11775826cSJeremy Fitzhardinge /****************************************************************************** 21775826cSJeremy Fitzhardinge * balloon.c 31775826cSJeremy Fitzhardinge * 41775826cSJeremy Fitzhardinge * Xen balloon driver - enables returning/claiming memory to/from Xen. 51775826cSJeremy Fitzhardinge * 61775826cSJeremy Fitzhardinge * Copyright (c) 2003, B Dragovic 71775826cSJeremy Fitzhardinge * Copyright (c) 2003-2004, M Williamson, K Fraser 81775826cSJeremy Fitzhardinge * Copyright (c) 2005 Dan M. Smith, IBM Corporation 91775826cSJeremy Fitzhardinge * 101775826cSJeremy Fitzhardinge * This program is free software; you can redistribute it and/or 111775826cSJeremy Fitzhardinge * modify it under the terms of the GNU General Public License version 2 121775826cSJeremy Fitzhardinge * as published by the Free Software Foundation; or, when distributed 131775826cSJeremy Fitzhardinge * separately from the Linux kernel or incorporated into other 141775826cSJeremy Fitzhardinge * software packages, subject to the following license: 151775826cSJeremy Fitzhardinge * 161775826cSJeremy Fitzhardinge * Permission is hereby granted, free of charge, to any person obtaining a copy 171775826cSJeremy Fitzhardinge * of this source file (the "Software"), to deal in the Software without 181775826cSJeremy Fitzhardinge * restriction, including without limitation the rights to use, copy, modify, 191775826cSJeremy Fitzhardinge * merge, publish, distribute, sublicense, and/or sell copies of the Software, 201775826cSJeremy Fitzhardinge * and to permit persons to whom the Software is furnished to do so, subject to 211775826cSJeremy Fitzhardinge * the following conditions: 221775826cSJeremy Fitzhardinge * 231775826cSJeremy Fitzhardinge * The above copyright notice and this permission notice shall be included in 241775826cSJeremy Fitzhardinge * all copies or substantial portions of the Software. 251775826cSJeremy Fitzhardinge * 261775826cSJeremy Fitzhardinge * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 271775826cSJeremy Fitzhardinge * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 281775826cSJeremy Fitzhardinge * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 291775826cSJeremy Fitzhardinge * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 301775826cSJeremy Fitzhardinge * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 311775826cSJeremy Fitzhardinge * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 321775826cSJeremy Fitzhardinge * IN THE SOFTWARE. 331775826cSJeremy Fitzhardinge */ 341775826cSJeremy Fitzhardinge 351775826cSJeremy Fitzhardinge #include <linux/kernel.h> 361775826cSJeremy Fitzhardinge #include <linux/module.h> 371775826cSJeremy Fitzhardinge #include <linux/sched.h> 381775826cSJeremy Fitzhardinge #include <linux/errno.h> 391775826cSJeremy Fitzhardinge #include <linux/mm.h> 401775826cSJeremy Fitzhardinge #include <linux/bootmem.h> 411775826cSJeremy Fitzhardinge #include <linux/pagemap.h> 421775826cSJeremy Fitzhardinge #include <linux/highmem.h> 431775826cSJeremy Fitzhardinge #include <linux/mutex.h> 441775826cSJeremy Fitzhardinge #include <linux/list.h> 451775826cSJeremy Fitzhardinge #include <linux/sysdev.h> 465a0e3ad6STejun Heo #include <linux/gfp.h> 471775826cSJeremy Fitzhardinge 481775826cSJeremy Fitzhardinge #include <asm/page.h> 491775826cSJeremy Fitzhardinge #include <asm/pgalloc.h> 501775826cSJeremy Fitzhardinge #include <asm/pgtable.h> 511775826cSJeremy Fitzhardinge #include <asm/uaccess.h> 521775826cSJeremy Fitzhardinge #include <asm/tlb.h> 5366946f67SJeremy Fitzhardinge #include <asm/e820.h> 541775826cSJeremy Fitzhardinge 55ecbf29cdSJeremy Fitzhardinge #include <asm/xen/hypervisor.h> 56ecbf29cdSJeremy Fitzhardinge #include <asm/xen/hypercall.h> 571ccbf534SJeremy Fitzhardinge 581ccbf534SJeremy Fitzhardinge #include <xen/xen.h> 59ecbf29cdSJeremy Fitzhardinge #include <xen/interface/xen.h> 601775826cSJeremy Fitzhardinge #include <xen/interface/memory.h> 611775826cSJeremy Fitzhardinge #include <xen/xenbus.h> 621775826cSJeremy Fitzhardinge #include <xen/features.h> 631775826cSJeremy Fitzhardinge #include <xen/page.h> 641775826cSJeremy Fitzhardinge 651775826cSJeremy Fitzhardinge #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) 661775826cSJeremy Fitzhardinge 67167e6cf6SJeremy Fitzhardinge #define BALLOON_CLASS_NAME "xen_memory" 681775826cSJeremy Fitzhardinge 6995d2ac4aSDaniel Kiper /* 7095d2ac4aSDaniel Kiper * balloon_process() state: 7195d2ac4aSDaniel Kiper * 7295d2ac4aSDaniel Kiper * BP_DONE: done or nothing to do, 7395d2ac4aSDaniel Kiper * BP_EAGAIN: error, go to sleep, 7495d2ac4aSDaniel Kiper * BP_ECANCELED: error, balloon operation canceled. 