linux-kernel - [PATCH v4 09/19] x86/resctrl: Initialize ABMC counters bitmap

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Message-ID: <395f8ad5bba4e572cb8bcee11fa19b02cc950253.1716552602.git.babu.moger@amd.com>
Date: Fri, 24 May 2024 07:23:28 -0500
From: Babu Moger <babu.moger@....com>
To: <corbet@....net>, <fenghua.yu@...el.com>, <reinette.chatre@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
CC: <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
	<rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
	<yanjiewtw@...il.com>, <babu.moger@....com>, <kim.phillips@....com>,
	<lukas.bulwahn@...il.com>, <seanjc@...gle.com>, <jmattson@...gle.com>,
	<leitao@...ian.org>, <jpoimboe@...nel.org>, <rick.p.edgecombe@...el.com>,
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	<daniel.sneddon@...ux.intel.com>, <pbonzini@...hat.com>,
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	<peternewman@...gle.com>, <maciej.wieczor-retman@...el.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<eranian@...gle.com>, <james.morse@....com>
Subject: [PATCH v4 09/19] x86/resctrl: Initialize ABMC counters bitmap

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 supported.

Introduce num_cntrs_free_map bitmap to track available and free counters.

Signed-off-by: Babu Moger <babu.moger@....com>
---
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 | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 3071bbb7a15e..400ae405e10e 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -186,6 +186,23 @@ bool closid_allocated(unsigned int closid)
 	return !test_bit(closid, &closid_free_map);
 }
 
+/*
+ * ABMC Counter bitmap and 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 num_cntrs_free_map;
+static u32 num_cntrs_free_map_len;
+
+static void num_cntrs_init(void)
+{
+	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
+
+	bitmap_fill(&num_cntrs_free_map, r->mon.num_cntrs);
+	num_cntrs_free_map_len = r->mon.num_cntrs;
+}
+
 /**
  * rdtgroup_mode_by_closid - Return mode of resource group with closid
  * @closid: closid if the resource group
@@ -2459,6 +2476,12 @@ static int resctrl_abmc_set_all(enum resctrl_res_level l, bool enable)
 	struct rdt_resource *r = &rdt_resources_all[l].r_resctrl;
 	struct rdt_domain *d;
 
+	/*
+	 * The bitmap num_cntrs_free_map needs to be reset when switching
+	 * the monitor mode.
+	 */
+	num_cntrs_init();
+
 	/*
 	 * Update QOS_CFG MSR on all the CPUs associated with the resource
 	 * Hardware counters will reset after switching the monotor mode.
-- 
2.34.1