Re: [PATCH v4 6/7] selftests: kvm/x86: Add testing for KVM_SET_PMU_EVENT_FILTER

[Jim Mattson <jmattson@google.com>]

On Wed, Aug 31, 2022 at 9:21 AM Aaron Lewis <aaronlewis@google.com> wrote:
>
> Test that masked events are not using invalid bits, and if they are,
> ensure the pmu event filter is not accepted by KVM_SET_PMU_EVENT_FILTER.
> The only valid bits that can be used for masked events are set when
> using KVM_PMU_EVENT_ENCODE_MASKED_EVENT() with one exception: If any
> of the high bits (11:8) of the event select are set when using Intel,
> the PMU event filter will fail.
>
> Also, because validation was not being done prior to the introduction
> of masked events, only expect validation to fail when masked events
> are used.  E.g. in the first test a filter event with all it's bits set

Nit: its

> is accepted by KVM_SET_PMU_EVENT_FILTER when flags = 0.
>
> Signed-off-by: Aaron Lewis <aaronlewis@google.com>
> ---
>  .../kvm/x86_64/pmu_event_filter_test.c        | 35 +++++++++++++++++++
>  1 file changed, 35 insertions(+)
>
> diff --git a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
> index bd7054a53981..73a81262ca72 100644
> --- a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
> @@ -442,6 +442,39 @@ static bool use_amd_pmu(void)
>                  is_zen3(entry->eax));
>  }
>
> +static int run_filter_test(struct kvm_vcpu *vcpu, const uint64_t *events,
> +                          int nevents, uint32_t flags)
> +{
> +       struct kvm_pmu_event_filter *f;
> +       int r;
> +
> +       f = create_pmu_event_filter(events, nevents, KVM_PMU_EVENT_ALLOW, flags);
> +       r = __vm_ioctl(vcpu->vm, KVM_SET_PMU_EVENT_FILTER, f);
> +       free(f);
> +
> +       return r;
> +}
> +
> +static void test_filter_ioctl(struct kvm_vcpu *vcpu)
> +{
> +       uint64_t e = ~0ul;
> +       int r;
> +
> +       /*
> +        * Unfortunately having invalid bits set in event data is expected to
> +        * pass when flags == 0 (bits other than eventsel+umask).
> +        */
> +       r = run_filter_test(vcpu, &e, 1, 0);
> +       TEST_ASSERT(r == 0, "Valid PMU Event Filter is failing");
> +
> +       r = run_filter_test(vcpu, &e, 1, KVM_PMU_EVENT_FLAG_MASKED_EVENTS);

Before using KVM_PMU_EVENT_FLAG_MASKED_EVENTS, we need to test for
KVM_CAP_PMU_EVENT_MASKED_EVENTS.