7595d2ac4aSDaniel Kiper */ 7695d2ac4aSDaniel Kiper 7795d2ac4aSDaniel Kiper enum bp_state { 7895d2ac4aSDaniel Kiper BP_DONE, 7995d2ac4aSDaniel Kiper BP_EAGAIN, 8095d2ac4aSDaniel Kiper BP_ECANCELED 8195d2ac4aSDaniel Kiper }; 8295d2ac4aSDaniel Kiper 8395d2ac4aSDaniel Kiper #define RETRY_UNLIMITED 0 8495d2ac4aSDaniel Kiper 851775826cSJeremy Fitzhardinge struct balloon_stats { 861775826cSJeremy Fitzhardinge /* We aim for 'current allocation' == 'target allocation'. */ 871775826cSJeremy Fitzhardinge unsigned long current_pages; 881775826cSJeremy Fitzhardinge unsigned long target_pages; 891775826cSJeremy Fitzhardinge /* Number of pages in high- and low-memory balloons. */ 901775826cSJeremy Fitzhardinge unsigned long balloon_low; 911775826cSJeremy Fitzhardinge unsigned long balloon_high; 9295d2ac4aSDaniel Kiper unsigned long schedule_delay; 9395d2ac4aSDaniel Kiper unsigned long max_schedule_delay; 9495d2ac4aSDaniel Kiper unsigned long retry_count; 9595d2ac4aSDaniel Kiper unsigned long max_retry_count; 961775826cSJeremy Fitzhardinge }; 971775826cSJeremy Fitzhardinge 981775826cSJeremy Fitzhardinge static DEFINE_MUTEX(balloon_mutex); 991775826cSJeremy Fitzhardinge 1001775826cSJeremy Fitzhardinge static struct sys_device balloon_sysdev; 1011775826cSJeremy Fitzhardinge 1021775826cSJeremy Fitzhardinge static int register_balloon(struct sys_device *sysdev); 1031775826cSJeremy Fitzhardinge 1041775826cSJeremy Fitzhardinge static struct balloon_stats balloon_stats; 1051775826cSJeremy Fitzhardinge 1061775826cSJeremy Fitzhardinge /* We increase/decrease in batches which fit in a page */ 1071775826cSJeremy Fitzhardinge static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)]; 1081775826cSJeremy Fitzhardinge 1091775826cSJeremy Fitzhardinge #ifdef CONFIG_HIGHMEM 1101775826cSJeremy Fitzhardinge #define inc_totalhigh_pages() (totalhigh_pages++) 1111775826cSJeremy Fitzhardinge #define dec_totalhigh_pages() (totalhigh_pages--) 1121775826cSJeremy Fitzhardinge #else 1131775826cSJeremy Fitzhardinge #define inc_totalhigh_pages() do {} while(0) 1141775826cSJeremy Fitzhardinge #define dec_totalhigh_pages() do {} while(0) 1151775826cSJeremy Fitzhardinge #endif 1161775826cSJeremy Fitzhardinge 1171775826cSJeremy Fitzhardinge /* List of ballooned pages, threaded through the mem_map array. */ 1181775826cSJeremy Fitzhardinge static LIST_HEAD(ballooned_pages); 1191775826cSJeremy Fitzhardinge 1201775826cSJeremy Fitzhardinge /* Main work function, always executed in process context. */ 1211775826cSJeremy Fitzhardinge static void balloon_process(struct work_struct *work); 12295170b2eSDaniel Kiper static DECLARE_DELAYED_WORK(balloon_worker, balloon_process); 1231775826cSJeremy Fitzhardinge 1241775826cSJeremy Fitzhardinge /* When ballooning out (allocating memory to return to Xen) we don't really 1251775826cSJeremy Fitzhardinge want the kernel to try too hard since that can trigger the oom killer. */ 1261775826cSJeremy Fitzhardinge #define GFP_BALLOON \ 1271775826cSJeremy Fitzhardinge (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) 1281775826cSJeremy Fitzhardinge 1291775826cSJeremy Fitzhardinge static void scrub_page(struct page *page) 1301775826cSJeremy Fitzhardinge { 1311775826cSJeremy Fitzhardinge #ifdef CONFIG_XEN_SCRUB_PAGES 13226a3e991SJeremy Fitzhardinge clear_highpage(page); 1331775826cSJeremy Fitzhardinge #endif 1341775826cSJeremy Fitzhardinge } 1351775826cSJeremy Fitzhardinge 1361775826cSJeremy Fitzhardinge /* balloon_append: add the given page to the balloon. */ 1379be4d457SJeremy Fitzhardinge static void __balloon_append(struct page *page) 1381775826cSJeremy Fitzhardinge { 1391775826cSJeremy Fitzhardinge /* Lowmem is re-populated first, so highmem pages go at list tail. */ 1401775826cSJeremy Fitzhardinge if (PageHighMem(page)) { 1411775826cSJeremy Fitzhardinge list_add_tail(&page->lru, &ballooned_pages); 1421775826cSJeremy Fitzhardinge balloon_stats.balloon_high++; 1431775826cSJeremy Fitzhardinge dec_totalhigh_pages(); 