linux-kernel - [PATCH v11 11/23] x86/resctrl: Introduce mbm_cntr_cfg to track assignable counters at domain

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Message-ID: <30652061d4a21eb5952a1323b76ca70927412a30.1737577229.git.babu.moger@amd.com>
Date: Wed, 22 Jan 2025 14:20:19 -0600
From: Babu Moger <babu.moger@....com>
To: <corbet@....net>, <reinette.chatre@...el.com>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
	<tony.luck@...el.com>, <peternewman@...gle.com>
CC: <fenghua.yu@...el.com>, <x86@...nel.org>, <hpa@...or.com>,
	<paulmck@...nel.org>, <akpm@...ux-foundation.org>, <thuth@...hat.com>,
	<rostedt@...dmis.org>, <xiongwei.song@...driver.com>,
	<pawan.kumar.gupta@...ux.intel.com>, <daniel.sneddon@...ux.intel.com>,
	<jpoimboe@...nel.org>, <perry.yuan@....com>, <sandipan.das@....com>,
	<kai.huang@...el.com>, <xiaoyao.li@...el.com>, <seanjc@...gle.com>,
	<babu.moger@....com>, <xin3.li@...el.com>, <andrew.cooper3@...rix.com>,
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	<tan.shaopeng@...itsu.com>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <maciej.wieczor-retman@...el.com>,
	<eranian@...gle.com>
Subject: [PATCH v11 11/23] x86/resctrl: Introduce mbm_cntr_cfg to track assignable counters at domain

In mbm_cntr_assign mode hardware counters are assigned/unassigned to an
MBM event of a monitor group. Hardware 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.

Suggested-by: Peter Newman <peternewman@...gle.com>
Signed-off-by: Babu Moger <babu.moger@....com>
---
v11: Refined the change log based on Reinette's feedback.
     Fixed few style issues.

v10: Patch changed completely to handle the counters at domain level.
     https://lore.kernel.org/lkml/CALPaoCj+zWq1vkHVbXYP0znJbe6Ke3PXPWjtri5AFgD9cQDCUg@mail.gmail.com/
     Removed Reviewed-by tag.
     Did not see the need to add cntr_id in mbm_state structure. Not used in the code.

v9: Added Reviewed-by tag. No other changes.

v8: Minor commit message changes.

v7: Added check mbm_cntr_assignable for allocating bitmap mbm_cntr_map

v6: New patch to add domain level assignment.
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 11 +++++++++++
 include/linux/resctrl.h                | 14 ++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 18110a1afb6d..75a3b56996ca 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -4009,6 +4009,7 @@ static void __init rdtgroup_setup_default(void)
 
 static void domain_destroy_mon_state(struct rdt_mon_domain *d)
 {
+	kfree(d->cntr_cfg);
 	bitmap_free(d->rmid_busy_llc);
 	kfree(d->mbm_total);
 	kfree(d->mbm_local);
@@ -4082,6 +4083,16 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_mon_domain
 			return -ENOMEM;
 		}
 	}
+	if (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) {
+			bitmap_free(d->rmid_busy_llc);
+			kfree(d->mbm_total);
+			kfree(d->mbm_local);
+			return -ENOMEM;
+		}
+	}
 
 	return 0;
 }
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 511cfce8fc21..9a54e307d340 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -94,6 +94,18 @@ 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.
+ * @rdtgroup:		 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
@@ -105,6 +117,7 @@ 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:		assignable counters configuration
  */
 struct rdt_mon_domain {
 	struct rdt_domain_hdr		hdr;
@@ -116,6 +129,7 @@ struct rdt_mon_domain {
 	struct delayed_work		cqm_limbo;
 	int				mbm_work_cpu;
 	int				cqm_work_cpu;
+	struct mbm_cntr_cfg		*cntr_cfg;
 };
 
 /**
-- 
2.34.1