xen: add extra pages to balloon

Add extra pages in the pseudo-physical address space to the balloon
so we can extend into them later.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 500290b150bb..df26ee9caa68 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -119,7 +119,7 @@ static void scrub_page(struct page *page)
 }
 
 /* balloon_append: add the given page to the balloon. */
-static void balloon_append(struct page *page)
+static void __balloon_append(struct page *page)
 {
         /* Lowmem is re-populated first, so highmem pages go at list tail. */
         if (PageHighMem(page)) {
@@ -130,7 +130,11 @@ static void balloon_append(struct page *page)
                 list_add(&page->lru, &ballooned_pages);
                 balloon_stats.balloon_low++;
         }
+}
 
+static void balloon_append(struct page *page)
+{
+        __balloon_append(page);
         totalram_pages--;
 }
 
@@ -416,10 +420,13 @@ static int __init balloon_init(void)
         register_balloon(&balloon_sysdev);
 
         /* Initialise the balloon with excess memory space. */
-        for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) {
+        for (pfn = PFN_UP(xen_extra_mem_start);
+             pfn < PFN_DOWN(xen_extra_mem_start + xen_extra_mem_size);
+             pfn++) {
                 page = pfn_to_page(pfn);
-                if (!PageReserved(page))
-                        balloon_append(page);
+                /* totalram_pages doesn't include the boot-time
+                   balloon extension, so don't subtract from it. */
+                __balloon_append(page);
         }
 
         target_watch.callback = watch_target;