1441775826cSJeremy Fitzhardinge } else { 1451775826cSJeremy Fitzhardinge list_add(&page->lru, &ballooned_pages); 1461775826cSJeremy Fitzhardinge balloon_stats.balloon_low++; 1471775826cSJeremy Fitzhardinge } 1489be4d457SJeremy Fitzhardinge } 1493d65c948SGianluca Guida 1509be4d457SJeremy Fitzhardinge static void balloon_append(struct page *page) 1519be4d457SJeremy Fitzhardinge { 1529be4d457SJeremy Fitzhardinge __balloon_append(page); 1533d65c948SGianluca Guida totalram_pages--; 1541775826cSJeremy Fitzhardinge } 1551775826cSJeremy Fitzhardinge 1561775826cSJeremy Fitzhardinge /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ 1571775826cSJeremy Fitzhardinge static struct page *balloon_retrieve(void) 1581775826cSJeremy Fitzhardinge { 1591775826cSJeremy Fitzhardinge struct page *page; 1601775826cSJeremy Fitzhardinge 1611775826cSJeremy Fitzhardinge if (list_empty(&ballooned_pages)) 1621775826cSJeremy Fitzhardinge return NULL; 1631775826cSJeremy Fitzhardinge 1641775826cSJeremy Fitzhardinge page = list_entry(ballooned_pages.next, struct page, lru); 1651775826cSJeremy Fitzhardinge list_del(&page->lru); 1661775826cSJeremy Fitzhardinge 1671775826cSJeremy Fitzhardinge if (PageHighMem(page)) { 1681775826cSJeremy Fitzhardinge balloon_stats.balloon_high--; 1691775826cSJeremy Fitzhardinge inc_totalhigh_pages(); 1701775826cSJeremy Fitzhardinge } 1711775826cSJeremy Fitzhardinge else 1721775826cSJeremy Fitzhardinge balloon_stats.balloon_low--; 1731775826cSJeremy Fitzhardinge 1743d65c948SGianluca Guida totalram_pages++; 1753d65c948SGianluca Guida 1761775826cSJeremy Fitzhardinge return page; 1771775826cSJeremy Fitzhardinge } 1781775826cSJeremy Fitzhardinge 1791775826cSJeremy Fitzhardinge static struct page *balloon_first_page(void) 1801775826cSJeremy Fitzhardinge { 1811775826cSJeremy Fitzhardinge if (list_empty(&ballooned_pages)) 1821775826cSJeremy Fitzhardinge return NULL; 1831775826cSJeremy Fitzhardinge return list_entry(ballooned_pages.next, struct page, lru); 1841775826cSJeremy Fitzhardinge } 1851775826cSJeremy Fitzhardinge 1861775826cSJeremy Fitzhardinge static struct page *balloon_next_page(struct page *page) 1871775826cSJeremy Fitzhardinge { 1881775826cSJeremy Fitzhardinge struct list_head *next = page->lru.next; 1891775826cSJeremy Fitzhardinge if (next == &ballooned_pages) 1901775826cSJeremy Fitzhardinge return NULL; 1911775826cSJeremy Fitzhardinge return list_entry(next, struct page, lru); 1921775826cSJeremy Fitzhardinge } 1931775826cSJeremy Fitzhardinge 19495d2ac4aSDaniel Kiper static enum bp_state update_schedule(enum bp_state state) 19595d2ac4aSDaniel Kiper { 19695d2ac4aSDaniel Kiper if (state == BP_DONE) { 19795d2ac4aSDaniel Kiper balloon_stats.schedule_delay = 1; 19895d2ac4aSDaniel Kiper balloon_stats.retry_count = 1; 19995d2ac4aSDaniel Kiper return BP_DONE; 20095d2ac4aSDaniel Kiper } 20195d2ac4aSDaniel Kiper 20295d2ac4aSDaniel Kiper ++balloon_stats.retry_count; 20395d2ac4aSDaniel Kiper 20495d2ac4aSDaniel Kiper if (balloon_stats.max_retry_count != RETRY_UNLIMITED && 20595d2ac4aSDaniel Kiper balloon_stats.retry_count > balloon_stats.max_retry_count) { 20695d2ac4aSDaniel Kiper balloon_stats.schedule_delay = 1; 20795d2ac4aSDaniel Kiper balloon_stats.retry_count = 1; 20895d2ac4aSDaniel Kiper return BP_ECANCELED; 20995d2ac4aSDaniel Kiper } 21095d2ac4aSDaniel Kiper 21195d2ac4aSDaniel Kiper balloon_stats.schedule_delay <<= 1; 21295d2ac4aSDaniel Kiper 21395d2ac4aSDaniel Kiper if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay) 21495d2ac4aSDaniel Kiper balloon_stats.schedule_delay = balloon_stats.max_schedule_delay; 21595d2ac4aSDaniel Kiper 21695d2ac4aSDaniel Kiper return BP_EAGAIN; 21795d2ac4aSDaniel Kiper } 21895d2ac4aSDaniel Kiper 2191775826cSJeremy Fitzhardinge static unsigned long current_target(void) 2201775826cSJeremy Fitzhardinge { 221bc2c0303SIan Campbell unsigned long target = balloon_stats.target_pages; 2221775826cSJeremy Fitzhardinge 2231775826cSJeremy Fitzhardinge target = min(target, 2241775826cSJeremy Fitzhardinge balloon_stats.current_pages + 2251775826cSJeremy Fitzhardinge balloon_stats.balloon_low + 2261775826cSJeremy Fitzhardinge balloon_stats.balloon_high); 2271775826cSJeremy Fitzhardinge 2281775826cSJeremy Fitzhardinge return target; 2291775826cSJeremy Fitzhardinge } 2301775826cSJeremy Fitzhardinge 23195d2ac4aSDaniel Kiper