2 files changed, 12 insertions, 0 deletions
diff --git a/OvmfPkg/ResetVector/Ia32/AmdSev.asm b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
index aa95d06ead..87d81b01e2 100644
--- a/OvmfPkg/ResetVector/Ia32/AmdSev.asm
+++ b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
@@ -171,6 +171,9 @@ CheckSevFeatures:
     bt        eax, 0
     jnc       NoSev
 
+    ; Set the work area header to indicate that the SEV is enabled
+    mov     byte[WORK_AREA_GUEST_TYPE], 1
+
     ; Check for SEV-ES memory encryption feature:
     ; CPUID  Fn8000_001F[EAX] - Bit 3
     ;   CPUID raises a #VC exception if running as an SEV-ES guest
@@ -257,6 +260,11 @@ SevExit:
 IsSevEsEnabled:
     xor       eax, eax
 
+    ; During CheckSevFeatures, the WORK_AREA_GUEST_TYPE is set
+    ; to 1 if SEV is enabled.
+    cmp       byte[WORK_AREA_GUEST_TYPE], 1
+    jne       SevEsDisabled
+
     ; During CheckSevFeatures, the SEV_ES_WORK_AREA was set to 1 if
     ; SEV-ES is enabled.
     cmp       byte[SEV_ES_WORK_AREA], 1
diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
index eacdb69ddb..f688909f1c 100644
--- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm
+++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
@@ -42,6 +42,10 @@ BITS    32
 ;
 SetCr3ForPageTables64:
 
+    ; Clear the WorkArea header. The SEV probe routines will populate the
+    ; work area when detected.
+    mov     byte[WORK_AREA_GUEST_TYPE], 0
+
     OneTimeCall   CheckSevFeatures
     xor     edx, edx
     test    eax, eax