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>
Sat, 29 Oct 2022 08:12:55 +0000 (10:12 +0200)
commitc439cafce8cfbc50d3faa0d707577e27bfaa5fbd
treef1e4aa5c4c6aa167720b7fcfcce718ddecdfaf78
parentd31f4bc225967fdd41957533e53f48cbaf897878
x86/topology: Fix duplicated core ID within a package

commit 71eac7063698b7d7b8fafb1683ac24a034541141 upstream.

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/x86/kernel/cpu/topology.c