static enum bp_state increase_reservation(unsigned long nr_pages) 2321775826cSJeremy Fitzhardinge { 23395d2ac4aSDaniel Kiper int rc; 2342f70e0acSJeremy Fitzhardinge unsigned long pfn, i; 2351775826cSJeremy Fitzhardinge struct page *page; 2361775826cSJeremy Fitzhardinge struct xen_memory_reservation reservation = { 2371775826cSJeremy Fitzhardinge .address_bits = 0, 2381775826cSJeremy Fitzhardinge .extent_order = 0, 2391775826cSJeremy Fitzhardinge .domid = DOMID_SELF 2401775826cSJeremy Fitzhardinge }; 2411775826cSJeremy Fitzhardinge 2421775826cSJeremy Fitzhardinge if (nr_pages > ARRAY_SIZE(frame_list)) 2431775826cSJeremy Fitzhardinge nr_pages = ARRAY_SIZE(frame_list); 2441775826cSJeremy Fitzhardinge 2451775826cSJeremy Fitzhardinge page = balloon_first_page(); 2461775826cSJeremy Fitzhardinge for (i = 0; i < nr_pages; i++) { 24795d2ac4aSDaniel Kiper if (!page) { 24895d2ac4aSDaniel Kiper nr_pages = i; 24995d2ac4aSDaniel Kiper break; 25095d2ac4aSDaniel Kiper } 251a419aef8SJoe Perches frame_list[i] = page_to_pfn(page); 2521775826cSJeremy Fitzhardinge page = balloon_next_page(page); 2531775826cSJeremy Fitzhardinge } 2541775826cSJeremy Fitzhardinge 255a90971ebSIsaku Yamahata set_xen_guest_handle(reservation.extent_start, frame_list); 2561775826cSJeremy Fitzhardinge reservation.nr_extents = nr_pages; 257fde28e8fSJeremy Fitzhardinge rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); 25840095de1SKonrad Rzeszutek Wilk if (rc <= 0) 25995d2ac4aSDaniel Kiper return BP_EAGAIN; 2601775826cSJeremy Fitzhardinge 261bc2c0303SIan Campbell for (i = 0; i < rc; i++) { 2621775826cSJeremy Fitzhardinge page = balloon_retrieve(); 2631775826cSJeremy Fitzhardinge BUG_ON(page == NULL); 2641775826cSJeremy Fitzhardinge 2651775826cSJeremy Fitzhardinge pfn = page_to_pfn(page); 2661775826cSJeremy Fitzhardinge BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) && 2671775826cSJeremy Fitzhardinge phys_to_machine_mapping_valid(pfn)); 2681775826cSJeremy Fitzhardinge 2691775826cSJeremy Fitzhardinge set_phys_to_machine(pfn, frame_list[i]); 2701775826cSJeremy Fitzhardinge 2711775826cSJeremy Fitzhardinge /* Link back into the page tables if not highmem. */ 2721775826cSJeremy Fitzhardinge if (pfn < max_low_pfn) { 2731775826cSJeremy Fitzhardinge int ret; 2741775826cSJeremy Fitzhardinge ret = HYPERVISOR_update_va_mapping( 2751775826cSJeremy Fitzhardinge (unsigned long)__va(pfn << PAGE_SHIFT), 2761775826cSJeremy Fitzhardinge mfn_pte(frame_list[i], PAGE_KERNEL), 2771775826cSJeremy Fitzhardinge 0); 2781775826cSJeremy Fitzhardinge BUG_ON(ret); 2791775826cSJeremy Fitzhardinge } 2801775826cSJeremy Fitzhardinge 2811775826cSJeremy Fitzhardinge /* Relinquish the page back to the allocator. */ 2821775826cSJeremy Fitzhardinge ClearPageReserved(page); 2831775826cSJeremy Fitzhardinge init_page_count(page); 2841775826cSJeremy Fitzhardinge __free_page(page); 2851775826cSJeremy Fitzhardinge } 2861775826cSJeremy Fitzhardinge 287bc2c0303SIan Campbell balloon_stats.current_pages += rc; 2881775826cSJeremy Fitzhardinge 28995d2ac4aSDaniel Kiper return BP_DONE; 2901775826cSJeremy Fitzhardinge } 2911775826cSJeremy Fitzhardinge 29295d2ac4aSDaniel Kiper static enum bp_state decrease_reservation(unsigned long nr_pages) 2931775826cSJeremy Fitzhardinge { 29495d2ac4aSDaniel Kiper enum bp_state state = BP_DONE; 2952f70e0acSJeremy Fitzhardinge unsigned long pfn, i; 2961775826cSJeremy Fitzhardinge struct page *page; 2971775826cSJeremy Fitzhardinge int ret; 2981775826cSJeremy Fitzhardinge struct xen_memory_reservation reservation = { 2991775826cSJeremy Fitzhardinge .address_bits = 0, 3001775826cSJeremy Fitzhardinge .extent_order = 0, 3011775826cSJeremy Fitzhardinge .domid = DOMID_SELF 3021775826cSJeremy Fitzhardinge }; 3031775826cSJeremy Fitzhardinge 3041775826cSJeremy Fitzhardinge if (nr_pages > ARRAY_SIZE(frame_list)) 3051775826cSJeremy Fitzhardinge nr_pages = ARRAY_SIZE(frame_list); 3061775826cSJeremy Fitzhardinge 3071775826cSJeremy Fitzhardinge for (i = 0; i < nr_pages; i++) { 3081775826cSJeremy Fitzhardinge if ((page = alloc_page(GFP_BALLOON)) == NULL) { 3091775826cSJeremy Fitzhardinge nr_pages = i; 31095d2ac4aSDaniel Kiper state = BP_EAGAIN; 3111775826cSJeremy Fitzhardinge break; 3121775826cSJeremy Fitzhardinge } 3131775826cSJeremy Fitzhardinge 3141775826cSJeremy Fitzhardinge pfn = page_to_pfn(page); 