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> 461775826cSJeremy Fitzhardinge 471775826cSJeremy Fitzhardinge #include <asm/page.h> 481775826cSJeremy Fitzhardinge #include <asm/pgalloc.h> 491775826cSJeremy Fitzhardinge #include <asm/pgtable.h> 501775826cSJeremy Fitzhardinge #include <asm/uaccess.h> 511775826cSJeremy Fitzhardinge #include <asm/tlb.h> 521775826cSJeremy Fitzhardinge 53ecbf29cdSJeremy Fitzhardinge #include <asm/xen/hypervisor.h> 54ecbf29cdSJeremy Fitzhardinge #include <asm/xen/hypercall.h> 55ecbf29cdSJeremy Fitzhardinge #include <xen/interface/xen.h> 561775826cSJeremy Fitzhardinge #include <xen/interface/memory.h> 571775826cSJeremy Fitzhardinge #include <xen/xenbus.h> 581775826cSJeremy Fitzhardinge #include <xen/features.h> 591775826cSJeremy Fitzhardinge #include <xen/page.h> 601775826cSJeremy Fitzhardinge 611775826cSJeremy Fitzhardinge #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) 621775826cSJeremy Fitzhardinge 63167e6cf6SJeremy Fitzhardinge #define BALLOON_CLASS_NAME "xen_memory" 641775826cSJeremy Fitzhardinge 651775826cSJeremy Fitzhardinge struct balloon_stats { 661775826cSJeremy Fitzhardinge /* We aim for 'current allocation' == 'target allocation'. */ 671775826cSJeremy Fitzhardinge unsigned long current_pages; 681775826cSJeremy Fitzhardinge unsigned long target_pages; 691775826cSJeremy Fitzhardinge /* We may hit the hard limit in Xen. If we do then we remember it. */ 701775826cSJeremy Fitzhardinge unsigned long hard_limit; 711775826cSJeremy Fitzhardinge /* 721775826cSJeremy Fitzhardinge * Drivers may alter the memory reservation independently, but they 731775826cSJeremy Fitzhardinge * must inform the balloon driver so we avoid hitting the hard limit. 741775826cSJeremy Fitzhardinge */ 751775826cSJeremy Fitzhardinge unsigned long driver_pages; 761775826cSJeremy Fitzhardinge /* Number of pages in high- and low-memory balloons. */ 771775826cSJeremy Fitzhardinge unsigned long balloon_low; 781775826cSJeremy Fitzhardinge unsigned long balloon_high; 791775826cSJeremy Fitzhardinge }; 801775826cSJeremy Fitzhardinge 811775826cSJeremy Fitzhardinge static DEFINE_MUTEX(balloon_mutex); 821775826cSJeremy Fitzhardinge 831775826cSJeremy Fitzhardinge static struct sys_device balloon_sysdev; 841775826cSJeremy Fitzhardinge 851775826cSJeremy Fitzhardinge static int register_balloon(struct sys_device *sysdev); 861775826cSJeremy Fitzhardinge 871775826cSJeremy Fitzhardinge /* 881775826cSJeremy Fitzhardinge * Protects atomic reservation decrease/increase against concurrent increases. 891775826cSJeremy Fitzhardinge * Also protects non-atomic updates of current_pages and driver_pages, and 901775826cSJeremy Fitzhardinge * balloon lists. 911775826cSJeremy Fitzhardinge */ 921775826cSJeremy Fitzhardinge static DEFINE_SPINLOCK(balloon_lock); 931775826cSJeremy Fitzhardinge 941775826cSJeremy Fitzhardinge static struct balloon_stats balloon_stats; 951775826cSJeremy Fitzhardinge 961775826cSJeremy Fitzhardinge /* We increase/decrease in batches which fit in a page */ 971775826cSJeremy Fitzhardinge static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)]; 981775826cSJeremy Fitzhardinge 991775826cSJeremy Fitzhardinge /* VM /proc information for memory */ 1001775826cSJeremy Fitzhardinge extern unsigned long totalram_pages; 1011775826cSJeremy Fitzhardinge 1021775826cSJeremy Fitzhardinge #ifdef CONFIG_HIGHMEM 1031775826cSJeremy Fitzhardinge extern unsigned long totalhigh_pages; 1041775826cSJeremy Fitzhardinge #define inc_totalhigh_pages() (totalhigh_pages++) 1051775826cSJeremy Fitzhardinge #define dec_totalhigh_pages() (totalhigh_pages--) 1061775826cSJeremy Fitzhardinge #else 1071775826cSJeremy Fitzhardinge #define inc_totalhigh_pages() do {} while(0) 1081775826cSJeremy Fitzhardinge #define dec_totalhigh_pages() do {} while(0) 1091775826cSJeremy Fitzhardinge #endif 