Improve robustness of the Xen balloon driver.
sys/dev/xen/balloon/balloon.c: Remove unused and commented out code. Fix deadlock caused by performing a sleepable malloc while holding the balloon mutex. Perform proper accounting of the memory used by the domain. Submitted by: Roger Pau Monné Sponsored by: Citrix Systems R&D Reviewed by: gibbs MFC after: 2 days
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gibbs
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@ -52,18 +52,13 @@ __FBSDID("$FreeBSD$");
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static MALLOC_DEFINE(M_BALLOON, "Balloon", "Xen Balloon Driver");
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struct mtx balloon_mutex;
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/* Convert from KB (as fetched from xenstore) to number of PAGES */
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#define KB_TO_PAGE_SHIFT (PAGE_SHIFT - 10)
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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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struct mtx balloon_lock;
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struct mtx balloon_mutex;
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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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#define ARRAY_SIZE(A) (sizeof(A) / sizeof(A[0]))
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struct balloon_stats {
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/* We aim for 'current allocation' == 'target allocation'. */
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@ -116,15 +111,21 @@ static void balloon_process(void *unused);
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printk(KERN_WARNING "xen_mem: " fmt, ##args)
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/* balloon_append: add the given page to the balloon. */
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static void
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static int
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balloon_append(vm_page_t page)
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{
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struct balloon_entry *entry;
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entry = malloc(sizeof(struct balloon_entry), M_BALLOON, M_WAITOK);
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mtx_assert(&balloon_mutex, MA_OWNED);
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entry = malloc(sizeof(struct balloon_entry), M_BALLOON, M_NOWAIT);
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if (!entry)
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return (ENOMEM);
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entry->page = page;
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STAILQ_INSERT_HEAD(&ballooned_pages, entry, list);
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bs.balloon_low++;
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return (0);
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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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@ -134,8 +135,10 @@ balloon_retrieve(void)
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vm_page_t page;
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struct balloon_entry *entry;
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mtx_assert(&balloon_mutex, MA_OWNED);
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if (STAILQ_EMPTY(&ballooned_pages))
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return NULL;
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return (NULL);
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entry = STAILQ_FIRST(&ballooned_pages);
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STAILQ_REMOVE_HEAD(&ballooned_pages, list);
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@ -145,7 +148,7 @@ balloon_retrieve(void)
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bs.balloon_low--;
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return page;
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return (page);
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}
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static unsigned long
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@ -154,21 +157,22 @@ current_target(void)
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unsigned long target = min(bs.target_pages, bs.hard_limit);
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if (target > (bs.current_pages + bs.balloon_low + bs.balloon_high))
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target = bs.current_pages + bs.balloon_low + bs.balloon_high;
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return target;
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return (target);
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}
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static unsigned long
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minimum_target(void)
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{
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#ifdef XENHVM
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#define max_pfn physmem
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#define max_pfn realmem
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#else
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#define max_pfn HYPERVISOR_shared_info->arch.max_pfn
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#endif
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unsigned long min_pages, curr_pages = current_target();
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#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
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/* Simple continuous piecewiese linear function:
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/*
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* Simple continuous piecewiese linear function:
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* max MiB -> min MiB gradient
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* 0 0
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* 16 16
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@ -189,12 +193,10 @@ minimum_target(void)
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else
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min_pages = MB2PAGES(296) + (max_pfn >> 5);
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#undef MB2PAGES
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#undef max_pfn
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/* Don't enforce growth */
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return min(min_pages, curr_pages);
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#ifndef CONFIG_XEN
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#undef max_pfn
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#endif
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return (min(min_pages, curr_pages));
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}
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static int
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@ -210,10 +212,10 @@ increase_reservation(unsigned long nr_pages)
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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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mtx_assert(&balloon_mutex, MA_OWNED);
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mtx_lock(&balloon_lock);
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if (nr_pages > nitems(frame_list))
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nr_pages = nitems(frame_list);
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for (entry = STAILQ_FIRST(&ballooned_pages), i = 0;
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i < nr_pages; i++, entry = STAILQ_NEXT(entry, list)) {
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@ -253,33 +255,14 @@ increase_reservation(unsigned long nr_pages)
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set_phys_to_machine(pfn, frame_list[i]);
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#if 0
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#ifndef XENHVM
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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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pfn_pte_ma(frame_list[i], PAGE_KERNEL),
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0);
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PASSING(ret == 0,
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("HYPERVISOR_update_va_mapping failed"));
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}
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#endif
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#endif
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/* Relinquish the page back to the allocator. */
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vm_page_unwire(page, 0);
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vm_page_free(page);
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}
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bs.current_pages += nr_pages;
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//totalram_pages = bs.current_pages;
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out:
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mtx_unlock(&balloon_lock);
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return 0;
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return (0);
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}
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static int
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@ -295,8 +278,10 @@ decrease_reservation(unsigned long nr_pages)
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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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mtx_assert(&balloon_mutex, MA_OWNED);
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if (nr_pages > nitems(frame_list))
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nr_pages = nitems(frame_list);
