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

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Message-ID: <CAE9FiQWnaGzDEko=sCzvT8LS7heZ7miwiVU+T4eJk-JgSr_Z4w@mail.gmail.com>
Date:	Wed, 20 Feb 2013 16:16:59 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	mingo@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org, matt.fleming@...el.com,
	takeuchi_satoru@...fujitsu.com, tglx@...utronix.de,
	walt0924@...il.com, hpa@...ux.intel.com
Cc:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86, efi: Make "noefi" really disable EFI
 runtime serivces

On Wed, Feb 20, 2013 at 3:25 PM, tip-bot for Matt Fleming
<tipbot@...or.com> wrote:
> 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;

__initdata please.

>  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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