1101775826cSJeremy Fitzhardinge 1111775826cSJeremy Fitzhardinge /* List of ballooned pages, threaded through the mem_map array. */ 1121775826cSJeremy Fitzhardinge static LIST_HEAD(ballooned_pages); 1131775826cSJeremy Fitzhardinge 1141775826cSJeremy Fitzhardinge /* Main work function, always executed in process context. */ 1151775826cSJeremy Fitzhardinge static void balloon_process(struct work_struct *work); 1161775826cSJeremy Fitzhardinge static DECLARE_WORK(balloon_worker, balloon_process); 1171775826cSJeremy Fitzhardinge static struct timer_list balloon_timer; 1181775826cSJeremy Fitzhardinge 1191775826cSJeremy Fitzhardinge /* When ballooning out (allocating memory to return to Xen) we don't really 1201775826cSJeremy Fitzhardinge want the kernel to try too hard since that can trigger the oom killer. */ 1211775826cSJeremy Fitzhardinge #define GFP_BALLOON \ 1221775826cSJeremy Fitzhardinge (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) 1231775826cSJeremy Fitzhardinge 1241775826cSJeremy Fitzhardinge static void scrub_page(struct page *page) 1251775826cSJeremy Fitzhardinge { 1261775826cSJeremy Fitzhardinge #ifdef CONFIG_XEN_SCRUB_PAGES 12726a3e991SJeremy Fitzhardinge clear_highpage(page); 1281775826cSJeremy Fitzhardinge #endif 1291775826cSJeremy Fitzhardinge } 1301775826cSJeremy Fitzhardinge 1311775826cSJeremy Fitzhardinge /* balloon_append: add the given page to the balloon. */ 1321775826cSJeremy Fitzhardinge static void balloon_append(struct page *page) 1331775826cSJeremy Fitzhardinge { 1341775826cSJeremy Fitzhardinge /* Lowmem is re-populated first, so highmem pages go at list tail. */ 1351775826cSJeremy Fitzhardinge if (PageHighMem(page)) { 1361775826cSJeremy Fitzhardinge list_add_tail(&page->lru, &ballooned_pages); 1371775826cSJeremy Fitzhardinge balloon_stats.balloon_high++; 1381775826cSJeremy Fitzhardinge dec_totalhigh_pages(); 1391775826cSJeremy Fitzhardinge } else { 1401775826cSJeremy Fitzhardinge list_add(&page->lru, &ballooned_pages); 1411775826cSJeremy Fitzhardinge balloon_stats.balloon_low++; 1421775826cSJeremy Fitzhardinge } 1431775826cSJeremy Fitzhardinge } 1441775826cSJeremy Fitzhardinge 1451775826cSJeremy Fitzhardinge /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ 1461775826cSJeremy Fitzhardinge static struct page *balloon_retrieve(void) 1471775826cSJeremy Fitzhardinge { 1481775826cSJeremy Fitzhardinge struct page *page; 1491775826cSJeremy Fitzhardinge 1501775826cSJeremy Fitzhardinge if (list_empty(&ballooned_pages)) 1511775826cSJeremy Fitzhardinge return NULL; 1521775826cSJeremy Fitzhardinge 1531775826cSJeremy Fitzhardinge page = list_entry(ballooned_pages.next, struct page, lru); 1541775826cSJeremy Fitzhardinge list_del(&page->lru); 1551775826cSJeremy Fitzhardinge 1561775826cSJeremy Fitzhardinge if (PageHighMem(page)) { 1571775826cSJeremy Fitzhardinge balloon_stats.balloon_high--; 1581775826cSJeremy Fitzhardinge inc_totalhigh_pages(); 1591775826cSJeremy Fitzhardinge } 1601775826cSJeremy Fitzhardinge else 1611775826cSJeremy Fitzhardinge balloon_stats.balloon_low--; 1621775826cSJeremy Fitzhardinge 1631775826cSJeremy Fitzhardinge return page; 1641775826cSJeremy Fitzhardinge } 1651775826cSJeremy Fitzhardinge 1661775826cSJeremy Fitzhardinge static struct page *balloon_first_page(void) 1671775826cSJeremy Fitzhardinge { 1681775826cSJeremy Fitzhardinge if (list_empty(&ballooned_pages)) 1691775826cSJeremy Fitzhardinge return NULL; 1701775826cSJeremy Fitzhardinge return list_entry(ballooned_pages.next, struct page, lru); 1711775826cSJeremy Fitzhardinge } 1721775826cSJeremy Fitzhardinge 1731775826cSJeremy Fitzhardinge static struct page *balloon_next_page(struct page *page) 1741775826cSJeremy Fitzhardinge { 1751775826cSJeremy Fitzhardinge struct list_head *next = page->lru.next; 1761775826cSJeremy Fitzhardinge if (next == &ballooned_pages) 