From: Zhang Rui rui.zhang@intel.com
[ 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 | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c index 696309749d62..37d48ab3d077 100644 --- a/arch/x86/kernel/cpu/topology.c +++ b/arch/x86/kernel/cpu/topology.c @@ -141,7 +141,7 @@ int detect_extended_topology(struct cpuinfo_x86 *c) sub_index++; }
- core_select_mask = (~(-1 << core_plus_mask_width)) >> ht_mask_width; + core_select_mask = (~(-1 << pkg_mask_width)) >> ht_mask_width; die_select_mask = (~(-1 << die_plus_mask_width)) >> core_plus_mask_width;