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From: Alexandru Elisei <alexandru.elisei@arm.com>
To: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, maz@kernel.org,
	james.morse@arm.com, julien.thierry.kdev@gmail.com,
	suzuki.poulose@arm.com
Subject: [PATCH 5/5] KVM: arm64: Remove redundant call to kvm_pmu_vcpu_reset()
Date: Tue,  1 Dec 2020 15:01:57 +0000	[thread overview]
Message-ID: <20201201150157.223625-6-alexandru.elisei@arm.com> (raw)
In-Reply-To: <20201201150157.223625-1-alexandru.elisei@arm.com>

KVM_ARM_VCPU_INIT ioctl calls kvm_reset_vcpu(), which in turn resets the
PMU with a call to kvm_pmu_vcpu_reset(). The function zeroes the PMU
chained counters bitmap and stops all the counters with a perf event
attached. Because it is called before the VCPU has had the chance to run,
no perf events are in use and none are released.

kvm_arm_pmu_v3_enable(), called by kvm_vcpu_first_run_init() only if the
VCPU has not been initialized, also resets the PMU. kvm_pmu_vcpu_reset() in
this case does the exact same thing as the previous call, so remove it.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arch/arm64/kvm/pmu-emul.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 398f6df1bbe4..4ad66a532e38 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -850,8 +850,6 @@ int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu)
 		   return -EINVAL;
 	}
 
-	kvm_pmu_vcpu_reset(vcpu);
-
 	return 0;
 }
 
-- 
2.29.2

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Alexandru Elisei <alexandru.elisei@arm.com>
To: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, maz@kernel.org,
	james.morse@arm.com, julien.thierry.kdev@gmail.com,
	suzuki.poulose@arm.com
Subject: [PATCH 5/5] KVM: arm64: Remove redundant call to kvm_pmu_vcpu_reset()
Date: Tue,  1 Dec 2020 15:01:57 +0000	[thread overview]
Message-ID: <20201201150157.223625-6-alexandru.elisei@arm.com> (raw)
In-Reply-To: <20201201150157.223625-1-alexandru.elisei@arm.com>

KVM_ARM_VCPU_INIT ioctl calls kvm_reset_vcpu(), which in turn resets the
PMU with a call to kvm_pmu_vcpu_reset(). The function zeroes the PMU
chained counters bitmap and stops all the counters with a perf event
attached. Because it is called before the VCPU has had the chance to run,
no perf events are in use and none are released.

kvm_arm_pmu_v3_enable(), called by kvm_vcpu_first_run_init() only if the
VCPU has not been initialized, also resets the PMU. kvm_pmu_vcpu_reset() in
this case does the exact same thing as the previous call, so remove it.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arch/arm64/kvm/pmu-emul.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 398f6df1bbe4..4ad66a532e38 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -850,8 +850,6 @@ int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu)
 		   return -EINVAL;
 	}
 
-	kvm_pmu_vcpu_reset(vcpu);
-
 	return 0;
 }
 
-- 
2.29.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2020-12-01 15:00 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-01 15:01 [PATCH 0/5] KVM: arm64: Miscellaneous improvements Alexandru Elisei
2020-12-01 15:01 ` Alexandru Elisei
2020-12-01 15:01 ` [PATCH 1/5] KVM: Documentation: Add arm64 KVM_RUN error codes Alexandru Elisei
2020-12-01 15:01   ` Alexandru Elisei
2020-12-01 15:01 ` [PATCH 2/5] KVM: arm64: arch_timer: Remove VGIC initialization check Alexandru Elisei
2020-12-01 15:01   ` Alexandru Elisei
2020-12-14 12:45   ` Auger Eric
2020-12-14 12:45     ` Auger Eric
2020-12-01 15:01 ` [PATCH 3/5] KVM: arm64: Move double-checked lock to kvm_vgic_map_resources() Alexandru Elisei
2020-12-01 15:01   ` Alexandru Elisei
2020-12-14 12:55   ` Auger Eric
2020-12-14 12:55     ` Auger Eric
2020-12-27 14:36     ` Marc Zyngier
2020-12-27 14:36       ` Marc Zyngier
2020-12-01 15:01 ` [PATCH 4/5] KVM: arm64: Update comment in kvm_vgic_map_resources() Alexandru Elisei
2020-12-01 15:01   ` Alexandru Elisei
2020-12-14 12:59   ` Auger Eric
2020-12-14 12:59     ` Auger Eric
2020-12-01 15:01 ` Alexandru Elisei [this message]
2020-12-01 15:01   ` [PATCH 5/5] KVM: arm64: Remove redundant call to kvm_pmu_vcpu_reset() Alexandru Elisei
2020-12-14 13:48   ` Auger Eric
2020-12-14 13:48     ` Auger Eric
2020-12-14 14:02     ` Alexandru Elisei
2020-12-14 14:02       ` Alexandru Elisei
2020-12-15  9:15       ` Auger Eric
2020-12-15  9:15         ` Auger Eric
2020-12-27 14:41 ` [PATCH 0/5] KVM: arm64: Miscellaneous improvements Marc Zyngier
2020-12-27 14:41   ` Marc Zyngier

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