1771775826cSJeremy Fitzhardinge return NULL; 1781775826cSJeremy Fitzhardinge return list_entry(next, struct page, lru); 1791775826cSJeremy Fitzhardinge } 1801775826cSJeremy Fitzhardinge 1811775826cSJeremy Fitzhardinge static void balloon_alarm(unsigned long unused) 1821775826cSJeremy Fitzhardinge { 1831775826cSJeremy Fitzhardinge schedule_work(&balloon_worker); 1841775826cSJeremy Fitzhardinge } 1851775826cSJeremy Fitzhardinge 1861775826cSJeremy Fitzhardinge static unsigned long current_target(void) 1871775826cSJeremy Fitzhardinge { 1881775826cSJeremy Fitzhardinge unsigned long target = min(balloon_stats.target_pages, balloon_stats.hard_limit); 1891775826cSJeremy Fitzhardinge 1901775826cSJeremy Fitzhardinge target = min(target, 1911775826cSJeremy Fitzhardinge balloon_stats.current_pages + 1921775826cSJeremy Fitzhardinge balloon_stats.balloon_low + 1931775826cSJeremy Fitzhardinge balloon_stats.balloon_high); 1941775826cSJeremy Fitzhardinge 1951775826cSJeremy Fitzhardinge return target; 1961775826cSJeremy Fitzhardinge } 1971775826cSJeremy Fitzhardinge 1981775826cSJeremy Fitzhardinge static int increase_reservation(unsigned long nr_pages) 1991775826cSJeremy Fitzhardinge { 2001775826cSJeremy Fitzhardinge unsigned long pfn, i, flags; 2011775826cSJeremy Fitzhardinge struct page *page; 2021775826cSJeremy Fitzhardinge long rc; 2031775826cSJeremy Fitzhardinge struct xen_memory_reservation reservation = { 2041775826cSJeremy Fitzhardinge .address_bits = 0, 2051775826cSJeremy Fitzhardinge .extent_order = 0, 2061775826cSJeremy Fitzhardinge .domid = DOMID_SELF 2071775826cSJeremy Fitzhardinge }; 2081775826cSJeremy Fitzhardinge 2091775826cSJeremy Fitzhardinge if (nr_pages > ARRAY_SIZE(frame_list)) 2101775826cSJeremy Fitzhardinge nr_pages = ARRAY_SIZE(frame_list); 2111775826cSJeremy Fitzhardinge 2121775826cSJeremy Fitzhardinge spin_lock_irqsave(&balloon_lock, flags); 2131775826cSJeremy Fitzhardinge 2141775826cSJeremy Fitzhardinge page = balloon_first_page(); 2151775826cSJeremy Fitzhardinge for (i = 0; i < nr_pages; i++) { 2161775826cSJeremy Fitzhardinge BUG_ON(page == NULL); 217a419aef8SJoe Perches frame_list[i] = page_to_pfn(page); 2181775826cSJeremy Fitzhardinge page = balloon_next_page(page); 2191775826cSJeremy Fitzhardinge } 2201775826cSJeremy Fitzhardinge 221a90971ebSIsaku Yamahata set_xen_guest_handle(reservation.extent_start, frame_list); 2221775826cSJeremy Fitzhardinge reservation.nr_extents = nr_pages; 223fde28e8fSJeremy Fitzhardinge rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); 2241775826cSJeremy Fitzhardinge if (rc < nr_pages) { 2251775826cSJeremy Fitzhardinge if (rc > 0) { 2261775826cSJeremy Fitzhardinge int ret; 2271775826cSJeremy Fitzhardinge 2281775826cSJeremy Fitzhardinge /* We hit the Xen hard limit: reprobe. */ 2291775826cSJeremy Fitzhardinge reservation.nr_extents = rc; 2301775826cSJeremy Fitzhardinge ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, 2311775826cSJeremy Fitzhardinge &reservation); 2321775826cSJeremy Fitzhardinge BUG_ON(ret != rc); 2331775826cSJeremy Fitzhardinge } 2341775826cSJeremy Fitzhardinge if (rc >= 0) 2351775826cSJeremy Fitzhardinge balloon_stats.hard_limit = (balloon_stats.current_pages + rc - 2361775826cSJeremy Fitzhardinge balloon_stats.driver_pages); 2371775826cSJeremy Fitzhardinge goto out; 2381775826cSJeremy Fitzhardinge } 2391775826cSJeremy Fitzhardinge 2401775826cSJeremy Fitzhardinge for (i = 0; i < nr_pages; i++) { 2411775826cSJeremy Fitzhardinge page = balloon_retrieve(); 2421775826cSJeremy Fitzhardinge BUG_ON(page == NULL); 2431775826cSJeremy Fitzhardinge 2441775826cSJeremy Fitzhardinge pfn = page_to_pfn(page); 2451775826cSJeremy Fitzhardinge BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) && 2461775826cSJeremy Fitzhardinge phys_to_machine_mapping_valid(pfn)); 2471775826cSJeremy Fitzhardinge 2481775826cSJeremy