[PATCH 21/23] KVM: arm64: pmu: Fix chained SW_INCR counters

Marc Zyngier
2020-01-30T13:29:35Z

From: Eric Auger <eric.auger@redhat.com>

At the moment a SW_INCR counter always overflows on 32-bit
boundary, independently on whether the n+1th counter is
programmed as CHAIN.

Check whether the SW_INCR counter is a 64b counter and if so,
implement the 64b logic.

Fixes: 80f393a23be6 ("KVM: arm/arm64: Support chained PMU counters")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200124142535.29386-4-eric.auger@redhat.com
---
virt/kvm/arm/pmu.c | 43 ++++++++++++++++++++++++++++++-------------
1 file changed, 30 insertions(+), 13 deletions(-)

diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 9f605e0b8dd7..560db6282137 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -477,28 +477,45 @@ static void kvm_pmu_perf_overflow(struct perf_event *perf_event,
*/
void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val)
{
+ struct kvm_pmu *pmu = &vcpu->arch.pmu;
int i;
- u64 type, enable, reg;
-
- if (val == 0)
- return;

if (!(__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E))
return;

- enable = __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
+ /* Weed out disabled counters */
+ val &= __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
+
for (i = 0; i < ARMV8_PMU_CYCLE_IDX; i++) {
+ u64 type, reg;
+
if (!(val & BIT(i)))
continue;
- type = __vcpu_sys_reg(vcpu, PMEVTYPER0_EL0 + i)
- & ARMV8_PMU_EVTYPE_EVENT;
- if ((type == ARMV8_PMUV3_PERFCTR_SW_INCR)
- && (enable & BIT(i))) {
- reg = __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) + 1;
+
+ /* PMSWINC only applies to ... SW_INC! */
+ type = __vcpu_sys_reg(vcpu, PMEVTYPER0_EL0 + i);
+ type &= ARMV8_PMU_EVTYPE_EVENT;
+ if (type != ARMV8_PMUV3_PERFCTR_SW_INCR)
+ continue;
+
+ /* increment this even SW_INC counter */
+ reg = __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) + 1;
+ reg = lower_32_bits(reg);
+ __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg;
+
+ if (reg) /* no overflow on the low part */
+ continue;
+
+ if (kvm_pmu_pmc_is_chained(&pmu->pmc[i])) {
+ /* increment the high counter */
+ reg = __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i + 1) + 1;
reg = lower_32_bits(reg);
- __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg;
- if (!reg)
- __vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(i);
+ __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i + 1) = reg;
+ if (!reg) /* mark overflow on the high counter */
+ __vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(i + 1);
+ } else {
+ /* mark overflow on low counter */
+ __vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(i);
}
}
}
--
2.20.1