From 4d32c24a74f2c12ff440d381ba01de574f6631ce Mon Sep 17 00:00:00 2001 From: Babu Moger Date: Fri, 5 Sep 2025 16:34:11 -0500 Subject: [PATCH] fs/resctrl: Introduce mbm_cntr_cfg to track assignable counters per domain The "mbm_event" counter assignment mode allows users to assign a hardware counter to an RMID, event pair and monitor bandwidth usage as long as it is assigned. The hardware continues to track the assigned counter until it is explicitly unassigned by the user. Counters are assigned/unassigned at monitoring domain level. Manage a monitoring domain's hardware counters using a per monitoring domain array of struct mbm_cntr_cfg that is indexed by the hardware counter ID. A hardware counter's configuration contains the MBM event ID and points to the monitoring group that it is assigned to, with a NULL pointer meaning that the hardware counter is available for assignment. There is no direct way to determine which hardware counters are assigned to a particular monitoring group. Check every entry of every hardware counter configuration array in every monitoring domain to query which MBM events of a monitoring group is tracked by hardware. Such queries are acceptable because of a very small number of assignable counters (32 to 64). Suggested-by: Peter Newman Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com --- fs/resctrl/rdtgroup.c | 8 ++++++++ include/linux/resctrl.h | 15 +++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c index 9d95d01da3f9d..61f7b68f22730 100644 --- a/fs/resctrl/rdtgroup.c +++ b/fs/resctrl/rdtgroup.c @@ -4029,6 +4029,7 @@ static void domain_destroy_mon_state(struct rdt_mon_domain *d) { int idx; + kfree(d->cntr_cfg); bitmap_free(d->rmid_busy_llc); for_each_mbm_idx(idx) { kfree(d->mbm_states[idx]); @@ -4112,6 +4113,13 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_mon_domain goto cleanup; } + if (resctrl_is_mbm_enabled() && r->mon.mbm_cntr_assignable) { + tsize = sizeof(*d->cntr_cfg); + d->cntr_cfg = kcalloc(r->mon.num_mbm_cntrs, tsize, GFP_KERNEL); + if (!d->cntr_cfg) + goto cleanup; + } + return 0; cleanup: bitmap_free(d->rmid_busy_llc); diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h index 919806122c509..e013caba66414 100644 --- a/include/linux/resctrl.h +++ b/include/linux/resctrl.h @@ -156,6 +156,18 @@ struct rdt_ctrl_domain { u32 *mbps_val; }; +/** + * struct mbm_cntr_cfg - Assignable counter configuration. + * @evtid: MBM event to which the counter is assigned. Only valid + * if @rdtgroup is not NULL. + * @rdtgrp: resctrl group assigned to the counter. NULL if the + * counter is free. + */ +struct mbm_cntr_cfg { + enum resctrl_event_id evtid; + struct rdtgroup *rdtgrp; +}; + /** * struct rdt_mon_domain - group of CPUs sharing a resctrl monitor resource * @hdr: common header for different domain types @@ -168,6 +180,8 @@ struct rdt_ctrl_domain { * @cqm_limbo: worker to periodically read CQM h/w counters * @mbm_work_cpu: worker CPU for MBM h/w counters * @cqm_work_cpu: worker CPU for CQM h/w counters + * @cntr_cfg: array of assignable counters' configuration (indexed + * by counter ID) */ struct rdt_mon_domain { struct rdt_domain_hdr hdr; @@ -178,6 +192,7 @@ struct rdt_mon_domain { struct delayed_work cqm_limbo; int mbm_work_cpu; int cqm_work_cpu; + struct mbm_cntr_cfg *cntr_cfg; }; /** -- 2.47.3