Fitzhardinge set_phys_to_machine(pfn, frame_list[i]); 2491775826cSJeremy Fitzhardinge 2501775826cSJeremy Fitzhardinge /* Link back into the page tables if not highmem. */ 2511775826cSJeremy Fitzhardinge if (pfn < max_low_pfn) { 2521775826cSJeremy Fitzhardinge int ret; 2531775826cSJeremy Fitzhardinge ret = HYPERVISOR_update_va_mapping( 2541775826cSJeremy Fitzhardinge (unsigned long)__va(pfn << PAGE_SHIFT), 2551775826cSJeremy Fitzhardinge mfn_pte(frame_list[i], PAGE_KERNEL), 2561775826cSJeremy Fitzhardinge 0); 2571775826cSJeremy Fitzhardinge BUG_ON(ret); 2581775826cSJeremy Fitzhardinge } 2591775826cSJeremy Fitzhardinge 2601775826cSJeremy Fitzhardinge /* Relinquish the page back to the allocator. */ 2611775826cSJeremy Fitzhardinge ClearPageReserved(page); 2621775826cSJeremy Fitzhardinge init_page_count(page); 2631775826cSJeremy Fitzhardinge __free_page(page); 2641775826cSJeremy Fitzhardinge } 2651775826cSJeremy Fitzhardinge 2661775826cSJeremy Fitzhardinge balloon_stats.current_pages += nr_pages; 2671775826cSJeremy Fitzhardinge totalram_pages = balloon_stats.current_pages; 2681775826cSJeremy Fitzhardinge 2691775826cSJeremy Fitzhardinge out: 2701775826cSJeremy Fitzhardinge spin_unlock_irqrestore(&balloon_lock, flags); 2711775826cSJeremy Fitzhardinge 2721775826cSJeremy Fitzhardinge return 0; 2731775826cSJeremy Fitzhardinge } 2741775826cSJeremy Fitzhardinge 2751775826cSJeremy Fitzhardinge static int decrease_reservation(unsigned long nr_pages) 2761775826cSJeremy Fitzhardinge { 2771775826cSJeremy Fitzhardinge unsigned long pfn, i, flags; 2781775826cSJeremy Fitzhardinge struct page *page; 2791775826cSJeremy Fitzhardinge int need_sleep = 0; 2801775826cSJeremy Fitzhardinge int ret; 2811775826cSJeremy Fitzhardinge struct xen_memory_reservation reservation = { 2821775826cSJeremy Fitzhardinge .address_bits = 0, 2831775826cSJeremy Fitzhardinge .extent_order = 0, 2841775826cSJeremy Fitzhardinge .domid = DOMID_SELF 2851775826cSJeremy Fitzhardinge }; 2861775826cSJeremy Fitzhardinge 2871775826cSJeremy Fitzhardinge if (nr_pages > ARRAY_SIZE(frame_list)) 2881775826cSJeremy Fitzhardinge nr_pages = ARRAY_SIZE(frame_list); 2891775826cSJeremy Fitzhardinge 2901775826cSJeremy Fitzhardinge for (i = 0; i < nr_pages; i++) { 2911775826cSJeremy Fitzhardinge if ((page = alloc_page(GFP_BALLOON)) == NULL) { 2921775826cSJeremy Fitzhardinge nr_pages = i; 2931775826cSJeremy Fitzhardinge need_sleep = 1; 2941775826cSJeremy Fitzhardinge break; 2951775826cSJeremy Fitzhardinge } 2961775826cSJeremy Fitzhardinge 2971775826cSJeremy Fitzhardinge pfn = page_to_pfn(page); 2981775826cSJeremy Fitzhardinge frame_list[i] = pfn_to_mfn(pfn); 2991775826cSJeremy Fitzhardinge 3001775826cSJeremy Fitzhardinge scrub_page(page); 3011058a75fSDan Magenheimer 302ff4ce8c3SIan Campbell if (!PageHighMem(page)) { 3031058a75fSDan Magenheimer ret = HYPERVISOR_update_va_mapping( 3041058a75fSDan Magenheimer (unsigned long)__va(pfn << PAGE_SHIFT), 3051058a75fSDan Magenheimer __pte_ma(0), 0); 3061058a75fSDan Magenheimer BUG_ON(ret); 3071775826cSJeremy Fitzhardinge } 3081775826cSJeremy Fitzhardinge 309ff4ce8c3SIan Campbell } 310ff4ce8c3SIan Campbell 3111775826cSJeremy Fitzhardinge /* Ensure that ballooned highmem pages don't have kmaps. */ 3121775826cSJeremy Fitzhardinge kmap_flush_unused(); 3131775826cSJeremy Fitzhardinge flush_tlb_all(); 3141775826cSJeremy Fitzhardinge 3151775826cSJeremy Fitzhardinge spin_lock_irqsave(&balloon_lock, flags); 3161775826cSJeremy Fitzhardinge 3171775826cSJeremy Fitzhardinge /* No more mappings: invalidate P2M and add to balloon. */ 3181775826cSJeremy Fitzhardinge for (i = 0; i < nr_pages; i++) { 3191775826cSJeremy Fitzhardinge pfn = mfn_to_pfn(frame_list[i]); 3201775826cSJeremy Fitzhardinge set_phys_to_machine(pfn, INVALID_P2M_ENTRY); 3211775826cSJeremy Fitzhardinge balloon_append(pfn_to_page(pfn)); 