Patch here adds cpu hotplug functions to hv_gpci pmu.
A new cpuhp_state "CPUHP_AP_PERF_POWERPC_HV_GPCI_ONLINE" enum
is added.
The online callback function updates the cpumask only if its
empty. As the primary intention of adding hotplug support
is to designate a CPU to make HCALL to collect the
counter data.
The offline function test and clear corresponding cpu in a cpumask
and update cpumask to any other active cpu.
Signed-off-by: Kajol Jain <kj...@linux.ibm.com>
---
arch/powerpc/perf/hv-gpci.c | 46 +++++++++++++++++++++++++++++++++++++
include/linux/cpuhotplug.h | 1 +
2 files changed, 47 insertions(+)
diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c
index 6884d16ec19b..b9dc407c3159 100644
--- a/arch/powerpc/perf/hv-gpci.c
+++ b/arch/powerpc/perf/hv-gpci.c
@@ -48,6 +48,8 @@ EVENT_DEFINE_RANGE_FORMAT(length, config1, 24, 31);
/* u32, byte offset */
EVENT_DEFINE_RANGE_FORMAT(offset, config1, 32, 63);
+static cpumask_t hv_gpci_cpumask;
+
static struct attribute *format_attrs[] = {
&format_attr_request.attr,
&format_attr_starting_index.attr,
@@ -275,6 +277,45 @@ static struct pmu h_gpci_pmu = {
.capabilities = PERF_PMU_CAP_NO_EXCLUDE,
};
+static int ppc_hv_gpci_cpu_online(unsigned int cpu)
+{
+ if (cpumask_empty(&hv_gpci_cpumask))
+ cpumask_set_cpu(cpu, &hv_gpci_cpumask);
+
+ return 0;
+}
+
+static int ppc_hv_gpci_cpu_offline(unsigned int cpu)
+{
+ int target;
+
+ /* Check if exiting cpu is used for collecting gpci events */
+ if (!cpumask_test_and_clear_cpu(cpu, &hv_gpci_cpumask))
+ return 0;
+
+ /* Find a new cpu to collect gpci events */
+ target = cpumask_last(cpu_active_mask);
+
+ if (target < 0 || target >= nr_cpu_ids) {
+ pr_err("hv_gpci: CPU hotplug init failed\n");
+ return -1;
+ }
+
+ /* Migrate gpci events to the new target */
+ cpumask_set_cpu(target, &hv_gpci_cpumask);
+ perf_pmu_migrate_context(&h_gpci_pmu, cpu, target);
+
+ return 0;
+}
+
+static int hv_gpci_cpu_hotplug_init(void)
+{
+ return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_HV_GPCI_ONLINE,
+ "perf/powerpc/hv_gcpi:online",
+ ppc_hv_gpci_cpu_online,
+ ppc_hv_gpci_cpu_offline);
+}
+
static int hv_gpci_init(void)
{
int r;
@@ -295,6 +336,11 @@ static int hv_gpci_init(void)
return -ENODEV;
}
+ /* init cpuhotplug */
+ r = hv_gpci_cpu_hotplug_init();
+ if (r)
+ return r;
+
/* sampling not supported */
h_gpci_pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index bf9181cef444..b79d3d4b06e8 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -182,6 +182,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE,
CPUHP_AP_PERF_POWERPC_HV_24x7_ONLINE,
+ CPUHP_AP_PERF_POWERPC_HV_GPCI_ONLINE,
CPUHP_AP_WATCHDOG_ONLINE,
CPUHP_AP_WORKQUEUE_ONLINE,
CPUHP_AP_RCUTREE_ONLINE,
--
2.26.2
