[PATCH v8 10/25] x86/resctrl: Introduce bitmap mbm_cntr_free_map to track assignable counters

[Babu Moger]

Hardware provides a set of counters when mbm_assign_mode is supported.
These counters are assigned to the MBM monitoring events of a MON group
that needs to be tracked. The kernel must manage and track the available
counters.

Introduce mbm_cntr_free_map bitmap to track available counters and set
of routines to allocate and free the counters. Move dom_data_init() after
mbm_cntr_assign detection.

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
v8: Moved the init and exit functionality inside dom_data_init()
    and dom_data_exit() respectively.

v7: Removed the static allocation and now allocating bitmap mbm_cntr_free_map
    dynamically.
    Passed the struct rdt_resource mbm_cntr_alloc and mbm_cntr_free.
    Removed the reference of ABMC and changed it mbm_cntr_assign.
    Few other text changes.

v6: Removed the variable mbm_cntrs_free_map_len. This is not required.
    Removed the call mbm_cntrs_init() in arch code. This needs to be
    done at higher level.
    Used DECLARE_BITMAP to initialize mbm_cntrs_free_map.
    Moved all the counter interfaces mbm_cntr_alloc() and mbm_cntr_free()
    in here as part of separating arch and fs bits.

v5:
   Updated the comments and commit log.
   Few renames
    num_cntrs_free_map -> mbm_cntrs_free_map
    num_cntrs_init -> mbm_cntrs_init
    Added initialization in rdt_get_tree because the default ABMC
    enablement happens during the init.

v4: Changed the name to num_cntrs where applicable.
     Used bitmap apis.
     Added more comments for the globals.

v3: Changed the bitmap name to assign_cntrs_free_map. Removed abmc
     from the name.

v2: Changed the bitmap name to assignable_counter_free_map from
     abmc_counter_free_map.
---
 arch/x86/kernel/cpu/resctrl/internal.h |  2 ++
 arch/x86/kernel/cpu/resctrl/monitor.c  | 43 +++++++++++++++++++++++---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 ++++++++++++
 include/linux/resctrl.h                |  2 ++
 4 files changed, 62 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 92eae4672312..99f9103a35ba 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -654,6 +654,8 @@ void __check_limbo(struct rdt_mon_domain *d, bool force_free);
 void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
 void __init resctrl_file_fflags_init(const char *config,
 				     unsigned long fflags);
+int mbm_cntr_alloc(struct rdt_resource *r);
+void mbm_cntr_free(struct rdt_resource *r, u32 cntr_id);
 void rdt_staged_configs_clear(void);
 bool closid_allocated(unsigned int closid);
 int resctrl_find_cleanest_closid(void);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 66b06574f660..5c2a28565747 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -983,6 +983,27 @@ void mbm_setup_overflow_handler(struct rdt_mon_domain *dom, unsigned long delay_
 		schedule_delayed_work_on(cpu, &dom->mbm_over, delay);
 }
 
+/*
+ * Counter bitmap for tracking the available counters.
+ * 'mbm_cntr_assign' mode provides set of hardware counters for assigning
+ * RMID, event pair. Each RMID and event pair takes one hardware counter.
+ */
+static __init unsigned long *mbm_cntrs_init(struct rdt_resource *r)
+{
+	r->mon.mbm_cntr_free_map = bitmap_zalloc(r->mon.num_mbm_cntrs,
+						 GFP_KERNEL);
+	if (r->mon.mbm_cntr_free_map)
+		bitmap_fill(r->mon.mbm_cntr_free_map, r->mon.num_mbm_cntrs);
+
+	return r->mon.mbm_cntr_free_map;
+}
+
+static  __exit void mbm_cntrs_exit(struct rdt_resource *r)
+{
+	bitmap_free(r->mon.mbm_cntr_free_map);
+	r->mon.mbm_cntr_free_map = NULL;
+}
+
 static __init int dom_data_init(struct rdt_resource *r)
 {
 	u32 idx_limit = resctrl_arch_system_num_rmid_idx();
@@ -1020,6 +1041,17 @@ static __init int dom_data_init(struct rdt_resource *r)
 		goto out_unlock;
 	}
 
+	if (r->mon.mbm_cntr_assignable && !mbm_cntrs_init(r)) {
+		if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
+			kfree(closid_num_dirty_rmid);
+			closid_num_dirty_rmid = NULL;
+		}
+		kfree(rmid_ptrs);
+		rmid_ptrs = NULL;
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+
 	for (i = 0; i < idx_limit; i++) {
 		entry = &rmid_ptrs[i];
 		INIT_LIST_HEAD(&entry->list);
@@ -1056,6 +1088,9 @@ static void __exit dom_data_exit(struct rdt_resource *r)
 	kfree(rmid_ptrs);
 	rmid_ptrs = NULL;
 
+	if (r->mon.mbm_cntr_assignable)
+		mbm_cntrs_exit(r);
+
 	mutex_unlock(&rdtgroup_mutex);
 }
 
@@ -1210,10 +1245,6 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 	 */
 	resctrl_rmid_realloc_threshold = resctrl_arch_round_mon_val(threshold);
 
-	ret = dom_data_init(r);
-	if (ret)
-		return ret;
-
 	if (rdt_cpu_has(X86_FEATURE_BMEC)) {
 		u32 eax, ebx, ecx, edx;
 
@@ -1240,6 +1271,10 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 		}
 	}
 
+	ret = dom_data_init(r);
+	if (ret)
+		return ret;
+
 	l3_mon_evt_init(r);
 
 	r->mon_capable = true;
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index c48b5450e6c2..8ffebd203c31 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -185,6 +185,25 @@ bool closid_allocated(unsigned int closid)
 	return !test_bit(closid, &closid_free_map);
 }
 
+int mbm_cntr_alloc(struct rdt_resource *r)
+{
+	int cntr_id;
+
+	cntr_id = find_first_bit(r->mon.mbm_cntr_free_map,
+				 r->mon.num_mbm_cntrs);
+	if (cntr_id >= r->mon.num_mbm_cntrs)
+		return -ENOSPC;
+
+	__clear_bit(cntr_id, r->mon.mbm_cntr_free_map);
+
+	return cntr_id;
+}
+
+void mbm_cntr_free(struct rdt_resource *r, u32 cntr_id)
+{
+	__set_bit(cntr_id, r->mon.mbm_cntr_free_map);
+}
+
 /**
  * rdtgroup_mode_by_closid - Return mode of resource group with closid
  * @closid: closid if the resource group
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index f11d6fdfd977..5a4d6adec974 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -187,12 +187,14 @@ enum resctrl_scope {
  * @num_rmid:		Number of RMIDs available
  * @num_mbm_cntrs:	Number of assignable monitoring counters
  * @mbm_cntr_assignable:Is system capable of supporting monitor assignment?
+ * @mbm_cntr_free_map:	bitmap of free MBM counters
  * @evt_list:		List of monitoring events
  */
 struct resctrl_mon {
 	int			num_rmid;
 	int			num_mbm_cntrs;
 	bool			mbm_cntr_assignable;
+	unsigned long		*mbm_cntr_free_map;
 	struct list_head	evt_list;
 };
 
-- 
2.34.1