Clear CR4.CET bit before restoring MSR IA32_S_CET.
Backup/restore MSR IA32_U_CET in SMI.

Signed-off-by: Sheng Wei <w.sh...@intel.com>
Cc: Eric Dong <eric.d...@intel.com>
Cc: Ray Ni <ray...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Wu Jiaxin <jiaxin...@intel.com>
Cc: Tan Dun <dun....@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm | 53 ++++++++++++---
 UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm  | 69 ++++++++++++++++----
 2 files changed, 98 insertions(+), 24 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm 
b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm
index 19de5f614e..68332e2c3f 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm
@@ -16,18 +16,19 @@
 %include "StuffRsbNasm.inc"
 %include "Nasm.inc"
 
+%define MSR_IA32_U_CET                     0x6A0
 %define MSR_IA32_S_CET                     0x6A2
-%define   MSR_IA32_CET_SH_STK_EN             0x1
-%define   MSR_IA32_CET_WR_SHSTK_EN           0x2
-%define   MSR_IA32_CET_ENDBR_EN              0x4
-%define   MSR_IA32_CET_LEG_IW_EN             0x8
-%define   MSR_IA32_CET_NO_TRACK_EN           0x10
-%define   MSR_IA32_CET_SUPPRESS_DIS          0x20
-%define   MSR_IA32_CET_SUPPRESS              0x400
-%define   MSR_IA32_CET_TRACKER               0x800
+%define MSR_IA32_CET_SH_STK_EN             0x1
+%define MSR_IA32_CET_WR_SHSTK_EN           0x2
+%define MSR_IA32_CET_ENDBR_EN              0x4
+%define MSR_IA32_CET_LEG_IW_EN             0x8
+%define MSR_IA32_CET_NO_TRACK_EN           0x10
+%define MSR_IA32_CET_SUPPRESS_DIS          0x20
+%define MSR_IA32_CET_SUPPRESS              0x400
+%define MSR_IA32_CET_TRACKER               0x800
 %define MSR_IA32_PL0_SSP                   0x6A4
 
-%define CR4_CET                            0x800000
+%define CR4_CET_BIT                        23
 
 %define MSR_IA32_MISC_ENABLE 0x1A0
 %define MSR_EFER      0xc0000080
@@ -214,11 +215,21 @@ ASM_PFX(mPatchCetSupported):
     push    edx
     push    eax
 
+    mov     ecx, MSR_IA32_U_CET
+    rdmsr
+    push    edx
+    push    eax
+
     mov     ecx, MSR_IA32_PL0_SSP
     rdmsr
     push    edx
     push    eax
 
+    mov     ecx, MSR_IA32_U_CET
+    xor     eax, eax
+    xor     edx, edx
+    wrmsr
+
     mov     ecx, MSR_IA32_S_CET
     mov     eax, MSR_IA32_CET_SH_STK_EN
     xor     edx, edx
@@ -276,6 +287,11 @@ CetDone:
     cmp     al, 0
     jz      CetDone2
 
+    mov     ecx, MSR_IA32_S_CET
+    xor     eax, eax
+    xor     edx, edx
+    wrmsr
+
     mov     eax, 0x668
     mov     cr4, eax       ; disable CET
 
@@ -284,10 +300,15 @@ CetDone:
     pop     edx
     wrmsr
 
-    mov     ecx, MSR_IA32_S_CET
+    mov     ecx, MSR_IA32_U_CET
     pop     eax
     pop     edx
     wrmsr
+
+    mov     ecx, MSR_IA32_S_CET
+    pop     eax
+    pop     edx
+    mov     ebx, eax
 CetDone2:
 
     mov     eax, ASM_PFX(mXdSupported)
@@ -305,6 +326,18 @@ CetDone2:
 .7:
 
     StuffRsb32
+
+    mov     eax, ASM_PFX(mCetSupported)
+    mov     al, [eax]
+    cmp     al, 0
+    jz      CetDone3
+
+    mov     ecx, MSR_IA32_S_CET
+    mov     eax, ebx
+    xor     edx, edx
+    wrmsr
+CetDone3:
+
     rsm
 
 ASM_PFX(gcSmiHandlerSize): DW $ - _SmiEntryPoint
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm 
b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm
index d302ca8d01..007fbff640 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm
@@ -20,19 +20,20 @@
 ; Variables referenced by C code
 ;
 
