From: Wei Liu <wei.liu2@citrix.com>

After inspection ARM doesn't have alloc_xen_pagetable so this function
is x86 only, which means it is safe for us to change.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 xen/common/efi/boot.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index a6f84c945a..8e96ef8de2 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1454,16 +1454,20 @@ static __init void copy_mapping(unsigned long mfn, unsigned long end,
             continue;
         if ( !(l4e_get_flags(l4e) & _PAGE_PRESENT) )
         {
-            l3dst = alloc_xen_pagetable();
-            BUG_ON(!l3dst);
+            mfn_t l3mfn = alloc_xen_pagetable_new();
+
+            BUG_ON(mfn_eq(l3mfn, INVALID_MFN));
+            l3dst = map_domain_page(l3mfn);
             clear_page(l3dst);
             efi_l4_pgtable[l4_table_offset(mfn << PAGE_SHIFT)] =
-                l4e_from_paddr(virt_to_maddr(l3dst), __PAGE_HYPERVISOR);
+                l4e_from_mfn(l3mfn, __PAGE_HYPERVISOR);
         }
         else
-            l3dst = l4e_to_l3e(l4e);
-        l3src = l4e_to_l3e(idle_pg_table[l4_table_offset(va)]);
+            l3dst = map_l3t_from_l4e(l4e);
+        l3src = map_l3t_from_l4e(idle_pg_table[l4_table_offset(va)]);
         l3dst[l3_table_offset(mfn << PAGE_SHIFT)] = l3src[l3_table_offset(va)];
+        unmap_domain_page(l3src);
+        unmap_domain_page(l3dst);
     }
 }
 
-- 
2.24.1.AMZN

On 24.04.2020 16:09, Hongyan Xia wrote:
> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -1454,16 +1454,20 @@ static __init void copy_mapping(unsigned long mfn, unsigned long end,
>              continue;
>          if ( !(l4e_get_flags(l4e) & _PAGE_PRESENT) )
>          {
> -            l3dst = alloc_xen_pagetable();
> -            BUG_ON(!l3dst);
> +            mfn_t l3mfn = alloc_xen_pagetable_new();
> +
> +            BUG_ON(mfn_eq(l3mfn, INVALID_MFN));
> +            l3dst = map_domain_page(l3mfn);
>              clear_page(l3dst);
>              efi_l4_pgtable[l4_table_offset(mfn << PAGE_SHIFT)] =
> -                l4e_from_paddr(virt_to_maddr(l3dst), __PAGE_HYPERVISOR);
> +                l4e_from_mfn(l3mfn, __PAGE_HYPERVISOR);
>          }
>          else
> -            l3dst = l4e_to_l3e(l4e);
> -        l3src = l4e_to_l3e(idle_pg_table[l4_table_offset(va)]);
> +            l3dst = map_l3t_from_l4e(l4e);
> +        l3src = map_l3t_from_l4e(idle_pg_table[l4_table_offset(va)]);
>          l3dst[l3_table_offset(mfn << PAGE_SHIFT)] = l3src[l3_table_offset(va)];
> +        unmap_domain_page(l3src);
> +        unmap_domain_page(l3dst);
>      }
>  }

This looks very inefficient - you establish and tear down two mappings
per loop iteration, when really you may end up copying all 512 slots
between the same pair of L3 tables.

Jan