From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: Will Deacon <will@kernel.org>
Subject: [PATCH v2 3/5] KVM: arm64: pmu: Set the CHAINED attribute before creating the in-kernel event
Date: Tue, 8 Oct 2019 17:01:26 +0100 [thread overview]
Message-ID: <20191008160128.8872-4-maz@kernel.org> (raw)
In-Reply-To: <20191008160128.8872-1-maz@kernel.org>
The current convention for KVM to request a chained event from the
host PMU is to set bit[0] in attr.config1 (PERF_ATTR_CFG1_KVM_PMU_CHAINED).
But as it turns out, this bit gets set *after* we create the kernel
event that backs our virtual counter, meaning that we never get
a 64bit counter.
Moving the setting to an earlier point solves the problem.
Fixes: 80f393a23be6 ("KVM: arm/arm64: Support chained PMU counters")
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
virt/kvm/arm/pmu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index c30c3a74fc7f..f291d4ac3519 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -569,12 +569,12 @@ static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx)
* high counter.
*/
attr.sample_period = (-counter) & GENMASK(63, 0);
+ if (kvm_pmu_counter_is_enabled(vcpu, pmc->idx + 1))
+ attr.config1 |= PERF_ATTR_CFG1_KVM_PMU_CHAINED;
+
event = perf_event_create_kernel_counter(&attr, -1, current,
kvm_pmu_perf_overflow,
pmc + 1);
-
- if (kvm_pmu_counter_is_enabled(vcpu, pmc->idx + 1))
- attr.config1 |= PERF_ATTR_CFG1_KVM_PMU_CHAINED;
} else {
/* The initial sample period (overflow count) of an event. */
if (kvm_pmu_idx_is_64bit(vcpu, pmc->idx))
--
2.20.1
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next prev parent reply other threads:[~2019-10-08 16:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-08 16:01 [PATCH v2 0/5] KVM: arm64: Assorted PMU emulation fixes Marc Zyngier
2019-10-08 16:01 ` [PATCH v2 1/5] KVM: arm64: pmu: Fix cycle counter truncation Marc Zyngier
2019-10-08 16:01 ` [PATCH v2 2/5] arm64: KVM: Handle PMCR_EL0.LC as RES1 on pure AArch64 systems Marc Zyngier
2019-10-08 16:01 ` Marc Zyngier [this message]
2019-10-08 19:22 ` [PATCH v2 3/5] KVM: arm64: pmu: Set the CHAINED attribute before creating the in-kernel event Andrew Murray
2019-10-08 16:01 ` [PATCH v2 4/5] arm64: perf: Add reload-on-overflow capability Marc Zyngier
2019-10-08 17:55 ` Marc Zyngier
2019-10-08 19:52 ` Andrew Murray
2019-10-08 16:01 ` [PATCH v2 5/5] KVM: arm64: pmu: Reset sample period on overflow handling Marc Zyngier
2019-10-08 22:42 ` Andrew Murray
2019-10-11 11:28 ` Marc Zyngier
2019-10-11 11:41 ` Andrew Murray
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