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Message-ID: <20250711235341.113933-14-tony.luck@intel.com>
Date: Fri, 11 Jul 2025 16:53:20 -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 v7 13/31] x86,fs/resctrl: Handle events that can be read from any CPU
Resctrl file system code was built with the assumption that monitor
events can only be read from a CPU in the cpumask_t set for each
domain.
This was true for x86 events accessed with an MSR interface, but may
not be true for other access methods such as MMIO.
Add a flag to struct mon_evt to indicate if the event can be read on
any CPU.
Architecture uses resctrl_enable_mon_event() to enable an event and
set the flag appropriately.
Bypass all the smp_call*() code for events that can be read on any CPU
and call mon_event_count() directly from mon_event_read().
Add a test for events that can be read from any domain to skip checks
in __mon_event_count() that the read is being done from a CPU in the
correct domain or cache scope.
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
include/linux/resctrl.h | 2 +-
fs/resctrl/internal.h | 2 ++
arch/x86/kernel/cpu/resctrl/core.c | 6 ++--
fs/resctrl/ctrlmondata.c | 7 ++++-
fs/resctrl/monitor.c | 46 +++++++++++++++++++++++-------
5 files changed, 47 insertions(+), 16 deletions(-)
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 5788e1970d8c..17a21f193a3d 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -379,7 +379,7 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
u32 resctrl_arch_system_num_rmid_idx(void);
int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
-void resctrl_enable_mon_event(enum resctrl_event_id eventid);
+void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu);
bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid);
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index ef3ec2a4860f..23dd0b39a117 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -57,6 +57,7 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
* @rid: resource id for this event
* @name: name of the event
* @configurable: true if the event is configurable
+ * @any_cpu: true if the event can be read from any CPU
* @enabled: true if the event is enabled
*/
struct mon_evt {
@@ -64,6 +65,7 @@ struct mon_evt {
enum resctrl_res_level rid;
char *name;
bool configurable;
+ bool any_cpu;
bool enabled;
};
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 304fe0b61e6d..0a564285d829 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -887,15 +887,15 @@ static __init bool get_rdt_mon_resources(void)
bool ret = false;
if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
- resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID);
+ resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false);
ret = true;
}
if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
- resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
+ resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false);
ret = true;
}
if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL)) {
- resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
+ resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID, false);
ret = true;
}
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index a99903ac5d27..2e65fddc3408 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -569,6 +569,11 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
return;
}
+ if (evt->any_cpu) {
+ mon_event_count(rr);
+ goto out_ctx_free;
+ }
+
cpu = cpumask_any_housekeeping(cpumask, RESCTRL_PICK_ANY_CPU);
/*
@@ -581,7 +586,7 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
smp_call_function_any(cpumask, mon_event_count, rr, 1);
else
smp_call_on_cpu(cpu, smp_mon_event_count, rr, false);
-
+out_ctx_free:
resctrl_arch_mon_ctx_free(r, evt->evtid, rr->arch_mon_ctx);
}
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 6d4191eff391..a6d11011cb8e 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -356,15 +356,43 @@ static struct mbm_state *get_mbm_state(struct rdt_l3_mon_domain *d, u32 closid,
return state ? &state[idx] : NULL;
}
+/*
+ * For events that can be read on any CPU this function is called
+ * in preemptible context with a direct call from mon_event_read()
+ * to mon_event_count() instead of using smp_call*() to execute on a
+ * specific CPU. For other events it is called in non-preemptible context.
+ */
+static bool cpu_on_correct_domain(struct rmid_read *rr)
+{
+ struct cacheinfo *ci;
+ int cpu;
+
+ /* Any CPU is OK for this event */
+ if (rr->evt->any_cpu)
+ return true;
+
+ cpu = smp_processor_id();
+
+ /* Single domain. Must be on a CPU in that domain. */
+ if (rr->hdr)
+ return cpumask_test_cpu(cpu, &rr->hdr->cpu_mask);
+
+ /* Summing domains that share a cache, must be on a CPU for that cache. */
+ ci = get_cpu_cacheinfo_level(cpu, RESCTRL_L3_CACHE);
+
+ return ci && ci->id == rr->ci_id;
+}
+
static int __mon_event_count(u32 closid, u32 rmid, struct rmid_read *rr)
{
- int cpu = smp_processor_id();
struct rdt_l3_mon_domain *d;
- struct cacheinfo *ci;
struct mbm_state *m;
int err, ret;
u64 tval = 0;
+ if (!cpu_on_correct_domain(rr))
+ return -EINVAL;
+
if (rr->r->rid == RDT_RESOURCE_L3 && rr->first) {
if (WARN_ON_ONCE(!domain_header_is_valid(rr->hdr, RESCTRL_MON_DOMAIN,
RDT_RESOURCE_L3)))
@@ -378,9 +406,7 @@ static int __mon_event_count(u32 closid, u32 rmid, struct rmid_read *rr)
}
if (rr->hdr) {
- /* Reading a single domain, must be on a CPU in that domain. */
- if (!cpumask_test_cpu(cpu, &rr->hdr->cpu_mask))
- return -EINVAL;
+ /* Single domain. */
rr->err = resctrl_arch_rmid_read(rr->r, rr->hdr, closid, rmid,
rr->evt->evtid, &tval, rr->arch_mon_ctx);
if (rr->err)
@@ -394,12 +420,9 @@ static int __mon_event_count(u32 closid, u32 rmid, struct rmid_read *rr)
if (WARN_ON_ONCE(rr->r->rid != RDT_RESOURCE_L3))
return -EINVAL;
- /* Summing domains that share a cache, must be on a CPU for that cache. */
- ci = get_cpu_cacheinfo_level(cpu, RESCTRL_L3_CACHE);
- if (!ci || ci->id != rr->ci_id)
- return -EINVAL;
-
/*
+ * Sum across multiple domains.
+ *
* Legacy files must report the sum of an event across all
* domains that share the same L3 cache instance.
* Report success if a read from any domain succeeds, -EINVAL
@@ -878,7 +901,7 @@ struct mon_evt mon_event_all[QOS_NUM_EVENTS] = {
},
};
-void resctrl_enable_mon_event(enum resctrl_event_id eventid)
+void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu)
{
if (WARN_ON_ONCE(eventid < QOS_FIRST_EVENT || eventid >= QOS_NUM_EVENTS))
return;
@@ -887,6 +910,7 @@ void resctrl_enable_mon_event(enum resctrl_event_id eventid)
return;
}
+ mon_event_all[eventid].any_cpu = any_cpu;
mon_event_all[eventid].enabled = true;
}
--
2.50.0
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