[Xen-changelog] [xen-unstable] PoD: Check p2m assumption in debug builds

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1253002418 -3600
# Node ID 582970a2d2dcd1d041ab29237ea8f8a2e31b8989
# Parent  973f4bbf472331a59a9f3ae716bfb72347767f46
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@xxxxxxxxxxxxx>
---
 xen/arch/x86/mm/p2m.c |   30 ++++++++++++++++++++++++++++++
 1 files changed, 30 insertions(+)

diff -r 973f4bbf4723 -r 582970a2d2dc xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c     Tue Sep 15 09:13:01 2009 +0100
+++ b/xen/arch/x86/mm/p2m.c     Tue Sep 15 09:13:38 2009 +0100
@@ -1530,6 +1530,36 @@ int set_p2m_entry(struct domain *d, unsi
                 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 )

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