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Message-Id: <d5b7a976-b0a6-a4d6-c062-75d65d8a6eac@linux.vnet.ibm.com>
Date: Mon, 28 Aug 2017 11:25:05 -0500
From: Nathan Fontenot <nfont@...ux.vnet.ibm.com>
To: Michael Bringmann <mwb@...ux.vnet.ibm.com>,
linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Cc: John Allen <jallen@...ux.vnet.ibm.com>
Subject: Re: [PATCH V10 1/2] powerpc/numa: Update CPU topology when VPHN
enabled
On 08/24/2017 05:07 PM, Michael Bringmann wrote:
>
> powerpc/numa: Correct the currently broken capability to set the
> topology for shared CPUs in LPARs. At boot time for shared CPU
> lpars, the topology for each shared CPU is set to node zero, however,
> this is now updated correctly using the Virtual Processor Home Node
> (VPHN) capabilities information provided by the pHyp.
>
> Also, update initialization checks for device-tree attributes to
> independently recognize PRRN or VPHN usage.
>
> Finally, try to distinguish the VPHN code from the NUMA code better,
> and move relevant functions to another file.
You need to split the move of the vphn code to a different file into
a separate patch. With thia all in one patch it is really difficult
to distinguish what pieces are code changes and what is just moving
code around.
-Nathan
>
> Signed-off-by: Michael Bringmann <mwb@...ux.vnet.ibm.com>
> ---
> Changes in V10:
> -- Reorganize VPHN code to distinguish it from NUMA processing
> ---
> arch/powerpc/include/asm/topology.h | 8
> arch/powerpc/mm/numa.c | 503 ----------------------
> arch/powerpc/mm/vphn.c | 586 ++++++++++++++++++++++++++
> arch/powerpc/mm/vphn.h | 4
> arch/powerpc/platforms/pseries/hotplug-cpu.c | 2
> 5 files changed, 609 insertions(+), 494 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
> index dc4e159..600e1c6 100644
> --- a/arch/powerpc/include/asm/topology.h
> +++ b/arch/powerpc/include/asm/topology.h
> @@ -98,6 +98,14 @@ static inline int prrn_is_enabled(void)
> }
> #endif /* CONFIG_NUMA && CONFIG_PPC_SPLPAR */
>
> +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_NEED_MULTIPLE_NODES)
> +#if defined(CONFIG_PPC_SPLPAR)
> +extern int timed_topology_update(int nsecs);
> +#else
> +#define timed_topology_update(nsecs) 0
> +#endif /* CONFIG_PPC_SPLPAR */
> +#endif /* CONFIG_HOTPLUG_CPU || CONFIG_NEED_MULTIPLE_NODES */
> +
> #include <asm-generic/topology.h>
>
> #ifdef CONFIG_SMP
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index b95c584..73427e290 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -29,6 +29,7 @@
> #include <linux/seq_file.h>
> #include <linux/uaccess.h>
> #include <linux/slab.h>
> +#include <linux/sched.h>
> #include <asm/cputhreads.h>
> #include <asm/sparsemem.h>
> #include <asm/prom.h>
> @@ -41,8 +42,12 @@
> #include <asm/setup.h>
> #include <asm/vdso.h>
>
> +#include "vphn.h"
> +
> static int numa_enabled = 1;
>
> +bool topology_updates_enabled = true;
> +
> static char *cmdline __initdata;
>
> static int numa_debug;
> @@ -60,8 +65,7 @@
> static int n_mem_addr_cells, n_mem_size_cells;
> static int form1_affinity;
>
> -#define MAX_DISTANCE_REF_POINTS 4
> -static int distance_ref_points_depth;
> +int distance_ref_points_depth;
> static const __be32 *distance_ref_points;
> static int distance_lookup_table[MAX_NUMNODES][MAX_DISTANCE_REF_POINTS];
>
> @@ -142,12 +146,12 @@ static void reset_numa_cpu_lookup_table(void)
> numa_cpu_lookup_table[cpu] = -1;
> }
>
> -static void update_numa_cpu_lookup_table(unsigned int cpu, int node)
> +void update_numa_cpu_lookup_table(unsigned int cpu, int node)
> {
> numa_cpu_lookup_table[cpu] = node;
> }
>
> -static void map_cpu_to_node(int cpu, int node)
> +void map_cpu_to_node(int cpu, int node)
> {
> update_numa_cpu_lookup_table(cpu, node);
>
> @@ -158,7 +162,7 @@ static void map_cpu_to_node(int cpu, int node)
> }
>
> #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_PPC_SPLPAR)
> -static void unmap_cpu_from_node(unsigned long cpu)
> +void unmap_cpu_from_node(unsigned long cpu)
> {
> int node = numa_cpu_lookup_table[cpu];
>
> @@ -233,7 +237,7 @@ static void initialize_distance_lookup_table(int nid,
> /* Returns nid in the range [0..MAX_NUMNODES-1], or -1 if no useful numa
> * info is found.