3221775826cSJeremy Fitzhardinge } 3231775826cSJeremy Fitzhardinge 324a90971ebSIsaku Yamahata set_xen_guest_handle(reservation.extent_start, frame_list); 3251775826cSJeremy Fitzhardinge reservation.nr_extents = nr_pages; 3261775826cSJeremy Fitzhardinge ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); 3271775826cSJeremy Fitzhardinge BUG_ON(ret != nr_pages); 3281775826cSJeremy Fitzhardinge 3291775826cSJeremy Fitzhardinge balloon_stats.current_pages -= nr_pages; 3301775826cSJeremy Fitzhardinge totalram_pages = balloon_stats.current_pages; 3311775826cSJeremy Fitzhardinge 3321775826cSJeremy Fitzhardinge spin_unlock_irqrestore(&balloon_lock, flags); 3331775826cSJeremy Fitzhardinge 3341775826cSJeremy Fitzhardinge return need_sleep; 3351775826cSJeremy Fitzhardinge } 3361775826cSJeremy Fitzhardinge 3371775826cSJeremy Fitzhardinge /* 3381775826cSJeremy Fitzhardinge * We avoid multiple worker processes conflicting via the balloon mutex. 3391775826cSJeremy Fitzhardinge * We may of course race updates of the target counts (which are protected 3401775826cSJeremy Fitzhardinge * by the balloon lock), or with changes to the Xen hard limit, but we will 3411775826cSJeremy Fitzhardinge * recover from these in time. 3421775826cSJeremy Fitzhardinge */ 3431775826cSJeremy Fitzhardinge static void balloon_process(struct work_struct *work) 3441775826cSJeremy Fitzhardinge { 3451775826cSJeremy Fitzhardinge int need_sleep = 0; 3461775826cSJeremy Fitzhardinge long credit; 3471775826cSJeremy Fitzhardinge 3481775826cSJeremy Fitzhardinge mutex_lock(&balloon_mutex); 3491775826cSJeremy Fitzhardinge 3501775826cSJeremy Fitzhardinge do { 3511775826cSJeremy Fitzhardinge credit = current_target() - balloon_stats.current_pages; 3521775826cSJeremy Fitzhardinge if (credit > 0) 3531775826cSJeremy Fitzhardinge need_sleep = (increase_reservation(credit) != 0); 3541775826cSJeremy Fitzhardinge if (credit < 0) 3551775826cSJeremy Fitzhardinge need_sleep = (decrease_reservation(-credit) != 0); 3561775826cSJeremy Fitzhardinge 3571775826cSJeremy Fitzhardinge #ifndef CONFIG_PREEMPT 3581775826cSJeremy Fitzhardinge if (need_resched()) 3591775826cSJeremy Fitzhardinge schedule(); 3601775826cSJeremy Fitzhardinge #endif 3611775826cSJeremy Fitzhardinge } while ((credit != 0) && !need_sleep); 3621775826cSJeremy Fitzhardinge 3631775826cSJeremy Fitzhardinge /* Schedule more work if there is some still to be done. */ 3641775826cSJeremy Fitzhardinge if (current_target() != balloon_stats.current_pages) 3651775826cSJeremy Fitzhardinge mod_timer(&balloon_timer, jiffies + HZ); 3661775826cSJeremy Fitzhardinge 3671775826cSJeremy Fitzhardinge mutex_unlock(&balloon_mutex); 3681775826cSJeremy Fitzhardinge } 3691775826cSJeremy Fitzhardinge 3701775826cSJeremy Fitzhardinge /* Resets the Xen limit, sets new target, and kicks off processing. */ 371955d6f17SAdrian Bunk static void balloon_set_new_target(unsigned long target) 3721775826cSJeremy Fitzhardinge { 3731775826cSJeremy Fitzhardinge /* No need for lock. Not read-modify-write updates. */ 3741775826cSJeremy Fitzhardinge balloon_stats.hard_limit = ~0UL; 3751775826cSJeremy Fitzhardinge balloon_stats.target_pages = target; 3761775826cSJeremy Fitzhardinge schedule_work(&balloon_worker); 3771775826cSJeremy Fitzhardinge } 3781775826cSJeremy Fitzhardinge 3791775826cSJeremy Fitzhardinge static struct xenbus_watch target_watch = 3801775826cSJeremy Fitzhardinge { 3811775826cSJeremy Fitzhardinge .node = "memory/target" 3821775826cSJeremy Fitzhardinge }; 3831775826cSJeremy Fitzhardinge 3841775826cSJeremy Fitzhardinge /* React to a change in the target key */ 3851775826cSJeremy Fitzhardinge static void watch_target(struct xenbus_watch *watch, 3861775826cSJeremy Fitzhardinge const char **vec, unsigned int len) 3871775826cSJeremy Fitzhardinge { 3881775826cSJeremy Fitzhardinge unsigned long long new_target; 