[PATCH v7 09/24] x86/resctrl: Introduce bitmap mbm_cntr_free_map to track assignable counters

[Babu Moger]

Hardware provides a set of counters when mbm_cntr_assignable feature is
supported. These counters are used for assigning the events in resctrl
a group when the feature is enabled. The kernel must manage and track the
number of available counters.

Introduce mbm_cntr_free_map bitmap to track available counters and set
of routines to allocate and free the counters.

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
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/core.c     |  2 +-
 arch/x86/kernel/cpu/resctrl/internal.h |  4 +++-
 arch/x86/kernel/cpu/resctrl/monitor.c  | 31 +++++++++++++++++++++++++-
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 ++++++++++++++++
 include/linux/resctrl.h                |  2 ++
 5 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 49d147e2e4e5..00ad00258df2 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -1140,7 +1140,7 @@ static void __exit resctrl_exit(void)
 	rdtgroup_exit();
 
 	if (r->mon_capable)
-		rdt_put_mon_l3_config();
+		rdt_put_mon_l3_config(r);
 }
 
 __exitcall(resctrl_exit);
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index a45ae410274c..99f9103a35ba 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -633,7 +633,7 @@ void closid_free(int closid);
 int alloc_rmid(u32 closid);
 void free_rmid(u32 closid, u32 rmid);
 int rdt_get_mon_l3_config(struct rdt_resource *r);
-void __exit rdt_put_mon_l3_config(void);
+void __exit rdt_put_mon_l3_config(struct rdt_resource *r);
 bool __init rdt_cpu_has(int flag);
 void mon_event_count(void *info);
 int rdtgroup_mondata_show(struct seq_file *m, void *arg);
@@ -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 e3e71843401a..f98cc5b9bebc 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -1175,6 +1175,30 @@ static __init int snc_get_config(void)
 	return ret;
 }
 
+/*
+ * 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.
+ * Kernel needs to keep track of the number of available counters.
+ */
+static int mbm_cntrs_init(struct rdt_resource *r)
+{
+	if (r->mon.mbm_cntr_assignable) {
+		r->mon.mbm_cntr_free_map = bitmap_zalloc(r->mon.num_mbm_cntrs,
+							 GFP_KERNEL);
+		if (!r->mon.mbm_cntr_free_map)
+			return -ENOMEM;
+		bitmap_fill(r->mon.mbm_cntr_free_map, r->mon.num_mbm_cntrs);
+	}
+	return 0;
+}
+
+static void __exit mbm_cntrs_exit(struct rdt_resource *r)
+{
+	if (r->mon.mbm_cntr_assignable)
+		bitmap_free(r->mon.mbm_cntr_free_map);
+}
+
 int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 {
 	unsigned int mbm_offset = boot_cpu_data.x86_cache_mbm_width_offset;
@@ -1240,6 +1264,10 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 		}
 	}
 
+	ret = mbm_cntrs_init(r);
+	if (ret)
+		return ret;
+
 	l3_mon_evt_init(r);
 
 	r->mon_capable = true;
@@ -1247,9 +1275,10 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 	return 0;
 }
 
-void __exit rdt_put_mon_l3_config(void)
+void __exit rdt_put_mon_l3_config(struct rdt_resource *r)
 {
 	dom_data_exit();
+	mbm_cntrs_exit(r);
 }
 
 void __init intel_rdt_mbm_apply_quirk(void)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index ba737890d5c2..a51992984832 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..aab22ff8e0c1 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 number of assignable 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