balloon.c (803eb047a28d239809fff1f87274cdaa94e0d8ea) balloon.c (b6f3067985f12d514187059fb10fe3c877f87cb2)
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 *
8 * This program is free software; you can redistribute it and/or

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123
124static void balloon_append(struct page *page)
125{
126 __balloon_append(page);
127 totalram_pages--;
128}
129
130/* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
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 *
8 * This program is free software; you can redistribute it and/or

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123
124static void balloon_append(struct page *page)
125{
126 __balloon_append(page);
127 totalram_pages--;
128}
129
130/* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
131static struct page *balloon_retrieve(void)
131static struct page *balloon_retrieve(bool prefer_highmem)
132{
133 struct page *page;
134
135 if (list_empty(&ballooned_pages))
136 return NULL;
137
132{
133 struct page *page;
134
135 if (list_empty(&ballooned_pages))
136 return NULL;
137
138 page = list_entry(ballooned_pages.next, struct page, lru);
138 if (prefer_highmem)
139 page = list_entry(ballooned_pages.prev, struct page, lru);
140 else
141 page = list_entry(ballooned_pages.next, struct page, lru);
139 list_del(&page->lru);
140
141 if (PageHighMem(page)) {
142 balloon_stats.balloon_high--;
143 inc_totalhigh_pages();
144 }
145 else
146 balloon_stats.balloon_low--;

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228
229 set_xen_guest_handle(reservation.extent_start, frame_list);
230 reservation.nr_extents = nr_pages;
231 rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
232 if (rc <= 0)
233 return BP_EAGAIN;
234
235 for (i = 0; i < rc; i++) {
142 list_del(&page->lru);
143
144 if (PageHighMem(page)) {
145 balloon_stats.balloon_high--;
146 inc_totalhigh_pages();
147 }
148 else
149 balloon_stats.balloon_low--;

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231
232 set_xen_guest_handle(reservation.extent_start, frame_list);
233 reservation.nr_extents = nr_pages;
234 rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
235 if (rc <= 0)
236 return BP_EAGAIN;
237
238 for (i = 0; i < rc; i++) {
236 page = balloon_retrieve();
239 page = balloon_retrieve(false);
237 BUG_ON(page == NULL);
238
239 pfn = page_to_pfn(page);
240 BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
241 phys_to_machine_mapping_valid(pfn));
242
243 set_phys_to_machine(pfn, frame_list[i]);
244

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258 __free_page(page);
259 }
260
261 balloon_stats.current_pages += rc;
262
263 return BP_DONE;
264}
265
240 BUG_ON(page == NULL);
241
242 pfn = page_to_pfn(page);
243 BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
244 phys_to_machine_mapping_valid(pfn));
245
246 set_phys_to_machine(pfn, frame_list[i]);
247

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261 __free_page(page);
262 }
263
264 balloon_stats.current_pages += rc;
265
266 return BP_DONE;
267}
268
266static enum bp_state decrease_reservation(unsigned long nr_pages)
269static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
267{
268 enum bp_state state = BP_DONE;
269 unsigned long pfn, i;
270 struct page *page;
271 int ret;
272 struct xen_memory_reservation reservation = {
273 .address_bits = 0,
274 .extent_order = 0,
275 .domid = DOMID_SELF
276 };
277
278 if (nr_pages > ARRAY_SIZE(frame_list))
279 nr_pages = ARRAY_SIZE(frame_list);
280
281 for (i = 0; i < nr_pages; i++) {
270{
271 enum bp_state state = BP_DONE;
272 unsigned long pfn, i;
273 struct page *page;
274 int ret;
275 struct xen_memory_reservation reservation = {
276 .address_bits = 0,
277 .extent_order = 0,
278 .domid = DOMID_SELF
279 };
280
281 if (nr_pages > ARRAY_SIZE(frame_list))
282 nr_pages = ARRAY_SIZE(frame_list);
283
284 for (i = 0; i < nr_pages; i++) {
282 if ((page = alloc_page(GFP_BALLOON)) == NULL) {
285 if ((page = alloc_page(gfp)) == NULL) {
283 nr_pages = i;
284 state = BP_EAGAIN;
285 break;
286 }
287
288 pfn = page_to_pfn(page);
289 frame_list[i] = pfn_to_mfn(pfn);
290

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335
336 do {
337 credit = current_target() - balloon_stats.current_pages;
338
339 if (credit > 0)
340 state = increase_reservation(credit);
341
342 if (credit < 0)
286 nr_pages = i;
287 state = BP_EAGAIN;
288 break;
289 }
290
291 pfn = page_to_pfn(page);
292 frame_list[i] = pfn_to_mfn(pfn);
293

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338
339 do {
340 credit = current_target() - balloon_stats.current_pages;
341
342 if (credit > 0)
343 state = increase_reservation(credit);
344
345 if (credit < 0)
343 state = decrease_reservation(-credit);
346 state = decrease_reservation(-credit, GFP_BALLOON);
344
345 state = update_schedule(state);
346
347#ifndef CONFIG_PREEMPT
348 if (need_resched())
349 schedule();
350#endif
351 } while (credit && state == BP_DONE);

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361void balloon_set_new_target(unsigned long target)
362{
363 /* No need for lock. Not read-modify-write updates. */
364 balloon_stats.target_pages = target;
365 schedule_delayed_work(&balloon_worker, 0);
366}
367EXPORT_SYMBOL_GPL(balloon_set_new_target);
368
347
348 state = update_schedule(state);
349
350#ifndef CONFIG_PREEMPT
351 if (need_resched())
352 schedule();
353#endif
354 } while (credit && state == BP_DONE);

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364void balloon_set_new_target(unsigned long target)
365{
366 /* No need for lock. Not read-modify-write updates. */
367 balloon_stats.target_pages = target;
368 schedule_delayed_work(&balloon_worker, 0);
369}
370EXPORT_SYMBOL_GPL(balloon_set_new_target);
371
372/**
373 * alloc_xenballooned_pages - get pages that have been ballooned out
374 * @nr_pages: Number of pages to get
375 * @pages: pages returned
376 * @return 0 on success, error otherwise
377 */
378int alloc_xenballooned_pages(int nr_pages, struct page** pages)
379{
380 int pgno = 0;
381 struct page* page;
382 mutex_lock(&balloon_mutex);
383 while (pgno < nr_pages) {
384 page = balloon_retrieve(true);
385 if (page) {
386 pages[pgno++] = page;
387 } else {
388 enum bp_state st;
389 st = decrease_reservation(nr_pages - pgno, GFP_HIGHUSER);
390 if (st != BP_DONE)
391 goto out_undo;
392 }
393 }
394 mutex_unlock(&balloon_mutex);
395 return 0;
396 out_undo:
397 while (pgno)
398 balloon_append(pages[--pgno]);
399 /* Free the memory back to the kernel soon */
400 schedule_delayed_work(&balloon_worker, 0);
401 mutex_unlock(&balloon_mutex);
402 return -ENOMEM;
403}
404EXPORT_SYMBOL(alloc_xenballooned_pages);
405
406/**
407 * free_xenballooned_pages - return pages retrieved with get_ballooned_pages
408 * @nr_pages: Number of pages
409 * @pages: pages to return
410 */
411void free_xenballooned_pages(int nr_pages, struct page** pages)
412{
413 int i;
414
415 mutex_lock(&balloon_mutex);
416
417 for (i = 0; i < nr_pages; i++) {
418 if (pages[i])
419 balloon_append(pages[i]);
420 }
421
422 /* The balloon may be too large now. Shrink it if needed. */
423 if (current_target() != balloon_stats.current_pages)
424 schedule_delayed_work(&balloon_worker, 0);
425
426 mutex_unlock(&balloon_mutex);
427}
428EXPORT_SYMBOL(free_xenballooned_pages);
429
369static int __init balloon_init(void)
370{
371 unsigned long pfn, extra_pfn_end;
372 struct page *page;
373
374 if (!xen_pv_domain())
375 return -ENODEV;
376

--- 38 unchanged lines hidden --- 		430static int __init balloon_init(void)
431{
432 unsigned long pfn, extra_pfn_end;
433 struct page *page;
434
435 if (!xen_pv_domain())
436 return -ENODEV;
437

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