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Date: Fri, 20 Jan 2023 08:54:06 -0800
From: kan.liang@...ux.intel.com
To: joro@...tes.org, will@...nel.org, baolu.lu@...ux.intel.com,
dwmw2@...radead.org, robin.murphy@....com, robert.moore@...el.com,
rafael.j.wysocki@...el.com, lenb@...nel.org, iommu@...ts.linux.dev,
linux-kernel@...r.kernel.org
Cc: yu-cheng.yu@...el.com, Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V3 5/7] iommu/vt-d: Support cpumask for IOMMU perfmon
From: Kan Liang <kan.liang@...ux.intel.com>
The perf subsystem assumes that all counters are by default per-CPU. So
the user space tool reads a counter from each CPU. However, the IOMMU
counters are system-wide and can be read from any CPU. Here we use a CPU
mask to restrict counting to one CPU to handle the issue. (with CPU
hotplug notifier to choose a different CPU if the chosen one is taken
off-line).
The CPU is exposed to /sys/bus/event_source/devices/dmar*/cpumask for
the user space perf tool.
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
.../sysfs-bus-event_source-devices-iommu | 8 ++
drivers/iommu/intel/perfmon.c | 115 ++++++++++++++++--
include/linux/cpuhotplug.h | 1 +
3 files changed, 116 insertions(+), 8 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-event_source-devices-iommu b/Documentation/ABI/testing/sysfs-bus-event_source-devices-iommu
index 04e08851d8e6..3519954fe713 100644
--- a/Documentation/ABI/testing/sysfs-bus-event_source-devices-iommu
+++ b/Documentation/ABI/testing/sysfs-bus-event_source-devices-iommu
@@ -22,3 +22,11 @@ Description: Read-only. Attribute group to describe the magic bits
filter_pasid = "config1:32-53" - PASID filter
filter_ats = "config2:0-4" - Address Type filter
filter_page_table = "config2:8-12" - Page Table Level filter
+
+What: /sys/bus/event_source/devices/dmar*/cpumask
+Date: Jan 2023
+KernelVersion: 6.3
+Contact: Kan Liang <kan.liang@...ux.intel.com>
+Description: Read-only. This file always returns the CPU to which the
+ IOMMU pmu is bound for access to all IOMMU pmu
+ performance monitoring events.
diff --git a/drivers/iommu/intel/perfmon.c b/drivers/iommu/intel/perfmon.c
index 06e95b9b88d5..ed06bf121b50 100644
--- a/drivers/iommu/intel/perfmon.c
+++ b/drivers/iommu/intel/perfmon.c
@@ -32,9 +32,30 @@ static struct attribute_group iommu_pmu_events_attr_group = {
.attrs = attrs_empty,
};
+static cpumask_t iommu_pmu_cpu_mask;
+
+static ssize_t iommu_pmu_cpumask_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return cpumap_print_to_pagebuf(true, buf, &iommu_pmu_cpu_mask);
+}
+
+static DEVICE_ATTR(cpumask, S_IRUGO, iommu_pmu_cpumask_show, NULL);
+
+static struct attribute *iommu_pmu_cpumask_attrs[] = {
+ &dev_attr_cpumask.attr,
+ NULL
+};
+
+static struct attribute_group iommu_pmu_cpumask_attr_group = {
+ .attrs = iommu_pmu_cpumask_attrs,
+};
+
static const struct attribute_group *iommu_pmu_attr_groups[] = {
&iommu_pmu_format_attr_group,
&iommu_pmu_events_attr_group,
+ &iommu_pmu_cpumask_attr_group,
NULL
};
@@ -660,20 +681,98 @@ void free_iommu_pmu(struct intel_iommu *iommu)
iommu->pmu = NULL;
}
+static int iommu_pmu_cpu_online(unsigned int cpu)
+{
+ if (cpumask_empty(&iommu_pmu_cpu_mask))
+ cpumask_set_cpu(cpu, &iommu_pmu_cpu_mask);
+
+ return 0;
+}
+
+static int iommu_pmu_cpu_offline(unsigned int cpu)
+{
+ struct dmar_drhd_unit *drhd;
+ struct intel_iommu *iommu;
+ int target;
+
+ if (!cpumask_test_and_clear_cpu(cpu, &iommu_pmu_cpu_mask))
+ return 0;
+
+ target = cpumask_any_but(cpu_online_mask, cpu);
+
+ if (target < nr_cpu_ids)
+ cpumask_set_cpu(target, &iommu_pmu_cpu_mask);
+ else
+ target = -1;
+
+ rcu_read_lock();
+
+ for_each_iommu(iommu, drhd) {
+ if (!iommu->pmu)
+ continue;
+ perf_pmu_migrate_context(&iommu->pmu->pmu, cpu, target);
+ }
+ rcu_read_unlock();
+
+ return 0;
+}
+
+static int nr_iommu_pmu;
+
+static int iommu_pmu_cpuhp_setup(struct iommu_pmu *iommu_pmu)
+{
+ int ret;
+
+ if (nr_iommu_pmu++)
+ return 0;
+
+ ret = cpuhp_setup_state(CPUHP_AP_PERF_X86_IOMMU_PERF_ONLINE,
+ "driver/iommu/intel/perfmon:online",
+ iommu_pmu_cpu_online,
+ iommu_pmu_cpu_offline);
+ if (ret)
+ nr_iommu_pmu = 0;
+
+ return ret;
+}
+
+static void iommu_pmu_cpuhp_free(struct iommu_pmu *iommu_pmu)
+{
+ if (--nr_iommu_pmu)
+ return;
+
+ cpuhp_remove_state(CPUHP_AP_PERF_X86_IOMMU_PERF_ONLINE);
+}
+
void iommu_pmu_register(struct intel_iommu *iommu)
{
- if (!iommu->pmu)
+ struct iommu_pmu *iommu_pmu = iommu->pmu;
+
+ if (!iommu_pmu)
return;
- if (__iommu_pmu_register(iommu)) {
- pr_err("Failed to register PMU for iommu (seq_id = %d)\n",
- iommu->seq_id);
- free_iommu_pmu(iommu);
- }
+ if (__iommu_pmu_register(iommu))
+ goto err;
+
+ if (iommu_pmu_cpuhp_setup(iommu_pmu))
+ goto unregister;
+
+ return;
+
+unregister:
+ perf_pmu_unregister(&iommu_pmu->pmu);
+err:
+ pr_err("Failed to register PMU for iommu (seq_id = %d)\n", iommu->seq_id);
+ free_iommu_pmu(iommu);
}
void iommu_pmu_unregister(struct intel_iommu *iommu)
{
- if (iommu->pmu)
- perf_pmu_unregister(&iommu->pmu->pmu);
+ struct iommu_pmu *iommu_pmu = iommu->pmu;
+
+ if (!iommu_pmu)
+ return;
+
+ iommu_pmu_cpuhp_free(iommu_pmu);
+ perf_pmu_unregister(&iommu_pmu->pmu);
}
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 6c6859bfc454..f2ea348ce3b0 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -221,6 +221,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_X86_CQM_ONLINE,
CPUHP_AP_PERF_X86_CSTATE_ONLINE,
CPUHP_AP_PERF_X86_IDXD_ONLINE,
+ CPUHP_AP_PERF_X86_IOMMU_PERF_ONLINE,
CPUHP_AP_PERF_S390_CF_ONLINE,
CPUHP_AP_PERF_S390_SF_ONLINE,
CPUHP_AP_PERF_ARM_CCI_ONLINE,
--
2.35.1
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