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UefiCpuPkg/RegisterCpuFeaturesLib: Supports test then write new value logic.

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REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2040

Supports new logic which test current value before write new value.
Only write new value when current value not same as new value.

Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Dong, Eric 2019-08-16 11:57:29 +08:00 committed by Ray Ni
parent 6b3645ade5
commit 95cfe6c247
1 changed files with 30 additions and 1 deletions
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31
UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
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@ -826,6 +826,7 @@ ProgramProcessorRegister (
UINTN ValidThreadCount;
UINT32 *ValidCoreCountPerPackage;
EFI_STATUS Status;
UINT64 CurrentValue;
//
// Traverse Register Table of this logical processor
@ -848,7 +849,16 @@ ProgramProcessorRegister (
if (EFI_ERROR (Status)) {
break;
}
if (RegisterTableEntry->TestThenWrite) {
CurrentValue = BitFieldRead64 (
Value,
RegisterTableEntry->ValidBitStart,
RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1
);
if (CurrentValue == RegisterTableEntry->Value) {
break;
}
}
Value = (UINTN) BitFieldWrite64 (
Value,
RegisterTableEntry->ValidBitStart,
@ -857,10 +867,29 @@ ProgramProcessorRegister (
);
ReadWriteCr (RegisterTableEntry->Index, FALSE, &Value);
break;
//
// The specified register is Model Specific Register
//
case Msr:
if (RegisterTableEntry->TestThenWrite) {
Value = (UINTN)AsmReadMsr64 (RegisterTableEntry->Index);
if (RegisterTableEntry->ValidBitLength >= 64) {
if (Value == RegisterTableEntry->Value) {
break;
}
} else {
CurrentValue = BitFieldRead64 (
Value,
RegisterTableEntry->ValidBitStart,
RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1
);
if (CurrentValue == RegisterTableEntry->Value) {
break;
}
}
}
if (RegisterTableEntry->ValidBitLength >= 64) {
//
// If length is not less than 64 bits, then directly write without reading