[PATCH] x86, efi: Make "noefi" really disable EFI runtime serivces

From: Matt Fleming
Date: Wed Feb 20 2013 - 15:36:22 EST

From: Matt Fleming <matt.fleming@xxxxxxxxx>

commit 1de63d60cd5b ("efi: Clear EFI_RUNTIME_SERVICES rather than
EFI_BOOT by "noefi" boot parameter") attempted to make "noefi" true to
its documentation and disable EFI runtime services to prevent the
bricking bug described in commit e0094244e41c ("samsung-laptop:
Disable on EFI hardware"). However, it's not possible to clear
EFI_RUNTIME_SERVICES from an early param function because
EFI_RUNTIME_SERVICES is set in efi_init() *after* parse_early_param().

This resulted in "noefi" effectively becoming a no-op and no longer
providing users with a way to disable EFI, which is bad for those
users that have buggy machines.

Reported-by: Walt Nelson Jr <walt0924@xxxxxxxxx>
Cc: Satoru Takeuchi <takeuchi_satoru@xxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
arch/x86/platform/efi/efi.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 928bf83..e2cd38f 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -85,9 +85,10 @@ int efi_enabled(int facility)

+static bool disable_runtime = false;
static int __init setup_noefi(char *arg)
- clear_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
+ disable_runtime = true;
return 0;
early_param("noefi", setup_noefi);
@@ -734,7 +735,7 @@ void __init efi_init(void)
if (!efi_is_native())
pr_info("No EFI runtime due to 32/64-bit mismatch with kernel\n");
else {
- if (efi_runtime_init())
+ if (disable_runtime || efi_runtime_init())
set_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);

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