[PATCH v3 1/3] Revert "powerpc/perf: Add per-task/process monitoring to vpa_pmu driver"

[Gautam Menghani]

This reverts commit f26f9933e3e31b2117b804b6b8932388db88a131.

The local_paca holds a pointer to the vCPU currently running on the given
host CPU. When the vpa-pmu driver tries to get the vCPU pointer from
local_paca, it either receives NULL or the pointer to the vCPU which was
running on that host CPU previously. This is because the vCPU pointer in
PACA is updated by kvmhv_run_single_vcpu(), which runs after
vpa_pmu_add(). Also, on vCPU exit, the vCPU pointer in PACA is never
cleared. This results in incorrect numbers being reported by the vpa-pmu
driver.

Fix the problem by avoiding the use of vCPU pointer in PACA altogether.
When a vCPU is scheduled in and out on a host vCPU, vpa_pmu_add() and
vpa_pmu_del() can already calculate the correct latency values in
event->count. Drop the usage of the vCPU pointer in PACA and just rely
on the VPA counter values.

Fixes: f26f9933e3e3 ("powerpc/perf: Add per-task/process monitoring to vpa_pmu driver")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Gautam Menghani <gautam@xxxxxxxxxxxxx>
---
 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, 3 insertions(+), 60 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index b936e174eefd..f620e3126d68 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -691,9 +691,6 @@ 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 22283d46e8fe..5fa6f93548ad 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4212,51 +4212,6 @@ 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 bff4cfab7b94..01d9196fcb0f 100644
--- a/arch/powerpc/perf/vpa-pmu.c
+++ b/arch/powerpc/perf/vpa-pmu.c
@@ -98,22 +98,13 @@ static unsigned long get_counter_data(struct perf_event *event)
 
 	switch (config) {
 	case L1_TO_L2_CS_LAT:
-		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();
+		data = kvmhv_get_l1_to_l2_cs_time();
 		break;
 	case L2_TO_L1_CS_LAT:
-		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();
+		data = kvmhv_get_l2_to_l1_cs_time();
 		break;
 	case L2_RUNTIME_AGG:
-		if (event->attach_state & PERF_ATTACH_TASK)
-			data = kvmhv_get_l2_runtime_agg_vcpu();
-		else
-			data = kvmhv_get_l2_runtime_agg();
+		data = kvmhv_get_l2_runtime_agg();
 		break;
 	default:
 		data = 0;
-- 
2.56.0