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for (i = 0; i < nr_pages; i++) {
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if ((page = vm_page_alloc(NULL, 0,
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@ -310,39 +295,15 @@ decrease_reservation(unsigned long nr_pages)
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pfn = (VM_PAGE_TO_PHYS(page) >> PAGE_SHIFT);
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frame_list[i] = PFNTOMFN(pfn);
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#if 0
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if (!PageHighMem(page)) {
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v = phys_to_virt(pfn << PAGE_SHIFT);
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scrub_pages(v, 1);
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#ifdef CONFIG_XEN
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ret = HYPERVISOR_update_va_mapping(
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(unsigned long)v, __pte_ma(0), 0);
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BUG_ON(ret);
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#endif
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}
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#endif
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#ifdef CONFIG_XEN_SCRUB_PAGES
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else {
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v = kmap(page);
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scrub_pages(v, 1);
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kunmap(page);
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}
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#endif
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}
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#ifdef CONFIG_XEN
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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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#endif
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mtx_lock(&balloon_lock);
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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 = MFNTOPFN(frame_list[i]);
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set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
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balloon_append(PHYS_TO_VM_PAGE(pfn << PAGE_SHIFT));
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if (balloon_append(page) != 0) {
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vm_page_unwire(page, 0);
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vm_page_free(page);
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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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}
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set_xen_guest_handle(reservation.extent_start, frame_list);
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@ -351,9 +312,6 @@ decrease_reservation(unsigned long nr_pages)
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KASSERT(ret == nr_pages, ("HYPERVISOR_memory_op failed"));
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bs.current_pages -= nr_pages;
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//totalram_pages = bs.current_pages;
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mtx_unlock(&balloon_lock);
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return (need_sleep);
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}
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@ -425,11 +383,11 @@ watch_target(struct xs_watch *watch,
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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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set_new_target(new_target >> (PAGE_SHIFT - 10));
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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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set_new_target(new_target >> KB_TO_PAGE_SHIFT);
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}
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static void
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@ -461,13 +419,12 @@ balloon_init(void *arg)
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if (!is_running_on_xen())
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return;
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mtx_init(&balloon_lock, "balloon_lock", NULL, MTX_DEF);
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mtx_init(&balloon_mutex, "balloon_mutex", NULL, MTX_DEF);
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#ifndef XENHVM
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bs.current_pages = min(xen_start_info->nr_pages, max_pfn);
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#else
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bs.current_pages = physmem;
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bs.current_pages = realmem;
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#endif
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bs.target_pages = bs.current_pages;
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bs.balloon_low = 0;
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@ -497,76 +454,7 @@ void balloon_update_driver_allowance(long delta);
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void
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balloon_update_driver_allowance(long delta)
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{
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mtx_lock(&balloon_lock);
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mtx_lock(&balloon_mutex);
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bs.driver_pages += delta;
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mtx_unlock(&balloon_lock);
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mtx_unlock(&balloon_mutex);
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}
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#if 0
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static int dealloc_pte_fn(
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pte_t *pte, struct page *pte_page, unsigned long addr, void *data)
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{
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unsigned long mfn = pte_mfn(*pte);
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int ret;
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struct xen_memory_reservation reservation = {
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.extent_start = &mfn,
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.nr_extents = 1,
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.extent_order = 0,
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.domid = DOMID_SELF
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};
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set_pte_at(&init_mm, addr, pte, __pte_ma(0));
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set_phys_to_machine(__pa(addr) >> PAGE_SHIFT, INVALID_P2M_ENTRY);
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ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
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KASSERT(ret == 1, ("HYPERVISOR_memory_op failed"));
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return 0;
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}
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#endif
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#if 0
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vm_page_t
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balloon_alloc_empty_page_range(unsigned long nr_pages)
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{
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vm_page_t pages;
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int i, rc;
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unsigned long *mfn_list;
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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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pages = vm_page_alloc_contig(nr_pages, 0, -1, 4, 4)
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if (pages == NULL)
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return NULL;
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mfn_list = malloc(nr_pages*sizeof(unsigned long), M_DEVBUF, M_WAITOK);
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for (i = 0; i < nr_pages; i++) {
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mfn_list[i] = PFNTOMFN(VM_PAGE_TO_PHYS(pages[i]) >> PAGE_SHIFT);
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PFNTOMFN(i) = INVALID_P2M_ENTRY;
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reservation.extent_start = mfn_list;
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reservation.nr_extents = nr_pages;
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rc = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
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&reservation);
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KASSERT(rc == nr_pages, ("HYPERVISOR_memory_op failed"));
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}
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current_pages -= nr_pages;
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wakeup(balloon_process);
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return pages;
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}
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void
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balloon_dealloc_empty_page_range(vm_page_t page, unsigned long nr_pages)
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{
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unsigned long i;
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for (i = 0; i < nr_pages; i++)
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balloon_append(page + i);
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wakeup(balloon_process);
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}
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#endif
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