On 4/29/19 8:30 PM, Michael D Kinney wrote:
Use PcdSpeculationBarrierType in the x86 implementation
of SpeculationBarrier() to select between AsmLfence(),
AsmCpuid(), and no operation.
Cc: Liming Gao <liming....@intel.com>
Signed-off-by: Michael D Kinney <michael.d.kin...@intel.com>
---
MdePkg/Library/BaseLib/BaseLib.inf | 1 +
MdePkg/Library/BaseLib/X86SpeculationBarrier.c | 8 ++++++--
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/MdePkg/Library/BaseLib/BaseLib.inf
b/MdePkg/Library/BaseLib/BaseLib.inf
index 533e83e0b2..3586beb0ab 100644
--- a/MdePkg/Library/BaseLib/BaseLib.inf
+++ b/MdePkg/Library/BaseLib/BaseLib.inf
@@ -394,6 +394,7 @@ [Pcd]
gEfiMdePkgTokenSpaceGuid.PcdMaximumAsciiStringLength ##
SOMETIMES_CONSUMES
gEfiMdePkgTokenSpaceGuid.PcdMaximumUnicodeStringLength ##
SOMETIMES_CONSUMES
gEfiMdePkgTokenSpaceGuid.PcdControlFlowEnforcementPropertyMask ##
SOMETIMES_CONSUMES
+ gEfiMdePkgTokenSpaceGuid.PcdSpeculationBarrierType ##
SOMETIMES_CONSUMES
[FeaturePcd]
gEfiMdePkgTokenSpaceGuid.PcdVerifyNodeInList ## CONSUMES
diff --git a/MdePkg/Library/BaseLib/X86SpeculationBarrier.c
b/MdePkg/Library/BaseLib/X86SpeculationBarrier.c
index 8e5f983bb8..b28fd8de9b 100644
--- a/MdePkg/Library/BaseLib/X86SpeculationBarrier.c
+++ b/MdePkg/Library/BaseLib/X86SpeculationBarrier.c
@@ -1,7 +1,7 @@
/** @file
SpeculationBarrier() function for IA32 and x64.
- Copyright (C) 2018, Intel Corporation. All rights reserved.<BR>
+ Copyright (C) 2018 - 2019, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
@@ -22,5 +22,9 @@ SpeculationBarrier (
VOID
)
{
- AsmLfence ();
+ if (PcdGet8 (PcdSpeculationBarrierType) == 0x01) {
+ AsmLfence ();
+ } else if (PcdGet8 (PcdSpeculationBarrierType) == 0x02) {
+ AsmCpuid (0x01, NULL, NULL, NULL, NULL);
+ }
}
Looks good. I'm not a maintainer, but FWIW:
Reviewed-by: Brian J. Johnson <brian.john...@hpe.com>
--
Brian J. Johnson
Enterprise X86 Lab
Hewlett Packard Enterprise
brian.john...@hpe.com
+1 651 683 7521 Office
Eagan, MN
hpe.com
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