[Patch 2/4] UefiCpuPkg/RegisterCpuFeaturesLib: Supports detect before set new value logic.

["Dong, Eric" <eric.dong@intel.com>]

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

Supports new logic which detect current value before set new value.
Only set new value when current value not same as new value.

Signed-off-by: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
---
 .../CpuFeaturesInitialize.c                   | 141 ++++++++++++------
 1 file changed, 93 insertions(+), 48 deletions(-)

diff --git a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
index fb0535edd6..2b8816e1d8 100644
--- a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
+++ b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
@@ -744,6 +744,58 @@ LibWaitForSemaphore (
              ) != Value);
 }
 
+/**
+  Read / write CR value.
+
+  @param[in]      CrIndex         The CR index which need to read/write.
+  @param[in]      Read            Read or write. TRUE is read.
+  @param[in,out]  CrValue         CR value.
+
+  @retval    EFI_SUCCESS means read/write success, else return EFI_UNSUPPORTED.
+**/
+UINTN
+ReadWriteCr (
+  IN     UINT32       CrIndex,
+  IN     BOOLEAN      Read,
+  IN OUT UINTN        *CrValue
+  )
+{
+  switch (CrIndex) {
+  case 0:
+    if (Read) {
+      *CrValue = AsmReadCr0 ();
+    } else {
+      AsmWriteCr0 (*CrValue);
+    }
+    break;
+  case 2:
+    if (Read) {
+      *CrValue = AsmReadCr2 ();
+    } else {
+      AsmWriteCr2 (*CrValue);
+    }
+    break;
+  case 3:
+    if (Read) {
+      *CrValue = AsmReadCr3 ();
+    } else {
+      AsmWriteCr3 (*CrValue);
+    }
+    break;
+  case 4:
+    if (Read) {
+      *CrValue = AsmReadCr4 ();
+    } else {
+      AsmWriteCr4 (*CrValue);
+    }
+    break;
+  default:
+    return EFI_UNSUPPORTED;;
+  }
+
+  return EFI_SUCCESS;
+}
+
 /**
   Initialize the CPU registers from a register table.
 
@@ -773,6 +825,8 @@ ProgramProcessorRegister (
   UINTN                     ProcessorIndex;
   UINTN                     ValidThreadCount;
   UINT32                    *ValidCoreCountPerPackage;
+  EFI_STATUS                Status;
+  UINT64                    CurrentValue;
 
   //
   // Traverse Register Table of this logical processor
@@ -791,60 +845,51 @@ ProgramProcessorRegister (
     // The specified register is Control Register
     //
     case ControlRegister:
-      switch (RegisterTableEntry->Index) {
-      case 0:
-        Value = AsmReadCr0 ();
-        Value = (UINTN) BitFieldWrite64 (
-                          Value,
-                          RegisterTableEntry->ValidBitStart,
-                          RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1,
-                          RegisterTableEntry->Value
-                          );
-        AsmWriteCr0 (Value);
-        break;
-      case 2:
-        Value = AsmReadCr2 ();
-        Value = (UINTN) BitFieldWrite64 (
-                          Value,
-                          RegisterTableEntry->ValidBitStart,
-                          RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1,
-                          RegisterTableEntry->Value
-                          );
-        AsmWriteCr2 (Value);
-        break;
-      case 3:
-        Value = AsmReadCr3 ();
-        Value = (UINTN) BitFieldWrite64 (
-                          Value,
-                          RegisterTableEntry->ValidBitStart,
-                          RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1,
-                          RegisterTableEntry->Value
-                          );
-        AsmWriteCr3 (Value);
-        break;
-      case 4:
-        Value = AsmReadCr4 ();
-        Value = (UINTN) BitFieldWrite64 (
-                          Value,
-                          RegisterTableEntry->ValidBitStart,
-                          RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1,
-                          RegisterTableEntry->Value
-                          );
-        AsmWriteCr4 (Value);
-        break;
-      case 8:
-        //
-        //  Do we need to support CR8?
-        //
-        break;
-      default:
-        break;
+      Status = ReadWriteCr(RegisterTableEntry->Index, TRUE, &Value);
+      if (EFI_ERROR (Status)) {
+        return;
+      }
+      if (RegisterTableEntry->DetectIt) {
+        CurrentValue = BitFieldRead64(
+                         Value,
+                         RegisterTableEntry->ValidBitStart,
+                         RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1
+                         );
+        if (CurrentValue == RegisterTableEntry->Value) {
+          return;
+        }
       }
+      Value = (UINTN) BitFieldWrite64 (
+                        Value,
+                        RegisterTableEntry->ValidBitStart,
+                        RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1,
+                        RegisterTableEntry->Value
+                        );
+      ReadWriteCr (RegisterTableEntry->Index, FALSE, &Value);
       break;
+
     //
     // The specified register is Model Specific Register
     //
     case Msr:
+      if (RegisterTableEntry->DetectIt) {
+        Value = (UINTN)AsmReadMsr64 (RegisterTableEntry->Index);
+        if (RegisterTableEntry->ValidBitLength >= 64) {
+          if (Value == RegisterTableEntry->Value) {
+            return;
+          }
+        } else {
+          CurrentValue = BitFieldRead64(
+                           Value,
+                           RegisterTableEntry->ValidBitStart,
+                           RegisterTableEntry->ValidBitStart + RegisterTableEntry->ValidBitLength - 1
+                           );
+          if (CurrentValue == RegisterTableEntry->Value) {
+            return;
+          }
+        }
+      }
+
       if (RegisterTableEntry->ValidBitLength >= 64) {
         //
         // If length is not less than 64 bits, then directly write without reading
-- 
2.21.0.windows.1