[PATCH v7 08/15] x86_64/mm: switch to new APIs in setup_m2p_table

[Hongyan Xia <hx242@xxxxxxx>]

From: Wei Liu <wei.liu2@xxxxxxxxxx>

Avoid repetitive mapping of l2_ro_mpt by keeping it across loops, and
only unmap and map it when crossing 1G boundaries.

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

---
Changed in v7:
- avoid repetitive mapping of l2_ro_mpt.
- edit commit message.
- switch to alloc_map_clear_xen_pt().
---
 xen/arch/x86/x86_64/mm.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 8877ac7bb7..cfc3de9091 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -385,7 +385,8 @@ static int setup_m2p_table(struct mem_hotadd_info *info)
 
     ASSERT(l4e_get_flags(idle_pg_table[l4_table_offset(RO_MPT_VIRT_START)])
             & _PAGE_PRESENT);
-    l3_ro_mpt = l4e_to_l3e(idle_pg_table[l4_table_offset(RO_MPT_VIRT_START)]);
+    l3_ro_mpt = map_l3t_from_l4e(
+                    idle_pg_table[l4_table_offset(RO_MPT_VIRT_START)]);
 
     smap = (info->spfn & (~((1UL << (L2_PAGETABLE_SHIFT - 3)) -1)));
     emap = ((info->epfn + ((1UL << (L2_PAGETABLE_SHIFT - 3)) - 1 )) &
@@ -403,6 +404,10 @@ static int setup_m2p_table(struct mem_hotadd_info *info)
     i = smap;
     while ( i < emap )
     {
+        if ( (RO_MPT_VIRT_START + i * sizeof(*machine_to_phys_mapping)) &
+             ((1UL << L3_PAGETABLE_SHIFT) - 1) )
+            UNMAP_DOMAIN_PAGE(l2_ro_mpt);
+
         switch ( m2p_mapped(i) )
         {
         case M2P_1G_MAPPED:
@@ -438,32 +443,29 @@ static int setup_m2p_table(struct mem_hotadd_info *info)
 
             ASSERT(!(l3e_get_flags(l3_ro_mpt[l3_table_offset(va)]) &
                   _PAGE_PSE));
-            if ( l3e_get_flags(l3_ro_mpt[l3_table_offset(va)]) &
-              _PAGE_PRESENT )
-                l2_ro_mpt = l3e_to_l2e(l3_ro_mpt[l3_table_offset(va)]) +
-                  l2_table_offset(va);
-            else
+            if ( (l3e_get_flags(l3_ro_mpt[l3_table_offset(va)]) &
+                  _PAGE_PRESENT) && !l2_ro_mpt)
+                l2_ro_mpt = map_l2t_from_l3e(l3_ro_mpt[l3_table_offset(va)]);
+            else if ( !l2_ro_mpt )
             {
-                l2_ro_mpt = alloc_xen_pagetable();
+                mfn_t l2_ro_mpt_mfn;
+
+                l2_ro_mpt = alloc_map_clear_xen_pt(&l2_ro_mpt_mfn);
                 if ( !l2_ro_mpt )
                 {
                     ret = -ENOMEM;
                     goto error;
                 }
 
-                clear_page(l2_ro_mpt);
                 l3e_write(&l3_ro_mpt[l3_table_offset(va)],
-                          l3e_from_paddr(__pa(l2_ro_mpt),
-                                         __PAGE_HYPERVISOR_RO | _PAGE_USER));
-                l2_ro_mpt += l2_table_offset(va);
+                          l3e_from_mfn(l2_ro_mpt_mfn,
+                                       __PAGE_HYPERVISOR_RO | _PAGE_USER));
             }
 
             /* NB. Cannot be GLOBAL: guest user mode should not see it. */
-            l2e_write(l2_ro_mpt, l2e_from_mfn(mfn,
+            l2e_write(&l2_ro_mpt[l2_table_offset(va)], l2e_from_mfn(mfn,
                    /*_PAGE_GLOBAL|*/_PAGE_PSE|_PAGE_USER|_PAGE_PRESENT));
         }
-        if ( !((unsigned long)l2_ro_mpt & ~PAGE_MASK) )
-            l2_ro_mpt = NULL;
         i += ( 1UL << (L2_PAGETABLE_SHIFT - 3));
     }
 #undef CNT
@@ -471,6 +473,8 @@ static int setup_m2p_table(struct mem_hotadd_info *info)
 
     ret = setup_compat_m2p_table(info);
 error:
+    unmap_domain_page(l2_ro_mpt);
+    unmap_domain_page(l3_ro_mpt);
     return ret;
 }
 
-- 
2.24.1.AMZN