PoD: Check p2m assumption in debug builds

The PoD code assumes that if:
* A page is in a domain's p2m table
* And it's owned by the domain
* And it's not a xenheap page
then:
* It's on the domain's page list.

This patch adds a check for this assumption when debug=y.

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 79777932d13a9369b47264f6b24b36c159a5e6bd..de6e50b998bcbd8c4825fc2918e88b8b845b98bd 100644 (file)
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1530,6 +1530,36 @@ int set_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn,
                 9 : 0;
         else
             order = 0;
+
+#ifndef NDEBUG
+        /* PoD code assumes that a page owned by the domain, not from the xenheap, and in the p2m
+         * is on the domain page list.  Verify this assumption. */
+        if ( mfn_valid(mfn)
+             && p2m_is_ram(p2mt)
+             && page_get_owner(mfn_to_page(mfn))==d
+             && ( (mfn_to_page(mfn)->count_info & PGC_xen_heap) == 0 ) )
+        {
+            struct page_info *p, *q;
+
+            p = mfn_to_page(mfn);
+
+            spin_lock(&d->page_alloc_lock);
+           
+            /* Walk the domain page list and make sure this page is on it... */
+            for ( q = page_list_first(&d->page_list) ; q; q = page_list_next(q, &d->page_list) )
+                if ( q == p )
+                    break;
+            if ( !q )
+            {
+                printk("%s: mfn %lx owned by d%d, not xen_heap, but not on domain page_list!\n",
+                       __func__, mfn_x(mfn), d->domain_id);
+                BUG();
+            }   
+
+            spin_unlock(&d->page_alloc_lock);
+        }
+#endif
+
         rc = d->arch.p2m->set_entry(d, gfn, mfn, order, p2mt);
         gfn += 1ul << order;
         if ( mfn_x(mfn) != INVALID_MFN )