diff options
| -rw-r--r-- | UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c b/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c index aa4eb11181..c0a8475833 100644 --- a/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c +++ b/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c @@ -1294,11 +1294,12 @@ GetProcessorLocationByApicId ( NULL
);
//
- // If CPUID.(EAX=0BH, ECX=0H):EBX returns zero and maximum input value for
- // basic CPUID information is greater than 0BH, then CPUID.0BH leaf is not
- // supported on that processor.
+ // Quoting Intel SDM:
+ // Software must detect the presence of CPUID leaf 0BH by
+ // verifying (a) the highest leaf index supported by CPUID is >=
+ // 0BH, and (b) CPUID.0BH:EBX[15:0] reports a non-zero value.
//
- if (ExtendedTopologyEbx.Uint32 != 0) {
+ if (ExtendedTopologyEbx.Bits.LogicalProcessors != 0) {
TopologyLeafSupported = TRUE;
//
@@ -1424,6 +1425,7 @@ GetProcessorLocation2ByApicId ( )
{
CPUID_EXTENDED_TOPOLOGY_EAX ExtendedTopologyEax;
+ CPUID_EXTENDED_TOPOLOGY_EBX ExtendedTopologyEbx;
CPUID_EXTENDED_TOPOLOGY_ECX ExtendedTopologyEcx;
UINT32 MaxStandardCpuIdIndex;
UINT32 Index;
@@ -1436,10 +1438,19 @@ GetProcessorLocation2ByApicId ( }
//
- // Get max index of CPUID
+ // Quoting Intel SDM:
+ // Software must detect the presence of CPUID leaf 1FH by verifying
+ // (a) the highest leaf index supported by CPUID is >= 1FH, and (b)
+ // CPUID.1FH:EBX[15:0] reports a non-zero value.
//
AsmCpuid (CPUID_SIGNATURE, &MaxStandardCpuIdIndex, NULL, NULL, NULL);
if (MaxStandardCpuIdIndex < CPUID_V2_EXTENDED_TOPOLOGY) {
+ ExtendedTopologyEbx.Bits.LogicalProcessors = 0;
+ } else {
+ AsmCpuidEx (CPUID_V2_EXTENDED_TOPOLOGY, 0, NULL, &ExtendedTopologyEbx.Uint32, NULL, NULL);
+ }
+
+ if (ExtendedTopologyEbx.Bits.LogicalProcessors == 0) {
if (Die != NULL) {
*Die = 0;
}
|