diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c index 7e970f81d8ff..e1f224320102 100644 --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c @@ -39,6 +39,12 @@ /* This version can't take the spinlock, because it never returns */ static int rtas_stop_self_token = RTAS_UNKNOWN_SERVICE; +/* + * Record the CPU ids used on each nodes. + * Protected by cpu_add_remove_lock. + */ +static cpumask_var_t node_recorded_ids_map[MAX_NUMNODES]; + static void rtas_stop_self(void) { static struct rtas_args args; @@ -139,72 +145,148 @@ static void pseries_cpu_die(unsigned int cpu) paca_ptrs[cpu]->cpu_start = 0; } +/** + * find_cpu_id_range - found a linear ranger of @nthreads free CPU ids. + * @nthreads : the number of threads (cpu ids) + * @assigned_node : the node it belongs to or NUMA_NO_NODE if free ids from any + * node can be peek. + * @cpu_mask: the returned CPU mask. + * + * Returns 0 on success. + */ +static int find_cpu_id_range(unsigned int nthreads, int assigned_node, + cpumask_var_t *cpu_mask) +{ + cpumask_var_t candidate_mask; + unsigned int cpu, node; + int rc = -ENOSPC; + + if (!zalloc_cpumask_var(&candidate_mask, GFP_KERNEL)) + return -ENOMEM; + + cpumask_clear(*cpu_mask); + for (cpu = 0; cpu < nthreads; cpu++) + cpumask_set_cpu(cpu, *cpu_mask); + + BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask)); + + /* Get a bitmap of unoccupied slots. */ + cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask); + + if (assigned_node != NUMA_NO_NODE) { + /* + * Remove free ids previously assigned on the other nodes. We + * can walk only online nodes because once a node became online + * it is not turned offlined back. + */ + for_each_online_node(node) { + if (node == assigned_node) + continue; + cpumask_andnot(candidate_mask, candidate_mask, + node_recorded_ids_map[node]); + } + } + + if (cpumask_empty(candidate_mask)) + goto out; + + while (!cpumask_empty(*cpu_mask)) { + if (cpumask_subset(*cpu_mask, candidate_mask)) + /* Found a range where we can insert the new cpu(s) */ + break; + cpumask_shift_left(*cpu_mask, *cpu_mask, nthreads); + } + + if (!cpumask_empty(*cpu_mask)) + rc = 0; + +out: + free_cpumask_var(candidate_mask); + return rc; +} + /* * Update cpu_present_mask and paca(s) for a new cpu node. The wrinkle - * here is that a cpu device node may represent up to two logical cpus + * here is that a cpu device node may represent multiple logical cpus * in the SMT case. We must honor the assumption in other code that * the logical ids for sibling SMT threads x and y are adjacent, such * that x^1 == y and y^1 == x. */ static int pseries_add_processor(struct device_node *np) { - unsigned int cpu; - cpumask_var_t candidate_mask, tmp; - int err = -ENOSPC, len, nthreads, i; + int len, nthreads, node, cpu, assigned_node; + int rc = 0; + cpumask_var_t cpu_mask; const __be32 *intserv; intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); if (!intserv) return 0; - zalloc_cpumask_var(&candidate_mask, GFP_KERNEL); - zalloc_cpumask_var(&tmp, GFP_KERNEL); - nthreads = len / sizeof(u32); - for (i = 0; i < nthreads; i++) - cpumask_set_cpu(i, tmp); + + if (!alloc_cpumask_var(&cpu_mask, GFP_KERNEL)) + return -ENOMEM; + + /* + * Fetch from the DT nodes read by dlpar_configure_connector() the NUMA + * node id the added CPU belongs to. + */ + node = of_node_to_nid(np); + if (node < 0 || !node_possible(node)) + node = first_online_node; + + BUG_ON(node == NUMA_NO_NODE); + assigned_node = node; cpu_maps_update_begin(); - BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask)); - - /* Get a bitmap of unoccupied slots. */ - cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask); - if (cpumask_empty(candidate_mask)) { - /* If we get here, it most likely means that NR_CPUS is - * less than the partition's max processors setting. + rc = find_cpu_id_range(nthreads, node, &cpu_mask); + if (rc && nr_node_ids > 1) { + /* + * Try again, considering the free CPU ids from the other node. */ - printk(KERN_ERR "Cannot add cpu %pOF; this system configuration" - " supports %d logical cpus.\n", np, - num_possible_cpus()); - goto out_unlock; + node = NUMA_NO_NODE; + rc = find_cpu_id_range(nthreads, NUMA_NO_NODE, &cpu_mask); } - while (!cpumask_empty(tmp)) - if (cpumask_subset(tmp, candidate_mask)) - /* Found a range where we can insert the new cpu(s) */ - break; - else - cpumask_shift_left(tmp, tmp, nthreads); - - if (cpumask_empty(tmp)) { - printk(KERN_ERR "Unable to find space in cpu_present_mask for" - " processor %pOFn with %d thread(s)\n", np, - nthreads); - goto out_unlock; + if (rc) { + pr_err("Cannot add cpu %pOF; this system configuration" + " supports %d logical cpus.\n", np, num_possible_cpus()); + goto out; } - for_each_cpu(cpu, tmp) { + for_each_cpu(cpu, cpu_mask) { BUG_ON(cpu_present(cpu)); set_cpu_present(cpu, true); set_hard_smp_processor_id(cpu, be32_to_cpu(*intserv++)); } - err = 0; -out_unlock: + + /* Record the newly used CPU ids for the associate node. */ + cpumask_or(node_recorded_ids_map[assigned_node], + node_recorded_ids_map[assigned_node], cpu_mask); + + /* + * If node is set to NUMA_NO_NODE, CPU ids have be reused from + * another node, remove them from its mask. + */ + if (node == NUMA_NO_NODE) { + cpu = cpumask_first(cpu_mask); + pr_warn("Reusing free CPU ids %d-%d from another node\n", + cpu, cpu + nthreads - 1); + for_each_online_node(node) { + if (node == assigned_node) + continue; + cpumask_andnot(node_recorded_ids_map[node], + node_recorded_ids_map[node], + cpu_mask); + } + } + +out: cpu_maps_update_done(); - free_cpumask_var(candidate_mask); - free_cpumask_var(tmp); - return err; + free_cpumask_var(cpu_mask); + return rc; } /* @@ -908,6 +990,7 @@ static struct notifier_block pseries_smp_nb = { static int __init pseries_cpu_hotplug_init(void) { int qcss_tok; + unsigned int node; #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE ppc_md.cpu_probe = dlpar_cpu_probe; @@ -929,8 +1012,18 @@ static int __init pseries_cpu_hotplug_init(void) smp_ops->cpu_die = pseries_cpu_die; /* Processors can be added/removed only on LPAR */ - if (firmware_has_feature(FW_FEATURE_LPAR)) + if (firmware_has_feature(FW_FEATURE_LPAR)) { + for_each_node(node) { + alloc_bootmem_cpumask_var(&node_recorded_ids_map[node]); + + /* Record ids of CPU added at boot time */ + cpumask_or(node_recorded_ids_map[node], + node_recorded_ids_map[node], + node_to_cpumask_map[node]); + } + of_reconfig_notifier_register(&pseries_smp_nb); + } return 0; }