> */
> -static int associativity_to_nid(const __be32 *associativity)
> +int associativity_to_nid(const __be32 *associativity)
> {
> int nid = -1;
>
> @@ -957,8 +961,6 @@ static int __init early_numa(char *p)
> }
> early_param("numa", early_numa);
>
> -static bool topology_updates_enabled = true;
> -
> static int __init early_topology_updates(char *p)
> {
> if (!p)
> @@ -1135,488 +1137,3 @@ u64 memory_hotplug_max(void)
> return max(hot_add_drconf_memory_max(), memblock_end_of_DRAM());
> }
> #endif /* CONFIG_MEMORY_HOTPLUG */
> -
> -/* Virtual Processor Home Node (VPHN) support */
> -#ifdef CONFIG_PPC_SPLPAR
> -
> -#include "vphn.h"
> -
> -struct topology_update_data {
> - struct topology_update_data *next;
> - unsigned int cpu;
> - int old_nid;
> - int new_nid;
> -};
> -
> -static u8 vphn_cpu_change_counts[NR_CPUS][MAX_DISTANCE_REF_POINTS];
> -static cpumask_t cpu_associativity_changes_mask;
> -static int vphn_enabled;
> -static int prrn_enabled;
> -static void reset_topology_timer(void);
> -
> -/*
> - * Store the current values of the associativity change counters in the
> - * hypervisor.
> - */
> -static void setup_cpu_associativity_change_counters(void)
> -{
> - int cpu;
> -
> - /* The VPHN feature supports a maximum of 8 reference points */
> - BUILD_BUG_ON(MAX_DISTANCE_REF_POINTS > 8);
> -
> - for_each_possible_cpu(cpu) {
> - int i;
> - u8 *counts = vphn_cpu_change_counts[cpu];
> - volatile u8 *hypervisor_counts = lppaca[cpu].vphn_assoc_counts;
> -
> - for (i = 0; i < distance_ref_points_depth; i++)
> - counts[i] = hypervisor_counts[i];
> - }
> -}
> -
> -/*
> - * The hypervisor maintains a set of 8 associativity change counters in
> - * the VPA of each cpu that correspond to the associativity levels in the
> - * ibm,associativity-reference-points property. When an associativity
> - * level changes, the corresponding counter is incremented.
> - *
> - * Set a bit in cpu_associativity_changes_mask for each cpu whose home
> - * node associativity levels have changed.
> - *
> - * Returns the number of cpus with unhandled associativity changes.
> - */
> -static int update_cpu_associativity_changes_mask(void)
> -{
> - int cpu;
> - cpumask_t *changes = &cpu_associativity_changes_mask;
> -
> - for_each_possible_cpu(cpu) {
> - int i, changed = 0;
> - u8 *counts = vphn_cpu_change_counts[cpu];
> - volatile u8 *hypervisor_counts = lppaca[cpu].vphn_assoc_counts;
> -
> - for (i = 0; i < distance_ref_points_depth; i++) {
> - if (hypervisor_counts[i] != counts[i]) {
> - counts[i] = hypervisor_counts[i];
> - changed = 1;
> - }
> - }
> - if (changed) {
> - cpumask_or(changes, changes, cpu_sibling_mask(cpu));
> - cpu = cpu_last_thread_sibling(cpu);
> - }
> - }
> -
> - return cpumask_weight(changes);
> -}
> -
> -/*
> - * Retrieve the new associativity information for a virtual processor's
> - * home node.
> - */
> -static long hcall_vphn(unsigned long cpu, __be32 *associativity)
> -{
> - long rc;
> - long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};
> - u64 flags = 1;
> - int hwcpu = get_hard_smp_processor_id(cpu);
> -
> - rc = plpar_hcall9(H_HOME_NODE_ASSOCIATIVITY, retbuf, flags, hwcpu);
> - vphn_unpack_associativity(retbuf, associativity);
> -
> - return rc;
> -}
> -
> -static long vphn_get_associativity(unsigned long cpu,
> - __be32 *associativity)
> -{
> - long rc;
> -
> - rc = hcall_vphn(cpu, associativity);
> -
> - switch (rc) {
> - case H_FUNCTION:
> - printk(KERN_INFO
> - "VPHN is not supported. Disabling polling...\n");
> - stop_topology_update();
> - break;
> - case H_HARDWARE:
> - printk(KERN_ERR
> - "hcall_vphn() experienced a hardware fault "
> - "preventing VPHN. Disabling polling...\n");
> - stop_topology_update();
> - }
> -
> - return rc;
> -}
> -
> -/*
> - * Update the CPU maps and sysfs entries for a single CPU when its NUMA
> - * characteristics change. This function doesn't perform any locking and is
> - * only safe to call from stop_machine().
> - */
> -static int update_cpu_topology(void *data)
> -{
> - struct topology_update_data *update;
> - unsigned long cpu;
> -
> - if (!data)
> - return -EINVAL;
> -
> - cpu = smp_processor_id();
> -
> - for (update = data; update; update = update->next) {
> - int new_nid = update->new_nid;
> - if (cpu != update->cpu)
> - continue;
> -
> - unmap_cpu_from_node(cpu);
> - map_cpu_to_node(cpu, new_nid);
> - set_cpu_numa_node(cpu, new_nid);
> - set_cpu_numa_mem(cpu, local_memory_node(new_nid));
> - vdso_getcpu_init();
> - }
> -
> - return 0;
> -}
> -
> -static int update_lookup_table(void *data)
> -{
> - struct topology_update_data *update;
> -
> - if (!data)
> - return -EINVAL;
> -
> - /*
> - * Upon topology update, the numa-cpu lookup table needs to be updated
> - * for all threads in the core, including offline CPUs, to ensure that
> - * future hotplug operations respect the cpu-to-node associativity
> - * properly.