3151775826cSJeremy Fitzhardinge frame_list[i] = pfn_to_mfn(pfn); 3161775826cSJeremy Fitzhardinge 3171775826cSJeremy Fitzhardinge scrub_page(page); 3181058a75fSDan Magenheimer 319ff4ce8c3SIan Campbell if (!PageHighMem(page)) { 3201058a75fSDan Magenheimer ret = HYPERVISOR_update_va_mapping( 3211058a75fSDan Magenheimer (unsigned long)__va(pfn << PAGE_SHIFT), 3221058a75fSDan Magenheimer __pte_ma(0), 0); 3231058a75fSDan Magenheimer BUG_ON(ret); 3241775826cSJeremy Fitzhardinge } 3251775826cSJeremy Fitzhardinge 326ff4ce8c3SIan Campbell } 327ff4ce8c3SIan Campbell 3281775826cSJeremy Fitzhardinge /* Ensure that ballooned highmem pages don't have kmaps. */ 3291775826cSJeremy Fitzhardinge kmap_flush_unused(); 3301775826cSJeremy Fitzhardinge flush_tlb_all(); 3311775826cSJeremy Fitzhardinge 3321775826cSJeremy Fitzhardinge /* No more mappings: invalidate P2M and add to balloon. */ 3331775826cSJeremy Fitzhardinge for (i = 0; i < nr_pages; i++) { 3341775826cSJeremy Fitzhardinge pfn = mfn_to_pfn(frame_list[i]); 3351775826cSJeremy Fitzhardinge set_phys_to_machine(pfn, INVALID_P2M_ENTRY); 3361775826cSJeremy Fitzhardinge balloon_append(pfn_to_page(pfn)); 3371775826cSJeremy Fitzhardinge } 3381775826cSJeremy Fitzhardinge 339a90971ebSIsaku Yamahata set_xen_guest_handle(reservation.extent_start, frame_list); 3401775826cSJeremy Fitzhardinge reservation.nr_extents = nr_pages; 3411775826cSJeremy Fitzhardinge ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); 3421775826cSJeremy Fitzhardinge BUG_ON(ret != nr_pages); 3431775826cSJeremy Fitzhardinge 3441775826cSJeremy Fitzhardinge balloon_stats.current_pages -= nr_pages; 3451775826cSJeremy Fitzhardinge 34695d2ac4aSDaniel Kiper return state; 3471775826cSJeremy Fitzhardinge } 3481775826cSJeremy Fitzhardinge 3491775826cSJeremy Fitzhardinge /* 3501775826cSJeremy Fitzhardinge * We avoid multiple worker processes conflicting via the balloon mutex. 3511775826cSJeremy Fitzhardinge * We may of course race updates of the target counts (which are protected 3521775826cSJeremy Fitzhardinge * by the balloon lock), or with changes to the Xen hard limit, but we will 3531775826cSJeremy Fitzhardinge * recover from these in time. 3541775826cSJeremy Fitzhardinge */ 3551775826cSJeremy Fitzhardinge static void balloon_process(struct work_struct *work) 3561775826cSJeremy Fitzhardinge { 35795d2ac4aSDaniel Kiper enum bp_state state = BP_DONE; 3581775826cSJeremy Fitzhardinge long credit; 3591775826cSJeremy Fitzhardinge 3601775826cSJeremy Fitzhardinge mutex_lock(&balloon_mutex); 3611775826cSJeremy Fitzhardinge 3621775826cSJeremy Fitzhardinge do { 3631775826cSJeremy Fitzhardinge credit = current_target() - balloon_stats.current_pages; 36495d2ac4aSDaniel Kiper 3651775826cSJeremy Fitzhardinge if (credit > 0) 36695d2ac4aSDaniel Kiper state = increase_reservation(credit); 36795d2ac4aSDaniel Kiper 3681775826cSJeremy Fitzhardinge if (credit < 0) 36995d2ac4aSDaniel Kiper state = decrease_reservation(-credit); 37095d2ac4aSDaniel Kiper 37195d2ac4aSDaniel Kiper state = update_schedule(state); 3721775826cSJeremy Fitzhardinge 3731775826cSJeremy Fitzhardinge #ifndef CONFIG_PREEMPT 3741775826cSJeremy Fitzhardinge if (need_resched()) 3751775826cSJeremy Fitzhardinge schedule(); 3761775826cSJeremy Fitzhardinge #endif 37795d2ac4aSDaniel Kiper } while (credit && state == BP_DONE); 3781775826cSJeremy Fitzhardinge 3791775826cSJeremy Fitzhardinge /* Schedule more work if there is some still to be done. */ 38095d2ac4aSDaniel Kiper if (state == BP_EAGAIN) 38195d2ac4aSDaniel Kiper schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ); 3821775826cSJeremy Fitzhardinge 3831775826cSJeremy Fitzhardinge mutex_unlock(&balloon_mutex); 3841775826cSJeremy Fitzhardinge } 3851775826cSJeremy Fitzhardinge 3861775826cSJeremy Fitzhardinge /* Resets the Xen limit, sets new target, and kicks off processing. */ 387955d6f17SAdrian Bunk static void balloon_set_new_target(unsigned long target) 3881775826cSJeremy Fitzhardinge { 3891775826cSJeremy Fitzhardinge /* No need for lock. Not read-modify-write updates. */ 3901775826cSJeremy Fitzhardinge balloon_stats.target_pages = target; 39195170b2eSDaniel Kiper schedule_delayed_work(&balloon_worker, 0); 3921775826cSJeremy Fitzhardinge } 3931775826cSJeremy Fitzhardinge 3941775826cSJeremy Fitzhardinge static struct xenbus_watch target_watch = 