 | ||
ecbf29cd JF |
66 | #include <asm/xen/hypervisor.h> |
67 | #include <asm/xen/hypercall.h> | |
1ccbf534 JF |
68 | |
69 | #include <xen/xen.h> | |
ecbf29cd | 70 | #include <xen/interface/xen.h> |
1775826c | 71 | #include <xen/interface/memory.h> |
803eb047 | 72 | #include <xen/balloon.h> |
1775826c JF |
73 | #include <xen/features.h> |
74 | #include <xen/page.h> | |
ae4c51a5 | 75 | #include <xen/mem-reservation.h> |
1775826c | 76 | |
e0af2c30 JG |
77 | #undef MODULE_PARAM_PREFIX |
78 | #define MODULE_PARAM_PREFIX "xen." | |
79 | ||
80 | static uint __read_mostly balloon_boot_timeout = 180; | |
81 | module_param(balloon_boot_timeout, uint, 0444); | |
82 | ||
1cf6a6c8 DV |
83 | static int xen_hotplug_unpopulated; |
84 | ||
85 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG | |
86 | ||
1cf6a6c8 DV |
87 | static struct ctl_table balloon_table[] = { |
88 | { | |
89 | .procname = "hotplug_unpopulated", | |
90 | .data = &xen_hotplug_unpopulated, | |
91 | .maxlen = sizeof(int), | |
92 | .mode = 0644, | |
93 | .proc_handler = proc_dointvec_minmax, | |
eec4844f MC |
94 | .extra1 = SYSCTL_ZERO, |
95 | .extra2 = SYSCTL_ONE, | |
1cf6a6c8 DV |
96 | }, |
97 | { } | |
98 | }; | |
99 | ||
100 | static struct ctl_table balloon_root[] = { | |
101 | { | |
102 | .procname = "balloon", | |
103 | .mode = 0555, | |
104 | .child = balloon_table, | |
105 | }, | |
106 | { } | |
107 | }; | |
108 | ||
109 | static struct ctl_table xen_root[] = { | |
110 | { | |
111 | .procname = "xen", | |
112 | .mode = 0555, | |
113 | .child = balloon_root, | |
114 | }, | |
115 | { } | |
116 | }; | |
117 | ||
118 | #endif | |
119 | ||
30756c62 JG |
120 | /* |
121 | * Use one extent per PAGE_SIZE to avoid to break down the page into | |
122 | * multiple frame. | |
123 | */ | |
124 | #define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1) | |
125 | ||
95d2ac4a | 126 | /* |
8480ed9c | 127 | * balloon_thread() state: |
95d2ac4a DK |
128 | * |
129 | * BP_DONE: done or nothing to do, | |
b2ac6aa8 | 130 | * BP_WAIT: wait to be rescheduled, |
95d2ac4a DK |
131 | * BP_EAGAIN: error, go to sleep, |
132 | * BP_ECANCELED: error, balloon operation canceled. | |
133 | */ | |
1775826c | 134 | |
e0af2c30 | 135 | static enum bp_state { |
95d2ac4a | 136 | BP_DONE, |
b2ac6aa8 | 137 | BP_WAIT, |
95d2ac4a DK |
138 | BP_EAGAIN, |
139 | BP_ECANCELED | |
e0af2c30 | 140 | } balloon_state = BP_DONE; |
1775826c | 141 | |
8480ed9c JG |
142 | /* Main waiting point for xen-balloon thread. */ |
143 | static DECLARE_WAIT_QUEUE_HEAD(balloon_thread_wq); | |
1775826c | 144 | |
1775826c | 145 | static DEFINE_MUTEX(balloon_mutex); |
1775826c | 146 | |
803eb047 DDG |
147 | struct balloon_stats balloon_stats; |
148 | EXPORT_SYMBOL_GPL(balloon_stats); | |
1775826c JF |
149 | |
150 | /* We increase/decrease in batches which fit in a page */ | |
3990dd27 | 151 | static xen_pfn_t frame_list[PAGE_SIZE / sizeof(xen_pfn_t)]; |
cd9151e2 | 152 | |
1775826c | 153 | |
1775826c JF |
154 | /* List of ballooned pages, threaded through the mem_map array. */ |
155 | static LIST_HEAD(ballooned_pages); | |
1cf6a6c8 | 156 | static DECLARE_WAIT_QUEUE_HEAD(balloon_wq); |
1775826c | 157 | |
1775826c JF |
158 | /* When ballooning out (allocating memory to return to Xen) we don't really |
159 | want the kernel to try too hard since that can trigger the oom killer. */ | |
160 | #define GFP_BALLOON \ | |
161 | (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) | |