> - */
> - for (update = data; update; update = update->next) {
> - int nid, base, j;
> -
> - nid = update->new_nid;
> - base = cpu_first_thread_sibling(update->cpu);
> -
> - for (j = 0; j < threads_per_core; j++) {
> - update_numa_cpu_lookup_table(base + j, nid);
> - }
> - }
> -
> - return 0;
> -}
> -
> -/*
> - * Update the node maps and sysfs entries for each cpu whose home node
> - * has changed. Returns 1 when the topology has changed, and 0 otherwise.
> - *
> - * cpus_locked says whether we already hold cpu_hotplug_lock.
> - */
> -int numa_update_cpu_topology(bool cpus_locked)
> -{
> - unsigned int cpu, sibling, changed = 0;
> - struct topology_update_data *updates, *ud;
> - __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
> - cpumask_t updated_cpus;
> - struct device *dev;
> - int weight, new_nid, i = 0;
> -
> - if (!prrn_enabled && !vphn_enabled)
> - return 0;
> -
> - weight = cpumask_weight(&cpu_associativity_changes_mask);
> - if (!weight)
> - return 0;
> -
> - updates = kzalloc(weight * (sizeof(*updates)), GFP_KERNEL);
> - if (!updates)
> - return 0;
> -
> - cpumask_clear(&updated_cpus);
> -
> - for_each_cpu(cpu, &cpu_associativity_changes_mask) {
> - /*
> - * If siblings aren't flagged for changes, updates list
> - * will be too short. Skip on this update and set for next
> - * update.
> - */
> - if (!cpumask_subset(cpu_sibling_mask(cpu),
> - &cpu_associativity_changes_mask)) {
> - pr_info("Sibling bits not set for associativity "
> - "change, cpu%d\n", cpu);
> - cpumask_or(&cpu_associativity_changes_mask,
> - &cpu_associativity_changes_mask,
> - cpu_sibling_mask(cpu));
> - cpu = cpu_last_thread_sibling(cpu);
> - continue;
> - }
> -
> - /* Use associativity from first thread for all siblings */
> - vphn_get_associativity(cpu, associativity);
> - new_nid = associativity_to_nid(associativity);
> - if (new_nid < 0 || !node_online(new_nid))
> - new_nid = first_online_node;
> -
> - if (new_nid == numa_cpu_lookup_table[cpu]) {
> - cpumask_andnot(&cpu_associativity_changes_mask,
> - &cpu_associativity_changes_mask,
> - cpu_sibling_mask(cpu));
> - cpu = cpu_last_thread_sibling(cpu);
> - continue;
> - }
> -
> - for_each_cpu(sibling, cpu_sibling_mask(cpu)) {
> - ud = &updates[i++];
> - ud->cpu = sibling;
> - ud->new_nid = new_nid;
> - ud->old_nid = numa_cpu_lookup_table[sibling];
> - cpumask_set_cpu(sibling, &updated_cpus);
> - if (i < weight)
> - ud->next = &updates[i];
> - }
> - cpu = cpu_last_thread_sibling(cpu);
> - }
> -
> - pr_debug("Topology update for the following CPUs:\n");
> - if (cpumask_weight(&updated_cpus)) {
> - for (ud = &updates[0]; ud; ud = ud->next) {
> - pr_debug("cpu %d moving from node %d "
> - "to %d\n", ud->cpu,
> - ud->old_nid, ud->new_nid);
> - }
> - }
> -
> - /*
> - * In cases where we have nothing to update (because the updates list
> - * is too short or because the new topology is same as the old one),
> - * skip invoking update_cpu_topology() via stop-machine(). This is
> - * necessary (and not just a fast-path optimization) since stop-machine
> - * can end up electing a random CPU to run update_cpu_topology(), and
> - * thus trick us into setting up incorrect cpu-node mappings (since
> - * 'updates' is kzalloc()'ed).
> - *
> - * And for the similar reason, we will skip all the following updating.
> - */
> - if (!cpumask_weight(&updated_cpus))
> - goto out;
> -
> - if (cpus_locked)
> - stop_machine_cpuslocked(update_cpu_topology, &updates[0],
> - &updated_cpus);
> - else
> - stop_machine(update_cpu_topology, &updates[0], &updated_cpus);
> -
> - /*
> - * Update the numa-cpu lookup table with the new mappings, even for
> - * offline CPUs. It is best to perform this update from the stop-
> - * machine context.
