[PATCH v14 23/32] x86,fs/resctrl: Handle domain creation/deletion for RDT_RESOURCE_PERF_PKG

Tony Luck
2025-11-24T18:55:04Z

The L3 resource has several requirements for domains. There are per-domain
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.

Update resctrl_online_mon_domain() for RDT_RESOURCE_PERF_PKG. The only action
needed for this resource is to create and populate domain directories if a
domain is added while resctrl is mounted.

Similarly resctrl_offline_mon_domain() only needs to remove domain directories.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
---
arch/x86/kernel/cpu/resctrl/internal.h | 13 +++++++++++
arch/x86/kernel/cpu/resctrl/core.c | 17 +++++++++++++++
arch/x86/kernel/cpu/resctrl/intel_aet.c | 29 +++++++++++++++++++++++++
fs/resctrl/rdtgroup.c | 17 ++++++++++-----
4 files changed, 71 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 88095cae4ac2..0b7f8317be14 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -87,6 +87,14 @@ static inline struct rdt_hw_l3_mon_domain *resctrl_to_arch_mon_dom(struct rdt_l3
return container_of(r, struct rdt_hw_l3_mon_domain, d_resctrl);
}

+/**
+ * struct rdt_perf_pkg_mon_domain - CPUs sharing an package scoped resctrl monitor resource
+ * @hdr: common header for different domain types
+ */
+struct rdt_perf_pkg_mon_domain {
+ struct rdt_domain_hdr hdr;
+};
+
/**
* struct msr_param - set a range of MSRs from a domain
* @res: The resource to use
@@ -226,6 +234,8 @@ void resctrl_arch_mbm_cntr_assign_set_one(struct rdt_resource *r);
bool intel_aet_get_events(void);
void __exit intel_aet_exit(void);
int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val);
+void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
+ struct list_head *add_pos);
#else
static inline bool intel_aet_get_events(void) { return false; }
static inline void __exit intel_aet_exit(void) { }
@@ -233,6 +243,9 @@ static inline int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64
{
return -EINVAL;
}
+
+static inline void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
+ struct list_head *add_pos) { }
#endif

#endif /* _ASM_X86_RESCTRL_INTERNAL_H */
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 3c6946a5ff1b..283d653002a2 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -580,6 +580,10 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
if (!hdr)
l3_mon_domain_setup(cpu, id, r, add_pos);
break;
+ case RDT_RESOURCE_PERF_PKG:
+ if (!hdr)
+ intel_aet_mon_domain_setup(cpu, id, r, add_pos);
+ break;
default:
pr_warn_once("Unknown resource rid=%d\n", r->rid);
break;
@@ -679,6 +683,19 @@ static void domain_remove_cpu_mon(int cpu, struct rdt_resource *r)
l3_mon_domain_free(hw_dom);
break;
}
+ case RDT_RESOURCE_PERF_PKG: {
+ struct rdt_perf_pkg_mon_domain *pkgd;
+
+ if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_PERF_PKG))
+ return;
+
+ pkgd = container_of(hdr, struct rdt_perf_pkg_mon_domain, hdr);
+ resctrl_offline_mon_domain(r, hdr);
+ list_del_rcu(&hdr->list);
+ synchronize_rcu();
+ kfree(pkgd);
+ break;
+ }
default:
pr_warn_once("Unknown resource rid=%d\n", r->rid);
break;
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index bf3c70590d4c..46c64419ec10 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -17,16 +17,21 @@
#include <linux/compiler_types.h>
#include <linux/container_of.h>
#include <linux/cpu.h>
+#include <linux/cpumask.h>
#include <linux/err.h>
#include <linux/errno.h>
+#include <linux/gfp_types.h>
#include <linux/init.h>
#include <linux/intel_pmt_features.h>
#include <linux/intel_vsec.h>
#include <linux/io.h>
#include <linux/overflow.h>
#include <linux/printk.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
#include <linux/resctrl.h>
#include <linux/resctrl_types.h>
+#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/topology.h>
#include <linux/types.h>
@@ -272,3 +277,27 @@ int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val)

return valid ? 0 : -EINVAL;
}
+
+void intel_aet_mon_domain_setup(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 = RDT_RESOURCE_PERF_PKG;
+ 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);
+ }
+}
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 679247c43b1a..ac3c6e44b7c5 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -4307,11 +4307,6 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *h

mutex_lock(&rdtgroup_mutex);

- if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
- goto out_unlock;
-
- d = container_of(hdr, struct rdt_l3_mon_domain, hdr);
-
/*
* If resctrl is mounted, remove all the
* per domain monitor data directories.
@@ -4319,6 +4314,13 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *h
if (resctrl_mounted && resctrl_arch_mon_capable())
rmdir_mondata_subdir_allrdtgrp(r, hdr);

+ if (r->rid != RDT_RESOURCE_L3)
+ goto out_unlock;
+
+ if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
+ goto out_unlock;
+
+ d = container_of(hdr, struct rdt_l3_mon_domain, hdr);
if (resctrl_is_mbm_enabled())
cancel_delayed_work(&d->mbm_over);
if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID) && has_busy_rmid(d)) {
@@ -4415,6 +4417,9 @@ int resctrl_online_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *hdr

mutex_lock(&rdtgroup_mutex);

+ if (r->rid != RDT_RESOURCE_L3)
+ goto mkdir;
+
if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
goto out_unlock;

@@ -4432,6 +4437,8 @@ 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);

+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
--
2.51.1