Bit SMM_Code_Access_Chk (SMM-RO) in MSR_SMM_MCA_CAP is defined in SDM. If set to 1 indicates that the SMM code access restriction is supported and the MSR_SMM_FEATURE_CONTROL is supported.
If this bit is not set, we needn't to access register SmmFetureControl. Otherwise, #GP exception may happen. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Jeff Fan <[email protected]> CC: Michael Kinney <[email protected]> CC: Jiewen Yao <[email protected]> --- UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c index de681c0..532ac09 100644 --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c @@ -1309,9 +1309,9 @@ ConfigSmmCodeAccessCheckOnCurrentProcessor ( NewSmmFeatureControlMsr = SmmFeatureControlMsr; if (mSmmCodeAccessCheckEnable) { NewSmmFeatureControlMsr |= SMM_CODE_CHK_EN_BIT; - } - if (FeaturePcdGet (PcdCpuSmmFeatureControlMsrLock)) { - NewSmmFeatureControlMsr |= SMM_FEATURE_CONTROL_LOCK_BIT; + if (FeaturePcdGet (PcdCpuSmmFeatureControlMsrLock)) { + NewSmmFeatureControlMsr |= SMM_FEATURE_CONTROL_LOCK_BIT; + } } // @@ -1354,13 +1354,6 @@ ConfigSmmCodeAccessCheck ( // if ((AsmReadMsr64 (EFI_MSR_SMM_MCA_CAP) & SMM_CODE_ACCESS_CHK_BIT) == 0) { mSmmCodeAccessCheckEnable = FALSE; - } - - // - // If the SMM Code Access Check feature is disabled and the Feature Control MSR - // is not being locked, then no additional work is required - // - if (!mSmmCodeAccessCheckEnable && !FeaturePcdGet (PcdCpuSmmFeatureControlMsrLock)) { return; } -- 1.9.5.msysgit.0 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