> - */
> - if (cpus_locked)
> - stop_machine_cpuslocked(update_lookup_table, &updates[0],
> - cpumask_of(raw_smp_processor_id()));
> - else
> - stop_machine(update_lookup_table, &updates[0],
> - cpumask_of(raw_smp_processor_id()));
> -
> - for (ud = &updates[0]; ud; ud = ud->next) {
> - unregister_cpu_under_node(ud->cpu, ud->old_nid);
> - register_cpu_under_node(ud->cpu, ud->new_nid);
> -
> - dev = get_cpu_device(ud->cpu);
> - if (dev)
> - kobject_uevent(&dev->kobj, KOBJ_CHANGE);
> - cpumask_clear_cpu(ud->cpu, &cpu_associativity_changes_mask);
> - changed = 1;
> - }
> -
> -out:
> - kfree(updates);
> - return changed;
> -}
> -
> -int arch_update_cpu_topology(void)
> -{
> - lockdep_assert_cpus_held();
> - return numa_update_cpu_topology(true);
> -}
> -
> -static void topology_work_fn(struct work_struct *work)
> -{
> - rebuild_sched_domains();
> -}
> -static DECLARE_WORK(topology_work, topology_work_fn);
> -
> -static void topology_schedule_update(void)
> -{
> - schedule_work(&topology_work);
> -}
> -
> -static void topology_timer_fn(unsigned long ignored)
> -{
> - if (prrn_enabled && cpumask_weight(&cpu_associativity_changes_mask))
> - topology_schedule_update();
> - else if (vphn_enabled) {
> - if (update_cpu_associativity_changes_mask() > 0)
> - topology_schedule_update();
> - reset_topology_timer();
> - }
> -}
> -static struct timer_list topology_timer =
> - TIMER_INITIALIZER(topology_timer_fn, 0, 0);
> -
> -static void reset_topology_timer(void)
> -{
> - topology_timer.data = 0;
> - topology_timer.expires = jiffies + 60 * HZ;
> - mod_timer(&topology_timer, topology_timer.expires);
> -}
> -
> -#ifdef CONFIG_SMP
> -
> -static void stage_topology_update(int core_id)
> -{
> - cpumask_or(&cpu_associativity_changes_mask,
> - &cpu_associativity_changes_mask, cpu_sibling_mask(core_id));
> - reset_topology_timer();
> -}
> -
> -static int dt_update_callback(struct notifier_block *nb,
> - unsigned long action, void *data)
> -{
> - struct of_reconfig_data *update = data;
> - int rc = NOTIFY_DONE;
> -
> - switch (action) {
> - case OF_RECONFIG_UPDATE_PROPERTY:
> - if (!of_prop_cmp(update->dn->type, "cpu") &&
> - !of_prop_cmp(update->prop->name, "ibm,associativity")) {
> - u32 core_id;
> - of_property_read_u32(update->dn, "reg", &core_id);
> - stage_topology_update(core_id);
> - rc = NOTIFY_OK;
> - }
> - break;
> - }
> -
> - return rc;
> -}
> -
> -static struct notifier_block dt_update_nb = {
> - .notifier_call = dt_update_callback,
> -};
> -
> -#endif
> -
> -/*
> - * Start polling for associativity changes.
> - */
> -int start_topology_update(void)
> -{
> - int rc = 0;
> -
> - if (firmware_has_feature(FW_FEATURE_PRRN)) {
> - if (!prrn_enabled) {
> - prrn_enabled = 1;
> - vphn_enabled = 0;
> -#ifdef CONFIG_SMP
> - rc = of_reconfig_notifier_register(&dt_update_nb);
> -#endif
> - }
> - } else if (firmware_has_feature(FW_FEATURE_VPHN) &&
> - lppaca_shared_proc(get_lppaca())) {
> - if (!vphn_enabled) {
> - prrn_enabled = 0;
> - vphn_enabled = 1;
> - setup_cpu_associativity_change_counters();
> - init_timer_deferrable(&topology_timer);
> - reset_topology_timer();
> - }
> - }
> -
> - return rc;
> -}
> -
> -/*
> - * Disable polling for VPHN associativity changes.
> - */
> -int stop_topology_update(void)
> -{
> - int rc = 0;
> -
> - if (prrn_enabled) {
> - prrn_enabled = 0;
> -#ifdef CONFIG_SMP
> - rc = of_reconfig_notifier_unregister(&dt_update_nb);
> -#endif
> - } else if (vphn_enabled) {
> - vphn_enabled = 0;
> - rc = del_timer_sync(&topology_timer);
> - }
> -
> - return rc;
> -}
> -
> -int prrn_is_enabled(void)
> -{
> - return prrn_enabled;
> -}
> -
> -static int topology_read(struct seq_file *file, void *v)
> -{
> - if (vphn_enabled || prrn_enabled)
> - seq_puts(file, "on\n");
> - else
> - seq_puts(file, "off\n");
> -
> - return 0;
> -}
> -
> -static int topology_open(struct inode *inode, struct file *file)
> -{
> - return single_open(file, topology_read, NULL);
> -}
> -
> -static ssize_t topology_write(struct file *file, const char __user *buf,
> - size_t count, loff_t *off)
> -{
> - char kbuf[4]; /* "on" or "off" plus null. */
> - int read_len;
> -
> - read_len = count < 3 ? count : 3;
> - if (copy_from_user(kbuf, buf, read_len))
> - return -EINVAL;
> -
> - kbuf[read_len] = '\0';
> -
> - if (!strncmp(kbuf, "on", 2))
> - start_topology_update();
> - else if (!strncmp(kbuf, "off", 3))
