[Xen-changelog] [xen-unstable] x86/mem_sharing: Fix test for "empty" physmap entry in sharing_add_to_physmap

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Tim Deegan <tim@xxxxxxx>
# Date 1337247429 -3600
# Node ID 25bdef4493aefa0b52d9e94271aaf20c17654b87
# Parent  9edad3d37fe2d40ee49c706f621e7fcf546a5ffd
x86/mem_sharing: Fix test for "empty" physmap entry in sharing_add_to_physmap

Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
Signed-off-by: Tim Deegan <tim@xxxxxxx>
Committed-by: Tim Deegan <tim@xxxxxxx>
---


diff -r 9edad3d37fe2 -r 25bdef4493ae xen/arch/x86/mm/mem_sharing.c
--- a/xen/arch/x86/mm/mem_sharing.c     Thu May 17 10:24:54 2012 +0100
+++ b/xen/arch/x86/mm/mem_sharing.c     Thu May 17 10:37:09 2012 +0100
@@ -1073,9 +1073,10 @@ int mem_sharing_add_to_physmap(struct do
     if ( spage->sharing->handle != sh )
         goto err_unlock;
 
-    /* Make sure the target page is a hole in the physmap */
-    if ( mfn_valid(cmfn) ||
-         (!(p2m_is_ram(cmfn_type))) )
+    /* Make sure the target page is a hole in the physmap. These are typically
+     * p2m_mmio_dm, but also accept p2m_invalid and paged out pages. See the
+     * definition of p2m_is_hole in p2m.h. */
+    if ( !p2m_is_hole(cmfn_type) )
     {
         ret = XENMEM_SHARING_OP_C_HANDLE_INVALID;
         goto err_unlock;
diff -r 9edad3d37fe2 -r 25bdef4493ae xen/include/asm-x86/p2m.h
--- a/xen/include/asm-x86/p2m.h Thu May 17 10:24:54 2012 +0100
+++ b/xen/include/asm-x86/p2m.h Thu May 17 10:37:09 2012 +0100
@@ -133,6 +133,12 @@ typedef unsigned int p2m_query_t;
                        | p2m_to_mask(p2m_ram_paging_in)       \
                        | p2m_to_mask(p2m_ram_shared))
 
+/* Types that represent a physmap hole that is ok to replace with a shared
+ * entry */
+#define P2M_HOLE_TYPES (p2m_to_mask(p2m_mmio_dm)        \
+                       | p2m_to_mask(p2m_invalid)       \
+                       | p2m_to_mask(p2m_ram_paged))
+
 /* Grant mapping types, which map to a real machine frame in another
  * VM */
 #define P2M_GRANT_TYPES (p2m_to_mask(p2m_grant_map_rw)  \
@@ -173,6 +179,7 @@ typedef unsigned int p2m_query_t;
 
 /* Useful predicates */
 #define p2m_is_ram(_t) (p2m_to_mask(_t) & P2M_RAM_TYPES)
+#define p2m_is_hole(_t) (p2m_to_mask(_t) & P2M_HOLE_TYPES)
 #define p2m_is_mmio(_t) (p2m_to_mask(_t) & P2M_MMIO_TYPES)
 #define p2m_is_readonly(_t) (p2m_to_mask(_t) & P2M_RO_TYPES)
 #define p2m_is_magic(_t) (p2m_to_mask(_t) & P2M_MAGIC_TYPES)

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