From fd1dd8568c78c594540990eaa4fbe37fdd3b1839 Mon Sep 17 00:00:00 2001
From: Sheng Wei <w.sheng@intel.com>
Date: Thu, 9 Nov 2023 16:41:05 +0800
Subject: UefiCpuPkg: Only change CR4.CET bit for enable and disable CET.

Signed-off-by: Sheng Wei <w.sheng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Wu Jiaxin <jiaxin.wu@intel.com>
Cc: Tan Dun <dun.tan@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm | 10 +++++++---
 UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm  | 10 +++++++---
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm
index d17b1a7dd4..87a31b71a9 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm
@@ -237,7 +237,9 @@ CetInterruptDone:
     bts     ecx, 16                     ; set WP
     mov     cr0, ecx
 
-    mov     eax, 0x668 | CR4_CET
+    ; set CR4.CET bit for enable CET
+    mov     eax, cr4
+    bts     eax, CR4_CET_BIT
     mov     cr4, eax
 
     setssbsy
@@ -264,8 +266,10 @@ CetDone:
     cmp     al, 0
     jz      CetDone2
 
-    mov     eax, 0x668
-    mov     cr4, eax       ; disable CET
+    ; clear CR4.CET bit for disable CET
+    mov     eax, cr4
+    btr     eax, CR4_CET_BIT
+    mov     cr4, eax
 
     mov     ecx, MSR_IA32_PL0_SSP
     pop     eax
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm
index f72013a718..e7c51e6950 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm
@@ -263,7 +263,9 @@ CetInterruptDone:
     bts     ecx, 16                     ; set WP
     mov     cr0, rcx
 
-    mov     eax, 0x668 | CR4_CET
+    ; set CR4.CET bit for enable CET
+    mov     rax, cr4
+    bts     rax, CR4_CET_BIT
     mov     cr4, rax
 
     setssbsy
@@ -308,8 +310,10 @@ mCetSupportedAbsAddr:
     cmp     al, 0
     jz      CetDone2
 
-    mov     eax, 0x668
-    mov     cr4, rax       ; disable CET
+    ; clear CR4.CET bit for disable CET
+    mov     rax, cr4
+    btr     rax, CR4_CET_BIT
+    mov     cr4, rax
 
     mov     ecx, MSR_IA32_INTERRUPT_SSP_TABLE_ADDR
     pop     rax
-- 
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