> - stop_topology_update();
> - else
> - return -EINVAL;
> -
> - return count;
> -}
> -
> -static const struct file_operations topology_ops = {
> - .read = seq_read,
> - .write = topology_write,
> - .open = topology_open,
> - .release = single_release
> -};
> -
> -static int topology_update_init(void)
> -{
> - /* Do not poll for changes if disabled at boot */
> - if (topology_updates_enabled)
> - start_topology_update();
> -
> - if (!proc_create("powerpc/topology_updates", 0644, NULL, &topology_ops))
> - return -ENOMEM;
> -
> - return 0;
> -}
> -device_initcall(topology_update_init);
> -#endif /* CONFIG_PPC_SPLPAR */
> diff --git a/arch/powerpc/mm/vphn.c b/arch/powerpc/mm/vphn.c
> index 5f8ef50..006bcc2 100644
> --- a/arch/powerpc/mm/vphn.c
> +++ b/arch/powerpc/mm/vphn.c
> @@ -1,4 +1,46 @@
> -#include <asm/byteorder.h>
> +/*
> + * pSeries VPHN support
> + *
> + * Copyright (C) 2016 Greg Kurz <gkurz@...ux.vnet.ibm.com>, IBM
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#include <linux/threads.h>
> +#include <linux/bootmem.h>
> +#include <linux/init.h>
> +#include <linux/mm.h>
> +#include <linux/mmzone.h>
> +#include <linux/export.h>
> +#include <linux/nodemask.h>
> +#include <linux/cpu.h>
> +#include <linux/notifier.h>
> +#include <linux/memblock.h>
> +#include <linux/of.h>
> +#include <linux/pfn.h>
> +#include <linux/cpuset.h>
> +#include <linux/node.h>
> +#include <linux/stop_machine.h>
> +#include <linux/proc_fs.h>
> +#include <linux/seq_file.h>
> +#include <linux/uaccess.h>
> +#include <linux/slab.h>
> +#include <linux/sched.h>
> +#include <asm/cputhreads.h>
> +#include <asm/sparsemem.h>
> +#include <asm/prom.h>
> +#include <asm/smp.h>
> +#include <asm/cputhreads.h>
> +#include <asm/topology.h>
> +#include <asm/firmware.h>
> +#include <asm/paca.h>
> +#include <asm/hvcall.h>
> +#include <asm/setup.h>
> +#include <asm/vdso.h>
> +
> #include "vphn.h"
>
> /*
> @@ -68,3 +110,545 @@ int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
>
> return nr_assoc_doms;
> }
> +
> +
> +/* Virtual Processor Home Node (VPHN) support */
> +#ifdef CONFIG_PPC_SPLPAR
> +
> +extern bool topology_updates_enabled;
> +extern int distance_ref_points_depth;
> +
> +extern int associativity_to_nid(const __be32 *associativity);
> +extern void unmap_cpu_from_node(unsigned long cpu);
> +extern void map_cpu_to_node(int cpu, int node);
> +extern void update_numa_cpu_lookup_table(unsigned int cpu, int node);
> +
> +
> +struct topology_update_data {
> + struct topology_update_data *next;
> + unsigned int cpu;
> + int old_nid;
> + int new_nid;
> +};
> +
> +#define TOPOLOGY_DEF_TIMER_SECS 60
> +
> +static u8 vphn_cpu_change_counts[NR_CPUS][MAX_DISTANCE_REF_POINTS];
> +static cpumask_t cpu_associativity_changes_mask;
> +static int topology_timer_secs = TOPOLOGY_DEF_TIMER_SECS;
> +static int vphn_enabled;
> +static int prrn_enabled;
> +static int topology_inited;
> +static int topology_update_needed;
> +
> +static void reset_topology_timer(void);
> +
> +/*
> + * Change polling interval for associativity changes.
> + */
> +int timed_topology_update(int nsecs)
> +{
> + if (nsecs > 0)
> + topology_timer_secs = nsecs;
> + else
> + topology_timer_secs = TOPOLOGY_DEF_TIMER_SECS;
> +
> + if (vphn_enabled)
> + reset_topology_timer();
> +
> + return 0;
> +}
> +
> +/*
> + * Store the current values of the associativity change counters in the
> + * hypervisor.
> + */
> +static void setup_cpu_associativity_change_counters(void)
> +{
> + int cpu;
> +
> + /* The VPHN feature supports a maximum of 8 reference points */
> + BUILD_BUG_ON(MAX_DISTANCE_REF_POINTS > 8);
> +
> + for_each_possible_cpu(cpu) {
> + int i;
> + u8 *counts = vphn_cpu_change_counts[cpu];
> + volatile u8 *hypervisor_counts = lppaca[cpu].vphn_assoc_counts;
> +
> + for (i = 0; i < distance_ref_points_depth; i++)
> + counts[i] = hypervisor_counts[i];
> + }
> +}
> +
> +/*
> + * The hypervisor maintains a set of 8 associativity change counters in
> + * the VPA of each cpu that correspond to the associativity levels in the
> + * ibm,associativity-reference-points property. When an associativity
> + * level changes, the corresponding counter is incremented.
> + *
> + * Set a bit in cpu_associativity_changes_mask for each cpu whose home
> + * node associativity levels have changed.
> + *
> + * Returns the number of cpus with unhandled associativity changes.
