commit 85588389222a3636baf0f9ed8227f2434af4c3f9
author Ruiyu Ni <ruiyu.ni@intel.com> Tue Nov 13 15:34:33 2018 +0800
committer Ruiyu Ni <ruiyu.ni@intel.com> Wed Nov 14 11:02:48 2018 +0800
tree 5a948f9bad2ab4fc7c74bc7ec47f6757aa06a106
parent bd224a5dad4d32f5224f5e8ae998b70e4621dcd3

UefiCpuPkg/CommonFeature: Always set FEATURE_CONTROL.Lock

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1305

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

diff --git a/UefiCpuPkg/Library/CpuCommonFeaturesLib/FeatureControl.c b/UefiCpuPkg/Library/CpuCommonFeaturesLib/FeatureControl.c
index 631c836..8c1eb5e 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

@@ -185,15 +185,6 @@
   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

   // core.