[PATCH v11 08/21] Revert "KVM: arm64: PMU: Reload when resetting"

[Akihiko Odaki]

This reverts commit fe53538069bb4f625bc8734103ba044a83138fea.

Restore PMU event teardown before system-register reset so existing
perf events cannot retain configuration from the previous run. All
counters are disabled by the reset PMCR_EL0 and MDCR_EL2 values, so
reset does not need to request a PMU reload.

Assisted-by: Codex:gpt-6-astra
Signed-off-by: Akihiko Odaki <odaki at rsg.ci.i.u-tokyo.ac.jp>
---
 arch/arm64/kvm/pmu-emul.c | 14 ++++++++++++++
 arch/arm64/kvm/reset.c    |  3 +++
 arch/arm64/kvm/sys_regs.c |  3 ---
 include/kvm/arm_pmu.h     |  2 ++
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index a5ccb6ae44d5..14fcdbdb4587 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -258,6 +258,20 @@ void kvm_pmu_vcpu_init(struct kvm_vcpu *vcpu)
 		pmu->pmc[i].idx = i;
 }
 
+/**
+ * kvm_pmu_vcpu_reset - reset pmu state for cpu
+ * @vcpu: The vcpu pointer
+ *
+ */
+void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu)
+{
+	unsigned long mask = kvm_pmu_implemented_counter_mask(vcpu);
+	int i;
+
+	for_each_set_bit(i, &mask, 32)
+		kvm_pmu_stop_counter(kvm_vcpu_idx_to_pmc(vcpu, i));
+}
+
 /**
  * kvm_pmu_vcpu_destroy - free perf event of PMU for cpu
  * @vcpu: The vcpu pointer
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 10eb7249aa9e..adcb460a5287 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -185,6 +185,9 @@ void kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 	vcpu->arch.reset_state.reset = false;
 	spin_unlock(&vcpu->arch.mp_state_lock);
 
+	/* Reset PMU outside of the non-preemptible section */
+	kvm_pmu_vcpu_reset(vcpu);
+
 	preempt_disable();
 	loaded = (vcpu->cpu != -1);
 	if (loaded)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 1481dd5c99a8..75624725adf1 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -5388,9 +5388,6 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu)
 	}
 
 	set_bit(KVM_ARCH_FLAG_ID_REGS_INITIALIZED, &kvm->arch.flags);
-
-	if (kvm_vcpu_has_pmu(vcpu))
-		kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu);
 }
 
 /**
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 6b4a118d17ca..51f5e4ca3326 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -48,6 +48,7 @@ u64 kvm_pmu_implemented_counter_mask(struct kvm_vcpu *vcpu);
 u64 kvm_pmu_accessible_counter_mask(struct kvm_vcpu *vcpu);
 u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1);
 void kvm_pmu_vcpu_init(struct kvm_vcpu *vcpu);
+void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu);
 void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu);
 void kvm_pmu_reprogram_counter_mask(struct kvm_vcpu *vcpu, u64 val);
 void kvm_pmu_flush_hwstate(struct kvm_vcpu *vcpu);
@@ -125,6 +126,7 @@ static inline u64 kvm_pmu_accessible_counter_mask(struct kvm_vcpu *vcpu)
 	return 0;
 }
 static inline void kvm_pmu_vcpu_init(struct kvm_vcpu *vcpu) {}
+static inline void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu) {}
 static inline void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu) {}
 static inline void kvm_pmu_reprogram_counter_mask(struct kvm_vcpu *vcpu, u64 val) {}
 static inline void kvm_pmu_flush_hwstate(struct kvm_vcpu *vcpu) {}

-- 
2.55.0