UefiCpuPkg/PiSmmCpu: Always set WP in CR0

So that we can use write-protection for code later.

It is REPOST.
It includes suggestion from Michael Kinney <michael.d.kinney@intel.com>:
- "For IA32 assembly, can we combine into a single OR instruction that
  sets both page enable and WP?"
- "For X64, does it make sense to use single OR instruction instead of 2
  BTS instructions as well?"

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: "Yao, Jiewen" <jiewen.yao@intel.com>
Suggested-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Cc: "Fan, Jeff" <jeff.fan@intel.com>
Cc: "Kinney, Michael D" <michael.d.kinney@intel.com>
Cc: "Laszlo Ersek" <lersek@redhat.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19068 6f19259b-4bc3-4df7-8a09-765794883524

UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.S

@@ -123,7 +123,7 @@ L11:
 L12:                                       # as cr4.PGE is not set here, refresh cr3
     movl    %eax, %cr4                     # in PreModifyMtrrs() to flush TLB.
     movl    %cr0, %ebx
-    orl     $0x080000000, %ebx             # enable paging
+    orl     $0x080010000, %ebx             # enable paging + WP
     movl    %ebx, %cr0
     leal    DSC_OFFSET(%edi),%ebx
     movw    DSC_DS(%ebx),%ax

UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.asm

@@ -129,7 +129,7 @@ gSmiCr3     DD      ?
 @@:                                     ; as cr4.PGE is not set here, refresh cr3
     mov     cr4, eax                    ; in PreModifyMtrrs() to flush TLB.
     mov     ebx, cr0
-    or      ebx, 080000000h             ; enable paging
+    or      ebx, 080010000h             ; enable paging + WP
     mov     cr0, ebx
     lea     ebx, [edi + DSC_OFFSET]
     mov     ax, [ebx + DSC_DS]

UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.S

@@ -144,7 +144,7 @@ Base:
     orb     $1,%ah
     wrmsr
     movq    %cr0, %rbx
-    btsl    $31, %ebx
+    orl     $0x080010000, %ebx          # enable paging + WP
     movq    %rbx, %cr0
     retf
 LongMode:                               # long mode (64-bit code) starts here

UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.asm

@@ -140,7 +140,7 @@ Base:
     or      ah, 1
     wrmsr
     mov     rbx, cr0
-    bts     ebx, 31
+    or      ebx, 080010000h            ; enable paging + WP
     mov     cr0, rbx
     retf
 @LongMode:                              ; long mode (64-bit code) starts here