efi: Introduce EFI_MEM_ATTR bit and set it from memory attributes table

UEFI v2.6 introduces a configuration table called
EFI_MEMORY_ATTRIBUTES_TABLE which provides additional information about
efi runtime regions. Currently this table describes memory protections
that may be applied to EFI Runtime code and data regions by kernel.
Allocate a EFI_XXX bit to keep track of whether this feature is
published by firmware or not.
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Reviewed-by: Lee, Chun-Yi <jlee@suse.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

drivers/firmware/efi/memattr.c

@@ -43,6 +43,7 @@ int __init efi_memattr_init(void)
 
 	tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size;
 	memblock_reserve(efi.mem_attr_table, tbl_size);
+	set_bit(EFI_MEM_ATTR, &efi.flags);
 
 unmap:
 	early_memunmap(tbl, sizeof(*tbl));

include/linux/efi.h

@@ -1065,6 +1065,7 @@ extern int __init efi_setup_pcdp_console(char *);
 #define EFI_ARCH_1		7	/* First arch-specific bit */
 #define EFI_DBG			8	/* Print additional debug info at runtime */
 #define EFI_NX_PE_DATA		9	/* Can runtime data regions be mapped non-executable? */
+#define EFI_MEM_ATTR		10	/* Did firmware publish EFI_MEMORY_ATTRIBUTES table? */
 
 #ifdef CONFIG_EFI
 /*