powerpc/numa: remove unreachable topology update code

Since the topology_updates_enabled flag is now always false, remove it
and the code which has become unreachable. This is the minimum change
that prevents 'defined but unused' warnings emitted by the compiler
after stubbing out the start/stop_topology_updates() functions.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200612051238.1007764-5-nathanl@linux.ibm.com

arch/powerpc/mm/numa.c

@@ -984,8 +984,6 @@ static int __init early_numa(char *p)
 }
 early_param("numa", early_numa);
 
-static const bool topology_updates_enabled;
-
 #ifdef CONFIG_MEMORY_HOTPLUG
 /*
  * Find the node associated with a hot added memory section for
@@ -1133,7 +1131,6 @@ struct topology_update_data {
 
 #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 vphn_enabled;
 static int prrn_enabled;
@@ -1158,63 +1155,6 @@ int timed_topology_update(int nsecs)
 	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_of(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_of(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.
@@ -1498,16 +1438,6 @@ static void topology_schedule_update(void)
 	schedule_work(&topology_work);
 }
 
-static void topology_timer_fn(struct timer_list *unused)
-{
-	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;
 
 static void reset_topology_timer(void)
@@ -1516,69 +1446,12 @@ static void reset_topology_timer(void)
 		mod_timer(&topology_timer, jiffies + topology_timer_secs * HZ);
 }
 
-#ifdef CONFIG_SMP
-
-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_node_is_type(update->dn, "cpu") &&
-		    !of_prop_cmp(update->prop->name, "ibm,associativity")) {
-			u32 core_id;
-			of_property_read_u32(update->dn, "reg", &core_id);
-			rc = dlpar_cpu_readd(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 (!topology_updates_enabled)
-		return 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();
-			timer_setup(&topology_timer, topology_timer_fn,
-				    TIMER_DEFERRABLE);
-			reset_topology_timer();
-		}
-	}
-
-	pr_info("Starting topology update%s%s\n",
-		(prrn_enabled ? " prrn_enabled" : ""),
-		(vphn_enabled ? " vphn_enabled" : ""));
-
-	return rc;
+	return 0;
 }
 
 /*
@@ -1586,25 +1459,7 @@ int start_topology_update(void)
  */
 int stop_topology_update(void)
 {
-	int rc = 0;
-
-	if (!topology_updates_enabled)
-		return 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);
-	}
-
-	pr_info("Stopping topology update\n");
-
-	return rc;
+	return 0;
 }
 
 int prrn_is_enabled(void)