[RFC,45/84] x86_64/mm: map and unmap page tables in destroy_m2p_mapping

Commit Message

Xia, Hongyan Sept. 26, 2019, 9:46 a.m. UTC

From: Wei Liu <[e-mail]>

Signed-off-by: Wei Liu <[e-mail]>
---
 xen/arch/x86/x86_64/mm.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

Patch

diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index f4779f5c0a..642fead4f6 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -292,7 +292,8 @@  static void destroy_m2p_mapping(struct mem_hotadd_info *info)
     unsigned long i, va, rwva;
     unsigned long smap = info->spfn, emap = info->epfn;
 
-    l3_ro_mpt = l4e_to_l3e(idle_pg_table[l4_table_offset(RO_MPT_VIRT_START)]);
+    l3_ro_mpt = map_xen_pagetable_new(
+        l4e_get_mfn(idle_pg_table[l4_table_offset(RO_MPT_VIRT_START)]));
 
     /*
      * No need to clean m2p structure existing before the hotplug
@@ -314,26 +315,35 @@  static void destroy_m2p_mapping(struct mem_hotadd_info *info)
             continue;
         }
 
-        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))
         {
             i = ( i & ~((1UL << (L2_PAGETABLE_SHIFT - 3)) - 1)) +
                     (1UL << (L2_PAGETABLE_SHIFT - 3)) ;
+            UNMAP_XEN_PAGETABLE_NEW(l2_ro_mpt);
             continue;
         }
 
         pt_pfn = l2e_get_pfn(l2_ro_mpt[l2_table_offset(va)]);
         if ( hotadd_mem_valid(pt_pfn, info) )
         {
+            l2_pgentry_t *l2t;
+
             destroy_xen_mappings(rwva, rwva + (1UL << L2_PAGETABLE_SHIFT));
 
-            l2_ro_mpt = l3e_to_l2e(l3_ro_mpt[l3_table_offset(va)]);
-            l2e_write(&l2_ro_mpt[l2_table_offset(va)], l2e_empty());
+            l2t = map_xen_pagetable_new(
+                l3e_get_mfn(l3_ro_mpt[l3_table_offset(va)]));
+            l2e_write(&l2t[l2_table_offset(va)], l2e_empty());
+            UNMAP_XEN_PAGETABLE_NEW(l2t);
         }
         i = ( i & ~((1UL << (L2_PAGETABLE_SHIFT - 3)) - 1)) +
               (1UL << (L2_PAGETABLE_SHIFT - 3));
+        UNMAP_XEN_PAGETABLE_NEW(l2_ro_mpt);
     }
 
+    UNMAP_XEN_PAGETABLE_NEW(l3_ro_mpt);
+
     destroy_compat_m2p_mapping(info);
 
     /* Brute-Force flush all TLB */