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

Babu Moger
2024-07-03T21:50:01Z

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@amd.com>
---
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