[PATCH] Use EfiACPIReclaimMemory for ESRT

[Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>]

As discussed on xen-devel, using EfiRuntimeServicesData for more than is
absolutely necessary is a bad idea.
---
 xen/common/efi/boot.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index 
db0340c8e2628314226c618dda11ede4c62fdf3b..dba23439758d1e842d267dcd19448e0f9113b115
 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -601,11 +601,13 @@ static size_t __init get_esrt_size(const 
EFI_MEMORY_DESCRIPTOR *desc)
     if ( physical_start > esrt || esrt - physical_start >= len )
         return 0;
     /*
-     * The specification requires EfiBootServicesData, but accept
-     * EfiRuntimeServicesData, which is a more logical choice.
+     * The specification requires EfiBootServicesData, but also accept
+     * EfiRuntimeServicesData (for compatibility) and EfiACPIReclaimMemory
+     * (which will contain the tables after successful kexec).
      */
     if ( (desc->Type != EfiRuntimeServicesData) &&
-         (desc->Type != EfiBootServicesData) )
+         (desc->Type != EfiBootServicesData) &&
+         (desc->Type != EfiACPIReclaimMemory) )
         return 0;
     available_len = len - (esrt - physical_start);
     if ( available_len <= offsetof(EFI_SYSTEM_RESOURCE_TABLE, Entries) )
@@ -1144,18 +1146,19 @@ static void __init efi_relocate_esrt(EFI_SYSTEM_TABLE 
*SystemTable)
     for ( i = 0; i < info_size; i += mdesc_size )
     {
         /*
-         * ESRT needs to be moved to memory of type EfiRuntimeServicesData
+         * ESRT needs to be moved to memory of type EfiACPIReclaimMemory
          * so that the memory it is in will not be used for other purposes.
          */
         void *new_esrt = NULL;
-        size_t esrt_size = get_esrt_size(memory_map + i);
+        const EFI_MEMORY_DESCRIPTOR *desc = memory_map + i;
+        size_t esrt_size = get_esrt_size(desc);
 
         if ( !esrt_size )
             continue;
-        if ( ((EFI_MEMORY_DESCRIPTOR *)(memory_map + i))->Type ==
-             EfiRuntimeServicesData )
+        if ( desc->Type == EfiRuntimeServicesData ||
+             desc->Type == EfiACPIReclaimMemory )
             break; /* ESRT already safe from reuse */
-        status = efi_bs->AllocatePool(EfiRuntimeServicesData, esrt_size,
+        status = efi_bs->AllocatePool(EfiACPIReclaimMemory, esrt_size,
                                       &new_esrt);
         if ( status == EFI_SUCCESS && new_esrt )
         {
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab