linux-kernel - Re: [PATCH v4 4/6] KVM: selftests: Add test cases for unsupported PMU event filter input values

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Date:   Wed, 19 Jul 2023 11:20:54 +0800
From:   Jinrong Liang <ljr.kernel@...il.com>
To:     Isaku Yamahata <isaku.yamahata@...il.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Shuah Khan <shuah@...nel.org>,
        Aaron Lewis <aaronlewis@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Vishal Annapurve <vannapurve@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Like Xu <like.xu.linux@...il.com>,
        Jinrong Liang <cloudliang@...cent.com>,
        linux-kselftest@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 4/6] KVM: selftests: Add test cases for unsupported PMU
 event filter input values

Isaku Yamahata <isaku.yamahata@...il.com> 于2023年7月19日周三 09:17写道：
>
> On Mon, Jul 17, 2023 at 02:23:41PM +0800,
> Jinrong Liang <ljr.kernel@...il.com> wrote:
>
> > From: Jinrong Liang <cloudliang@...cent.com>
> >
> > Add test cases to verify the handling of unsupported input values for the
> > PMU event filter. The tests cover unsupported "action" values, unsupported
> > "flags" values, and unsupported "nevents" values. All these cases should
> > return an error, as they are currently not supported by the filter.
> > Furthermore, the tests also cover the scenario where setting non-existent
> > fixed counters in the fixed bitmap does not fail.
> >
> > Signed-off-by: Jinrong Liang <cloudliang@...cent.com>
> > ---
> >  .../kvm/x86_64/pmu_event_filter_test.c        | 26 +++++++++++++++++++
> >  1 file changed, 26 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 ffcbbf25b29b..63f85f583ef8 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
> > @@ -32,6 +32,10 @@
> >  #define MAX_FILTER_EVENTS            300
> >  #define MAX_TEST_EVENTS              10
> >
> > +#define PMU_EVENT_FILTER_INVALID_ACTION              (KVM_PMU_EVENT_DENY + 1)
> > +#define PMU_EVENT_FILTER_INVALID_FLAGS                       (KVM_PMU_EVENT_FLAG_MASKED_EVENTS + 1)
>
> flag is a bit mask. Not number. So +1 sounds weird.
> As KVM_PMU_EVENT_FLAGS_VALID_MASK = 1,  this happens to get wanted result, though.

We need an invalid flags, KVM_PMU_EVENT_FLAGS_VALID_MASK is actually
equal to KVM_PMU_EVENT_FLAG_MASKED_EVENTS.

In kvm.h:

#define KVM_PMU_EVENT_FLAG_MASKED_EVENTS BIT(0)
#define KVM_PMU_EVENT_FLAGS_VALID_MASK (KVM_PMU_EVENT_FLAG_MASKED_EVENTS)

How about this modification:

#define PMU_EVENT_FILTER_INVALID_FLAGS
(KVM_PMU_EVENT_FLAGS_VALID_MASK << 1)

>
>
> > +#define PMU_EVENT_FILTER_INVALID_NEVENTS             (MAX_FILTER_EVENTS + 1)
> > +
> >  /*
> >   * This is how the event selector and unit mask are stored in an AMD
> >   * core performance event-select register. Intel's format is similar,
> > @@ -757,6 +761,8 @@ static int set_pmu_single_event_filter(struct kvm_vcpu *vcpu, uint64_t event,
> >
> >  static void test_filter_ioctl(struct kvm_vcpu *vcpu)
> >  {
> > +     uint8_t nr_fixed_counters = kvm_cpu_property(X86_PROPERTY_PMU_NR_FIXED_COUNTERS);
> > +     struct __kvm_pmu_event_filter f;
> >       uint64_t e = ~0ul;
> >       int r;
> >
> > @@ -777,6 +783,26 @@ static void test_filter_ioctl(struct kvm_vcpu *vcpu)
> >                                       KVM_PMU_EVENT_FLAG_MASKED_EVENTS,
> >                                       KVM_PMU_EVENT_ALLOW);
> >       TEST_ASSERT(r == 0, "Valid PMU Event Filter is failing");
> > +
> > +     f = base_event_filter;
> > +     f.action = PMU_EVENT_FILTER_INVALID_ACTION;
> > +     r = do_vcpu_set_pmu_event_filter(vcpu, &f);
> > +     TEST_ASSERT(r, "Set invalid action is expected to fail");
> > +
> > +     f = base_event_filter;
> > +     f.flags = PMU_EVENT_FILTER_INVALID_FLAGS;
> > +     r = do_vcpu_set_pmu_event_filter(vcpu, &f);
> > +     TEST_ASSERT(r, "Set invalid flags is expected to fail");
> > +
> > +     f = base_event_filter;
> > +     f.nevents = PMU_EVENT_FILTER_INVALID_NEVENTS;
> > +     r = do_vcpu_set_pmu_event_filter(vcpu, &f);
> > +     TEST_ASSERT(r, "Exceeding the max number of filter events should fail");
> > +
> > +     f = base_event_filter;
> > +     f.fixed_counter_bitmap = ~GENMASK_ULL(nr_fixed_counters, 0);
> > +     r = do_vcpu_set_pmu_event_filter(vcpu, &f);
> > +     TEST_ASSERT(!r, "Masking non-existent fixed counters should be allowed");
> >  }
> >
> >  int main(int argc, char *argv[])
> > --
> > 2.39.3
> >
>
> --
> Isaku Yamahata <isaku.yamahata@...il.com>