1 files changed, 91 insertions, 5 deletions

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 5a944f25e94f..86a63de072c6 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -31,6 +31,8 @@
 #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>
@@ -152,9 +154,22 @@ static void __init get_node_active_region(unsigned long pfn,
         }
 }
 
-static void map_cpu_to_node(int cpu, int node)
+static void reset_numa_cpu_lookup_table(void)
+{
+        unsigned int cpu;
+
+        for_each_possible_cpu(cpu)
+                numa_cpu_lookup_table[cpu] = -1;
+}
+
+static 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)
+{
+        update_numa_cpu_lookup_table(cpu, node);
 
         dbg("adding cpu %d to node %d\n", cpu, node);
 
@@ -522,11 +537,24 @@ static int of_drconf_to_nid_single(struct of_drconf_cell *drmem,
  */
 static int numa_setup_cpu(unsigned long lcpu)
 {
-        int nid = 0;
-        struct device_node *cpu = of_get_cpu_node(lcpu, NULL);
+        int nid;
+        struct device_node *cpu;
+
+        /*
+         * If a valid cpu-to-node mapping is already available, use it
+         * directly instead of querying the firmware, since it represents
+         * the most recent mapping notified to us by the platform (eg: VPHN).
+         */
+        if ((nid = numa_cpu_lookup_table[lcpu]) >= 0) {
+                map_cpu_to_node(lcpu, nid);
+                return nid;
+        }
+
+        cpu = of_get_cpu_node(lcpu, NULL);
 
         if (!cpu) {
                 WARN_ON(1);
+                nid = 0;
                 goto out;
         }
 
@@ -542,16 +570,38 @@ out:
         return nid;
 }
 
+static void verify_cpu_node_mapping(int cpu, int node)
+{
+        int base, sibling, i;
+
+        /* Verify that all the threads in the core belong to the same node */
+        base = cpu_first_thread_sibling(cpu);
+
+        for (i = 0; i < threads_per_core; i++) {
+                sibling = base + i;
+
+                if (sibling == cpu || cpu_is_offline(sibling))
+                        continue;
+
+                if (cpu_to_node(sibling) != node) {
+                        WARN(1, "CPU thread siblings %d and %d don't belong"
+                                " to the same node!\n", cpu, sibling);
+                        break;
+                }
+        }
+}
+
 static int cpu_numa_callback(struct notifier_block *nfb, unsigned long action,
                              void *hcpu)
 {
         unsigned long lcpu = (unsigned long)hcpu;
-        int ret = NOTIFY_DONE;
+        int ret = NOTIFY_DONE, nid;
 
         switch (action) {
         case CPU_UP_PREPARE:
         case CPU_UP_PREPARE_FROZEN:
-                numa_setup_cpu(lcpu);
+                nid = numa_setup_cpu(lcpu);
+                verify_cpu_node_mapping((int)lcpu, nid);
                 ret = NOTIFY_OK;
                 break;
 #ifdef CONFIG_HOTPLUG_CPU
@@ -1069,6 +1119,7 @@ void __init do_init_bootmem(void)
          */
         setup_node_to_cpumask_map();
 
+        reset_numa_cpu_lookup_table();
         register_cpu_notifier(&ppc64_numa_nb);
         cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
                           (void *)(unsigned long)boot_cpuid);
@@ -1447,6 +1498,33 @@ static int update_cpu_topology(void *data)
         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.
@@ -1515,6 +1593,14 @@ int arch_update_cpu_topology(void)
 
         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.
+         */
+        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);