The following commit has been merged into the x86/apic branch of tip:
Commit-ID: 3205c9833d69b97e8694efe3e193312dea4c571f
Gitweb: https://git.kernel.org/tip/3205c9833d69b97e8694efe3e193312dea4c571f
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Tue, 13 Feb 2024 22:06:10 +01:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 15 Feb 2024 22:07:45 +01:00
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@xxxxxxxxxxxxx>
Tested-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
Tested-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
Link: https://lore.kernel.org/r/20240213210252.956858282@xxxxxxxxxxxxx
---
arch/x86/kernel/cpu/topology.c | 43 ++++++++++++++++++++++++++-
arch/x86/kernel/cpu/topology.h | 11 +++++++-
arch/x86/kernel/cpu/topology_common.c | 18 +----------
3 files changed, 57 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index 29759b4..7db9df5 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 2a3c838..3732629 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 c21a387..a2c3f8f 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
|