x86/mem_sharing: Fix test for "empty" physmap entry in sharing_add_to_physmap

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Signed-off-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 5cc879578be18332d3ed9e69c0b12f36b9873984..a2d82e9bd87674962c5a25e57d33a7a8f8e266c1 100644 (file)
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -1073,9 +1073,10 @@ int mem_sharing_add_to_physmap(struct domain *sd, unsigned long sgfn, shr_handle
     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 --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 94bd13616840ec3adbf6a0e3a5421d64390d98a7..febf76458297bd7fbd4b303fb37edb99823acd6b 100644 (file)
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -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)