From: Thomas Gleixner Date: Tue, 13 Feb 2024 21:06:10 +0000 (+0100) Subject: x86/cpu/topology: Retrieve cores per package from topology bitmaps X-Git-Tag: v6.9-rc1~202^2~9 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3205c9833d69b97e8694efe3e193312dea4c571f;p=thirdparty%2Fkernel%2Flinux.git 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 Tested-by: Michael Kelley Tested-by: Sohil Mehta Link: https://lore.kernel.org/r/20240213210252.956858282@linutronix.de --- diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c index 29759b4f72136..7db9df50ada8d 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 diff --git a/arch/x86/kernel/cpu/topology.h b/arch/x86/kernel/cpu/topology.h index 2a3c838b6044d..37326297f80c8 100644 --- a/arch/x86/kernel/cpu/topology.h +++ b/arch/x86/kernel/cpu/topology.h @@ -53,4 +53,15 @@ static inline void topology_update_dom(struct topo_scan *tscan, enum x86_topolog tscan->dom_ncpus[dom] = ncpus; } +#ifdef CONFIG_X86_LOCAL_APIC +unsigned int topology_unit_count(u32 apicid, enum x86_topology_domains which_units, + enum x86_topology_domains at_level); +#else +static inline unsigned int topology_unit_count(u32 apicid, enum x86_topology_domains which_units, + enum x86_topology_domains at_level) +{ + return 1; +} +#endif + #endif /* ARCH_X86_TOPOLOGY_H */ diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c index c21a3871a8709..a2c3f8f5886d7 100644 --- a/arch/x86/kernel/cpu/topology_common.c +++ b/arch/x86/kernel/cpu/topology_common.c @@ -155,25 +155,15 @@ static void topo_set_ids(struct topo_scan *tscan) c->topo.core_id = (apicid & topo_domain_mask(TOPO_PKG_DOMAIN)) >> x86_topo_system.dom_shifts[TOPO_SMT_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_DIEGRP_DOMAIN] = 24; 24 / 2 = 12 !! - * - * Cannot be fixed without further topology enumeration changes. - */ - tscan->c->x86_max_cores = tscan->dom_ncpus[TOPO_DIEGRP_DOMAIN] >> - x86_topo_system.dom_shifts[TOPO_SMT_DOMAIN]; -} - void cpu_parse_topology(struct cpuinfo_x86 *c) { unsigned int dom, cpu = smp_processor_id(); @@ -201,7 +191,6 @@ void cpu_parse_topology(struct cpuinfo_x86 *c) } topo_set_ids(&tscan); - topo_set_max_cores(&tscan); } void __init cpu_init_topology(struct cpuinfo_x86 *c) @@ -223,7 +212,6 @@ void __init cpu_init_topology(struct cpuinfo_x86 *c) } topo_set_ids(&tscan); - topo_set_max_cores(&tscan); /* * AMD systems have Nodes per package which cannot be mapped to