+ unsigned long target = min(target_pages, hard_limit);
+ if (target > (current_pages + balloon_low + balloon_high))
+ target = current_pages + balloon_low + balloon_high;
+ return target;
+}
+
+static int increase_reservation(unsigned long nr_pages)
+{
+ unsigned long pfn, i, flags;
+ struct page *page;
+ long rc;
+ struct xen_memory_reservation reservation = {
+ .address_bits = 0,
+ .extent_order = 0,
+ .domid = DOMID_SELF
+ };
+
+ if (nr_pages > ARRAY_SIZE(frame_list))
+ nr_pages = ARRAY_SIZE(frame_list);
+
+ balloon_lock(flags);
+
+ page = balloon_first_page();
+ for (i = 0; i < nr_pages; i++) {
+ BUG_ON(page == NULL);
+ frame_list[i] = page_to_pfn(page);;
+ page = balloon_next_page(page);
+ }
+
+ set_xen_guest_handle(reservation.extent_start, frame_list);
+ reservation.nr_extents = nr_pages;
+ rc = HYPERVISOR_memory_op(
+ XENMEM_populate_physmap, &reservation);
+ if (rc < nr_pages) {
+ if (rc > 0) {
+ int ret;
+
+ /* We hit the Xen hard limit: reprobe. */
+ reservation.nr_extents = rc;
+ ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
+ &reservation);
+ BUG_ON(ret != rc);
+ }
+ if (rc >= 0)
+ hard_limit = current_pages + rc - driver_pages;
+ goto out;
+ }
+
+ for (i = 0; i < nr_pages; i++) {
+ page = balloon_retrieve();
+ BUG_ON(page == NULL);
+
+ pfn = page_to_pfn(page);
+ BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
+ phys_to_machine_mapping_valid(pfn));
+
+ /* Update P->M and M->P tables. */
+ set_phys_to_machine(pfn, frame_list[i]);
+ xen_machphys_update(frame_list[i], pfn);
+
+ /* Link back into the page tables if not highmem. */
+ if (pfn < max_low_pfn) {
+ int ret;
+ ret = HYPERVISOR_update_va_mapping(
+ (unsigned long)__va(pfn << PAGE_SHIFT),
+ pfn_pte_ma(frame_list[i], PAGE_KERNEL),
+ 0);
+ BUG_ON(ret);
+ }
+
+ /* Relinquish the page back to the allocator. */
+ ClearPageReserved(page);
+ init_page_count(page);
+ __free_page(page);
+ }
+
+ current_pages += nr_pages;
+ totalram_pages = current_pages;
+
+ out:
+ balloon_unlock(flags);
+
+ return 0;
+}
+
+static int decrease_reservation(unsigned long nr_pages)
+{
+ unsigned long pfn, i, flags;
+ struct page *page;
+ void *v;
+ int need_sleep = 0;
+ int ret;
+ struct xen_memory_reservation reservation = {
+ .address_bits = 0,
+ .extent_order = 0,
+ .domid = DOMID_SELF
+ };
+
+ if (nr_pages > ARRAY_SIZE(frame_list))
+ nr_pages = ARRAY_SIZE(frame_list);
+
+ for (i = 0; i < nr_pages; i++) {
+ if ((page = alloc_page(GFP_BALLOON)) == NULL) {
+ nr_pages = i;
+ need_sleep = 1;
+ break;
+ }
+
+ pfn = page_to_pfn(page);
+ frame_list[i] = pfn_to_mfn(pfn);
+
+ if (!PageHighMem(page)) {
+ v = phys_to_virt(pfn << PAGE_SHIFT);
+ scrub_pages(v, 1);
+ ret = HYPERVISOR_update_va_mapping(
+ (unsigned long)v, __pte_ma(0), 0);
+ BUG_ON(ret);
+ }
+#ifdef CONFIG_XEN_SCRUB_PAGES
+ else {
+ v = kmap(page);
+ scrub_pages(v, 1);
+ kunmap(page);
+ }
+#endif
+ }
+
+ /* Ensure that ballooned highmem pages don't have kmaps. */
+ kmap_flush_unused();
+ flush_tlb_all();
+
+ balloon_lock(flags);
+
+ /* No more mappings: invalidate P2M and add to balloon. */
+ for (i = 0; i < nr_pages; i++) {
+ pfn = mfn_to_pfn(frame_list[i]);
+ set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+ balloon_append(pfn_to_page(pfn));
+ }
+
+ set_xen_guest_handle(reservation.extent_start, frame_list);
+ reservation.nr_extents = nr_pages;
+ ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+ BUG_ON(ret != nr_pages);
+
+ current_pages -= nr_pages;
+ totalram_pages = current_pages;
+
+ balloon_unlock(flags);
+
+ return need_sleep;