[PATCH 1/1] KVM: ARM64: Fix the issues when PMCCFILTR is configured
cov at codeaurora.org
cov at codeaurora.org
Wed Nov 2 21:11:16 PDT 2016
Hi Wei,
On 2016-11-02 14:55, Wei Huang wrote:
> KVM calls kvm_pmu_set_counter_event_type() when PMCCFILTR is
> configured.
> But this function can't deals with PMCCFILTR correctly because the
> evtCount
> bit of PMCCFILTR, which is reserved 0, conflits with the SW_INCR event
> type of other PMXEVTYPER<n> registers. To fix it, when eventsel == 0,
> KVM
> shouldn't return immediately, but instead it needs to check further if
> select_idx is ARMV8_PMU_CYCLE_IDX.
>
> Another issue is that KVM shouldn't copy the eventsel bits of
> PMCCFILTER
> directly to attr.config. Istead it shoudl convert the request to
> perf_event of type 0x11 (i.e. the "cpu cycle" event type).
>
> Signed-off-by: Wei Huang <wei at redhat.com>
> ---
> virt/kvm/arm/pmu.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
> index 6e9c40e..13cc812 100644
> --- a/virt/kvm/arm/pmu.c
> +++ b/virt/kvm/arm/pmu.c
> @@ -379,7 +379,8 @@ void kvm_pmu_set_counter_event_type(struct
> kvm_vcpu *vcpu, u64 data,
> eventsel = data & ARMV8_PMU_EVTYPE_EVENT;
>
> /* Software increment event does't need to be backed by a perf event
> */
> - if (eventsel == ARMV8_PMU_EVTYPE_EVENT_SW_INCR)
> + if (eventsel == ARMV8_PMU_EVTYPE_EVENT_SW_INCR &&
> + select_idx != ARMV8_PMU_CYCLE_IDX)
> return;
>
> memset(&attr, 0, sizeof(struct perf_event_attr));
> @@ -391,7 +392,7 @@ void kvm_pmu_set_counter_event_type(struct
> kvm_vcpu *vcpu, u64 data,
> attr.exclude_kernel = data & ARMV8_PMU_EXCLUDE_EL1 ? 1 : 0;
> attr.exclude_hv = 1; /* Don't count EL2 events */
> attr.exclude_host = 1; /* Don't count host events */
> - attr.config = eventsel;
> + attr.config = (select_idx == ARMV8_PMU_CYCLE_IDX) ? 0x011 : eventsel;
Nit: Is there some way you could use ARMV8_PMUV3_PERFCTR_CPU_CYCLES
currently
defined in arch/arm64/kernel/perf_event.c?
Thanks,
Cov
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