[PATCH] powerpc/topology: Support coregroup in PowerNV
flat view
STALE132d
From: Srikar Dronamraju <hidden>
Date: 2026-05-24 01:01:17
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
Coregroup support was only available on PowerPC on PowerVM LPARs.
However if firmware were to expose coregroup-id to the kernel, then
coregroup can even be supported on PowerNV too.
PowerPC Linux kernel will detect support for coregroup by looking at the
primary_domain_index. Till now on PowerNV systems, primary_domain_index
has been the penultimate domain in cpunode ibm,associativity device-tree
property. This would be taken as hint that coregroup support is not
available in the firmware.
If on PowerNV systems, primary_domain_index is not the penultimate
domain in cpunode ibm,associativity device-tree property, then it would
be taken as a hint that coregroup support is available in the firmware.
This logic makes it compatible with PowerVM Systems, where
primary_domain_index is not the penultimate domain in cpunode
ibm,associativity device-tree property.
$ lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 480
On-line CPU(s) list: 0-479
Thread(s) per core: 8
Core(s) per socket: 15
Socket(s): 4
NUMA node(s): 4
Model: 2.0 (pvr 0080 0200)
Model name: POWER10, altivec supported
CPU max MHz: 3249.0000
CPU min MHz: 3249.0000
L1d cache: 32K
L1i cache: 48K
L2 cache: 1024K
L3 cache: 4096K
NUMA node0 CPU(s): 0-119
NUMA node1 CPU(s): 120-239
NUMA node2 CPU(s): 240-359
NUMA node3 CPU(s): 360-479
with-out patched firmware and/or Linux-kernel
---------------------------------------------
$ grep -h -r . /sys/devices/system/cpu/*/topology/die_id |sort | uniq -c | sort -n -r
120 27
120 18
120 9
120 0
$ grep -h -r . /sys/devices/system/cpu/*/topology/die_cpus_list |sort | uniq -c | sort -n -r
120 360-479
120 240-359
120 120-239
120 0-119
with patched firmware and Linux-kernel
--------------------------------------
grep -h -r . /sys/devices/system/cpu/*/topology/die_id |sort | uniq -c | sort -n -r
64 6
64 4
64 2
64 0
56 7
56 5
56 3
56 1
grep -h -r . /sys/devices/system/cpu/*/topology/die_cpus_list |sort | uniq -c | sort -n -r
64 360-375,392-407,424-439,456-471
64 240-255,272-287,296-311,328-343
64 120-135,152-167,184-199,208-223
64 0-15,32-47,64-79,88-103
56 376-391,408-423,440-455,472-479
56 256-271,288-295,312-327,344-359
56 16-31,48-63,80-87,104-119
56 136-151,168-183,200-207,224-239
Observation:
Without the patched kernel and/or skiboot, die-id and numa were same.
With patched kernel and/or skiboot, we see 2 die-id per node.
Signed-off-by: Srikar Dronamraju <redacted>
---
arch/powerpc/include/asm/topology.h | 15 +++--
arch/powerpc/mm/numa.c | 87 ++++++++++++++++++++++-------
2 files changed, 73 insertions(+), 29 deletions(-)
diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index 66ed5fe1b718..568e6bc55726 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h@@ -71,6 +71,7 @@ extern void map_cpu_to_node(int cpu, int node); extern void unmap_cpu_from_node(unsigned long cpu); #endif /* CONFIG_HOTPLUG_CPU */ +extern int cpu_to_coregroup_id(int cpu); #else static inline int early_cpu_to_node(int cpu) { return 0; }
@@ -107,14 +108,6 @@ static inline void map_cpu_to_node(int cpu, int node) {} static inline void unmap_cpu_from_node(unsigned long cpu) {} #endif /* CONFIG_HOTPLUG_CPU */ #endif /* CONFIG_SMP */ - -#endif /* CONFIG_NUMA */ - -#if defined(CONFIG_NUMA) && defined(CONFIG_PPC_SPLPAR) -void find_and_update_cpu_nid(int cpu); -extern int cpu_to_coregroup_id(int cpu); -#else -static inline void find_and_update_cpu_nid(int cpu) {} static inline int cpu_to_coregroup_id(int cpu) { #ifdef CONFIG_SMP
@@ -124,6 +117,12 @@ static inline int cpu_to_coregroup_id(int cpu) #endif } +#endif /* CONFIG_NUMA */ + +#if defined(CONFIG_NUMA) && defined(CONFIG_PPC_SPLPAR) +void find_and_update_cpu_nid(int cpu); +#else +static inline void find_and_update_cpu_nid(int cpu) {} #endif /* CONFIG_NUMA && CONFIG_PPC_SPLPAR */ #include <asm-generic/topology.h>