162 | ||
1775826c | 163 | /* balloon_append: add the given page to the balloon. */ |
dde3285f | 164 | static void balloon_append(struct page *page) |
1775826c | 165 | { |
59b52f10 DH |
166 | __SetPageOffline(page); |
167 | ||
1775826c JF |
168 | /* Lowmem is re-populated first, so highmem pages go at list tail. */ |
169 | if (PageHighMem(page)) { | |
170 | list_add_tail(&page->lru, &ballooned_pages); | |
171 | balloon_stats.balloon_high++; | |
1775826c JF |
172 | } else { |
173 | list_add(&page->lru, &ballooned_pages); | |
174 | balloon_stats.balloon_low++; | |
175 | } | |
1cf6a6c8 | 176 | wake_up(&balloon_wq); |
9be4d457 | 177 | } |
3d65c948 | 178 | |
1775826c | 179 | /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ |
81b286e0 | 180 | static struct page *balloon_retrieve(bool require_lowmem) |
1775826c JF |
181 | { |
182 | struct page *page; | |
183 | ||
184 | if (list_empty(&ballooned_pages)) | |
185 | return NULL; | |
186 | ||
81b286e0 DV |
187 | page = list_entry(ballooned_pages.next, struct page, lru); |
188 | if (require_lowmem && PageHighMem(page)) | |
189 | return NULL; | |
1775826c JF |
190 | list_del(&page->lru); |
191 | ||
3dcc0571 | 192 | if (PageHighMem(page)) |
1775826c | 193 | balloon_stats.balloon_high--; |
3dcc0571 | 194 | else |
1775826c JF |
195 | balloon_stats.balloon_low--; |
196 | ||
04ccbdc3 | 197 | __ClearPageOffline(page); |
1775826c JF |
198 | return page; |
199 | } | |
200 | ||
1775826c JF |
201 | static struct page *balloon_next_page(struct page *page) |
202 | { | |
203 | struct list_head *next = page->lru.next; | |
204 | if (next == &ballooned_pages) | |
205 | return NULL; | |
206 | return list_entry(next, struct page, lru); | |
207 | } | |
208 | ||
e0af2c30 | 209 | static void update_schedule(void) |
1775826c | 210 | { |
e0af2c30 JG |
211 | if (balloon_state == BP_WAIT || balloon_state == BP_ECANCELED) |
212 | return; | |
fd8b7951 | 213 | |
e0af2c30 | 214 | if (balloon_state == BP_DONE) { |
95d2ac4a DK |
215 | balloon_stats.schedule_delay = 1; |
216 | balloon_stats.retry_count = 1; | |
e0af2c30 | 217 | return; |
95d2ac4a DK |
218 | } |
219 | ||
95d2ac4a DK |
220 | ++balloon_stats.retry_count; |
221 | ||
222 | if (balloon_stats.max_retry_count != RETRY_UNLIMITED && | |
223 | balloon_stats.retry_count > balloon_stats.max_retry_count) { | |
95d2ac4a DK |
224 | balloon_stats.schedule_delay = 1; |
225 | balloon_stats.retry_count = 1; | |
e0af2c30 JG |
226 | balloon_state = BP_ECANCELED; |
227 | return; | |
95d2ac4a DK |
228 | } |
229 | ||
230 | balloon_stats.schedule_delay <<= 1; | |
231 | ||
232 | if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay) | |
233 | balloon_stats.schedule_delay = balloon_stats.max_schedule_delay; | |
234 | ||
e0af2c30 | 235 | balloon_state = BP_EAGAIN; |
1775826c JF |
236 | } |
237 | ||
080e2be7 | 238 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
842775f1 RL |
239 | static void release_memory_resource(struct resource *resource) |
240 | { | |
241 | if (!resource) | |
242 | return; | |
243 | ||
244 | /* | |
245 | * No need to reset region to identity mapped since we now | |
246 | * know that no I/O can be in this region | |
247 | */ | |
248 | release_resource(resource); | |
249 | kfree(resource); | |
250 | } | |
251 | ||
55b3da98 DV |
252 | static struct resource *additional_memory_resource(phys_addr_t size) |
253 | { | |
12366410 ID |
254 | struct resource *res; |
