UefiCpuPkg/MpInitLib: fix feature test for Extended Topology CPUID leaf

[mirror_edk2.git] / UefiCpuPkg / Library / MpInitLib / X64 / MpFuncs.nasm

diff --git a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
index aaabb50c54684493e1b5f9c2b4e98225f2c19efe..e7e7d8086dd01e989ab6114c983b9abd37d04513 100644 (file)
--- a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
+++ b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
@@ -158,21 +158,24 @@ GetApicId:
     mov        eax, 0\r
     cpuid\r
     cmp        eax, 0bh\r
-    jnb        X2Apic\r
+    jb         NoX2Apic             ; CPUID level below CPUID_EXTENDED_TOPOLOGY\r
+\r
+    mov        eax, 0bh\r
+    xor        ecx, ecx\r
+    cpuid\r
+    test       ebx, 0ffffh\r
+    jz         NoX2Apic             ; CPUID.0BH:EBX[15:0] is zero\r
+\r
+    ; Processor is x2APIC capable; 32-bit x2APIC ID is already in EDX\r
+    jmp        GetProcessorNumber\r
+\r
+NoX2Apic:\r
     ; Processor is not x2APIC capable, so get 8-bit APIC ID\r
     mov        eax, 1\r
     cpuid\r
     shr        ebx, 24\r
     mov        edx, ebx\r
-    jmp        GetProcessorNumber\r
 \r
-X2Apic:\r
-    ; Processor is x2APIC capable, so get 32-bit x2APIC ID\r
-    mov        eax, 0bh\r
-    xor        ecx, ecx\r
-    cpuid                   \r
-    ; edx save x2APIC ID\r
-    \r
 GetProcessorNumber:\r
     ;\r
     ; Get processor number for this AP\r