x86/resctrl: Free rmid_ptrs from resctrl_exit()

rmid_ptrs[] is allocated from dom_data_init() but never free()d.

While the exit text ends up in the linker script's DISCARD section,
the direction of travel is for resctrl to be/have loadable modules.

Add resctrl_put_mon_l3_config() to cleanup any memory allocated
by rdt_get_mon_l3_config().

There is no reason to backport this to a stable kernel.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-3-james.morse@arm.comSigned-off-by: Borislav Petkov (AMD) <bp@alien8.de>

arch/x86/kernel/cpu/resctrl/core.c

@@ -990,8 +990,14 @@ late_initcall(resctrl_late_init);
 
 static void __exit resctrl_exit(void)
 {
+	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
+
 	cpuhp_remove_state(rdt_online);
+
 	rdtgroup_exit();
+
+	if (r->mon_capable)
+		rdt_put_mon_l3_config();
 }
 
 __exitcall(resctrl_exit);

arch/x86/kernel/cpu/resctrl/internal.h

@@ -544,6 +544,7 @@ void closid_free(int closid);
 int alloc_rmid(void);
 void free_rmid(u32 rmid);
 int rdt_get_mon_l3_config(struct rdt_resource *r);
+void __exit rdt_put_mon_l3_config(void);
 bool __init rdt_cpu_has(int flag);
 void mon_event_count(void *info);
 int rdtgroup_mondata_show(struct seq_file *m, void *arg);

arch/x86/kernel/cpu/resctrl/monitor.c

@@ -719,6 +719,16 @@ static int dom_data_init(struct rdt_resource *r)
 	return 0;
 }
 
+static void __exit dom_data_exit(void)
+{
+	mutex_lock(&rdtgroup_mutex);
+
+	kfree(rmid_ptrs);
+	rmid_ptrs = NULL;
+
+	mutex_unlock(&rdtgroup_mutex);
+}
+
 static struct mon_evt llc_occupancy_event = {
 	.name		= "llc_occupancy",
 	.evtid		= QOS_L3_OCCUP_EVENT_ID,
@@ -814,6 +824,11 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 	return 0;
 }
 
+void __exit rdt_put_mon_l3_config(void)
+{
+	dom_data_exit();
+}
+
 void __init intel_rdt_mbm_apply_quirk(void)
 {
 	int cf_index;