+%define MSR_IA32_U_CET                     0x6A0
 %define MSR_IA32_S_CET                     0x6A2
-%define   MSR_IA32_CET_SH_STK_EN             0x1
-%define   MSR_IA32_CET_WR_SHSTK_EN           0x2
-%define   MSR_IA32_CET_ENDBR_EN              0x4
-%define   MSR_IA32_CET_LEG_IW_EN             0x8
-%define   MSR_IA32_CET_NO_TRACK_EN           0x10
-%define   MSR_IA32_CET_SUPPRESS_DIS          0x20
-%define   MSR_IA32_CET_SUPPRESS              0x400
-%define   MSR_IA32_CET_TRACKER               0x800
+%define MSR_IA32_CET_SH_STK_EN             0x1
+%define MSR_IA32_CET_WR_SHSTK_EN           0x2
+%define MSR_IA32_CET_ENDBR_EN              0x4
+%define MSR_IA32_CET_LEG_IW_EN             0x8
+%define MSR_IA32_CET_NO_TRACK_EN           0x10
+%define MSR_IA32_CET_SUPPRESS_DIS          0x20
+%define MSR_IA32_CET_SUPPRESS              0x400
+%define MSR_IA32_CET_TRACKER               0x800
 %define MSR_IA32_PL0_SSP                   0x6A4
 %define MSR_IA32_INTERRUPT_SSP_TABLE_ADDR  0x6A8
 
-%define CR4_CET                            0x800000
+%define CR4_CET_BIT                        23
 
 %define MSR_IA32_MISC_ENABLE 0x1A0
 %define MSR_EFER      0xc0000080
@@ -230,6 +231,11 @@ ASM_PFX(mPatchCetSupported):
     push    rdx
     push    rax
 
+    mov     ecx, MSR_IA32_U_CET
+    rdmsr
+    push    rdx
+    push    rax
+
     mov     ecx, MSR_IA32_PL0_SSP
     rdmsr
     push    rdx
@@ -240,6 +246,11 @@ ASM_PFX(mPatchCetSupported):
     push    rdx
     push    rax
 
+    mov     ecx, MSR_IA32_U_CET
+    xor     eax, eax
+    xor     edx, edx
+    wrmsr
+
     mov     ecx, MSR_IA32_S_CET
     mov     eax, MSR_IA32_CET_SH_STK_EN
     xor     edx, edx
@@ -316,13 +327,20 @@ CpuSmmDebugExitAbsAddr:
     add     rsp, 0x200
 
     mov     rax, strict qword 0        ;    mov     rax, ASM_PFX(mCetSupported)
-mCetSupportedAbsAddr:
+mCetSupportedAbsAddr1:
     mov     al, [rax]
     cmp     al, 0
     jz      CetDone2
 
-    mov     eax, 0x668
-    mov     cr4, rax       ; disable CET
+    mov     ecx, MSR_IA32_S_CET
+    xor     eax, eax
+    xor     edx, edx
+    wrmsr
+
+    ; clear CR4.CET bit
+    mov     rax, cr4
+    btr     rax, CR4_CET_BIT
+    mov     cr4, rax
 
     mov     ecx, MSR_IA32_INTERRUPT_SSP_TABLE_ADDR
     pop     rax
@@ -334,10 +352,15 @@ mCetSupportedAbsAddr:
     pop     rdx
     wrmsr
 
-    mov     ecx, MSR_IA32_S_CET
+    mov     ecx, MSR_IA32_U_CET
     pop     rax
     pop     rdx
     wrmsr
+
+    mov     ecx, MSR_IA32_S_CET
+    pop     rax
+    pop     rdx
+    mov     ebx, eax
 CetDone2:
 
     mov     rax, strict qword 0         ;       lea     rax, 
[ASM_PFX(mXdSupported)]
@@ -356,6 +379,19 @@ mXdSupportedAbsAddr:
 .1:
 
     StuffRsb64
+
+    mov     rax, strict qword 0        ;    mov     rax, ASM_PFX(mCetSupported)
+mCetSupportedAbsAddr2:
+    mov     al, [rax]
+    cmp     al, 0
+    jz      CetDone3
+
+    mov     ecx, MSR_IA32_S_CET
+    mov     eax, ebx
+    xor     edx, edx
+    wrmsr
+CetDone3:
+
     rsm
 
 ASM_PFX(gcSmiHandlerSize)    DW      $ - _SmiEntryPoint
@@ -391,6 +427,11 @@ ASM_PFX(PiSmmCpuSmiEntryFixupAddress):
     mov    qword [rcx - 8], rax
 
     lea    rax, [ASM_PFX(mCetSupported)]
-    lea    rcx, [mCetSupportedAbsAddr]
+    lea    rcx, [mCetSupportedAbsAddr1]
     mov    qword [rcx - 8], rax
+
+    lea    rax, [ASM_PFX(mCetSupported)]
+    lea    rcx, [mCetSupportedAbsAddr2]
+    mov    qword [rcx - 8], rax
+
     ret
-- 
2.26.2.windows.1



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