[Xen-devel] [RFC PATCH 42/84] x86_64/mm: map and unmap page tables in m2p_mapped

[<hongyax@xxxxxxxxxx>]

From: Wei Liu <wei.liu2@xxxxxxxxxx>

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/arch/x86/x86_64/mm.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 9163f08de9..36dfac11a3 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -130,28 +130,36 @@ static int m2p_mapped(unsigned long spfn)
 {
     unsigned long va;
     l3_pgentry_t *l3_ro_mpt;
-    l2_pgentry_t *l2_ro_mpt;
+    l2_pgentry_t *l2_ro_mpt = NULL;
+    int rc = M2P_NO_MAPPED;
 
     va = RO_MPT_VIRT_START + spfn * sizeof(*machine_to_phys_mapping);
-    l3_ro_mpt = l4e_to_l3e(idle_pg_table[l4_table_offset(va)]);
+    l3_ro_mpt = map_xen_pagetable_new(
+        l4e_get_mfn(idle_pg_table[l4_table_offset(va)]));
 
     switch ( l3e_get_flags(l3_ro_mpt[l3_table_offset(va)]) &
              (_PAGE_PRESENT |_PAGE_PSE))
     {
         case _PAGE_PSE|_PAGE_PRESENT:
-            return M2P_1G_MAPPED;
+            rc = M2P_1G_MAPPED;
+            goto out;
         /* Check for next level */
         case _PAGE_PRESENT:
             break;
         default:
-            return M2P_NO_MAPPED;
+            rc = M2P_NO_MAPPED;
+            goto out;
     }
-    l2_ro_mpt = l3e_to_l2e(l3_ro_mpt[l3_table_offset(va)]);
+    l2_ro_mpt = map_xen_pagetable_new(
+        l3e_get_mfn(l3_ro_mpt[l3_table_offset(va)]));
 
     if (l2e_get_flags(l2_ro_mpt[l2_table_offset(va)]) & _PAGE_PRESENT)
-        return M2P_2M_MAPPED;
+        rc = M2P_2M_MAPPED;
 
-    return M2P_NO_MAPPED;
+ out:
+    UNMAP_XEN_PAGETABLE_NEW(l2_ro_mpt);
+    UNMAP_XEN_PAGETABLE_NEW(l3_ro_mpt);
+    return rc;
 }
 
 static int share_hotadd_m2p_table(struct mem_hotadd_info *info)
-- 
2.17.1


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