![Linus Torvalds](/assets/img/avatar_default.png)
* 'stable/hvc-console' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: xen/hvc: Disable probe_irq_on/off from poking the hvc-console IRQ line. * 'stable/gntalloc.v6' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: xen: gntdev: fix build warning xen/p2m/m2p/gnttab: do not add failed grant maps to m2p override xen-gntdev: Add cast to pointer xen-gntdev: Fix incorrect use of zero handle xen: change xen/[gntdev/gntalloc] to default m xen-gntdev: prevent using UNMAP_NOTIFY_CLEAR_BYTE on read-only mappings xen-gntdev: Avoid double-mapping memory xen-gntdev: Avoid unmapping ranges twice xen-gntdev: Use map->vma for checking map validity xen-gntdev: Fix unmap notify on PV domains xen-gntdev: Fix memory leak when mmap fails xen/gntalloc,gntdev: Add unmap notify ioctl xen-gntalloc: Userspace grant allocation driver xen-gntdev: Support mapping in HVM domains xen-gntdev: Add reference counting to maps xen-gntdev: Use find_vma rather than iterating our vma list manually xen-gntdev: Change page limit to be global instead of per-open * 'stable/balloon' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: (24 commits) xen-gntdev: Use ballooned pages for grant mappings xen-balloon: Add interface to retrieve ballooned pages xen-balloon: Move core balloon functionality out of module xen/balloon: Remove pr_info's and don't alter retry_count xen/balloon: Protect against CPU exhaust by event/x process xen/balloon: Migration from mod_timer() to schedule_delayed_work() xen/balloon: Removal of driver_pages
480 lines
12 KiB
C
480 lines
12 KiB
C
/******************************************************************************
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* Xen balloon driver - enables returning/claiming memory to/from Xen.
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*
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* Copyright (c) 2003, B Dragovic
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* Copyright (c) 2003-2004, M Williamson, K Fraser
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* Copyright (c) 2005 Dan M. Smith, IBM Corporation
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/bootmem.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/mutex.h>
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#include <linux/list.h>
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#include <linux/gfp.h>
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#include <asm/page.h>
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#include <asm/pgalloc.h>
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#include <asm/pgtable.h>
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#include <asm/tlb.h>
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#include <asm/e820.h>
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#include <asm/xen/hypervisor.h>
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#include <asm/xen/hypercall.h>
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#include <xen/xen.h>
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#include <xen/interface/xen.h>
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#include <xen/interface/memory.h>
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#include <xen/balloon.h>
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#include <xen/features.h>
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#include <xen/page.h>
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/*
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* balloon_process() state:
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*
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* BP_DONE: done or nothing to do,
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* BP_EAGAIN: error, go to sleep,
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* BP_ECANCELED: error, balloon operation canceled.
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*/
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enum bp_state {
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BP_DONE,
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BP_EAGAIN,
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BP_ECANCELED
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};
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static DEFINE_MUTEX(balloon_mutex);
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struct balloon_stats balloon_stats;
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EXPORT_SYMBOL_GPL(balloon_stats);
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/* We increase/decrease in batches which fit in a page */
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static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)];
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#ifdef CONFIG_HIGHMEM
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#define inc_totalhigh_pages() (totalhigh_pages++)
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#define dec_totalhigh_pages() (totalhigh_pages--)
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#else
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#define inc_totalhigh_pages() do {} while(0)
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#define dec_totalhigh_pages() do {} while(0)
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#endif
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/* List of ballooned pages, threaded through the mem_map array. */
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static LIST_HEAD(ballooned_pages);
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/* Main work function, always executed in process context. */
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static void balloon_process(struct work_struct *work);
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static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
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/* When ballooning out (allocating memory to return to Xen) we don't really
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want the kernel to try too hard since that can trigger the oom killer. */
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#define GFP_BALLOON \
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(GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
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static void scrub_page(struct page *page)
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{
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#ifdef CONFIG_XEN_SCRUB_PAGES
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clear_highpage(page);
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#endif
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}
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/* balloon_append: add the given page to the balloon. */
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static void __balloon_append(struct page *page)
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{
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/* Lowmem is re-populated first, so highmem pages go at list tail. */
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if (PageHighMem(page)) {
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list_add_tail(&page->lru, &ballooned_pages);
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balloon_stats.balloon_high++;
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dec_totalhigh_pages();
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} else {
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list_add(&page->lru, &ballooned_pages);
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balloon_stats.balloon_low++;
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}
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}
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static void balloon_append(struct page *page)
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{
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__balloon_append(page);
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totalram_pages--;
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}
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/* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
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static struct page *balloon_retrieve(bool prefer_highmem)
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{
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struct page *page;
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if (list_empty(&ballooned_pages))
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return NULL;
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if (prefer_highmem)
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page = list_entry(ballooned_pages.prev, struct page, lru);
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else
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page = list_entry(ballooned_pages.next, struct page, lru);
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list_del(&page->lru);
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if (PageHighMem(page)) {
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balloon_stats.balloon_high--;
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inc_totalhigh_pages();
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}
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else
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balloon_stats.balloon_low--;
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totalram_pages++;
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return page;
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}
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static struct page *balloon_first_page(void)
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{
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if (list_empty(&ballooned_pages))
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return NULL;
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return list_entry(ballooned_pages.next, struct page, lru);
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}
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static struct page *balloon_next_page(struct page *page)
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{