3891775826cSJeremy Fitzhardinge int err; 3901775826cSJeremy Fitzhardinge 3911775826cSJeremy Fitzhardinge err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target); 3921775826cSJeremy Fitzhardinge if (err != 1) { 3931775826cSJeremy Fitzhardinge /* This is ok (for domain0 at least) - so just return */ 3941775826cSJeremy Fitzhardinge return; 3951775826cSJeremy Fitzhardinge } 3961775826cSJeremy Fitzhardinge 3971775826cSJeremy Fitzhardinge /* The given memory/target value is in KiB, so it needs converting to 3981775826cSJeremy Fitzhardinge * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. 3991775826cSJeremy Fitzhardinge */ 4001775826cSJeremy Fitzhardinge balloon_set_new_target(new_target >> (PAGE_SHIFT - 10)); 4011775826cSJeremy Fitzhardinge } 4021775826cSJeremy Fitzhardinge 4031775826cSJeremy Fitzhardinge static int balloon_init_watcher(struct notifier_block *notifier, 4041775826cSJeremy Fitzhardinge unsigned long event, 4051775826cSJeremy Fitzhardinge void *data) 4061775826cSJeremy Fitzhardinge { 4071775826cSJeremy Fitzhardinge int err; 4081775826cSJeremy Fitzhardinge 4091775826cSJeremy Fitzhardinge err = register_xenbus_watch(&target_watch); 4101775826cSJeremy Fitzhardinge if (err) 4111775826cSJeremy Fitzhardinge printk(KERN_ERR "Failed to set balloon watcher\n"); 4121775826cSJeremy Fitzhardinge 4131775826cSJeremy Fitzhardinge return NOTIFY_DONE; 4141775826cSJeremy Fitzhardinge } 4151775826cSJeremy Fitzhardinge 4161775826cSJeremy Fitzhardinge static struct notifier_block xenstore_notifier; 4171775826cSJeremy Fitzhardinge 4181775826cSJeremy Fitzhardinge static int __init balloon_init(void) 4191775826cSJeremy Fitzhardinge { 4201775826cSJeremy Fitzhardinge unsigned long pfn; 4211775826cSJeremy Fitzhardinge struct page *page; 4221775826cSJeremy Fitzhardinge 4236e833587SJeremy Fitzhardinge if (!xen_pv_domain()) 4241775826cSJeremy Fitzhardinge return -ENODEV; 4251775826cSJeremy Fitzhardinge 4261775826cSJeremy Fitzhardinge pr_info("xen_balloon: Initialising balloon driver.\n"); 4271775826cSJeremy Fitzhardinge 4281775826cSJeremy Fitzhardinge balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn); 4291775826cSJeremy Fitzhardinge totalram_pages = balloon_stats.current_pages; 4301775826cSJeremy Fitzhardinge balloon_stats.target_pages = balloon_stats.current_pages; 4311775826cSJeremy Fitzhardinge balloon_stats.balloon_low = 0; 4321775826cSJeremy Fitzhardinge balloon_stats.balloon_high = 0; 4331775826cSJeremy Fitzhardinge balloon_stats.driver_pages = 0UL; 4341775826cSJeremy Fitzhardinge balloon_stats.hard_limit = ~0UL; 4351775826cSJeremy Fitzhardinge 4361775826cSJeremy Fitzhardinge init_timer(&balloon_timer); 4371775826cSJeremy Fitzhardinge balloon_timer.data = 0; 4381775826cSJeremy Fitzhardinge balloon_timer.function = balloon_alarm; 4391775826cSJeremy Fitzhardinge 4401775826cSJeremy Fitzhardinge register_balloon(&balloon_sysdev); 4411775826cSJeremy Fitzhardinge 4421775826cSJeremy Fitzhardinge /* Initialise the balloon with excess memory space. */ 4431775826cSJeremy Fitzhardinge for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) { 4441775826cSJeremy Fitzhardinge page = pfn_to_page(pfn); 4451775826cSJeremy Fitzhardinge if (!PageReserved(page)) 4461775826cSJeremy Fitzhardinge balloon_append(page); 4471775826cSJeremy Fitzhardinge } 4481775826cSJeremy Fitzhardinge 4491775826cSJeremy Fitzhardinge target_watch.callback = watch_target; 4501775826cSJeremy Fitzhardinge xenstore_notifier.notifier_call = balloon_init_watcher; 4511775826cSJeremy Fitzhardinge 4521775826cSJeremy Fitzhardinge register_xenstore_notifier(&xenstore_notifier); 4531775826cSJeremy Fitzhardinge 4541775826cSJeremy Fitzhardinge return 0; 4551775826cSJeremy Fitzhardinge } 4561775826cSJeremy Fitzhardinge 4571775826cSJeremy Fitzhardinge subsys_initcall(balloon_init); 4581775826cSJeremy Fitzhardinge 