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KVM: arm64: pmu: Set the CHAINED attribute before creating the in-kernel event

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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: 80f393a23b ("KVM: arm/arm64: Support chained PMU counters")
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2019-10-08 15:09:55 +01:00
parent 6f16371453
commit 725ce66979
1 changed files with 3 additions and 3 deletions
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6
virt/kvm/arm/pmu.c
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@ -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))