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struct list_head *next = page->lru.next;
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if (next == &ballooned_pages)
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return NULL;
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return list_entry(next, struct page, lru);
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}
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static enum bp_state update_schedule(enum bp_state state)
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{
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if (state == BP_DONE) {
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balloon_stats.schedule_delay = 1;
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balloon_stats.retry_count = 1;
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return BP_DONE;
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}
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++balloon_stats.retry_count;
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if (balloon_stats.max_retry_count != RETRY_UNLIMITED &&
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balloon_stats.retry_count > balloon_stats.max_retry_count) {
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balloon_stats.schedule_delay = 1;
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balloon_stats.retry_count = 1;
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return BP_ECANCELED;
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}
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balloon_stats.schedule_delay <<= 1;
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if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay)
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balloon_stats.schedule_delay = balloon_stats.max_schedule_delay;
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return BP_EAGAIN;
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}
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static unsigned long current_target(void)
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{
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unsigned long target = balloon_stats.target_pages;
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target = min(target,
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balloon_stats.current_pages +
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balloon_stats.balloon_low +
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balloon_stats.balloon_high);
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return target;
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}
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static enum bp_state increase_reservation(unsigned long nr_pages)
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{
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int rc;
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unsigned long pfn, i;
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struct page *page;
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struct xen_memory_reservation reservation = {
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.address_bits = 0,
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.extent_order = 0,
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.domid = DOMID_SELF
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};
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if (nr_pages > ARRAY_SIZE(frame_list))
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nr_pages = ARRAY_SIZE(frame_list);
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page = balloon_first_page();
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for (i = 0; i < nr_pages; i++) {
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if (!page) {
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nr_pages = i;
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break;
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}
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frame_list[i] = page_to_pfn(page);
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page = balloon_next_page(page);
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}
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set_xen_guest_handle(reservation.extent_start, frame_list);
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reservation.nr_extents = nr_pages;
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rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
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if (rc <= 0)
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return BP_EAGAIN;
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for (i = 0; i < rc; i++) {
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page = balloon_retrieve(false);
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BUG_ON(page == NULL);
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pfn = page_to_pfn(page);
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BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
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phys_to_machine_mapping_valid(pfn));
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set_phys_to_machine(pfn, frame_list[i]);
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/* Link back into the page tables if not highmem. */
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if (!xen_hvm_domain() && pfn < max_low_pfn) {
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int ret;
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ret = HYPERVISOR_update_va_mapping(
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(unsigned long)__va(pfn << PAGE_SHIFT),
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mfn_pte(frame_list[i], PAGE_KERNEL),
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0);
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BUG_ON(ret);
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}
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/* Relinquish the page back to the allocator. */
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ClearPageReserved(page);
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init_page_count(page);
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__free_page(page);
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}
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balloon_stats.current_pages += rc;
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return BP_DONE;
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}
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static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
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{
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enum bp_state state = BP_DONE;
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unsigned long pfn, i;
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struct page *page;
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int ret;
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struct xen_memory_reservation reservation = {
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.address_bits = 0,
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.extent_order = 0,
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.domid = DOMID_SELF
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};
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if (nr_pages > ARRAY_SIZE(frame_list))
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nr_pages = ARRAY_SIZE(frame_list);
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for (i = 0; i < nr_pages; i++) {
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if ((page = alloc_page(gfp)) == NULL) {
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nr_pages = i;
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state = BP_EAGAIN;
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break;
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}
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pfn = page_to_pfn(page);
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frame_list[i] = pfn_to_mfn(pfn);
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scrub_page(page);
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if (!xen_hvm_domain() && !PageHighMem(page)) {
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ret = HYPERVISOR_update_va_mapping(
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(unsigned long)__va(pfn << PAGE_SHIFT),
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__pte_ma(0), 0);
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BUG_ON(ret);
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}
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}
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/* Ensure that ballooned highmem pages don't have kmaps. */
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kmap_flush_unused();
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flush_tlb_all();
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/* No more mappings: invalidate P2M and add to balloon. */
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for (i = 0; i < nr_pages; i++) {
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pfn = mfn_to_pfn(frame_list[i]);
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__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
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balloon_append(pfn_to_page(pfn));
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}
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set_xen_guest_handle(reservation.extent_start, frame_list);
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reservation.nr_extents = nr_pages;
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ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
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BUG_ON(ret != nr_pages);
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balloon_stats.current_pages -= nr_pages;
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return state;
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}
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/*
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* We avoid multiple worker processes conflicting via the balloon mutex.
