Messages in this thread Patch in this message | | | From | Thomas Gleixner <> | Subject | [patch 48/53] x86/cpu/topology: Retrieve cores per package from topology bitmaps | Date | Mon, 7 Aug 2023 15:53:48 +0200 (CEST) |
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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> --- arch/x86/kernel/cpu/topology.c | 43 ++++++++++++++++++++++++++++++++++ arch/x86/kernel/cpu/topology.h | 3 ++ arch/x86/kernel/cpu/topology_common.c | 18 ++------------ 3 files changed, 49 insertions(+), 15 deletions(-)
--- a/arch/x86/kernel/cpu/topology.c +++ b/arch/x86/kernel/cpu/topology.c @@ -227,6 +227,49 @@ int topology_get_logical_id(u32 apicid, } 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 --- a/arch/x86/kernel/cpu/topology.h +++ b/arch/x86/kernel/cpu/topology.h @@ -50,4 +50,7 @@ static inline void topology_update_dom(s extern const char *domain_names[TOPO_MAX_DOMAIN]; +unsigned int topology_unit_count(u32 apicid, enum x86_topology_domains which_units, + enum x86_topology_domains at_level); + #endif /* ARCH_X86_TOPOLOGY_H */ --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -154,25 +154,15 @@ static void topo_set_ids(struct topo_sca /* Relative core ID */ c->topo.core_id = topo_relative_domain_id(apicid, TOPO_CORE_DOMAIN); + /* Maximum number of cores on this package */ + c->x86_max_cores = topology_unit_count(apicid, TOPO_CORE_DOMAIN, TOPO_PKG_DOMAIN); + c->topo.amd_node_id = tscan->amd_node_id; if (c->x86_vendor == X86_VENDOR_AMD) cpu_topology_fixup_amd(tscan); } -static void topo_set_max_cores(struct topo_scan *tscan) -{ - /* - * Bug compatible for now. This is broken on hybrid systems: - * 8 cores SMT + 8 cores w/o SMT - * tscan.dom_ncpus[TOPO_CORE_DOMAIN] = 24; 24 / 2 = 12 !! - * - * Cannot be fixed without further topology enumeration changes. - */ - tscan->c->x86_max_cores = tscan->dom_ncpus[TOPO_CORE_DOMAIN] >> - x86_topo_system.dom_shifts[TOPO_SMT_DOMAIN]; -} - void cpu_parse_topology(struct cpuinfo_x86 *c) { unsigned int dom, cpu = smp_processor_id(); @@ -198,7 +188,6 @@ void cpu_parse_topology(struct cpuinfo_x } topo_set_ids(&tscan); - topo_set_max_cores(&tscan); } void __init cpu_init_topology(struct cpuinfo_x86 *c) @@ -220,7 +209,6 @@ void __init cpu_init_topology(struct cpu } topo_set_ids(&tscan); - topo_set_max_cores(&tscan); /* * AMD systems have Nodes per package which cannot be mapped to
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