This is because the P2M table, when placed at a kernel specified
location, gets populated with large pages, which the domain must have
a way to unmap/recycle.

Additionally when allowing Dom0 to use superpages, they ought to be
tracked accordingly in the superpage frame table.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- 2010-06-15.orig/xen/arch/x86/domain_build.c	2010-06-15 12:22:11.000000000 +0200
+++ 2010-06-15/xen/arch/x86/domain_build.c	2010-06-15 11:30:19.000000000 +0200
@@ -913,6 +913,8 @@ int __init construct_dom0(
                 {
                     *l2tab = l2e_from_page(page,
                                            L1_PROT|_PAGE_DIRTY|_PAGE_PSE);
+                    if ( opt_allow_superpage )
+                        get_superpage(page_to_mfn(page), d);
                     va += 1UL << L2_PAGETABLE_SHIFT;
                     continue;
                 }
--- 2010-06-15.orig/xen/arch/x86/mm.c	2010-06-15 12:22:11.000000000 +0200
+++ 2010-06-15/xen/arch/x86/mm.c	2010-06-15 11:31:24.000000000 +0200
@@ -154,7 +154,9 @@ unsigned long __read_mostly pdx_group_va
 int opt_allow_superpage;
 boolean_param("allowsuperpage", opt_allow_superpage);
 
+#ifdef __i386__
 static int get_superpage(unsigned long mfn, struct domain *d);
+#endif
 static void put_superpage(unsigned long mfn);
 
 #define l1_disallow_mask(d)                                     \
@@ -2567,7 +2569,7 @@ void clear_superpage_mark(struct page_in
 
 }
 
-static int get_superpage(unsigned long mfn, struct domain *d)
+int get_superpage(unsigned long mfn, struct domain *d)
 {
     struct spage_info *spage;
     unsigned long x, nx, y;
@@ -2610,7 +2612,11 @@ static void put_superpage(unsigned long 
     unsigned long x, nx, y;
     unsigned long do_pages = 0;
 
-    ASSERT(opt_allow_superpage);
+    if ( !opt_allow_superpage )
+    {
+        put_spage_pages(mfn_to_page(mfn));
+        return;
+    }
 
     spage = mfn_to_spage(mfn);
     y = spage->type_info;
--- 2010-06-15.orig/xen/include/asm-x86/mm.h	2010-06-15 12:22:11.000000000 +0200
+++ 2010-06-15/xen/include/asm-x86/mm.h	2010-06-15 11:28:58.000000000 +0200
@@ -281,6 +281,7 @@ extern void share_xen_page_with_privileg
 #define frame_table ((struct page_info *)FRAMETABLE_VIRT_START)
 #ifdef __x86_64__
 #define spage_table ((struct spage_info *)SPAGETABLE_VIRT_START)
+int get_superpage(unsigned long mfn, struct domain *d);
 #endif
 extern unsigned long max_page;
 extern unsigned long total_pages;