xen/balloon: factor out some helper functions

They will be used in the page migration routine.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 24efdf6996fbee9213d1e1c1fe716e8d61356127..815e1d5969dbe6d572d4b9f07f413e418e383346 100644 (file)
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -312,6 +312,67 @@ static inline void __reinsert_balloon_pages(struct list_head *head)
        spin_unlock_irqrestore(&xen_balloon.xb_dev_info->pages_lock, flags);
 }
 
+static int __memory_op_hypercall(int cmd, xen_pfn_t *list, xen_ulong_t nr)
+{
+       int rc;
+       struct xen_memory_reservation reservation = {
+               .address_bits = 0,
+               .extent_order = 0,
+               .domid        = DOMID_SELF
+       };
+
+       set_xen_guest_handle(reservation.extent_start, list);
+       reservation.nr_extents = nr;
+       rc = HYPERVISOR_memory_op(cmd, &reservation);
+
+       return rc;
+}
+
+static void __link_back_to_pagetable(struct page *page, xen_ulong_t mfn,
+                                    pte_t pte)
+{
+#ifdef CONFIG_XEN_HAVE_PVMMU
+       unsigned long pfn = page_to_pfn(page);
+
+       if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+               set_phys_to_machine(pfn, mfn);
+
+               /* Link back into the page tables if not highmem. */
+               if (!PageHighMem(page)) {
+                       int ret;
+                       ret = HYPERVISOR_update_va_mapping(
+                               (unsigned long)__va(pfn << PAGE_SHIFT),
+                               pte, 0);
+                       BUG_ON(ret);
+               }
+       }
+#endif
+}
+
+static void __replace_mapping_with_scratch_page(struct page *page)
+{
+#ifdef CONFIG_XEN_HAVE_PVMMU
+       /*
+        * Ballooned out frames are effectively replaced with
+        * a scratch frame.  Ensure direct mappings and the
+        * p2m are consistent.
+        */
+       if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+               unsigned long p, smfn;
+               struct page   *scratch_page = get_balloon_scratch_page();
+
+               p = page_to_pfn(scratch_page);
+               smfn = pfn_to_mfn(p);
+
+               __link_back_to_pagetable(page, smfn,
+                                        mfn_pte(smfn, PAGE_KERNEL_RO));
+
+               put_balloon_scratch_page();
+       }
+#endif
+}
+
+
 /* This function will always try to fill in pages managed by Xen
  * balloon driver, then pages managed by generic balloon driver.
  */
@@ -322,11 +383,6 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
        struct page   *page;
        LIST_HEAD(queue);
        bool xen_pages;
-       struct xen_memory_reservation reservation = {
-               .address_bits = 0,
-               .extent_order = 0,
-               .domid        = DOMID_SELF
-       };
 
 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
        if (!xen_balloon.balloon_stats.balloon_low &&
@@ -365,9 +421,8 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
        }
 
        /* Second step: issue hypercall */
-       set_xen_guest_handle(reservation.extent_start, frame_list);
-       reservation.nr_extents = nr_pages;
-       rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+       rc = __memory_op_hypercall(XENMEM_populate_physmap, frame_list,
+                                  nr_pages);
        if (rc <= 0) {
                rc = BP_EAGAIN;
                goto move_pages_back;
@@ -382,21 +437,8 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
                list_del(&page->lru);
                pfn = page_to_pfn(page);
 
-#ifdef CONFIG_XEN_HAVE_PVMMU
-               if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-                       set_phys_to_machine(pfn, frame_list[i]);
-
-                       /* Link back into the page tables if not highmem. */
-                       if (!PageHighMem(page)) {
-                               int ret;
-                               ret = HYPERVISOR_update_va_mapping(
-                                               (unsigned long)__va(pfn << PAGE_SHIFT),
-                                               mfn_pte(frame_list[i], PAGE_KERNEL),
-                                               0);
-                               BUG_ON(ret);
-                       }
-               }
-#endif
+               __link_back_to_pagetable(page, frame_list[i],
+                                        mfn_pte(frame_list[i], PAGE_KERNEL));
 
                /* Relinquish the page back to the allocator. */
                if (xen_pages)
@@ -439,11 +481,6 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp,
        unsigned long  pfn, i;
        struct page   *page;
        int ret;
-       struct xen_memory_reservation reservation = {
-               .address_bits = 0,
-               .extent_order = 0,
-               .domid        = DOMID_SELF
-       };
 
 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
        if (xen_balloon.balloon_stats.hotplug_pages) {
@@ -489,36 +526,14 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp,
                frame_list[i] = pfn_to_mfn(pfn);
                page = pfn_to_page(pfn);
 
-#ifdef CONFIG_XEN_HAVE_PVMMU
-               /*
-                * Ballooned out frames are effectively replaced with
-                * a scratch frame.  Ensure direct mappings and the
-                * p2m are consistent.
-                */
-               if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-                       if (!PageHighMem(page)) {
-                               struct page *scratch_page = get_balloon_scratch_page();
-
-                               ret = HYPERVISOR_update_va_mapping(
-                                               (unsigned long)__va(pfn << PAGE_SHIFT),
-                                               pfn_pte(page_to_pfn(scratch_page),
-                                                       PAGE_KERNEL_RO), 0);
-                               BUG_ON(ret);
-
-                               put_balloon_scratch_page();
-                       }
-                       __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
-               }
-#endif
-
+               __replace_mapping_with_scratch_page(page);
                balloon_append(page, core_driver);
        }
 
        flush_tlb_all();
 
-       set_xen_guest_handle(reservation.extent_start, frame_list);
-       reservation.nr_extents   = nr_pages;
-       ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+       ret = __memory_op_hypercall(XENMEM_decrease_reservation, frame_list,
+                                   nr_pages);
        BUG_ON(ret != nr_pages);
 
        xen_balloon.balloon_stats.current_pages -= nr_pages;