x86/topology: Fix duplicated core ID within a package
authorZhang Rui <rui.zhang@intel.com>
Fri, 14 Oct 2022 09:01:47 +0000 (17:01 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 10 Nov 2022 17:14:15 +0000 (18:14 +0100)
commit5bdbccc79c86424fef1960de76abab9e83cfbdc9
tree0bc8797c04cc6e9f8781ebf64f5f40e08fc69e62
parent6c31fc028a657e8d53cec5127a39a35cce6dba08
x86/topology: Fix duplicated core ID within a package

[ Upstream commit 71eac7063698b7d7b8fafb1683ac24a034541141 ]

Today, core ID is assumed to be unique within each package.

But an AlderLake-N platform adds a Module level between core and package,
Linux excludes the unknown modules bits from the core ID, resulting in
duplicate core ID's.

To keep core ID unique within a package, Linux must include all APIC-ID
bits for known or unknown levels above the core and below the package
in the core ID.

It is important to understand that core ID's have always come directly
from the APIC-ID encoding, which comes from the BIOS. Thus there is no
guarantee that they start at 0, or that they are contiguous.
As such, naively using them for array indexes can be problematic.

[ dhansen: un-known -> unknown ]

Fixes: 7745f03eb395 ("x86/topology: Add CPUID.1F multi-die/package support")
Suggested-by: Len Brown <len.brown@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20221014090147.1836-5-rui.zhang@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
arch/x86/kernel/cpu/topology.c