[PATCH v2 4/5] x86_64/mm: map and unmap page tables in destroy_compat_m2p_mapping

[Hongyan Xia <hx242@xxxxxxx>]

From: Wei Liu <wei.liu2@xxxxxxxxxx>

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
Signed-off-by: Hongyan Xia <hongyxia@xxxxxxxxxx>

---
Changed in v2:
- there is pretty much no point in keeping l3_ro_mpt mapped, just fetch
  the l3e instead, which also cleans up the code.
---
 xen/arch/x86/x86_64/mm.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index d23c7e4f5b..ae8f4dd0b9 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -220,7 +220,7 @@ static void destroy_compat_m2p_mapping(struct 
mem_hotadd_info *info)
     unsigned long i, va, rwva, pt_pfn;
     unsigned long smap = info->spfn, emap = info->spfn;
 
-    l3_pgentry_t *l3_ro_mpt;
+    l3_pgentry_t l3e_ro_mpt;
     l2_pgentry_t *l2_ro_mpt;
 
     if ( smap > ((RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START) >> 2) 
)
@@ -229,11 +229,13 @@ static void destroy_compat_m2p_mapping(struct 
mem_hotadd_info *info)
     if ( emap > ((RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START) >> 2) 
)
         emap = (RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START) >> 2;
 
-    l3_ro_mpt = 
l4e_to_l3e(idle_pg_table[l4_table_offset(HIRO_COMPAT_MPT_VIRT_START)]);
+    l3e_ro_mpt = l3e_from_l4e(idle_pg_table[
+                                  l4_table_offset(HIRO_COMPAT_MPT_VIRT_START)],
+                              l3_table_offset(HIRO_COMPAT_MPT_VIRT_START));
 
-    
ASSERT(l3e_get_flags(l3_ro_mpt[l3_table_offset(HIRO_COMPAT_MPT_VIRT_START)]) & 
_PAGE_PRESENT);
+    ASSERT(l3e_get_flags(l3e_ro_mpt) & _PAGE_PRESENT);
 
-    l2_ro_mpt = 
l3e_to_l2e(l3_ro_mpt[l3_table_offset(HIRO_COMPAT_MPT_VIRT_START)]);
+    l2_ro_mpt = map_l2t_from_l3e(l3e_ro_mpt);
 
     for ( i = smap; i < emap; )
     {
@@ -255,6 +257,8 @@ static void destroy_compat_m2p_mapping(struct 
mem_hotadd_info *info)
         i += 1UL << (L2_PAGETABLE_SHIFT - 2);
     }
 
+    UNMAP_DOMAIN_PAGE(l2_ro_mpt);
+
     return;
 }
 
-- 
2.24.1.AMZN