linux-kernel - [PATCH 4/4] powerpc/perf: Add per-task/process monitoring to vpa

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Message-ID: <20241114084013.1140010-4-kjain@linux.ibm.com>
Date: Thu, 14 Nov 2024 14:10:13 +0530
From: Kajol Jain <kjain@...ux.ibm.com>
To: mpe@...erman.id.au, maddy@...ux.ibm.com
Cc: atrajeev@...ux.vnet.ibm.com, kjain@...ux.ibm.com, disgoel@...ux.ibm.com,
        hbathini@...ux.ibm.com, adubey@...ux.ibm.com, gautam@...ux.ibm.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] powerpc/perf: Add per-task/process monitoring to vpa_pmu driver

Enhance the vpa_pmu driver with a feature to observe context switch
latency event for both per-task (tid) and per-pid (pid) option.
Couple of new helper functions are added to hide the abstraction of
reading the context switch latency counter from kvm_vcpu_arch struct
and these helper functions are defined in the "kvm/book3s_hv.c".

"PERF_ATTACH_TASK" flag is used to decide whether to read the counter
values from lppaca or kvm_vcpu_arch struct.

Signed-off-by: Kajol Jain <kjain@...ux.ibm.com>
Co-developed-by: Madhavan Srinivasan <maddy@...ux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@...ux.ibm.com>
---
 arch/powerpc/include/asm/kvm_book3s_64.h |  3 ++
 arch/powerpc/kvm/book3s_hv.c             | 45 ++++++++++++++++++++++++
 arch/powerpc/perf/vpa-pmu.c              | 15 ++++++--
 3 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index b9bcbf999bd9..300d0a774ce3 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -691,6 +691,9 @@ void kvmhv_set_l2_counters_status(int cpu, bool status);
 u64 kvmhv_get_l1_to_l2_cs_time(void);
 u64 kvmhv_get_l2_to_l1_cs_time(void);
 u64 kvmhv_get_l2_runtime_agg(void);
+u64 kvmhv_get_l1_to_l2_cs_time_vcpu(void);
+u64 kvmhv_get_l2_to_l1_cs_time_vcpu(void);
+u64 kvmhv_get_l2_runtime_agg_vcpu(void);
 
 #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
 
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index b5bdb981c3e3..e65b840d5f2a 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4214,6 +4214,51 @@ u64 kvmhv_get_l2_runtime_agg(void)
 }
 EXPORT_SYMBOL(kvmhv_get_l2_runtime_agg);
 
+u64 kvmhv_get_l1_to_l2_cs_time_vcpu(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vcpu_arch *arch;
+
+	vcpu = local_paca->kvm_hstate.kvm_vcpu;
+	if (vcpu) {
+		arch = &vcpu->arch;
+		return arch->l1_to_l2_cs;
+	} else {
+		return 0;
+	}
+}
+EXPORT_SYMBOL(kvmhv_get_l1_to_l2_cs_time_vcpu);
+
+u64 kvmhv_get_l2_to_l1_cs_time_vcpu(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vcpu_arch *arch;
+
+	vcpu = local_paca->kvm_hstate.kvm_vcpu;
+	if (vcpu) {
+		arch = &vcpu->arch;
+		return arch->l2_to_l1_cs;
+	} else {
+		return 0;
+	}
+}
+EXPORT_SYMBOL(kvmhv_get_l2_to_l1_cs_time_vcpu);
+
+u64 kvmhv_get_l2_runtime_agg_vcpu(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vcpu_arch *arch;
+
+	vcpu = local_paca->kvm_hstate.kvm_vcpu;
+	if (vcpu) {
+		arch = &vcpu->arch;
+		return arch->l2_runtime_agg;
+	} else {
+		return 0;
+	}
+}
+EXPORT_SYMBOL(kvmhv_get_l2_runtime_agg_vcpu);
+
 #else
 int kvmhv_get_l2_counters_status(void)
 {
diff --git a/arch/powerpc/perf/vpa-pmu.c b/arch/powerpc/perf/vpa-pmu.c
index 0382973aeb8e..e0035fd52e9b 100644
--- a/arch/powerpc/perf/vpa-pmu.c
+++ b/arch/powerpc/perf/vpa-pmu.c
@@ -97,13 +97,22 @@ static unsigned long get_counter_data(struct perf_event *event)
 
 	switch (config) {
 	case L1_TO_L2_CS_LAT:
-		data = kvmhv_get_l1_to_l2_cs_time();
+		if (event->attach_state & PERF_ATTACH_TASK)
+			data = kvmhv_get_l1_to_l2_cs_time_vcpu();
+		else
+			data = kvmhv_get_l1_to_l2_cs_time();
 		break;
 	case L2_TO_L1_CS_LAT:
-		data = kvmhv_get_l2_to_l1_cs_time();
+		if (event->attach_state & PERF_ATTACH_TASK)
+			data = kvmhv_get_l2_to_l1_cs_time_vcpu();
+		else
+			data = kvmhv_get_l2_to_l1_cs_time();
 		break;
 	case L2_RUNTIME_AGG:
-		data = kvmhv_get_l2_runtime_agg();
+		if (event->attach_state & PERF_ATTACH_TASK)
+			data = kvmhv_get_l2_runtime_agg_vcpu();
+		else
+			data = kvmhv_get_l2_runtime_agg();
 		break;
 	default:
 		data = 0;
-- 
2.43.5