4591775826cSJeremy Fitzhardinge static void balloon_exit(void) 4601775826cSJeremy Fitzhardinge { 4611775826cSJeremy Fitzhardinge /* XXX - release balloon here */ 4621775826cSJeremy Fitzhardinge return; 4631775826cSJeremy Fitzhardinge } 4641775826cSJeremy Fitzhardinge 4651775826cSJeremy Fitzhardinge module_exit(balloon_exit); 4661775826cSJeremy Fitzhardinge 4671775826cSJeremy Fitzhardinge #define BALLOON_SHOW(name, format, args...) \ 4681775826cSJeremy Fitzhardinge static ssize_t show_##name(struct sys_device *dev, \ 469167e6cf6SJeremy Fitzhardinge struct sysdev_attribute *attr, \ 4701775826cSJeremy Fitzhardinge char *buf) \ 4711775826cSJeremy Fitzhardinge { \ 4721775826cSJeremy Fitzhardinge return sprintf(buf, format, ##args); \ 4731775826cSJeremy Fitzhardinge } \ 4741775826cSJeremy Fitzhardinge static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL) 4751775826cSJeremy Fitzhardinge 4761775826cSJeremy Fitzhardinge BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); 4771775826cSJeremy Fitzhardinge BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); 4781775826cSJeremy Fitzhardinge BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); 4791775826cSJeremy Fitzhardinge BALLOON_SHOW(hard_limit_kb, 4801775826cSJeremy Fitzhardinge (balloon_stats.hard_limit!=~0UL) ? "%lu\n" : "???\n", 4811775826cSJeremy Fitzhardinge (balloon_stats.hard_limit!=~0UL) ? PAGES2KB(balloon_stats.hard_limit) : 0); 4821775826cSJeremy Fitzhardinge BALLOON_SHOW(driver_kb, "%lu\n", PAGES2KB(balloon_stats.driver_pages)); 4831775826cSJeremy Fitzhardinge 484167e6cf6SJeremy Fitzhardinge static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr, 485167e6cf6SJeremy Fitzhardinge char *buf) 4861775826cSJeremy Fitzhardinge { 4871775826cSJeremy Fitzhardinge return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages)); 4881775826cSJeremy Fitzhardinge } 4891775826cSJeremy Fitzhardinge 4901775826cSJeremy Fitzhardinge static ssize_t store_target_kb(struct sys_device *dev, 4914a0b2b4dSAndi Kleen struct sysdev_attribute *attr, 4921775826cSJeremy Fitzhardinge const char *buf, 4931775826cSJeremy Fitzhardinge size_t count) 4941775826cSJeremy Fitzhardinge { 495167e6cf6SJeremy Fitzhardinge char *endchar; 4961775826cSJeremy Fitzhardinge unsigned long long target_bytes; 4971775826cSJeremy Fitzhardinge 4981775826cSJeremy Fitzhardinge if (!capable(CAP_SYS_ADMIN)) 4991775826cSJeremy Fitzhardinge return -EPERM; 5001775826cSJeremy Fitzhardinge 501618b2c8dSJeremy Fitzhardinge target_bytes = simple_strtoull(buf, &endchar, 0) * 1024; 5021775826cSJeremy Fitzhardinge 5031775826cSJeremy Fitzhardinge balloon_set_new_target(target_bytes >> PAGE_SHIFT); 5041775826cSJeremy Fitzhardinge 5051775826cSJeremy Fitzhardinge return count; 5061775826cSJeremy Fitzhardinge } 5071775826cSJeremy Fitzhardinge 5081775826cSJeremy Fitzhardinge static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR, 5091775826cSJeremy Fitzhardinge show_target_kb, store_target_kb); 5101775826cSJeremy Fitzhardinge 511618b2c8dSJeremy Fitzhardinge 512618b2c8dSJeremy Fitzhardinge static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr, 513618b2c8dSJeremy Fitzhardinge char *buf) 514618b2c8dSJeremy Fitzhardinge { 515618b2c8dSJeremy Fitzhardinge return sprintf(buf, "%llu\n", 5160692698cSJan Beulich (unsigned long long)balloon_stats.target_pages 5170692698cSJan Beulich << PAGE_SHIFT); 518618b2c8dSJeremy Fitzhardinge } 519618b2c8dSJeremy Fitzhardinge 520618b2c8dSJeremy Fitzhardinge static ssize_t store_target(struct sys_device *dev, 521618b2c8dSJeremy Fitzhardinge struct sysdev_attribute *attr, 522618b2c8dSJeremy Fitzhardinge const char *buf, 523618b2c8dSJeremy Fitzhardinge size_t count) 524618b2c8dSJeremy Fitzhardinge { 525618b2c8dSJeremy Fitzhardinge char *endchar; 526618b2c8dSJeremy Fitzhardinge unsigned long long target_bytes; 527618b2c8dSJeremy