255 | int ret; | |
55b3da98 DV |
256 | |
257 | res = kzalloc(sizeof(*res), GFP_KERNEL); | |
258 | if (!res) | |
259 | return NULL; | |
260 | ||
261 | res->name = "System RAM"; | |
782b8664 | 262 | res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; |
55b3da98 | 263 | |
12366410 ID |
264 | ret = allocate_resource(&iomem_resource, res, |
265 | size, 0, -1, | |
266 | PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL); | |
267 | if (ret < 0) { | |
268 | pr_err("Cannot allocate new System RAM resource\n"); | |
269 | kfree(res); | |
270 | return NULL; | |
55b3da98 DV |
271 | } |
272 | ||
273 | return res; | |
274 | } | |
275 | ||
b2ac6aa8 | 276 | static enum bp_state reserve_additional_memory(void) |
080e2be7 | 277 | { |
b2ac6aa8 | 278 | long credit; |
55b3da98 | 279 | struct resource *resource; |
080e2be7 | 280 | int nid, rc; |
55b3da98 | 281 | unsigned long balloon_hotplug; |
080e2be7 | 282 | |
1cf6a6c8 DV |
283 | credit = balloon_stats.target_pages + balloon_stats.target_unpopulated |
284 | - balloon_stats.total_pages; | |
b2ac6aa8 DV |
285 | |
286 | /* | |
287 | * Already hotplugged enough pages? Wait for them to be | |
288 | * onlined. | |
289 | */ | |
290 | if (credit <= 0) | |
291 | return BP_WAIT; | |
292 | ||
55b3da98 DV |
293 | balloon_hotplug = round_up(credit, PAGES_PER_SECTION); |
294 | ||
295 | resource = additional_memory_resource(balloon_hotplug * PAGE_SIZE); | |
296 | if (!resource) | |
297 | goto err; | |
298 | ||
299 | nid = memory_add_physaddr_to_nid(resource->start); | |
080e2be7 | 300 | |
3c56b3a1 | 301 | #ifdef CONFIG_XEN_HAVE_PVMMU |
30756c62 JG |
302 | /* |
303 | * We don't support PV MMU when Linux and Xen is using | |
304 | * different page granularity. | |
305 | */ | |
306 | BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); | |
307 | ||
3c56b3a1 JG |
308 | /* |
309 | * add_memory() will build page tables for the new memory so | |
310 | * the p2m must contain invalid entries so the correct | |
311 | * non-present PTEs will be written. | |
312 | * | |
313 | * If a failure occurs, the original (identity) p2m entries | |
314 | * are not restored since this region is now known not to | |
315 | * conflict with any devices. | |
316 | */ | |
317 | if (!xen_feature(XENFEAT_auto_translated_physmap)) { | |
318 | unsigned long pfn, i; | |
319 | ||
55b3da98 | 320 | pfn = PFN_DOWN(resource->start); |
3c56b3a1 JG |
321 | for (i = 0; i < balloon_hotplug; i++) { |
322 | if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) { | |
323 | pr_warn("set_phys_to_machine() failed, no memory added\n"); | |
55b3da98 | 324 | goto err; |
3c56b3a1 JG |
325 | } |
326 | } | |
327 | } | |
328 | #endif | |
329 | ||
703fc13a VK |
330 | /* |
331 | * add_memory_resource() will call online_pages() which in its turn | |
332 | * will call xen_online_page() callback causing deadlock if we don't | |
333 | * release balloon_mutex here. Unlocking here is safe because the | |
334 | * callers drop the mutex before trying again. | |
335 | */ | |
336 | mutex_unlock(&balloon_mutex); | |
8df1d0e4 DH |
337 | /* add_memory_resource() requires the device_hotplug lock */ |
338 | lock_device_hotplug(); | |
26011267 | 339 | rc = add_memory_resource(nid, resource, MHP_MERGE_RESOURCE); |
8df1d0e4 | 340 | unlock_device_hotplug(); |
703fc13a VK |
341 | mutex_lock(&balloon_mutex); |
342 | ||
080e2be7 | 343 | if (rc) { |
