[PATCH v5 09/20] x86/resctrl: Initialize monitor counters bitmap

[Babu Moger <babu.moger@xxxxxxx>]

Hardware provides a set of counters when the ABMC feature is supported.
These counters are used for enabling the events in resctrl group when
the feature is enabled.

Introduce mbm_cntrs_free_map bitmap to track available and free counters.

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
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/rdtgroup.c | 29 ++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 4f47f52e01c2..b3d3fa048f15 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -185,6 +185,23 @@ bool closid_allocated(unsigned int closid)
 	return !test_bit(closid, &closid_free_map);
 }
 
+/*
+ * Counter bitmap and its length for tracking available counters.
+ * ABMC feature provides set of hardware counters for enabling events.
+ * Each event takes one hardware counter. Kernel needs to keep track
+ * of number of available counters.
+ */
+static unsigned long mbm_cntrs_free_map;
+static unsigned int mbm_cntrs_free_map_len;
+
+static void mbm_cntrs_init(void)
+{
+	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
+
+	bitmap_fill(&mbm_cntrs_free_map, r->mon.num_mbm_cntrs);
+	mbm_cntrs_free_map_len = r->mon.num_mbm_cntrs;
+}
+
 /**
  * rdtgroup_mode_by_closid - Return mode of resource group with closid
  * @closid: closid if the resource group
@@ -2466,6 +2483,12 @@ static int _resctrl_abmc_enable(struct rdt_resource *r, bool enable)
 {
 	struct rdt_mon_domain *d;
 
+	/*
+	 * Clear all the previous assignments while switching the monitor
+	 * mode.
+	 */
+	mbm_cntrs_init();
+
 	/*
 	 * Hardware counters will reset after switching the monitor mode.
 	 * Reset the architectural state so that reading of hardware
@@ -2724,10 +2747,10 @@ static void schemata_list_destroy(void)
 
 static int rdt_get_tree(struct fs_context *fc)
 {
+	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
 	struct rdt_fs_context *ctx = rdt_fc2context(fc);
 	unsigned long flags = RFTYPE_CTRL_BASE;
 	struct rdt_mon_domain *dom;
-	struct rdt_resource *r;
 	int ret;
 
 	cpus_read_lock();
@@ -2756,6 +2779,9 @@ static int rdt_get_tree(struct fs_context *fc)
 
 	closid_init();
 
+	if (r->mon.abmc_capable)
+		mbm_cntrs_init();
+
 	if (resctrl_arch_mon_capable())
 		flags |= RFTYPE_MON;
 
@@ -2800,7 +2826,6 @@ static int rdt_get_tree(struct fs_context *fc)
 		resctrl_mounted = true;
 
 	if (is_mbm_enabled()) {
-		r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
 		list_for_each_entry(dom, &r->mon_domains, hdr.list)
 			mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL,
 						   RESCTRL_PICK_ANY_CPU);
-- 
2.34.1