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index f4cf3ae036de..9b45cc9e1f27 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c@@ -432,7 +432,7 @@ static void __init initialize_form2_numa_distance_lookup_table(void) static int __init find_primary_domain_index(void) { - int index; + int index = -1; struct device_node *root; /*
@@ -502,12 +502,9 @@ static int __init find_primary_domain_index(void) distance_ref_points_depth = MAX_DISTANCE_REF_POINTS; } - of_node_put(root); - return index; - err: of_node_put(root); - return -1; + return index; } static void __init get_n_mem_cells(int *n_addr_cells, int *n_size_cells)
@@ -892,12 +889,32 @@ static int __init numa_setup_drmem_lmb(struct drmem_lmb *lmb, return 0; } +/* + * If hierarchy extends beyond primary_domain_index + 1, then next + * level corresponds to coregroup. + */ +static int detect_and_enable_coregroup(const __be32 *associativity, int index) +{ + if (!associativity) + return -1; + + if (!index) { + index = of_read_number(associativity, 1); + + if (index > primary_domain_index + 1) + coregroup_enabled = 1; + else + index = -1; + } + return index; +} + static int __init parse_numa_properties(void) { struct device_node *memory, *pci; - int default_nid = 0; - unsigned long i; + int default_nid = 0, index = 0; const __be32 *associativity; + unsigned long i; if (numa_enabled == 0) { pr_warn("disabled by user\n");
@@ -930,7 +947,6 @@ static int __init parse_numa_properties(void) */ for_each_present_cpu(i) { __be32 vphn_assoc[VPHN_ASSOC_BUFSIZE]; - struct device_node *cpu; int nid = NUMA_NO_NODE; memset(vphn_assoc, 0, VPHN_ASSOC_BUFSIZE * sizeof(__be32));
@@ -938,7 +954,10 @@ static int __init parse_numa_properties(void) if (__vphn_get_associativity(i, vphn_assoc) == 0) { nid = associativity_to_nid(vphn_assoc); initialize_form1_numa_distance(vphn_assoc); + if (!index) + index = detect_and_enable_coregroup(vphn_assoc, index); } else { + struct device_node *cpu; /* * Don't fall back to default_nid yet -- we will plug
@@ -951,6 +970,8 @@ static int __init parse_numa_properties(void) associativity = of_get_associativity(cpu); if (associativity) { nid = associativity_to_nid(associativity); + if (!index) + index = detect_and_enable_coregroup(associativity, index); initialize_form1_numa_distance(associativity); } of_node_put(cpu);
@@ -1431,9 +1452,26 @@ void find_and_update_cpu_nid(int cpu) pr_debug("%s:%d cpu %d nid %d\n", __func__, __LINE__, cpu, new_nid); } +static int topology_update_init(void) +{ + topology_inited = 1; + return 0; +} +device_initcall(topology_update_init); + +#else +static long vphn_get_associativity(unsigned long cpu, + __be32 *associativity) +{ + return -1; +} +#endif /* CONFIG_PPC_SPLPAR */ + int cpu_to_coregroup_id(int cpu) { - __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0}; + int coregroup_id = cpu_to_core_id(cpu); + struct device_node *cpunode = NULL; + const __be32 *associativity; int index; if (cpu < 0 || cpu > nr_cpu_ids)
@@ -1442,24 +1480,31 @@ int cpu_to_coregroup_id(int cpu) if (!coregroup_enabled) goto out; - if (!firmware_has_feature(FW_FEATURE_VPHN)) - goto out; + if (firmware_has_feature(FW_FEATURE_VPHN)) { + __be32 tmp[VPHN_ASSOC_BUFSIZE] = {0}; - if (vphn_get_associativity(cpu, associativity)) + if (vphn_get_associativity(cpu, tmp)) + goto out; + + associativity = tmp; + + } else { + cpunode = of_get_cpu_node(cpu, NULL); + if (!cpunode) + goto out; + + associativity = of_get_associativity(cpunode); + } + if (!associativity) goto out; index = of_read_number(associativity, 1); if (index > primary_domain_index + 1) - return of_read_number(&associativity[index - 1], 1); + coregroup_id = of_read_number(&associativity[index - 1], 1); out: - return cpu_to_core_id(cpu); -} + if (cpunode) + of_node_put(cpunode); -static int topology_update_init(void) -{ - topology_inited = 1; - return 0; + return coregroup_id; } -device_initcall(topology_update_init); -#endif /* CONFIG_PPC_SPLPAR */
--
2.43.0