3dcf6367 | 344 | pr_warn("Cannot add additional memory (%i)\n", rc); |
55b3da98 | 345 | goto err; |
080e2be7 DK |
346 | } |
347 | ||
de5a77d8 | 348 | balloon_stats.total_pages += balloon_hotplug; |
080e2be7 | 349 | |
b2ac6aa8 | 350 | return BP_WAIT; |
55b3da98 DV |
351 | err: |
352 | release_memory_resource(resource); | |
353 | return BP_ECANCELED; | |
080e2be7 DK |
354 | } |
355 | ||
a9cd410a | 356 | static void xen_online_page(struct page *page, unsigned int order) |
080e2be7 | 357 | { |
a9cd410a AK |
358 | unsigned long i, size = (1 << order); |
359 | unsigned long start_pfn = page_to_pfn(page); | |
360 | struct page *p; | |
080e2be7 | 361 | |
a9cd410a | 362 | pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn); |
080e2be7 | 363 | mutex_lock(&balloon_mutex); |
a9cd410a AK |
364 | for (i = 0; i < size; i++) { |
365 | p = pfn_to_page(start_pfn + i); | |
dde3285f | 366 | balloon_append(p); |
a9cd410a | 367 | } |
080e2be7 DK |
368 | mutex_unlock(&balloon_mutex); |
369 | } | |
370 | ||
371 | static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v) | |
372 | { | |
373 | if (val == MEM_ONLINE) | |
8480ed9c | 374 | wake_up(&balloon_thread_wq); |
080e2be7 DK |
375 | |
376 | return NOTIFY_OK; | |
377 | } | |
378 | ||
379 | static struct notifier_block xen_memory_nb = { | |
380 | .notifier_call = xen_memory_notifier, | |
381 | .priority = 0 | |
382 | }; | |
383 | #else | |
b2ac6aa8 | 384 | static enum bp_state reserve_additional_memory(void) |
1775826c | 385 | { |
c673ec61 JG |
386 | balloon_stats.target_pages = balloon_stats.current_pages + |
387 | balloon_stats.target_unpopulated; | |
1cf6a6c8 | 388 | return BP_ECANCELED; |
1775826c | 389 | } |
de5a77d8 | 390 | #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */ |
1775826c | 391 | |
de5a77d8 | 392 | static long current_credit(void) |
080e2be7 | 393 | { |
de5a77d8 | 394 | return balloon_stats.target_pages - balloon_stats.current_pages; |
080e2be7 DK |
395 | } |
396 | ||
de5a77d8 | 397 | static bool balloon_is_inflated(void) |
080e2be7 | 398 | { |
de5a77d8 | 399 | return balloon_stats.balloon_low || balloon_stats.balloon_high; |
080e2be7 | 400 | } |
080e2be7 | 401 | |
95d2ac4a | 402 | static enum bp_state increase_reservation(unsigned long nr_pages) |
1775826c | 403 | { |
95d2ac4a | 404 | int rc; |
30756c62 | 405 | unsigned long i; |
1775826c | 406 | struct page *page; |
1775826c JF |
407 | |
408 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
409 | nr_pages = ARRAY_SIZE(frame_list); | |
410 | ||
9346c2a8 | 411 | page = list_first_entry_or_null(&ballooned_pages, struct page, lru); |
1775826c | 412 | for (i = 0; i < nr_pages; i++) { |
95d2ac4a DK |
413 | if (!page) { |
414 | nr_pages = i; | |
415 | break; | |
416 | } | |
30756c62 | 417 | |
30756c62 | 418 | frame_list[i] = page_to_xen_pfn(page); |
1775826c JF |
419 | page = balloon_next_page(page); |
420 | } | |
421 | ||
ae4c51a5 | 422 | rc = xenmem_reservation_increase(nr_pages, frame_list); |
40095de1 | 423 | if (rc <= 0) |
95d2ac4a | 424 | return BP_EAGAIN; |
1775826c | 425 | |
bc2c0303 | 426 | for (i = 0; i < rc; i++) { |
b6f30679 | 427 | page = balloon_retrieve(false); |
1775826c JF |
428 | BUG_ON(page == NULL); |
429 | ||
ae4c51a5 | 430 | xenmem_reservation_va_mapping_update(1, &page, &frame_list[i]); |
1775826c JF |
431 | |
432 | /* Relinquish the page back to the allocator. */ | |
709613ad | 433 | free_reserved_page(page); |
1775826c JF |
434 | } |
435 | ||
