x86/efi: Only map RAM into EFI page tables if in mixed-mode

commit 1297667083d5442aafe3e337b9413bf02b114edb upstream.

Waiman reported that booting with CONFIG_EFI_MIXED enabled on his
multi-terabyte HP machine results in boot crashes, because the EFI
region mapping functions loop forever while trying to map those
regions describing RAM.

While this patch doesn't fix the underlying hang, there's really no
reason to map EFI_CONVENTIONAL_MEMORY regions into the EFI page tables
when mixed-mode is not in use at runtime.

Reported-by: Waiman Long <waiman.long@hpe.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
CC: Theodore Ts'o <tytso@mit.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Scott J Norton <scott.norton@hpe.com>
Cc: Douglas Hatch <doug.hatch@hpe.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index b226b3f497f1c75a465fa73f5171a695ea5c9e95..964c7022d31d4e36af9d7e63779ecc8434f0ee19 100644 (file)
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -244,7 +244,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
         * text and allocate a new stack because we can't rely on the
         * stack pointer being < 4GB.
         */
-       if (!IS_ENABLED(CONFIG_EFI_MIXED))
+       if (!IS_ENABLED(CONFIG_EFI_MIXED) || efi_is_native())
                return 0;
 
        /*