Re: [PATCH] UefiCpuPkg/CommonFeature: Always set FEATURE_CONTROL.Lock

["Ni, Ruiyu" <ruiyu.ni@intel.com>]

All Tianocore stewards,
I'd like to include the below patch (a revert patch) in this stable tag release.

It's to fix a potential security hole when platform mis-configures the
PcdCpuFeaturesUserConfiguration.

Thanks/Ray

> -----Original Message-----
> From: edk2-devel <edk2-devel-bounces@lists.01.org> On Behalf Of Ruiyu Ni
> Sent: Tuesday, November 13, 2018 3:35 PM
> To: edk2-devel@lists.01.org
> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Laszlo Ersek
> <lersek@redhat.com>; Dong, Eric <eric.dong@intel.com>
> Subject: [edk2] [PATCH] UefiCpuPkg/CommonFeature: Always set
> FEATURE_CONTROL.Lock
> 
> The patch reverts commit 1ed6498c4a0210204bf4b95cc0c0cd6623ad6a0b
> * UefiCpuPkg/CommonFeature: Skip locking when the feature is disabled
> 
> FEATURE_CONTROL.Lock bit is controlled by feature
> CPU_FEATURE_LOCK_FEATURE_CONTROL_REGISTER. The commit 1ed649
> fixes
> a bug that when the feature is disabled, the Lock bit is cleared.
> But it's a security hole if the bit is cleared when booting OS.
> We can argue that platform needs to make sure the value
> of PcdCpuFeaturesUserConfiguration should be set properly to make
> sure feature CPU_FEATURE_LOCK_FEATURE_CONTROL_REGISTER is enabled.
> 
> But it's better to guarantee this in the generic core code.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Andrew Fish <afish@apple.com>
> Cc: Leif Lindholm <leif.lindholm@linaro.org>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> ---
>  UefiCpuPkg/Library/CpuCommonFeaturesLib/FeatureControl.c | 11 +--------
> --
>  1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/CpuCommonFeaturesLib/FeatureControl.c
> b/UefiCpuPkg/Library/CpuCommonFeaturesLib/FeatureControl.c
> index 631c836857..8c1eb5eb4f 100644
> --- a/UefiCpuPkg/Library/CpuCommonFeaturesLib/FeatureControl.c
> +++ b/UefiCpuPkg/Library/CpuCommonFeaturesLib/FeatureControl.c
> @@ -1,7 +1,7 @@
>  /** @file
>    Features in MSR_IA32_FEATURE_CONTROL register.
> 
> -  Copyright (c) 2017 - 2018, Intel Corporation. All rights reserved.<BR>
> +  Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
>    This program and the accompanying materials
>    are licensed and made available under the terms and conditions of the BSD
> License
>    which accompanies this distribution.  The full text of the license may be
> found at
> @@ -184,15 +184,6 @@ LockFeatureControlRegisterInitialize (
>  {
>    MSR_IA32_FEATURE_CONTROL_REGISTER    *MsrRegister;
> 
> -  //
> -  // When Lock Feature Control Register feature is disabled,
> -  // just skip the MSR lock bit setting.
> -  // The MSR lock bit is cleared by default and write-once in a boot.
> -  //
> -  if (!State) {
> -    return RETURN_SUCCESS;
> -  }
> -
>    //
>    // The scope of Lock bit in the MSR_IA32_FEATURE_CONTROL is core for
>    // below processor type, only program MSR_IA32_FEATURE_CONTROL for
> thread 0 in each
> --
> 2.16.1.windows.1
> 
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