3951775826cSJeremy Fitzhardinge { 3961775826cSJeremy Fitzhardinge .node = "memory/target" 3971775826cSJeremy Fitzhardinge }; 3981775826cSJeremy Fitzhardinge 3991775826cSJeremy Fitzhardinge /* React to a change in the target key */ 4001775826cSJeremy Fitzhardinge static void watch_target(struct xenbus_watch *watch, 4011775826cSJeremy Fitzhardinge const char **vec, unsigned int len) 4021775826cSJeremy Fitzhardinge { 4031775826cSJeremy Fitzhardinge unsigned long long new_target; 4041775826cSJeremy Fitzhardinge int err; 4051775826cSJeremy Fitzhardinge 4061775826cSJeremy Fitzhardinge err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target); 4071775826cSJeremy Fitzhardinge if (err != 1) { 4081775826cSJeremy Fitzhardinge /* This is ok (for domain0 at least) - so just return */ 4091775826cSJeremy Fitzhardinge return; 4101775826cSJeremy Fitzhardinge } 4111775826cSJeremy Fitzhardinge 4121775826cSJeremy Fitzhardinge /* The given memory/target value is in KiB, so it needs converting to 4131775826cSJeremy Fitzhardinge * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. 4141775826cSJeremy Fitzhardinge */ 4151775826cSJeremy Fitzhardinge balloon_set_new_target(new_target >> (PAGE_SHIFT - 10)); 4161775826cSJeremy Fitzhardinge } 4171775826cSJeremy Fitzhardinge 4181775826cSJeremy Fitzhardinge static int balloon_init_watcher(struct notifier_block *notifier, 4191775826cSJeremy Fitzhardinge unsigned long event, 4201775826cSJeremy Fitzhardinge void *data) 4211775826cSJeremy Fitzhardinge { 4221775826cSJeremy Fitzhardinge int err; 4231775826cSJeremy Fitzhardinge 4241775826cSJeremy Fitzhardinge err = register_xenbus_watch(&target_watch); 4251775826cSJeremy Fitzhardinge if (err) 4261775826cSJeremy Fitzhardinge printk(KERN_ERR "Failed to set balloon watcher\n"); 4271775826cSJeremy Fitzhardinge 4281775826cSJeremy Fitzhardinge return NOTIFY_DONE; 4291775826cSJeremy Fitzhardinge } 4301775826cSJeremy Fitzhardinge 4311775826cSJeremy Fitzhardinge static struct notifier_block xenstore_notifier; 4321775826cSJeremy Fitzhardinge 4331775826cSJeremy Fitzhardinge static int __init balloon_init(void) 4341775826cSJeremy Fitzhardinge { 43566946f67SJeremy Fitzhardinge unsigned long pfn, extra_pfn_end; 4361775826cSJeremy Fitzhardinge struct page *page; 4371775826cSJeremy Fitzhardinge 4386e833587SJeremy Fitzhardinge if (!xen_pv_domain()) 4391775826cSJeremy Fitzhardinge return -ENODEV; 4401775826cSJeremy Fitzhardinge 4411775826cSJeremy Fitzhardinge pr_info("xen_balloon: Initialising balloon driver.\n"); 4421775826cSJeremy Fitzhardinge 4431775826cSJeremy Fitzhardinge balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn); 4441775826cSJeremy Fitzhardinge balloon_stats.target_pages = balloon_stats.current_pages; 4451775826cSJeremy Fitzhardinge balloon_stats.balloon_low = 0; 4461775826cSJeremy Fitzhardinge balloon_stats.balloon_high = 0; 4471775826cSJeremy Fitzhardinge 44895d2ac4aSDaniel Kiper balloon_stats.schedule_delay = 1; 44995d2ac4aSDaniel Kiper balloon_stats.max_schedule_delay = 32; 45095d2ac4aSDaniel Kiper balloon_stats.retry_count = 1; 45140095de1SKonrad Rzeszutek Wilk balloon_stats.max_retry_count = RETRY_UNLIMITED; 45295d2ac4aSDaniel Kiper 4531775826cSJeremy Fitzhardinge register_balloon(&balloon_sysdev); 4541775826cSJeremy Fitzhardinge 4552a4c92faSJeremy Fitzhardinge /* 4562a4c92faSJeremy Fitzhardinge * Initialise the balloon with excess memory space. We need 4572a4c92faSJeremy Fitzhardinge * to make sure we don't add memory which doesn't exist or 4582a4c92faSJeremy Fitzhardinge * logically exist. The E820 map can be trimmed to be smaller 4592a4c92faSJeremy Fitzhardinge * than the amount of physical memory due to the mem= command 4602a4c92faSJeremy Fitzhardinge * line parameter. And if this is a 32-bit non-HIGHMEM kernel 4612a4c92faSJeremy Fitzhardinge * on a system with memory which requires highmem to access, 4622a4c92faSJeremy Fitzhardinge * don't try to use it. 4632a4c92faSJeremy Fitzhardinge */ 4642a4c92faSJeremy Fitzhardinge extra_pfn_end = min(min(max_pfn, e820_end_of_ram_pfn()), 46566946f67SJeremy Fitzhardinge (unsigned long)PFN_DOWN(xen_extra_mem_start + xen_extra_mem_size)); 4669be4d457SJeremy Fitzhardinge for (pfn = PFN_UP(xen_extra_mem_start); 46766946f67SJeremy Fitzhardinge pfn < extra_pfn_end; 4689be4d457SJeremy Fitzhardinge pfn++) { 4691775826cSJeremy Fitzhardinge