linux-kernel - [tip:x86/urgent] x86, efi: Make "noefi" really disable EFI runtime serivces

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Date:	Wed, 20 Feb 2013 15:25:50 -0800
From:	tip-bot for Matt Fleming <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	stable@...r.kernel.org, matt.fleming@...el.com,
	takeuchi_satoru@...fujitsu.com, tglx@...utronix.de,
	hpa@...ux.intel.com, walt0924@...il.com
Subject: [tip:x86/urgent] x86, efi: Make "noefi"
  really disable EFI runtime serivces

Commit-ID:  fb834c7acc5e140cf4f9e86da93a66de8c0514da
Gitweb:     http://git.kernel.org/tip/fb834c7acc5e140cf4f9e86da93a66de8c0514da
Author:     Matt Fleming <matt.fleming@...el.com>
AuthorDate: Wed, 20 Feb 2013 20:36:12 +0000
Committer:  H. Peter Anvin <hpa@...ux.intel.com>
CommitDate: Wed, 20 Feb 2013 13:18:36 -0800

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

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@...il.com>
Cc: Satoru Takeuchi <takeuchi_satoru@...fujitsu.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@...el.com>
Link: http://lkml.kernel.org/r/1361392572-25657-1-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
---
 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)
 }
 EXPORT_SYMBOL(efi_enabled);
 
+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())
 			return;
 		set_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
 	}
--
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