linux-kernel - [PATCH v5 5/5] KVM: arm64: PMU: Reload when resetting

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Message-Id: <20250315-pmc-v5-5-ecee87dab216@daynix.com>
Date: Sat, 15 Mar 2025 18:12:14 +0900
From: Akihiko Odaki <akihiko.odaki@...nix.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
 Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
 Zenghui Yu <yuzenghui@...wei.com>, 
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
 Andrew Jones <andrew.jones@...ux.dev>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, devel@...nix.com, 
 Akihiko Odaki <akihiko.odaki@...nix.com>
Subject: [PATCH v5 5/5] KVM: arm64: PMU: Reload when resetting

Replace kvm_pmu_vcpu_reset() with the generic PMU reloading mechanism to
ensure the consistency with system registers and to reduce code size.

Signed-off-by: Akihiko Odaki <akihiko.odaki@...nix.com>
---
 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, 3 insertions(+), 19 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 8e10124a7420..aae5713d8993 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -254,20 +254,6 @@ 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 803e11b0dc8f..f82fcc614e13 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -196,9 +196,6 @@ 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 727579acc7f6..14f66c7a4545 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -4480,6 +4480,9 @@ 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 b6d0a682505d..d6ad13925978 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -53,7 +53,6 @@ u64 kvm_pmu_accessible_counter_mask(struct kvm_vcpu *vcpu);
 u64 kvm_pmu_valid_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);
@@ -126,7 +125,6 @@ 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) {}

-- 
2.48.1