> + */
> +static int update_cpu_associativity_changes_mask(void)
> +{
> + int cpu;
> + cpumask_t *changes = &cpu_associativity_changes_mask;
> +
> + for_each_possible_cpu(cpu) {
> + int i, changed = 0;
> + u8 *counts = vphn_cpu_change_counts[cpu];
> + volatile u8 *hypervisor_counts = lppaca[cpu].vphn_assoc_counts;
> +
> + for (i = 0; i < distance_ref_points_depth; i++) {
> + if (hypervisor_counts[i] != counts[i]) {
> + counts[i] = hypervisor_counts[i];
> + changed = 1;
> + }
> + }
> + if (changed) {
> + cpumask_or(changes, changes, cpu_sibling_mask(cpu));
> + cpu = cpu_last_thread_sibling(cpu);
> + }
> + }
> +
> + return cpumask_weight(changes);
> +}
> +
> +/*
> + * Retrieve the new associativity information for a virtual processor's
> + * home node.
> + */
> +static long hcall_vphn(unsigned long cpu, __be32 *associativity)
> +{
> + long rc;
> + long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};
> + u64 flags = 1;
> + int hwcpu = get_hard_smp_processor_id(cpu);
> +
> + rc = plpar_hcall9(H_HOME_NODE_ASSOCIATIVITY, retbuf, flags, hwcpu);
> + vphn_unpack_associativity(retbuf, associativity);
> +
> + return rc;
> +}
> +
> +static long vphn_get_associativity(unsigned long cpu,
> + __be32 *associativity)
> +{
> + long rc;
> +
> + rc = hcall_vphn(cpu, associativity);
> +
> + switch (rc) {
> + case H_FUNCTION:
> + pr_debug("VPHN is not supported. Disabling polling...\n");
> + stop_topology_update();
> + break;
> + case H_HARDWARE:
> + printk(KERN_ERR
> + "hcall_vphn() experienced a hardware fault "
> + "preventing VPHN. Disabling polling...\n");
> + stop_topology_update();
> + break;
> + case H_SUCCESS:
> + printk(KERN_INFO
> + "VPHN hcall succeeded. Reset polling...\n");
> + timed_topology_update(0);
> + break;
> + }
> +
> + return rc;
> +}
> +
> +/*
> + * Update the CPU maps and sysfs entries for a single CPU when its NUMA
> + * characteristics change. This function doesn't perform any locking and is
> + * only safe to call from stop_machine().
> + */
> +static int update_cpu_topology(void *data)
> +{
> + struct topology_update_data *update;
> + unsigned long cpu;
> +
> + if (!data)
> + return -EINVAL;
> +
> + cpu = smp_processor_id();
> +
> + for (update = data; update; update = update->next) {
> + int new_nid = update->new_nid;
> + if (cpu != update->cpu)
> + continue;
> +
> + unmap_cpu_from_node(cpu);
> + map_cpu_to_node(cpu, new_nid);
> + set_cpu_numa_node(cpu, new_nid);
> + set_cpu_numa_mem(cpu, local_memory_node(new_nid));
> + vdso_getcpu_init();
> + }
> +
> + return 0;
> +}
> +
> +static int update_lookup_table(void *data)
> +{
> + struct topology_update_data *update;
> +
> + if (!data)
> + return -EINVAL;
> +
> + /*
> + * Upon topology update, the numa-cpu lookup table needs to be updated
> + * for all threads in the core, including offline CPUs, to ensure that
> + * future hotplug operations respect the cpu-to-node associativity
> + * properly.
> + */
> + for (update = data; update; update = update->next) {
> + int nid, base, j;
> +
> + nid = update->new_nid;
> + base = cpu_first_thread_sibling(update->cpu);
> +
> + for (j = 0; j < threads_per_core; j++) {
> + update_numa_cpu_lookup_table(base + j, nid);
> + }
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * Update the node maps and sysfs entries for each cpu whose home node
> + * has changed. Returns 1 when the topology has changed, and 0 otherwise.
> + *
> + * cpus_locked says whether we already hold cpu_hotplug_lock.
> + */
> +int numa_update_cpu_topology(bool cpus_locked)
> +{
> + unsigned int cpu, sibling, changed = 0;
> + struct topology_update_data *updates, *ud;
> + __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
> + cpumask_t updated_cpus;
> + struct device *dev;
> + int weight, new_nid, i = 0;
> +
> + if (!prrn_enabled && !vphn_enabled) {
> + if (!topology_inited)
> + topology_update_needed = 1;
> + return 0;
> + }
> +
> + weight = cpumask_weight(&cpu_associativity_changes_mask);
> + if (!weight)
> + return 0;
> +
> + updates = kzalloc(weight * (sizeof(*updates)), GFP_KERNEL);
> + if (!updates)
> + return 0;
> +
> + cpumask_clear(&updated_cpus);
> +
> + for_each_cpu(cpu, &cpu_associativity_changes_mask) {
> + /*
> + * If siblings aren't flagged for changes, updates list
> + * will be too short. Skip on this update and set for next
> + * update.
