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| author | Thomas Gleixner <tglx@linutronix.de> | 2024-02-13 22:06:10 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2024-02-15 22:07:45 +0100 |
| commit | 3205c9833d69b97e8694efe3e193312dea4c571f (patch) | |
| tree | 8d15d470f15dcf272831365b1844c0ad522b8daf /arch/x86/kernel/cpu/topology.c | |
| parent | x86/cpu/topology: Use topology logical mapping mechanism (diff) | |
| download | linux-3205c9833d69b97e8694efe3e193312dea4c571f.tar.gz linux-3205c9833d69b97e8694efe3e193312dea4c571f.zip | |
x86/cpu/topology: Retrieve cores per package from topology bitmaps
Similar to other sizing information the number of cores per package can be
established from the topology bitmap.
Provide a function for retrieving that information and replace the buggy
hack in the CPUID evaluation with it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20240213210252.956858282@linutronix.de
Diffstat (limited to 'arch/x86/kernel/cpu/topology.c')
| -rw-r--r-- | arch/x86/kernel/cpu/topology.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c index 29759b4f7213..7db9df50ada8 100644 --- a/arch/x86/kernel/cpu/topology.c +++ b/arch/x86/kernel/cpu/topology.c @@ -257,6 +257,49 @@ int topology_get_logical_id(u32 apicid, enum x86_topology_domains at_level) } EXPORT_SYMBOL_GPL(topology_get_logical_id); +/** + * topology_unit_count - Retrieve the count of specified units at a given topology domain level + * @apicid: The APIC ID which specifies the search range + * @which_units: The domain level specifying the units to count + * @at_level: The domain level at which @which_units have to be counted + * + * This returns the number of possible units according to the enumerated + * information. + * + * E.g. topology_count_units(apicid, TOPO_CORE_DOMAIN, TOPO_PKG_DOMAIN) + * counts the number of possible cores in the package to which @apicid + * belongs. + * + * @at_level must obviously be greater than @which_level to produce useful + * results. If @at_level is equal to @which_units the result is + * unsurprisingly 1. If @at_level is less than @which_units the results + * is by definition undefined and the function returns 0. + */ +unsigned int topology_unit_count(u32 apicid, enum x86_topology_domains which_units, + enum x86_topology_domains at_level) +{ + /* Remove the bits below @at_level to get the proper level ID of @apicid */ + unsigned int lvlid = topo_apicid(apicid, at_level); + unsigned int id, end, cnt = 0; + + if (lvlid >= MAX_LOCAL_APIC) + return 0; + if (!test_bit(lvlid, apic_maps[at_level].map)) + return 0; + if (which_units > at_level) + return 0; + if (which_units == at_level) + return 1; + + /* Calculate the exclusive end */ + end = lvlid + (1U << x86_topo_system.dom_shifts[at_level]); + /* Unfortunately there is no bitmap_weight_range() */ + for (id = find_next_bit(apic_maps[which_units].map, end, lvlid); + id < end; id = find_next_bit(apic_maps[which_units].map, end, ++id)) + cnt++; + return cnt; +} + #ifdef CONFIG_ACPI_HOTPLUG_CPU /** * topology_hotplug_apic - Handle a physical hotplugged APIC after boot |