[Xen-devel] [PATCH 2 of 6] Fix handling of m2p map in set_shared_p2m_entry

[Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>]

 xen/arch/x86/mm/p2m.c |  5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)


When updating a p2m mapping to shared, previous code
unconditionally set the m2p entry for the old mfn to invalid.
We now check that the old mfn does not remain shared.

Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>

diff -r d9a344a5c1e3 -r 1ef55d87b459 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -714,8 +714,9 @@ set_shared_p2m_entry(struct domain *d, u
      * sharable first */
     ASSERT(p2m_is_shared(ot));
     ASSERT(mfn_valid(omfn));
-    /* XXX: M2P translations have to be handled properly for shared pages */
-    set_gpfn_from_mfn(mfn_x(omfn), INVALID_M2P_ENTRY);
+    if ( ((mfn_to_page(omfn)->u.inuse.type_info & PGT_type_mask) 
+                    != PGT_shared_page) )
+        set_gpfn_from_mfn(mfn_x(omfn), INVALID_M2P_ENTRY);
 
     P2M_DEBUG("set shared %lx %lx\n", gfn, mfn_x(mfn));
     rc = set_p2m_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2m_ram_shared, 
p2m->default_access);

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