tree 1885760d16e623b3b224099c30edcdd10813c526
parent f5c2f253a7dc8eced1c616ff9c79c6d196c86350
author Ronak Kanabar <ronak.kanabar@intel.com> 1645677569 +0530
committer Felix Held <felix-coreboot@felixheld.de> 1655213851 +0000

soc/intel/common: Remove use of CPUID_EXTENDED_CPU_TOPOLOGY_V2

In x86 processor as per Software Developer's manual there are 2 ways to
get CPU topology by querying the processor. BIOS can use CPUID
instruction using CPUID_EXTENDED_CPU_TOPOLOGY (0x0B) as input or
CPUID_EXTENDED_CPU_TOPOLOGY_V2 (0x1F) as an input. Both will return
valid CPU topology data.

While CPUID_EXTENDED_CPU_TOPOLOGY (0x0B) returns data related to number
of threads, core and package, CPUID_EXTENDED_CPU_TOPOLOGY_V2 (0x1F)
provides more granular information regarding Die, package etc.

coreboot uses V2 to in order to query and return CPU topology data as of
now since that's the highest instruction of CPUID which is supported,
there is a mismatch in the way FSP processes the data.

FSP queries coreboot MP services to get CPU topology data which uses
structure which is either compatible with CPUID_EXTENDED_CPU_TOPOLOGY or
CPUID_EXTENDED_CPU_TOPOLOGY_V2. Since coreboot returns V2 data in
structure which is expecting data for CPUID_EXTENDED_CPU_TOPOLOGY, there
is hang observed on ADL_N CPUs.

To solve this problem coreboot should assign CPUID_EXTENDED_CPU_TOPOLOGY
data to processor_info_buffer->Location structure so remove use of
CPUID_EXTENDED_CPU_TOPOLOGY_V2

Ref EDK2 code: https://github.com/tianocore/edk2/tree/edk2-stable202202
Files:
MdePkg/Include/Protocol/MpService.h#L182
UefiCpuPkg/Library/MpInitLib/MpLib.c#L2127
UefiCpuPkg/Library/MpInitLib/MpLib.c#L2120
Ref doc: Software Developer’s Manual volume 3 CH 8.9

BUG=b:220652104
TEST=Build and boot ADL-N RVP with debug FSP and verify CPU topology
value and observe system boots (no hang).

Change-Id: I1e6832fb03fcc59d33df0ba1664019727185d10a
Signed-off-by: Ronak Kanabar <ronak.kanabar@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62323
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Subrata Banik <subratabanik@google.com>