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

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Matt Fleming

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Feb 20, 2013, 3:40:01 PM2/20/13
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From: Matt Fleming <matt.f...@intel.com>

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 <walt...@gmail.com>
Cc: Satoru Takeuchi <takeuch...@jp.fujitsu.com>
Cc: H. Peter Anvin <h...@linux.intel.com>
Cc: <sta...@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.f...@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);
}
--
1.7.11.7

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tip-bot for Matt Fleming

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Feb 20, 2013, 6:30:02 PM2/20/13
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Commit-ID: fb834c7acc5e140cf4f9e86da93a66de8c0514da
Gitweb: http://git.kernel.org/tip/fb834c7acc5e140cf4f9e86da93a66de8c0514da
Author: Matt Fleming <matt.f...@intel.com>
AuthorDate: Wed, 20 Feb 2013 20:36:12 +0000
Committer: H. Peter Anvin <h...@linux.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 <walt...@gmail.com>
Cc: Satoru Takeuchi <takeuch...@jp.fujitsu.com>
Cc: <sta...@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.f...@intel.com>
Link: http://lkml.kernel.org/r/1361392572-25657-1-...@console-pimps.org
Signed-off-by: H. Peter Anvin <h...@linux.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);
}
--

Satoru Takeuchi

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Feb 20, 2013, 6:50:01 PM2/20/13
to
Hi Matt,

(2013/02/21 5:36), Matt Fleming wrote:
> From: Matt Fleming <matt.f...@intel.com>
>
> 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.

Sorry, my patch was imperfect. This patch looks good to me.

Reviewed-by: Satoru Takeuchi <takeuch...@jp.fujitsu.com>

Thanks,
Satoru

H. Peter Anvin

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Feb 20, 2013, 7:00:01 PM2/20/13
to
On 02/20/2013 03:46 PM, Satoru Takeuchi wrote:
>
> Sorry, my patch was imperfect. This patch looks good to me.
>

Perfection is something very rarely achieved. That's why we work with
gradual improvements.

-hpa

Yinghai Lu

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Feb 20, 2013, 7:20:02 PM2/20/13
to
__initdata please.

Matt Fleming

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Feb 21, 2013, 5:40:01 AM2/21/13
to
On Wed, 2013-02-20 at 16:16 -0800, Yinghai Lu wrote:
> > 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;
>
> __initdata please.

Sure. Peter, please drop this. I'll submit a v2.

Matt Fleming

unread,
Feb 21, 2013, 6:00:01 AM2/21/13
to
From: Matt Fleming <matt.f...@intel.com>

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 <walt...@gmail.com>
Cc: Satoru Takeuchi <takeuch...@jp.fujitsu.com>
Cc: H. Peter Anvin <h...@linux.intel.com>
Cc: Yinghai Lu <yin...@kernel.org>
Cc: <sta...@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.f...@intel.com>
---

v2: Annotate with __initdata as pointed out by Yinghai Lu.

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..ec9f325 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 __initdata 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);
}
--
1.7.11.7

H. Peter Anvin

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Feb 21, 2013, 12:10:01 PM2/21/13
to
On 02/21/2013 02:33 AM, Matt Fleming wrote:
> On Wed, 2013-02-20 at 16:16 -0800, Yinghai Lu wrote:
>>> 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;
>>
>> __initdata please.
>
> Sure. Peter, please drop this. I'll submit a v2.
>

Just do an incremental, please.

-hpa
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