From: Marc Zyngier <maz@kernel.org>
Date: Tue, 8 Oct 2019 15:09:55 +0100
Subject: KVM: arm64: pmu: Set the CHAINED attribute before creating the
in-kernel event
Patch-mainline: v5.4-rc5
Git-commit: 725ce66979fb6da5c1aec5b064d0871bedc23bf7
References: bsc#1133021
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")
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Liang Yan <lyan@suse.com>
---
virt/kvm/arm/pmu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -569,12 +569,12 @@ static void kvm_pmu_create_perf_event(st
* 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))