page = pfn_to_page(pfn); 4709be4d457SJeremy Fitzhardinge /* totalram_pages doesn't include the boot-time 4719be4d457SJeremy Fitzhardinge balloon extension, so don't subtract from it. */ 4729be4d457SJeremy Fitzhardinge __balloon_append(page); 4731775826cSJeremy Fitzhardinge } 4741775826cSJeremy Fitzhardinge 4751775826cSJeremy Fitzhardinge target_watch.callback = watch_target; 4761775826cSJeremy Fitzhardinge xenstore_notifier.notifier_call = balloon_init_watcher; 4771775826cSJeremy Fitzhardinge 4781775826cSJeremy Fitzhardinge register_xenstore_notifier(&xenstore_notifier); 4791775826cSJeremy Fitzhardinge 4801775826cSJeremy Fitzhardinge return 0; 4811775826cSJeremy Fitzhardinge } 4821775826cSJeremy Fitzhardinge 4831775826cSJeremy Fitzhardinge subsys_initcall(balloon_init); 4841775826cSJeremy Fitzhardinge 4851775826cSJeremy Fitzhardinge static void balloon_exit(void) 4861775826cSJeremy Fitzhardinge { 4871775826cSJeremy Fitzhardinge /* XXX - release balloon here */ 4881775826cSJeremy Fitzhardinge return; 4891775826cSJeremy Fitzhardinge } 4901775826cSJeremy Fitzhardinge 4911775826cSJeremy Fitzhardinge module_exit(balloon_exit); 4921775826cSJeremy Fitzhardinge 4931775826cSJeremy Fitzhardinge #define BALLOON_SHOW(name, format, args...) \ 4941775826cSJeremy Fitzhardinge static ssize_t show_##name(struct sys_device *dev, \ 495167e6cf6SJeremy Fitzhardinge struct sysdev_attribute *attr, \ 4961775826cSJeremy Fitzhardinge char *buf) \ 4971775826cSJeremy Fitzhardinge { \ 4981775826cSJeremy Fitzhardinge return sprintf(buf, format, ##args); \ 4991775826cSJeremy Fitzhardinge } \ 5001775826cSJeremy Fitzhardinge static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL) 5011775826cSJeremy Fitzhardinge 5021775826cSJeremy Fitzhardinge BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); 5031775826cSJeremy Fitzhardinge BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); 5041775826cSJeremy Fitzhardinge BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); 5051775826cSJeremy Fitzhardinge 50695d2ac4aSDaniel Kiper static SYSDEV_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay); 50795d2ac4aSDaniel Kiper static SYSDEV_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay); 50895d2ac4aSDaniel Kiper static SYSDEV_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count); 50995d2ac4aSDaniel Kiper static SYSDEV_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count); 51095d2ac4aSDaniel Kiper 511167e6cf6SJeremy Fitzhardinge static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr, 512167e6cf6SJeremy Fitzhardinge char *buf) 5131775826cSJeremy Fitzhardinge { 5141775826cSJeremy Fitzhardinge return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages)); 5151775826cSJeremy Fitzhardinge } 5161775826cSJeremy Fitzhardinge 5171775826cSJeremy Fitzhardinge static ssize_t store_target_kb(struct sys_device *dev, 5184a0b2b4dSAndi Kleen struct sysdev_attribute *attr, 5191775826cSJeremy Fitzhardinge const char *buf, 5201775826cSJeremy Fitzhardinge size_t count) 5211775826cSJeremy Fitzhardinge { 522167e6cf6SJeremy Fitzhardinge char *endchar; 5231775826cSJeremy Fitzhardinge unsigned long long target_bytes; 5241775826cSJeremy Fitzhardinge 5251775826cSJeremy Fitzhardinge if (!capable(CAP_SYS_ADMIN)) 5261775826cSJeremy Fitzhardinge return -EPERM; 5271775826cSJeremy Fitzhardinge 528618b2c8dSJeremy Fitzhardinge target_bytes = simple_strtoull(buf, &endchar, 0) * 1024; 5291775826cSJeremy Fitzhardinge 5301775826cSJeremy Fitzhardinge balloon_set_new_target(target_bytes >> PAGE_SHIFT); 5311775826cSJeremy Fitzhardinge 5321775826cSJeremy Fitzhardinge return count; 5331775826cSJeremy Fitzhardinge } 5341775826cSJeremy Fitzhardinge 5351775826cSJeremy Fitzhardinge static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR, 5361775826cSJeremy Fitzhardinge show_target_kb, store_target_kb); 5371775826cSJeremy Fitzhardinge 538618b2c8dSJeremy Fitzhardinge 539618b2c8dSJeremy Fitzhardinge static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr, 540618b2c8dSJeremy Fitzhardinge char *buf) 541618b2c8dSJeremy Fitzhardinge { 542618b2c8dSJeremy Fitzhardinge return sprintf(buf, "%llu\n", 5430692698cSJan Beulich (unsigned long long)balloon_stats.target_pages 5440692698cSJan Beulich << PAGE_SHIFT); 545618b2c8dSJeremy Fitzhardinge } 546618b2c8dSJeremy Fitzhardinge 