linux-kernel - [PATCH v5 22/29] x86,fs/resctrl: Handle domain creation/deletion for RDT_RESOURCE_PERF

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Message-ID: <20250521225049.132551-23-tony.luck@intel.com>
Date: Wed, 21 May 2025 15:50:40 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>,
	Babu Moger <babu.moger@....com>,
	Drew Fustini <dfustini@...libre.com>,
	Dave Martin <Dave.Martin@....com>,
	Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	Chen Yu <yu.c.chen@...el.com>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v5 22/29] x86,fs/resctrl: Handle domain creation/deletion for RDT_RESOURCE_PERF_PKG

The L3 resource has several requirements for domains. There are structures
that hold the 64-bit values of counters, and elements to keep track of
the overflow and limbo threads.

None of these are needed for the PERF_PKG resource. The hardware counters
are wide enough that they do not wrap around for decades.

Define a new rdt_perf_pkg_mon_domain structure which just consists of
the standard rdt_domain_hdr to keep track of domain id and CPU mask.

Change domain_add_cpu_mon(), domain_remove_cpu_mon(),
resctrl_offline_mon_domain(), and resctrl_online_mon_domain() to check
resource type and perform only the operations needed for domains in the
PERF_PKG resource.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/resctrl/core.c | 41 ++++++++++++++++++++++++++++++
 fs/resctrl/rdtgroup.c              |  4 +++
 2 files changed, 45 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 64ce561e77a0..18d84c497ee4 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -540,6 +540,38 @@ static void l3_mon_domain_setup(int cpu, int id, struct rdt_resource *r, struct
 	}
 }
 
+/**
+ * struct rdt_perf_pkg_mon_domain - CPUs sharing an Intel-PMT-scoped resctrl monitor resource
+ * @hdr:	common header for different domain types
+ */
+struct rdt_perf_pkg_mon_domain {
+	struct rdt_domain_hdr   hdr;
+};
+
+static void setup_intel_aet_mon_domain(int cpu, int id, struct rdt_resource *r,
+				       struct list_head *add_pos)
+{
+	struct rdt_perf_pkg_mon_domain *d;
+	int err;
+
+	d = kzalloc_node(sizeof(*d), GFP_KERNEL, cpu_to_node(cpu));
+	if (!d)
+		return;
+
+	d->hdr.id = id;
+	d->hdr.type = RESCTRL_MON_DOMAIN;
+	d->hdr.rid = r->rid;
+	cpumask_set_cpu(cpu, &d->hdr.cpu_mask);
+	list_add_tail_rcu(&d->hdr.list, add_pos);
+
+	err = resctrl_online_mon_domain(r, &d->hdr);
+	if (err) {
+		list_del_rcu(&d->hdr.list);
+		synchronize_rcu();
+		kfree(d);
+	}
+}
+
 static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
 {
 	int id = get_domain_id_from_scope(cpu, r->mon_scope);
@@ -567,6 +599,9 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
 	case RDT_RESOURCE_L3:
 		l3_mon_domain_setup(cpu, id, r, add_pos);
 		break;
+	case RDT_RESOURCE_PERF_PKG:
+		setup_intel_aet_mon_domain(cpu, id, r, add_pos);
+		break;
 	default:
 		WARN_ON_ONCE(1);
 	}
@@ -666,6 +701,12 @@ static void domain_remove_cpu_mon(int cpu, struct rdt_resource *r)
 	default:
 		pr_warn_once("Unknown resource rid=%d\n", r->rid);
 		break;
+	case RDT_RESOURCE_PERF_PKG:
+		resctrl_offline_mon_domain(r, hdr);
+		list_del_rcu(&hdr->list);
+		synchronize_rcu();
+		kfree(container_of(hdr, struct rdt_perf_pkg_mon_domain, hdr));
+		break;
 	}
 }
 
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 1e1cc8001cbc..6078cdd5cad0 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -4170,6 +4170,8 @@ int resctrl_online_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *hdr
 	if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, r->rid))
 		goto out_unlock;
 
+	if (r->rid == RDT_RESOURCE_PERF_PKG)
+		goto do_mkdir;
 	d = container_of(hdr, struct rdt_l3_mon_domain, hdr);
 	err = domain_setup_l3_mon_state(r, d);
 	if (err)
@@ -4184,6 +4186,8 @@ int resctrl_online_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *hdr
 	if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID))
 		INIT_DELAYED_WORK(&d->cqm_limbo, cqm_handle_limbo);
 
+do_mkdir:
+	err = 0;
 	/*
 	 * If the filesystem is not mounted then only the default resource group
 	 * exists. Creation of its directories is deferred until mount time
-- 
2.49.0