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![Jan Beulich](/assets/img/avatar_default.png)
- drivers/xen/events.c did not compile - xen_setup_hook caused a modpost section warning - the use of u64 (instead of unsigned long long) together with a %llu in drivers/xen/balloon.c caused a compiler warning Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
602 lines
16 KiB
C
602 lines
16 KiB
C
/******************************************************************************
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* balloon.c
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*
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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/module.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/sysdev.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/uaccess.h>
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#include <asm/tlb.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/interface/xen.h>
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#include <xen/interface/memory.h>
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#include <xen/xenbus.h>
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#include <xen/features.h>
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#include <xen/page.h>
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#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
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#define BALLOON_CLASS_NAME "xen_memory"
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struct balloon_stats {
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/* We aim for 'current allocation' == 'target allocation'. */
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unsigned long current_pages;
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unsigned long target_pages;
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/* We may hit the hard limit in Xen. If we do then we remember it. */
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unsigned long hard_limit;
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/*
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* Drivers may alter the memory reservation independently, but they
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* must inform the balloon driver so we avoid hitting the hard limit.
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*/
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unsigned long driver_pages;
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/* Number of pages in high- and low-memory balloons. */
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unsigned long balloon_low;
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unsigned long balloon_high;
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};
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static DEFINE_MUTEX(balloon_mutex);
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static struct sys_device balloon_sysdev;
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static int register_balloon(struct sys_device *sysdev);
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/*
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* Protects atomic reservation decrease/increase against concurrent increases.
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* Also protects non-atomic updates of current_pages and driver_pages, and
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* balloon lists.
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*/
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static DEFINE_SPINLOCK(balloon_lock);
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static struct balloon_stats 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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/* VM /proc information for memory */
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extern unsigned long totalram_pages;
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#ifdef CONFIG_HIGHMEM
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extern unsigned long totalhigh_pages;
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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_WORK(balloon_worker, balloon_process);
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static struct timer_list balloon_timer;
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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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/* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
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static struct page *balloon_retrieve(void)
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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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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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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 void balloon_alarm(unsigned long unused)
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{
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schedule_work(&balloon_worker);
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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 = min(balloon_stats.target_pages, balloon_stats.hard_limit);
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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 int increase_reservation(unsigned long nr_pages)
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{
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unsigned long pfn, i, flags;
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struct page *page;
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long rc;
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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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spin_lock_irqsave(&balloon_lock, flags);
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page = balloon_first_page();
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for (i = 0; i < nr_pages; i++) {
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BUG_ON(page == NULL);
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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 < nr_pages) {
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if (rc > 0) {
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int ret;
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/* We hit the Xen hard limit: reprobe. */
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reservation.nr_extents = rc;
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ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
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&reservation);
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BUG_ON(ret != rc);
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}
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if (rc >= 0)
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balloon_stats.hard_limit = (balloon_stats.current_pages + rc -
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balloon_stats.driver_pages);
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goto out;
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}
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for (i = 0; i < nr_pages; i++) {
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page = balloon_retrieve();
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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 (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 += nr_pages;
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totalram_pages = balloon_stats.current_pages;
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out:
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spin_unlock_irqrestore(&balloon_lock, flags);
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return 0;
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}
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static int decrease_reservation(unsigned long nr_pages)
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{
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unsigned long pfn, i, flags;
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struct page *page;
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int need_sleep = 0;
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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_BALLOON)) == NULL) {
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nr_pages = i;
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need_sleep = 1;
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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 (!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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spin_lock_irqsave(&balloon_lock, flags);
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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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totalram_pages = balloon_stats.current_pages;
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spin_unlock_irqrestore(&balloon_lock, flags);
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return need_sleep;
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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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int need_sleep = 0;
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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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need_sleep = (increase_reservation(credit) != 0);
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if (credit < 0)
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need_sleep = (decrease_reservation(-credit) != 0);
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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 != 0) && !need_sleep);
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/* Schedule more work if there is some still to be done. */
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if (current_target() != balloon_stats.current_pages)
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mod_timer(&balloon_timer, jiffies + 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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static 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.hard_limit = ~0UL;