bc2c0303 | 436 | balloon_stats.current_pages += rc; |
1775826c | 437 | |
95d2ac4a | 438 | return BP_DONE; |
1775826c JF |
439 | } |
440 | ||
b6f30679 | 441 | static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) |
1775826c | 442 | { |
95d2ac4a | 443 | enum bp_state state = BP_DONE; |
30756c62 JG |
444 | unsigned long i; |
445 | struct page *page, *tmp; | |
1775826c | 446 | int ret; |
30756c62 | 447 | LIST_HEAD(pages); |
1775826c JF |
448 | |
449 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
450 | nr_pages = ARRAY_SIZE(frame_list); | |
451 | ||
452 | for (i = 0; i < nr_pages; i++) { | |
fce92683 LN |
453 | page = alloc_page(gfp); |
454 | if (page == NULL) { | |
1775826c | 455 | nr_pages = i; |
95d2ac4a | 456 | state = BP_EAGAIN; |
1775826c JF |
457 | break; |
458 | } | |
709613ad | 459 | adjust_managed_page_count(page, -1); |
ae4c51a5 | 460 | xenmem_reservation_scrub_page(page); |
30756c62 | 461 | list_add(&page->lru, &pages); |
09ed3d5b | 462 | } |
1775826c | 463 | |
09ed3d5b WL |
464 | /* |
465 | * Ensure that ballooned highmem pages don't have kmaps. | |
466 | * | |
467 | * Do this before changing the p2m as kmap_flush_unused() | |
468 | * reads PTEs to obtain pages (and hence needs the original | |
469 | * p2m entry). | |
470 | */ | |
471 | kmap_flush_unused(); | |
472 | ||
30756c62 JG |
473 | /* |
474 | * Setup the frame, update direct mapping, invalidate P2M, | |
475 | * and add to balloon. | |
476 | */ | |
477 | i = 0; | |
478 | list_for_each_entry_safe(page, tmp, &pages, lru) { | |
30756c62 | 479 | frame_list[i++] = xen_page_to_gfn(page); |
1058a75f | 480 | |
ae4c51a5 | 481 | xenmem_reservation_va_mapping_reset(1, &page); |
30756c62 | 482 | |
30756c62 | 483 | list_del(&page->lru); |
24f69373 | 484 | |
09ed3d5b | 485 | balloon_append(page); |
1775826c JF |
486 | } |
487 | ||
24f69373 | 488 | flush_tlb_all(); |
2bad07ce | 489 | |
ae4c51a5 | 490 | ret = xenmem_reservation_decrease(nr_pages, frame_list); |
1775826c JF |
491 | BUG_ON(ret != nr_pages); |
492 | ||
493 | balloon_stats.current_pages -= nr_pages; | |
1775826c | 494 | |
95d2ac4a | 495 | return state; |
1775826c JF |
496 | } |
497 | ||
498 | /* | |
319933a8 JG |
499 | * Stop waiting if either state is BP_DONE and ballooning action is |
500 | * needed, or if the credit has changed while state is not BP_DONE. | |
8480ed9c | 501 | */ |
e0af2c30 | 502 | static bool balloon_thread_cond(long credit) |
8480ed9c | 503 | { |
e0af2c30 | 504 | if (balloon_state == BP_DONE) |
8480ed9c JG |
505 | credit = 0; |
506 | ||
507 | return current_credit() != credit || kthread_should_stop(); | |
508 | } | |
509 | ||
510 | /* | |
511 | * As this is a kthread it is guaranteed to run as a single instance only. | |
1775826c JF |
512 | * We may of course race updates of the target counts (which are protected |
513 | * by the balloon lock), or with changes to the Xen hard limit, but we will | |
514 | * recover from these in time. | |
515 | */ | |
8480ed9c | 516 | static int balloon_thread(void *unused) |
1775826c | 517 | { |
1775826c | 518 | long credit; |
8480ed9c JG |
519 | unsigned long timeout; |
520 | ||
521 | set_freezable(); | |
522 | for (;;) { | |
e0af2c30 | 523 | switch (balloon_state) { |
319933a8 JG |
524 | case BP_DONE: |
525 | case BP_ECANCELED: | |
8480ed9c | 526 | timeout = 3600 * HZ; |
319933a8 JG |
527 | break; |
528 | case BP_EAGAIN: | |
529 | timeout = balloon_stats.schedule_delay * HZ; | |
