x86/intel_rdt/cqm: Add CPU hotplug support

Resource groups have a per domain directory under "mon_data". Add or
remove these directories as and when domains come online and go offline.
Also update the per cpu rmids and cache upon onlining and offlining
cpus.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: reinette.chatre@intel.com
Link: http://lkml.kernel.org/r/1501017287-28083-26-git-send-email-vikas.shivappa@linux.intel.com

arch/x86/kernel/cpu/intel_rdt.c

@@ -479,6 +479,13 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r)
 
 	cpumask_set_cpu(cpu, &d->cpu_mask);
 	list_add_tail(&d->list, add_pos);
+
+	/*
+	 * If resctrl is mounted, add
+	 * per domain monitor data directories.
+	 */
+	if (static_branch_unlikely(&rdt_mon_enable_key))
+		mkdir_mondata_subdir_allrdtgrp(r, d);
 }
 
 static void domain_remove_cpu(int cpu, struct rdt_resource *r)
@@ -494,6 +501,12 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 
 	cpumask_clear_cpu(cpu, &d->cpu_mask);
 	if (cpumask_empty(&d->cpu_mask)) {
+		/*
+		 * If resctrl is mounted, remove all the
+		 * per domain monitor data directories.
+		 */
+		if (static_branch_unlikely(&rdt_mon_enable_key))
+			rmdir_mondata_subdir_allrdtgrp(r, d->id);
 		kfree(d->ctrl_val);
 		kfree(d->rmid_busy_llc);
 		list_del(&d->list);
@@ -501,13 +514,14 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 	}
 }
 
-static void clear_closid(int cpu)
+static void clear_closid_rmid(int cpu)
 {
 	struct intel_pqr_state *state = this_cpu_ptr(&pqr_state);
 
 	per_cpu(rdt_cpu_default.closid, cpu) = 0;
 	state->closid = 0;
-	wrmsr(IA32_PQR_ASSOC, state->rmid, 0);
+	state->rmid = 0;
+	wrmsr(IA32_PQR_ASSOC, 0, 0);
 }
 
 static int intel_rdt_online_cpu(unsigned int cpu)
@@ -515,29 +529,42 @@ static int intel_rdt_online_cpu(unsigned int cpu)
 	struct rdt_resource *r;
 
 	mutex_lock(&rdtgroup_mutex);
-	for_each_alloc_capable_rdt_resource(r)
+	for_each_capable_rdt_resource(r)
 		domain_add_cpu(cpu, r);
 	/* The cpu is set in default rdtgroup after online. */
 	cpumask_set_cpu(cpu, &rdtgroup_default.cpu_mask);
-	clear_closid(cpu);
+	clear_closid_rmid(cpu);
 	mutex_unlock(&rdtgroup_mutex);
 
 	return 0;
 }
 
+static void clear_childcpus(struct rdtgroup *r, unsigned int cpu)
+{
+	struct rdtgroup *cr;
+
+	list_for_each_entry(cr, &r->mon.crdtgrp_list, mon.crdtgrp_list) {
+		if (cpumask_test_and_clear_cpu(cpu, &cr->cpu_mask)) {
+			break;
+		}
+	}
+}
+
 static int intel_rdt_offline_cpu(unsigned int cpu)
 {
 	struct rdtgroup *rdtgrp;
 	struct rdt_resource *r;
 
 	mutex_lock(&rdtgroup_mutex);
-	for_each_alloc_capable_rdt_resource(r)
+	for_each_capable_rdt_resource(r)
 		domain_remove_cpu(cpu, r);
 	list_for_each_entry(rdtgrp, &rdt_all_groups, rdtgroup_list) {
-		if (cpumask_test_and_clear_cpu(cpu, &rdtgrp->cpu_mask))
+		if (cpumask_test_and_clear_cpu(cpu, &rdtgrp->cpu_mask)) {
+			clear_childcpus(rdtgrp, cpu);
 			break;
+		}
 	}
-	clear_closid(cpu);
+	clear_closid_rmid(cpu);
 	mutex_unlock(&rdtgroup_mutex);
 
 	return 0;

arch/x86/kernel/cpu/intel_rdt.h

@@ -301,6 +301,11 @@ enum {
 	RDT_NUM_RESOURCES,
 };
 
+#define for_each_capable_rdt_resource(r)				      \
+	for (r = rdt_resources_all; r < rdt_resources_all + RDT_NUM_RESOURCES;\
+	     r++)							      \
+		if (r->alloc_capable || r->mon_capable)
+
 #define for_each_alloc_capable_rdt_resource(r)				      \
 	for (r = rdt_resources_all; r < rdt_resources_all + RDT_NUM_RESOURCES;\
 	     r++)							      \
@@ -360,5 +365,9 @@ void free_rmid(u32 rmid);
 int rdt_get_mon_l3_config(struct rdt_resource *r);
 void mon_event_count(void *info);
 int rdtgroup_mondata_show(struct seq_file *m, void *arg);
+void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
+				    unsigned int dom_id);
+void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
+				    struct rdt_domain *d);
 
 #endif /* _ASM_X86_INTEL_RDT_H */

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c

@@ -1323,6 +1323,27 @@ static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
 	return ret;
 }
 
+/*
+ * Remove all subdirectories of mon_data of ctrl_mon groups
+ * and monitor groups with given domain id.
+ */
+void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r, unsigned int dom_id)
+{
+	struct rdtgroup *prgrp, *crgrp;
+	char name[32];
+
+	if (!r->mon_enabled)
+		return;
+
+	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
+		sprintf(name, "mon_%s_%02d", r->name, dom_id);
+		kernfs_remove_by_name(prgrp->mon.mon_data_kn, name);
+
+		list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
+			kernfs_remove_by_name(crgrp->mon.mon_data_kn, name);
+	}
+}
+
 static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
 				struct rdt_domain *d,
 				struct rdt_resource *r, struct rdtgroup *prgrp)
@@ -1369,6 +1390,32 @@ out_destroy:
 	return ret;
 }
 
+/*
+ * Add all subdirectories of mon_data for "ctrl_mon" groups
+ * and "monitor" groups with given domain id.
+ */
+void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
+				    struct rdt_domain *d)
+{
+	struct kernfs_node *parent_kn;
+	struct rdtgroup *prgrp, *crgrp;
+	struct list_head *head;
+
+	if (!r->mon_enabled)
+		return;
+
+	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
+		parent_kn = prgrp->mon.mon_data_kn;
+		mkdir_mondata_subdir(parent_kn, d, r, prgrp);
+
+		head = &prgrp->mon.crdtgrp_list;
+		list_for_each_entry(crgrp, head, mon.crdtgrp_list) {
+			parent_kn = crgrp->mon.mon_data_kn;
+			mkdir_mondata_subdir(parent_kn, d, r, crgrp);
+		}
+	}
+}
+
 static int mkdir_mondata_subdir_alldom(struct kernfs_node *parent_kn,
 				       struct rdt_resource *r,
 				       struct rdtgroup *prgrp)