Re: [PATCH v1] UefiCpuPkg: Add PCD to control SMRR enable & SmmFeatureControl support

["Ni, Ray" <ray.ni@intel.com>]

> -  //
> -  // Check CPUID(CPUID_VERSION_INFO).EDX[12] for MTRR capability
> -  //
> -  if ((RegEdx & BIT12) != 0) {
> -    //
> -    // Check MTRR_CAP MSR bit 11 for SMRR support
> -    //
> -    if ((AsmReadMsr64 (SMM_FEATURES_LIB_IA32_MTRR_CAP) & BIT11) != 0)
> {
> -      mSmrrSupported = TRUE;

1. can we keep the logic but just replace the above line as "ASSERT (FeaturePcdGet (PcdSmrrEnable));"?

>      if ((FeatureControl & BIT3) == 0) {
> -      if ((FeatureControl & BIT0) == 0) {
> +      if (((FeatureControl & BIT0) == 0) && (FeaturePcdGet (PcdSmrrEnable)))
> {
>          AsmWriteMsr64 (SMM_FEATURES_LIB_IA32_FEATURE_CONTROL,
> FeatureControl | BIT3);
>        } else {
> -        mSmrrSupported = FALSE;
> +        ASSERT (!FeaturePcdGet (PcdSmrrEnable));

2. If PcdSmrrEnable is TRUE but the FeatureControl MSR is locked (BIT0 is set),
  above assertion will be hit. We may need to reconsider the code logic.

> -    {
> -      //
> -      // Check to see if the CPU supports the SMM Code Access Check feature
> -      // Do not access this MSR unless the CPU supports the
> SmmRegFeatureControl
> -      //
> -      if ((AsmReadMsr64 (SMM_FEATURES_LIB_IA32_MCA_CAP) &
> SMM_CODE_ACCESS_CHK_BIT) != 0) {
> -        mSmmFeatureControlSupported = TRUE;

3. can we keep the logic but just replace the above line as "ASSERT (FeaturePcdGet (PcdSmmFeatureControlEnable))"?