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* We may of course race updates of the target counts (which are protected
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* by the balloon lock), or with changes to the Xen hard limit, but we will
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* recover from these in time.
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*/
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static void balloon_process(struct work_struct *work)
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{
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enum bp_state state = BP_DONE;
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long credit;
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mutex_lock(&balloon_mutex);
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do {
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credit = current_target() - balloon_stats.current_pages;
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if (credit > 0)
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state = increase_reservation(credit);
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if (credit < 0)
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state = decrease_reservation(-credit, GFP_BALLOON);
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state = update_schedule(state);
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#ifndef CONFIG_PREEMPT
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if (need_resched())
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schedule();
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#endif
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} while (credit && state == BP_DONE);
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/* Schedule more work if there is some still to be done. */
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if (state == BP_EAGAIN)
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schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ);
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mutex_unlock(&balloon_mutex);
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}
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/* Resets the Xen limit, sets new target, and kicks off processing. */
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void balloon_set_new_target(unsigned long target)
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{
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/* No need for lock. Not read-modify-write updates. */
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balloon_stats.target_pages = target;
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schedule_delayed_work(&balloon_worker, 0);
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}
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EXPORT_SYMBOL_GPL(balloon_set_new_target);
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/**
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* alloc_xenballooned_pages - get pages that have been ballooned out
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* @nr_pages: Number of pages to get
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* @pages: pages returned
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* @return 0 on success, error otherwise
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*/
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int alloc_xenballooned_pages(int nr_pages, struct page** pages)
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{
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int pgno = 0;
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struct page* page;
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mutex_lock(&balloon_mutex);
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while (pgno < nr_pages) {
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page = balloon_retrieve(true);
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if (page) {
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pages[pgno++] = page;
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} else {
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enum bp_state st;
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st = decrease_reservation(nr_pages - pgno, GFP_HIGHUSER);
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if (st != BP_DONE)
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goto out_undo;
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}
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}
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mutex_unlock(&balloon_mutex);
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return 0;
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out_undo:
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while (pgno)
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balloon_append(pages[--pgno]);
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/* Free the memory back to the kernel soon */
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schedule_delayed_work(&balloon_worker, 0);
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mutex_unlock(&balloon_mutex);
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return -ENOMEM;
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}
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EXPORT_SYMBOL(alloc_xenballooned_pages);
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/**
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* free_xenballooned_pages - return pages retrieved with get_ballooned_pages
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* @nr_pages: Number of pages
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* @pages: pages to return
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*/
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void free_xenballooned_pages(int nr_pages, struct page** pages)
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{
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int i;
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mutex_lock(&balloon_mutex);
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for (i = 0; i < nr_pages; i++) {
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if (pages[i])
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balloon_append(pages[i]);
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}
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/* The balloon may be too large now. Shrink it if needed. */
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if (current_target() != balloon_stats.current_pages)
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schedule_delayed_work(&balloon_worker, 0);
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mutex_unlock(&balloon_mutex);
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}
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EXPORT_SYMBOL(free_xenballooned_pages);
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static int __init balloon_init(void)
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{
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unsigned long pfn, nr_pages, extra_pfn_end;
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struct page *page;
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if (!xen_domain())
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return -ENODEV;
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pr_info("xen/balloon: Initialising balloon driver.\n");
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if (xen_pv_domain())
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nr_pages = xen_start_info->nr_pages;
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else
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nr_pages = max_pfn;
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balloon_stats.current_pages = min(nr_pages, max_pfn);
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balloon_stats.target_pages = balloon_stats.current_pages;
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balloon_stats.balloon_low = 0;
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balloon_stats.balloon_high = 0;
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balloon_stats.schedule_delay = 1;
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balloon_stats.max_schedule_delay = 32;
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balloon_stats.retry_count = 1;
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balloon_stats.max_retry_count = RETRY_UNLIMITED;
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/*
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* Initialise the balloon with excess memory space. We need
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* to make sure we don't add memory which doesn't exist or
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* logically exist. The E820 map can be trimmed to be smaller
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* than the amount of physical memory due to the mem= command
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* line parameter. And if this is a 32-bit non-HIGHMEM kernel
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* on a system with memory which requires highmem to access,
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* don't try to use it.
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*/
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extra_pfn_end = min(min(max_pfn, e820_end_of_ram_pfn()),
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(unsigned long)PFN_DOWN(xen_extra_mem_start + xen_extra_mem_size));
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for (pfn = PFN_UP(xen_extra_mem_start);
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pfn < extra_pfn_end;
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pfn++) {
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page = pfn_to_page(pfn);
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/* totalram_pages doesn't include the boot-time
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balloon extension, so don't subtract from it. */
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__balloon_append(page);
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}
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return 0;
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}
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subsys_initcall(balloon_init);
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MODULE_LICENSE("GPL");
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