xen/arm: during efi boot, improve the check for usable memory

When booting via EFI, the EFI memory map has information about memory
regions and their type. Improve the check for the type and attribute of
each memory region to figure out whether it is usable memory or not.
This patch brings the check on par with Linux v5.5-rc6 and makes more
memory reusable as normal memory by Xen (except that Linux also reuses
EFI_PERSISTENT_MEMORY, which we do not).

Specifically, this patch also reuses memory marked as
EfiLoaderCode/Data, and it uses both Attribute and Type for the check
(Attribute needs to be EFI_MEMORY_WB).

Reported-by: Roman Shaposhnik <roman@zededa.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Julien Grall <julien@xen.org>
(cherry picked from commit b31666c8912bf18d9eff963b06d856e7e818ff34)

diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
index ca655ff003c99f48ef50fc67eb486b7566a95a27..3c0772d3f2b2f23ea3100283fe54996c2ad6628a 100644 (file)
--- a/xen/arch/arm/efi/efi-boot.h
+++ b/xen/arch/arm/efi/efi-boot.h
@@ -149,10 +149,13 @@ static EFI_STATUS __init efi_process_memory_map_bootinfo(EFI_MEMORY_DESCRIPTOR *
 
     for ( Index = 0; Index < (mmap_size / desc_size); Index++ )
     {
-        if ( desc_ptr->Type == EfiConventionalMemory ||
-             (!map_bs &&
-              (desc_ptr->Type == EfiBootServicesCode ||
-               desc_ptr->Type == EfiBootServicesData)) )
+        if ( desc_ptr->Attribute & EFI_MEMORY_WB &&
+             (desc_ptr->Type == EfiConventionalMemory ||
+              desc_ptr->Type == EfiLoaderCode ||
+              desc_ptr->Type == EfiLoaderData ||
+              (!map_bs &&
+               (desc_ptr->Type == EfiBootServicesCode ||
+                desc_ptr->Type == EfiBootServicesData))) )
         {
             if ( !meminfo_add_bank(&bootinfo.mem, desc_ptr) )
             {