530 | break; | |
531 | case BP_WAIT: | |
532 | timeout = HZ; | |
533 | break; | |
534 | } | |
535 | ||
8480ed9c | 536 | credit = current_credit(); |
1775826c | 537 | |
96f5bd03 | 538 | wait_event_freezable_timeout(balloon_thread_wq, |
e0af2c30 | 539 | balloon_thread_cond(credit), timeout); |
8480ed9c JG |
540 | |
541 | if (kthread_should_stop()) | |
542 | return 0; | |
1775826c | 543 | |
929423fa JG |
544 | mutex_lock(&balloon_mutex); |
545 | ||
83be7e52 | 546 | credit = current_credit(); |
95d2ac4a | 547 | |
080e2be7 DK |
548 | if (credit > 0) { |
549 | if (balloon_is_inflated()) | |
e0af2c30 | 550 | balloon_state = increase_reservation(credit); |
080e2be7 | 551 | else |
e0af2c30 | 552 | balloon_state = reserve_additional_memory(); |
080e2be7 | 553 | } |
95d2ac4a | 554 | |
a1078e82 JG |
555 | if (credit < 0) { |
556 | long n_pages; | |
557 | ||
558 | n_pages = min(-credit, si_mem_available()); | |
e0af2c30 JG |
559 | balloon_state = decrease_reservation(n_pages, |
560 | GFP_BALLOON); | |
561 | if (balloon_state == BP_DONE && n_pages != -credit && | |
a1078e82 | 562 | n_pages < totalreserve_pages) |
e0af2c30 | 563 | balloon_state = BP_EAGAIN; |
a1078e82 | 564 | } |
95d2ac4a | 565 | |
e0af2c30 | 566 | update_schedule(); |
1775826c | 567 | |
929423fa JG |
568 | mutex_unlock(&balloon_mutex); |
569 | ||
570 | cond_resched(); | |
8480ed9c | 571 | } |
1775826c JF |
572 | } |
573 | ||
574 | /* Resets the Xen limit, sets new target, and kicks off processing. */ | |
803eb047 | 575 | void balloon_set_new_target(unsigned long target) |
1775826c JF |
576 | { |
577 | /* No need for lock. Not read-modify-write updates. */ | |
1775826c | 578 | balloon_stats.target_pages = target; |
8480ed9c | 579 | wake_up(&balloon_thread_wq); |
1775826c | 580 | } |
803eb047 | 581 | EXPORT_SYMBOL_GPL(balloon_set_new_target); |
1775826c | 582 | |
1cf6a6c8 DV |
583 | static int add_ballooned_pages(int nr_pages) |
584 | { | |
585 | enum bp_state st; | |
586 | ||
587 | if (xen_hotplug_unpopulated) { | |
588 | st = reserve_additional_memory(); | |
589 | if (st != BP_ECANCELED) { | |
88a479ff RPM |
590 | int rc; |
591 | ||
1cf6a6c8 | 592 | mutex_unlock(&balloon_mutex); |
88a479ff | 593 | rc = wait_event_interruptible(balloon_wq, |
1cf6a6c8 DV |
594 | !list_empty(&ballooned_pages)); |
595 | mutex_lock(&balloon_mutex); | |
88a479ff | 596 | return rc ? -ENOMEM : 0; |
1cf6a6c8 DV |
597 | } |
598 | } | |
599 | ||
a1078e82 JG |
600 | if (si_mem_available() < nr_pages) |
601 | return -ENOMEM; | |
602 | ||
1cf6a6c8 DV |
603 | st = decrease_reservation(nr_pages, GFP_USER); |
604 | if (st != BP_DONE) | |
605 | return -ENOMEM; | |
606 | ||
607 | return 0; | |
608 | } | |
609 | ||
b6f30679 KRW |
610 | /** |
611 | * alloc_xenballooned_pages - get pages that have been ballooned out | |
612 | * @nr_pages: Number of pages to get | |
613 | * @pages: pages returned | |
614 | * @return 0 on success, error otherwise | |
615 | */ | |
81b286e0 | 616 | int alloc_xenballooned_pages(int nr_pages, struct page **pages) |
1775826c | 617 | { |
b6f30679 | 618 | int pgno = 0; |
e882dc9c | 619 | struct page *page; |
1cf6a6c8 DV |
620 | int ret; |
621 | ||
b6f30679 | 622 | mutex_lock(&balloon_mutex); |
1cf6a6c8 DV |
623 | |
624 | balloon_stats.target_unpopulated += nr_pages; | |
625 | ||
b6f30679 | 626 | while (pgno < nr_pages) { |
81b286e0 DV |
627 | page = balloon_retrieve(true); |
628 | if (page) { | |
b6f30679 | 629 | pages[pgno++] = page; |
4a69c909 | 630 | #ifdef CONFIG_XEN_HAVE_PVMMU |
30756c62 JG |
631 | /* |
632 | * We don't support PV MMU when Linux and Xen is using | |
633 | * different page granularity. | |
634 | */ | |
635 | BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); | |
636 | ||
b194da25 BO |
637 | if (!xen_feature(XENFEAT_auto_translated_physmap)) { |
638 | ret = xen_alloc_p2m_entry(page_to_pfn(page)); | |
639 | if (ret < 0) | |
640 | goto out_undo; | |
641 | } | |
4a69c909 | 642 | #endif |
b6f30679 | 643 | } else { |
1cf6a6c8 DV |
644 | ret = add_ballooned_pages(nr_pages - pgno); |
645 | if (ret < 0) | |
b6f30679 KRW |
646 | goto out_undo; |
647 | } | |
1775826c | 648 | } |
b6f30679 KRW |
649 | mutex_unlock(&balloon_mutex); |
650 | return 0; | |
651 | out_undo: | |
b6f30679 | 652 | mutex_unlock(&balloon_mutex); |
1cf6a6c8 | 653 | free_xenballooned_pages(pgno, pages); |
1951fa33 RPM |
654 | /* |
655 | * NB: free_xenballooned_pages will only subtract pgno pages, but since | |
656 | * target_unpopulated is incremented with nr_pages at the start we need | |
657 | * to remove the remaining ones also, or accounting will be screwed. | |
658 | */ | |
659 | balloon_stats.target_unpopulated -= nr_pages - pgno; | |
1cf6a6c8 | 660 | return ret; |
1775826c | 661 | } |
b6f30679 | 662 | EXPORT_SYMBOL(alloc_xenballooned_pages); |
1775826c | 663 | |
b6f30679 KRW |
664 | /** |
665 | * free_xenballooned_pages - return pages retrieved with get_ballooned_pages | |
666 | * @nr_pages: Number of pages | |
667 | * @pages: pages to return | |
668 | */ | |
e882dc9c | 669 | void free_xenballooned_pages(int nr_pages, struct page **pages) |
1775826c | 670 | { |
b6f30679 | 671 | int i; |
1775826c | 672 | |
b6f30679 | 673 | mutex_lock(&balloon_mutex); |
1775826c | 674 | |
b6f30679 | 675 | for (i = 0; i < nr_pages; i++) { |
59b52f10 | 676 | if (pages[i]) |
b6f30679 KRW |
677 | balloon_append(pages[i]); |
678 | } | |
679 | ||
1cf6a6c8 DV |
680 | balloon_stats.target_unpopulated -= nr_pages; |
681 | ||
b6f30679 | 682 | /* The balloon may be too large now. Shrink it if needed. */ |
83be7e52 | 683 | if (current_credit()) |
8480ed9c | 684 | wake_up(&balloon_thread_wq); |
1775826c | 685 | |
b6f30679 KRW |
686 | mutex_unlock(&balloon_mutex); |
687 | } | |
688 | EXPORT_SYMBOL(free_xenballooned_pages); | |
1775826c | 689 | |
9e2369c0 | 690 | #if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC) |
8b5d44a5 DV |
691 | static void __init balloon_add_region(unsigned long start_pfn, |
692 | unsigned long pages) | |
1775826c | 693 | { |
4dfe22f5 | 694 | unsigned long pfn, extra_pfn_end; |
1775826c | 695 | |
8b5d44a5 DV |
696 | /* |
697 | * If the amount of usable memory has been limited (e.g., with | |
698 | * the 'mem' command line parameter), don't add pages beyond | |
699 | * this limit. | |
700 | */ | |
701 | extra_pfn_end = min(max_pfn, start_pfn + pages); | |
702 | ||
703 | for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) { | |
8b5d44a5 DV |
704 | /* totalram_pages and totalhigh_pages do not |
705 | include the boot-time balloon extension, so | |
706 | don't subtract from it. */ | |
59b52f10 | 707 | balloon_append(pfn_to_page(pfn)); |
8b5d44a5 | 708 | } |
de5a77d8 DV |
709 | |
710 | balloon_stats.total_pages += extra_pfn_end - start_pfn; | |
8b5d44a5 | 711 | } |
4fee9ad8 | 712 | #endif |
8b5d44a5 DV |
713 | |
714 | static int __init balloon_init(void) | |
