efi: Check EFI_MEMORY_DESCRIPTOR version explicitly

Our efi_memory_desc_t type is based on EFI_MEMORY_DESCRIPTOR version 1 in
the UEFI spec. No version updates are expected, but since we are about to
introduce support for new firmware tables that use the same descriptor
type, it makes sense to at least warn if we encounter other versions.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1461614832-17633-9-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/platform/efi/efi.c

@@ -211,6 +211,10 @@ int __init efi_memblock_x86_reserve_range(void)
 	efi.memmap.desc_size	= e->efi_memdesc_size;
 	efi.memmap.desc_version	= e->efi_memdesc_version;
 
+	WARN(efi.memmap.desc_version != 1,
+	     "Unexpected EFI_MEMORY_DESCRIPTOR version %ld",
+	     efi.memmap.desc_version);
+
 	memblock_reserve(pmap, efi.memmap.nr_map * efi.memmap.desc_size);
 
 	return 0;

drivers/firmware/efi/arm-init.c

@@ -198,6 +198,10 @@ void __init efi_init(void)
 	efi.memmap.desc_size = params.desc_size;
 	efi.memmap.desc_version = params.desc_ver;
 
+	WARN(efi.memmap.desc_version != 1,
+	     "Unexpected EFI_MEMORY_DESCRIPTOR version %ld",
+	      efi.memmap.desc_version);
+
 	if (uefi_init() < 0)
 		return;