547618b2c8dSJeremy Fitzhardinge static ssize_t store_target(struct sys_device *dev, 548618b2c8dSJeremy Fitzhardinge struct sysdev_attribute *attr, 549618b2c8dSJeremy Fitzhardinge const char *buf, 550618b2c8dSJeremy Fitzhardinge size_t count) 551618b2c8dSJeremy Fitzhardinge { 552618b2c8dSJeremy Fitzhardinge char *endchar; 553618b2c8dSJeremy Fitzhardinge unsigned long long target_bytes; 554618b2c8dSJeremy Fitzhardinge 555618b2c8dSJeremy Fitzhardinge if (!capable(CAP_SYS_ADMIN)) 556618b2c8dSJeremy Fitzhardinge return -EPERM; 557618b2c8dSJeremy Fitzhardinge 558618b2c8dSJeremy Fitzhardinge target_bytes = memparse(buf, &endchar); 559618b2c8dSJeremy Fitzhardinge 560618b2c8dSJeremy Fitzhardinge balloon_set_new_target(target_bytes >> PAGE_SHIFT); 561618b2c8dSJeremy Fitzhardinge 562618b2c8dSJeremy Fitzhardinge return count; 563618b2c8dSJeremy Fitzhardinge } 564618b2c8dSJeremy Fitzhardinge 565618b2c8dSJeremy Fitzhardinge static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR, 566618b2c8dSJeremy Fitzhardinge show_target, store_target); 567618b2c8dSJeremy Fitzhardinge 568618b2c8dSJeremy Fitzhardinge 5691775826cSJeremy Fitzhardinge static struct sysdev_attribute *balloon_attrs[] = { 5701775826cSJeremy Fitzhardinge &attr_target_kb, 571618b2c8dSJeremy Fitzhardinge &attr_target, 57295d2ac4aSDaniel Kiper &attr_schedule_delay.attr, 57395d2ac4aSDaniel Kiper &attr_max_schedule_delay.attr, 57495d2ac4aSDaniel Kiper &attr_retry_count.attr, 57595d2ac4aSDaniel Kiper &attr_max_retry_count.attr 5761775826cSJeremy Fitzhardinge }; 5771775826cSJeremy Fitzhardinge 5781775826cSJeremy Fitzhardinge static struct attribute *balloon_info_attrs[] = { 5791775826cSJeremy Fitzhardinge &attr_current_kb.attr, 5801775826cSJeremy Fitzhardinge &attr_low_kb.attr, 5811775826cSJeremy Fitzhardinge &attr_high_kb.attr, 5821775826cSJeremy Fitzhardinge NULL 5831775826cSJeremy Fitzhardinge }; 5841775826cSJeremy Fitzhardinge 5851775826cSJeremy Fitzhardinge static struct attribute_group balloon_info_group = { 5861775826cSJeremy Fitzhardinge .name = "info", 5871775826cSJeremy Fitzhardinge .attrs = balloon_info_attrs, 5881775826cSJeremy Fitzhardinge }; 5891775826cSJeremy Fitzhardinge 5901775826cSJeremy Fitzhardinge static struct sysdev_class balloon_sysdev_class = { 5911775826cSJeremy Fitzhardinge .name = BALLOON_CLASS_NAME, 5921775826cSJeremy Fitzhardinge }; 5931775826cSJeremy Fitzhardinge 5941775826cSJeremy Fitzhardinge static int register_balloon(struct sys_device *sysdev) 5951775826cSJeremy Fitzhardinge { 5961775826cSJeremy Fitzhardinge int i, error; 5971775826cSJeremy Fitzhardinge 5981775826cSJeremy Fitzhardinge error = sysdev_class_register(&balloon_sysdev_class); 5991775826cSJeremy Fitzhardinge if (error) 6001775826cSJeremy Fitzhardinge return error; 6011775826cSJeremy Fitzhardinge 6021775826cSJeremy Fitzhardinge sysdev->id = 0; 6031775826cSJeremy Fitzhardinge sysdev->cls = &balloon_sysdev_class; 6041775826cSJeremy Fitzhardinge 6051775826cSJeremy Fitzhardinge error = sysdev_register(sysdev); 6061775826cSJeremy Fitzhardinge if (error) { 6071775826cSJeremy Fitzhardinge sysdev_class_unregister(&balloon_sysdev_class); 6081775826cSJeremy Fitzhardinge return error; 6091775826cSJeremy Fitzhardinge } 6101775826cSJeremy Fitzhardinge 6111775826cSJeremy Fitzhardinge for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) { 6121775826cSJeremy Fitzhardinge error = sysdev_create_file(sysdev, balloon_attrs[i]); 6131775826cSJeremy Fitzhardinge if (error) 6141775826cSJeremy Fitzhardinge goto fail; 6151775826cSJeremy Fitzhardinge } 6161775826cSJeremy Fitzhardinge 6171775826cSJeremy Fitzhardinge error = sysfs_create_group(&sysdev->kobj, &balloon_info_group); 6181775826cSJeremy Fitzhardinge if (error) 6191775826cSJeremy Fitzhardinge goto fail; 6201775826cSJeremy Fitzhardinge 6211775826cSJeremy Fitzhardinge return 0; 6221775826cSJeremy Fitzhardinge 6231775826cSJeremy Fitzhardinge fail: 6241775826cSJeremy Fitzhardinge while (--i >= 0) 6251775826cSJeremy Fitzhardinge sysdev_remove_file(sysdev, balloon_attrs[i]); 6261775826cSJeremy Fitzhardinge sysdev_unregister(sysdev); 6271775826cSJeremy Fitzhardinge sysdev_class_unregister(&balloon_sysdev_class); 6281775826cSJeremy Fitzhardinge return error; 6291775826cSJeremy Fitzhardinge } 6301775826cSJeremy Fitzhardinge 6311775826cSJeremy Fitzhardinge MODULE_LICENSE("GPL"); 632