> + */
> + if (!cpumask_subset(cpu_sibling_mask(cpu),
> + &cpu_associativity_changes_mask)) {
> + pr_info("Sibling bits not set for associativity "
> + "change, cpu%d\n", cpu);
> + cpumask_or(&cpu_associativity_changes_mask,
> + &cpu_associativity_changes_mask,
> + cpu_sibling_mask(cpu));
> + cpu = cpu_last_thread_sibling(cpu);
> + continue;
> + }
> +
> + /* Use associativity from first thread for all siblings */
> + vphn_get_associativity(cpu, associativity);
> + new_nid = associativity_to_nid(associativity);
> + if (new_nid < 0 || !node_online(new_nid))
> + new_nid = first_online_node;
> +
> + if (new_nid == numa_cpu_lookup_table[cpu]) {
> + cpumask_andnot(&cpu_associativity_changes_mask,
> + &cpu_associativity_changes_mask,
> + cpu_sibling_mask(cpu));
> + cpu = cpu_last_thread_sibling(cpu);
> + continue;
> + }
> +
> + for_each_cpu(sibling, cpu_sibling_mask(cpu)) {
> + ud = &updates[i++];
> + ud->cpu = sibling;
> + ud->new_nid = new_nid;
> + ud->old_nid = numa_cpu_lookup_table[sibling];
> + cpumask_set_cpu(sibling, &updated_cpus);
> + if (i < weight)
> + ud->next = &updates[i];
> + else
> + ud->next = NULL; /* Don't overrun and use data
> + * from previous hotplug ops */
> + }
> + cpu = cpu_last_thread_sibling(cpu);
> + }
> +
> + pr_debug("Topology update for the following CPUs:\n");
> + if (cpumask_weight(&updated_cpus)) {
> + for (ud = &updates[0]; ud; ud = ud->next) {
> + pr_debug("cpu %d moving from node %d "
> + "to %d\n", ud->cpu,
> + ud->old_nid, ud->new_nid);
> + }
> + }
> +
> + /*
> + * In cases where we have nothing to update (because the updates list
> + * is too short or because the new topology is same as the old one),
> + * skip invoking update_cpu_topology() via stop-machine(). This is
> + * necessary (and not just a fast-path optimization) since stop-machine
> + * can end up electing a random CPU to run update_cpu_topology(), and
> + * thus trick us into setting up incorrect cpu-node mappings (since
> + * 'updates' is kzalloc()'ed).
> + *
> + * And for the similar reason, we will skip all the following updating.
> + */
> + if (!cpumask_weight(&updated_cpus))
> + goto out;
> +
> + if (cpus_locked)
> + stop_machine_cpuslocked(update_cpu_topology, &updates[0],
> + &updated_cpus);
> + else
> + stop_machine(update_cpu_topology, &updates[0], &updated_cpus);
> +
> + /*
> + * Update the numa-cpu lookup table with the new mappings, even for
> + * offline CPUs. It is best to perform this update from the stop-
> + * machine context.
> + */
> + if (cpus_locked)
> + stop_machine_cpuslocked(update_lookup_table, &updates[0],
> + cpumask_of(raw_smp_processor_id()));
> + else
> + stop_machine(update_lookup_table, &updates[0],
> + cpumask_of(raw_smp_processor_id()));
> +
> + for (ud = &updates[0]; ud; ud = ud->next) {
> + unregister_cpu_under_node(ud->cpu, ud->old_nid);
> + register_cpu_under_node(ud->cpu, ud->new_nid);
> +
> + dev = get_cpu_device(ud->cpu);
> + if (dev)
> + kobject_uevent(&dev->kobj, KOBJ_CHANGE);
> + cpumask_clear_cpu(ud->cpu, &cpu_associativity_changes_mask);
> + changed = 1;
> + }
> +
> +out:
> + kfree(updates);
> + topology_update_needed = 0;
> + return changed;
> +}
> +
> +int arch_update_cpu_topology(void)
> +{
> + lockdep_assert_cpus_held();
> + return numa_update_cpu_topology(true);
> +}
> +
> +static void topology_work_fn(struct work_struct *work)
> +{
> + rebuild_sched_domains();
> +}
> +static DECLARE_WORK(topology_work, topology_work_fn);
> +
> +static void topology_schedule_update(void)
> +{
> + schedule_work(&topology_work);
> +}
> +
> +static int shared_topology_update(void)
> +{
> + if (firmware_has_feature(FW_FEATURE_VPHN) &&
> + lppaca_shared_proc(get_lppaca()))
> + topology_schedule_update();
> +
> + return 0;
> +}
> +device_initcall(shared_topology_update);
> +
> +static void topology_timer_fn(unsigned long ignored)
> +{
> + if (prrn_enabled && cpumask_weight(&cpu_associativity_changes_mask))
> + topology_schedule_update();
> + else if (vphn_enabled) {
> + if (update_cpu_associativity_changes_mask() > 0)
> + topology_schedule_update();
> + reset_topology_timer();
> + }
> +}
> +static struct timer_list topology_timer =
> + TIMER_INITIALIZER(topology_timer_fn, 0, 0);
> +
> +static void reset_topology_timer(void)
> +{
> + topology_timer.data = 0;
> + topology_timer.expires = jiffies + topology_timer_secs * HZ;
> + mod_timer(&topology_timer, topology_timer.expires);
> +}
> +
> +#ifdef CONFIG_SMP
> +
> +static void stage_topology_update(int core_id)
> +{
> + cpumask_or(&cpu_associativity_changes_mask,
> + &cpu_associativity_changes_mask, cpu_sibling_mask(core_id));
> + reset_topology_timer();
> +}
> +
> +static int dt_update_callback(struct notifier_block *nb,
> + unsigned long action, void *data)
> +{
> + struct of_reconfig_data *update = data;
> + int rc = NOTIFY_DONE;
> +
> + switch (action) {
> + case OF_RECONFIG_UPDATE_PROPERTY:
> + if (!of_prop_cmp(update->dn->type, "cpu") &&
> + !of_prop_cmp(update->prop->name, "ibm,associativity")) {
> + u32 core_id;
> + of_property_read_u32(update->dn, "reg", &core_id);
> + stage_topology_update(core_id);
> + rc = NOTIFY_OK;
> + }
> + break;
> + }
> +
> + return rc;
> +}
> +
> +static struct notifier_block dt_update_nb = {
> + .notifier_call = dt_update_callback,
> +};
> +
> +#endif
> +
> +/*
> + * Start polling for associativity changes.
