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From: Eric Auger <eric.auger@redhat.com>
To: eric.auger.pro@gmail.com, eric.auger@redhat.com, maz@kernel.org,
	linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Subject: [RFC 1/3] KVM: arm64: pmu: Don't increment SW_INCR if PMCR.E is unset
Date: Wed,  4 Dec 2019 21:44:24 +0100
Message-ID: <20191204204426.9628-2-eric.auger@redhat.com> (raw)
In-Reply-To: <20191204204426.9628-1-eric.auger@redhat.com>

The specification says PMSWINC increments PMEVCNTR<n>_EL1 by 1
if PMEVCNTR<n>_EL0 is enabled and configured to count SW_INCR.

For PMEVCNTR<n>_EL0 to be enabled, we need both PMCNTENSET to
be set for the corresponding event counter but we also need
the PMCR.E bit to be set.

Fixes: 7a0adc7064b8 ("arm64: KVM: Add access handler for PMSWINC register")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 virt/kvm/arm/pmu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 8731dfeced8b..c3f8b059881e 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -486,6 +486,9 @@ void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val)
 	if (val == 0)
 		return;
 
+	if (!(__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E))
+		return;
+
 	enable = __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
 	for (i = 0; i < ARMV8_PMU_CYCLE_IDX; i++) {
 		if (!(val & BIT(i)))
-- 
2.20.1

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Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-04 20:44 [RFC 0/3] KVM/ARM: Misc PMU fixes Eric Auger
2019-12-04 20:44 ` Eric Auger [this message]
2019-12-05  9:54   ` [RFC 1/3] KVM: arm64: pmu: Don't increment SW_INCR if PMCR.E is unset Marc Zyngier
2019-12-06 10:35   ` Andrew Murray
2019-12-04 20:44 ` [RFC 2/3] KVM: arm64: pmu: Fix chained SW_INCR counters Eric Auger
2019-12-05  9:43   ` Marc Zyngier
2019-12-05 14:06     ` Auger Eric
2019-12-05 14:52       ` Marc Zyngier
2019-12-05 19:01         ` Auger Eric
2019-12-06  9:56           ` Auger Eric
2019-12-06 15:48           ` Andrew Murray
2019-12-06 15:21         ` Andrew Murray
2019-12-06 15:35           ` Marc Zyngier
2019-12-06 16:02             ` Andrew Murray
2019-12-04 20:44 ` [RFC 3/3] KVM: arm64: pmu: Enforce PMEVTYPER evtCount size Eric Auger
2019-12-05  9:02   ` Will Deacon
2019-12-05  9:37     ` Auger Eric

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