On Mon, Jun 17, 2019 at 05:33:40PM +0100, Suzuki K Poulose wrote: > > > On 17/06/2019 16:43, Andrew Murray wrote: > > On Thu, Jun 13, 2019 at 05:50:43PM +0100, Suzuki K Poulose wrote: > > > > > > > > > On 13/06/2019 10:39, Andrew Murray wrote: > > > > On Thu, Jun 13, 2019 at 08:30:51AM +0100, Julien Thierry wrote: > > > > > > > index ae1e886d4a1a..88ce24ae0b45 100644 > > > > > > --- a/virt/kvm/arm/pmu.c > > > > > > +++ b/virt/kvm/arm/pmu.c > > > > > > @@ -47,7 +47,10 @@ u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx) > > > > > > counter += perf_event_read_value(pmc->perf_event, &enabled, > > > > > > &running); > > > > > > - return counter & pmc->bitmask; > > > > > > + if (select_idx != ARMV8_PMU_CYCLE_IDX) > > > > > > + counter = lower_32_bits(counter); > > > > > > > > > > Shouldn't this depend on PMCR.LC as well? If PMCR.LC is clear we only > > > > > want the lower 32bits of the cycle counter. > > > > > > > > Yes that's correct. The hunk should look like this: > > > > > > > > - return counter & pmc->bitmask; > > > > + if (!(select_idx == ARMV8_PMU_CYCLE_IDX && > > > > + __vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_LC)) > > > > + counter = lower_32_bits(counter); > > > > + > > > > + return counter; > > > > > > May be you could add a macro : > > > > > > #define vcpu_pmu_counter_is_64bit(vcpu, idx) ? > > > > Yes I think a helper would be useful - though I'd prefer the name > > 'kvm_pmu_idx_is_long_cycle_counter'. This seems a little clearer as > > you could otherwise argue that a chained counter is also 64 bits. > > When you get to add 64bit PMU counter (v8.5), this would be handy. So > having it de-coupled from the cycle counter may be a good idea. Anyways, > I leave that to you. Yes that thought crossed my mind. I'll take your suggestion afterall. Thanks, Andrew Murray > > Cheers > Suzuki _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