> + */
> +int start_topology_update(void)
> +{
> + int rc = 0;
> +
> + if (firmware_has_feature(FW_FEATURE_PRRN)) {
> + if (!prrn_enabled) {
> + prrn_enabled = 1;
> +#ifdef CONFIG_SMP
> + rc = of_reconfig_notifier_register(&dt_update_nb);
> +#endif
> + }
> + }
> + if (firmware_has_feature(FW_FEATURE_VPHN) &&
> + lppaca_shared_proc(get_lppaca())) {
> + if (!vphn_enabled) {
> + vphn_enabled = 1;
> + setup_cpu_associativity_change_counters();
> + init_timer_deferrable(&topology_timer);
> + reset_topology_timer();
> + }
> + }
> +
> + return rc;
> +}
> +
> +/*
> + * Disable polling for VPHN associativity changes.
> + */
> +int stop_topology_update(void)
> +{
> + int rc = 0;
> +
> + if (prrn_enabled) {
> + prrn_enabled = 0;
> +#ifdef CONFIG_SMP
> + rc = of_reconfig_notifier_unregister(&dt_update_nb);
> +#endif
> + }
> + if (vphn_enabled) {
> + vphn_enabled = 0;
> + rc = del_timer_sync(&topology_timer);
> + }
> +
> + return rc;
> +}
> +
> +int prrn_is_enabled(void)
> +{
> + return prrn_enabled;
> +}
> +
> +static int topology_read(struct seq_file *file, void *v)
> +{
> + if (vphn_enabled || prrn_enabled)
> + seq_puts(file, "on\n");
> + else
> + seq_puts(file, "off\n");
> +
> + return 0;
> +}
> +
> +static int topology_open(struct inode *inode, struct file *file)
> +{
> + return single_open(file, topology_read, NULL);
> +}
> +
> +static ssize_t topology_write(struct file *file, const char __user *buf,
> + size_t count, loff_t *off)
> +{
> + char kbuf[4]; /* "on" or "off" plus null. */
> + int read_len;
> +
> + read_len = count < 3 ? count : 3;
> + if (copy_from_user(kbuf, buf, read_len))
> + return -EINVAL;
> +
> + kbuf[read_len] = '\0';
> +
> + if (!strncmp(kbuf, "on", 2))
> + start_topology_update();
> + else if (!strncmp(kbuf, "off", 3))
> + stop_topology_update();
> + else
> + return -EINVAL;
> +
> + return count;
> +}
> +
> +static const struct file_operations topology_ops = {
> + .read = seq_read,
> + .write = topology_write,
> + .open = topology_open,
> + .release = single_release
> +};
> +
> +static int topology_update_init(void)
> +{
> + /* Do not poll for changes if disabled at boot */
> + if (topology_updates_enabled)
> + start_topology_update();
> +
> + if (!proc_create("powerpc/topology_updates", 0644, NULL, &topology_ops))
> + return -ENOMEM;
> +
> + topology_inited = 1;
> + if (topology_update_needed)
> + bitmap_fill(cpumask_bits(&cpu_associativity_changes_mask),
> + nr_cpumask_bits);
> +
> + return 0;
> +}
> +device_initcall(topology_update_init);
> +#endif /* CONFIG_PPC_SPLPAR */
> diff --git a/arch/powerpc/mm/vphn.h b/arch/powerpc/mm/vphn.h
> index fe8b780..a8ec93b 100644
> --- a/arch/powerpc/mm/vphn.h
> +++ b/arch/powerpc/mm/vphn.h
> @@ -5,6 +5,10 @@
> */
> #define VPHN_REGISTER_COUNT 6
>
> +/* Maximum number of affinity reference points supported by NUMA/VPHN.
> + */
> +#define MAX_DISTANCE_REF_POINTS 4
> +
> /*
> * 6 64-bit registers unpacked into up to 24 be32 associativity values. To
> * form the complete property we have to add the length in the first cell.
> diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
> index 6afd1ef..5a7fb1e 100644
> --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
> +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
> @@ -356,6 +356,7 @@ static int dlpar_online_cpu(struct device_node *dn)
> BUG_ON(get_cpu_current_state(cpu)
> != CPU_STATE_OFFLINE);
> cpu_maps_update_done();
> + timed_topology_update(1);
> rc = device_online(get_cpu_device(cpu));
> if (rc)
> goto out;
> @@ -522,6 +523,7 @@ static int dlpar_offline_cpu(struct device_node *dn)
> set_preferred_offline_state(cpu,
> CPU_STATE_OFFLINE);
> cpu_maps_update_done();
> + timed_topology_update(1);
> rc = device_offline(get_cpu_device(cpu));
> if (rc)
> goto out;
>
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