Fitzhardinge 528618b2c8dSJeremy Fitzhardinge if (!capable(CAP_SYS_ADMIN)) 529618b2c8dSJeremy Fitzhardinge return -EPERM; 530618b2c8dSJeremy Fitzhardinge 531618b2c8dSJeremy Fitzhardinge target_bytes = memparse(buf, &endchar); 532618b2c8dSJeremy Fitzhardinge 533618b2c8dSJeremy Fitzhardinge balloon_set_new_target(target_bytes >> PAGE_SHIFT); 534618b2c8dSJeremy Fitzhardinge 535618b2c8dSJeremy Fitzhardinge return count; 536618b2c8dSJeremy Fitzhardinge } 537618b2c8dSJeremy Fitzhardinge 538618b2c8dSJeremy Fitzhardinge static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR, 539618b2c8dSJeremy Fitzhardinge show_target, store_target); 540618b2c8dSJeremy Fitzhardinge 541618b2c8dSJeremy Fitzhardinge 5421775826cSJeremy Fitzhardinge static struct sysdev_attribute *balloon_attrs[] = { 5431775826cSJeremy Fitzhardinge &attr_target_kb, 544618b2c8dSJeremy Fitzhardinge &attr_target, 5451775826cSJeremy Fitzhardinge }; 5461775826cSJeremy Fitzhardinge 5471775826cSJeremy Fitzhardinge static struct attribute *balloon_info_attrs[] = { 5481775826cSJeremy Fitzhardinge &attr_current_kb.attr, 5491775826cSJeremy Fitzhardinge &attr_low_kb.attr, 5501775826cSJeremy Fitzhardinge &attr_high_kb.attr, 5511775826cSJeremy Fitzhardinge &attr_hard_limit_kb.attr, 5521775826cSJeremy Fitzhardinge &attr_driver_kb.attr, 5531775826cSJeremy Fitzhardinge NULL 5541775826cSJeremy Fitzhardinge }; 5551775826cSJeremy Fitzhardinge 5561775826cSJeremy Fitzhardinge static struct attribute_group balloon_info_group = { 5571775826cSJeremy Fitzhardinge .name = "info", 5581775826cSJeremy Fitzhardinge .attrs = balloon_info_attrs, 5591775826cSJeremy Fitzhardinge }; 5601775826cSJeremy Fitzhardinge 5611775826cSJeremy Fitzhardinge static struct sysdev_class balloon_sysdev_class = { 5621775826cSJeremy Fitzhardinge .name = BALLOON_CLASS_NAME, 5631775826cSJeremy Fitzhardinge }; 5641775826cSJeremy Fitzhardinge 5651775826cSJeremy Fitzhardinge static int register_balloon(struct sys_device *sysdev) 5661775826cSJeremy Fitzhardinge { 5671775826cSJeremy Fitzhardinge int i, error; 5681775826cSJeremy Fitzhardinge 5691775826cSJeremy Fitzhardinge error = sysdev_class_register(&balloon_sysdev_class); 5701775826cSJeremy Fitzhardinge if (error) 5711775826cSJeremy Fitzhardinge return error; 5721775826cSJeremy Fitzhardinge 5731775826cSJeremy Fitzhardinge sysdev->id = 0; 5741775826cSJeremy Fitzhardinge sysdev->cls = &balloon_sysdev_class; 5751775826cSJeremy Fitzhardinge 5761775826cSJeremy Fitzhardinge error = sysdev_register(sysdev); 5771775826cSJeremy Fitzhardinge if (error) { 5781775826cSJeremy Fitzhardinge sysdev_class_unregister(&balloon_sysdev_class); 5791775826cSJeremy Fitzhardinge return error; 5801775826cSJeremy Fitzhardinge } 5811775826cSJeremy Fitzhardinge 5821775826cSJeremy Fitzhardinge for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) { 5831775826cSJeremy Fitzhardinge error = sysdev_create_file(sysdev, balloon_attrs[i]); 5841775826cSJeremy Fitzhardinge if (error) 5851775826cSJeremy Fitzhardinge goto fail; 5861775826cSJeremy Fitzhardinge } 5871775826cSJeremy Fitzhardinge 5881775826cSJeremy Fitzhardinge error = sysfs_create_group(&sysdev->kobj, &balloon_info_group); 5891775826cSJeremy Fitzhardinge if (error) 5901775826cSJeremy Fitzhardinge goto fail; 5911775826cSJeremy Fitzhardinge 5921775826cSJeremy Fitzhardinge return 0; 5931775826cSJeremy Fitzhardinge 5941775826cSJeremy Fitzhardinge fail: 5951775826cSJeremy Fitzhardinge while (--i >= 0) 5961775826cSJeremy Fitzhardinge sysdev_remove_file(sysdev, balloon_attrs[i]); 5971775826cSJeremy Fitzhardinge sysdev_unregister(sysdev); 5981775826cSJeremy Fitzhardinge sysdev_class_unregister(&balloon_sysdev_class); 5991775826cSJeremy Fitzhardinge return error; 6001775826cSJeremy Fitzhardinge } 6011775826cSJeremy Fitzhardinge 6021775826cSJeremy Fitzhardinge MODULE_LICENSE("GPL"); 603