Eric, Ray, Rahul -- can you ACK this patch please? I intend to merge it in one or two days.
Thanks Laszlo On 10/17/23 13:42, Laszlo Ersek wrote: > On 10/17/23 13:28, Gerd Hoffmann wrote: >> Checking the max cpuid leaf is not enough to figure whenever >> CPUID_V2_EXTENDED_TOPOLOGY is supported. Intel SDM says: >> >> 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. >> >> The same is true for CPUID leaf 0BH. >> >> This patch adds the EBX check to GetProcessorLocation2ByApicId(). The >> patch also fixes the existing check in GetProcessorLocationByApicId() to >> be in line with the spec by looking at bits 15:0. The comments are >> updated with a quote from the Intel SDM. >> >> Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2241388 >> Signed-off-by: Gerd Hoffmann <kra...@redhat.com> >> --- >> .../BaseXApicX2ApicLib/BaseXApicX2ApicLib.c | 21 ++++++++++++++----- >> 1 file changed, 16 insertions(+), 5 deletions(-) >> >> diff --git a/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c >> b/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c >> index aa4eb11181f6..c0a847583330 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; >> } > > Reviewed-by: Laszlo Ersek <ler...@redhat.com> > > Thanks! > Laszlo > > > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#110000): https://edk2.groups.io/g/devel/message/110000 Mute This Topic: https://groups.io/mt/102015439/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/leave/9847357/21656/1706620634/xyzzy [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