715 | { | |
8480ed9c JG |
716 | struct task_struct *task; |
717 | ||
53d5522c | 718 | if (!xen_domain()) |
1775826c JF |
719 | return -ENODEV; |
720 | ||
283c0972 | 721 | pr_info("Initialising balloon driver\n"); |
1775826c | 722 | |
4fee9ad8 | 723 | #ifdef CONFIG_XEN_PV |
aa24411b DV |
724 | balloon_stats.current_pages = xen_pv_domain() |
725 | ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn) | |
c275a57f | 726 | : get_num_physpages(); |
4fee9ad8 VK |
727 | #else |
728 | balloon_stats.current_pages = get_num_physpages(); | |
729 | #endif | |
1775826c JF |
730 | balloon_stats.target_pages = balloon_stats.current_pages; |
731 | balloon_stats.balloon_low = 0; | |
732 | balloon_stats.balloon_high = 0; | |
de5a77d8 | 733 | balloon_stats.total_pages = balloon_stats.current_pages; |
1775826c | 734 | |
95d2ac4a DK |
735 | balloon_stats.schedule_delay = 1; |
736 | balloon_stats.max_schedule_delay = 32; | |
737 | balloon_stats.retry_count = 1; | |
a1078e82 | 738 | balloon_stats.max_retry_count = 4; |
1775826c | 739 | |
080e2be7 | 740 | #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG |
080e2be7 DK |
741 | set_online_page_callback(&xen_online_page); |
742 | register_memory_notifier(&xen_memory_nb); | |
1cf6a6c8 | 743 | register_sysctl_table(xen_root); |
080e2be7 DK |
744 | #endif |
745 | ||
9e2369c0 | 746 | #if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC) |
4fee9ad8 VK |
747 | { |
748 | int i; | |
749 | ||
750 | /* | |
751 | * Initialize the balloon with pages from the extra memory | |
752 | * regions (see arch/x86/xen/setup.c). | |
753 | */ | |
754 | for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) | |
755 | if (xen_extra_mem[i].n_pfns) | |
756 | balloon_add_region(xen_extra_mem[i].start_pfn, | |
757 | xen_extra_mem[i].n_pfns); | |
758 | } | |
759 | #endif | |
1775826c | 760 | |
8480ed9c JG |
761 | task = kthread_run(balloon_thread, NULL, "xen-balloon"); |
762 | if (IS_ERR(task)) { | |
763 | pr_err("xen-balloon thread could not be started, ballooning will not work!\n"); | |
764 | return PTR_ERR(task); | |
765 | } | |
766 | ||
96edd61d JG |
767 | /* Init the xen-balloon driver. */ |
768 | xen_balloon_init(); | |
769 | ||
1775826c JF |
770 | return 0; |
771 | } | |
1775826c | 772 | subsys_initcall(balloon_init); |
e0af2c30 JG |
773 | |
774 | static int __init balloon_wait_finish(void) | |
775 | { | |
776 | long credit, last_credit = 0; | |
777 | unsigned long last_changed = 0; | |
778 | ||
779 | if (!xen_domain()) | |
780 | return -ENODEV; | |
781 | ||
782 | /* PV guests don't need to wait. */ | |
783 | if (xen_pv_domain() || !current_credit()) | |
784 | return 0; | |
785 | ||
786 | pr_notice("Waiting for initial ballooning down having finished.\n"); | |
787 | ||
788 | while ((credit = current_credit()) < 0) { | |
789 | if (credit != last_credit) { | |
790 | last_changed = jiffies; | |
791 | last_credit = credit; | |
792 | } | |
793 | if (balloon_state == BP_ECANCELED) { | |
794 | pr_warn_once("Initial ballooning failed, %ld pages need to be freed.\n", | |
795 | -credit); | |
796 | if (jiffies - last_changed >= HZ * balloon_boot_timeout) | |
797 | panic("Initial ballooning failed!\n"); | |
798 | } | |
799 | ||
800 | schedule_timeout_interruptible(HZ / 10); | |
801 | } | |
802 | ||
803 | pr_notice("Initial ballooning down finished.\n"); | |
804 | ||
805 | return 0; | |
806 | } | |
807 | late_initcall_sync(balloon_wait_finish); |