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balloon_stats.target_pages = target;
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schedule_work(&balloon_worker);
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}
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static struct xenbus_watch target_watch =
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{
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.node = "memory/target"
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};
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/* React to a change in the target key */
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static void watch_target(struct xenbus_watch *watch,
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const char **vec, unsigned int len)
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{
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unsigned long long new_target;
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int err;
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err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
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if (err != 1) {
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/* This is ok (for domain0 at least) - so just return */
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return;
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}
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/* The given memory/target value is in KiB, so it needs converting to
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* pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
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*/
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balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
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}
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static int balloon_init_watcher(struct notifier_block *notifier,
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unsigned long event,
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void *data)
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{
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int err;
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err = register_xenbus_watch(&target_watch);
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if (err)
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printk(KERN_ERR "Failed to set balloon watcher\n");
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return NOTIFY_DONE;
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}
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static struct notifier_block xenstore_notifier;
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static int __init balloon_init(void)
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{
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unsigned long pfn;
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struct page *page;
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if (!xen_pv_domain())
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return -ENODEV;
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pr_info("xen_balloon: Initialising balloon driver.\n");
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balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn);
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totalram_pages = balloon_stats.current_pages;
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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.driver_pages = 0UL;
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balloon_stats.hard_limit = ~0UL;
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init_timer(&balloon_timer);
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balloon_timer.data = 0;
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balloon_timer.function = balloon_alarm;
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register_balloon(&balloon_sysdev);
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/* Initialise the balloon with excess memory space. */
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for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) {
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page = pfn_to_page(pfn);
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if (!PageReserved(page))
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balloon_append(page);
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}
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target_watch.callback = watch_target;
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xenstore_notifier.notifier_call = balloon_init_watcher;
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register_xenstore_notifier(&xenstore_notifier);
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return 0;
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}
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subsys_initcall(balloon_init);
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static void balloon_exit(void)
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{
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/* XXX - release balloon here */
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return;
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}
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module_exit(balloon_exit);
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#define BALLOON_SHOW(name, format, args...) \
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static ssize_t show_##name(struct sys_device *dev, \
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struct sysdev_attribute *attr, \
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char *buf) \
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{ \
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return sprintf(buf, format, ##args); \
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} \
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static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL)
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BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
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BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
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BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
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BALLOON_SHOW(hard_limit_kb,
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(balloon_stats.hard_limit!=~0UL) ? "%lu\n" : "???\n",
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(balloon_stats.hard_limit!=~0UL) ? PAGES2KB(balloon_stats.hard_limit) : 0);
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BALLOON_SHOW(driver_kb, "%lu\n", PAGES2KB(balloon_stats.driver_pages));
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static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
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}
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static ssize_t store_target_kb(struct sys_device *dev,
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struct sysdev_attribute *attr,
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const char *buf,
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size_t count)
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{
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char *endchar;
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unsigned long long target_bytes;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
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balloon_set_new_target(target_bytes >> PAGE_SHIFT);
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return count;
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}
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static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR,
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show_target_kb, store_target_kb);
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static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr,
|
|
char *buf)
|
|
{
|
|
return sprintf(buf, "%llu\n",
|
|
(unsigned long long)balloon_stats.target_pages
|
|
<< PAGE_SHIFT);
|
|
}
|
|
|
|
static ssize_t store_target(struct sys_device *dev,
|
|
struct sysdev_attribute *attr,
|
|
const char *buf,
|
|
size_t count)
|
|
{
|
|
char *endchar;
|
|
unsigned long long target_bytes;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
target_bytes = memparse(buf, &endchar);
|
|
|
|
balloon_set_new_target(target_bytes >> PAGE_SHIFT);
|
|
|
|
return count;
|
|
}
|
|
|
|
static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR,
|
|
show_target, store_target);
|
|
|
|
|
|
static struct sysdev_attribute *balloon_attrs[] = {
|
|
&attr_target_kb,
|
|
&attr_target,
|
|
};
|
|
|
|
static struct attribute *balloon_info_attrs[] = {
|
|
&attr_current_kb.attr,
|
|
&attr_low_kb.attr,
|
|
&attr_high_kb.attr,
|
|
&attr_hard_limit_kb.attr,
|
|
&attr_driver_kb.attr,
|
|
NULL
|
|
};
|
|
|
|
static struct attribute_group balloon_info_group = {
|
|
.name = "info",
|
|
.attrs = balloon_info_attrs,
|
|
};
|
|
|
|
static struct sysdev_class balloon_sysdev_class = {
|
|
.name = BALLOON_CLASS_NAME,
|
|
};
|
|
|
|
static int register_balloon(struct sys_device *sysdev)
|
|
{
|
|
int i, error;
|
|
|
|
error = sysdev_class_register(&balloon_sysdev_class);
|
|
if (error)
|
|
return error;
|
|
|
|
sysdev->id = 0;
|
|
sysdev->cls = &balloon_sysdev_class;
|
|
|
|
error = sysdev_register(sysdev);
|
|
if (error) {
|
|
sysdev_class_unregister(&balloon_sysdev_class);
|
|
return error;
|
|
}
|
|
|
|
for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) {
|
|
error = sysdev_create_file(sysdev, balloon_attrs[i]);
|
|
if (error)
|
|
goto fail;
|
|
}
|
|
|
|
error = sysfs_create_group(&sysdev->kobj, &balloon_info_group);
|
|
if (error)
|
|
goto fail;
|
|
|
|
return 0;
|
|
|
|
fail:
|
|
while (--i >= 0)
|
|
sysdev_remove_file(sysdev, balloon_attrs[i]);
|
|
sysdev_unregister(sysdev);
|
|
sysdev_class_unregister(&balloon_sysdev_class);
|
|
return error;
|
|
}
|
|
|
|
MODULE_LICENSE("GPL");
|