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

["Dong, Eric" <eric.dong@intel.com>]

Reviewed-by: Eric Dong <eric.dong@intel.com>

> -----Original Message-----
> From: Ni, Ruiyu
> Sent: Tuesday, November 13, 2018 3:43 PM
> To: edk2-devel@lists.01.org; 'Andrew Fish (afish@apple.com)'
> <afish@apple.com>; Leif Lindholm <leif.lindholm@linaro.org>; Kinney,
> Michael D <michael.d.kinney@intel.com>; Laszlo Ersek <lersek@redhat.com>
> Cc: Dong, Eric <eric.dong@intel.com>
> Subject: RE: [edk2] [PATCH] UefiCpuPkg/CommonFeature: Always set
> FEATURE_CONTROL.Lock
> 
> 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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