linux-kernel - [PATCH v2 2/3] KVM: arm64: PMU: Reload when user modifies registers

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Message-Id: <20250307-pmc-v2-2-6c3375a5f1e4@daynix.com>
Date: Fri, 07 Mar 2025 19:55:29 +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 <drjones@...hat.com>, Shannon Zhao <shannon.zhao@...aro.org>
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 v2 2/3] KVM: arm64: PMU: Reload when user modifies
 registers

Commit d0c94c49792c ("KVM: arm64: Restore PMU configuration on first
run") added the code to reload the PMU configuration on first run.
Trigger the code when a user modifies a PMU register instead so that
PMU configuration changes made by users will be applied also after the
first run.

Signed-off-by: Akihiko Odaki <akihiko.odaki@...nix.com>
---
 arch/arm64/kvm/pmu-emul.c | 3 ---
 arch/arm64/kvm/sys_regs.c | 5 +++++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 1402cce5625bffa706aabe5e6121d1f3817a0aaf..04eb3856b96576fad5afc8927c8916ff9738f9d7 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -888,9 +888,6 @@ int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu)
 		   return -EINVAL;
 	}
 
-	/* One-off reload of the PMU on first run */
-	kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu);
-
 	return 0;
 }
 
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 27418dac791df9a89124f867879e899db175e506..51054b7befc0b4bd822cecf717ee4a4740c4a685 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1162,6 +1162,8 @@ static int set_pmreg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r, u64 va
 	else
 		__vcpu_sys_reg(vcpu, r->reg) &= ~val;
 
+	kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu);
+
 	return 0;
 }
 
@@ -1322,6 +1324,8 @@ static int set_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
 		val |= ARMV8_PMU_PMCR_LC;
 
 	__vcpu_sys_reg(vcpu, r->reg) = val;
+	kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu);
+
 	return 0;
 }
 
@@ -4276,6 +4280,7 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu)
 	}
 
 	set_bit(KVM_ARCH_FLAG_ID_REGS_INITIALIZED, &kvm->arch.flags);
+	kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu);
 }
 
 /**

-- 
2.48.1