On Thu, Apr 20, 2023, Jinrong Liang wrote: > From: Jinrong Liang <cloudliang@xxxxxxxxxxx> > > From: Jinrong Liang <cloudliang@xxxxxxxxxxx> > > Add test to verify the behavior of the pmu event filter when an > incomplete kvm_pmu_event_filter structure is used. By running the > test, we can ensure that the pmu event filter correctly handles > incomplete structures and does not allow events to be counted when > they should not be. > > Signed-off-by: Jinrong Liang <cloudliang@xxxxxxxxxxx> > --- > .../kvm/x86_64/pmu_event_filter_test.c | 23 +++++++++++++++++++ > 1 file changed, 23 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 9be4c6f8fb7e..a6b6e0d086ae 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 > @@ -881,6 +881,24 @@ static bool fixed_ctr_is_allowed(uint8_t idx, uint32_t action, uint32_t bitmap) > (action == KVM_PMU_EVENT_DENY && !(bitmap & BIT_ULL(idx))); > } > > +struct incompatible_pmu_event_filter { > + __u32 action; > + __u32 nevents; > + __u32 fixed_counter_bitmap; > +}; > + > +static uint64_t test_incompatible_filter(struct kvm_vcpu *vcpu, uint32_t action, > + uint32_t bitmap) > +{ > + struct incompatible_pmu_event_filter err_f; > + > + err_f.action = action; > + err_f.fixed_counter_bitmap = bitmap; > + ioctl((vcpu->vm)->fd, KVM_SET_PMU_EVENT_FILTER, &err_f.action); This is completely busted. It "passes" by luck, not because it's a valid test. The size of the argument is embedded in the IOCTL number itself, which means that unless glibc is being very nice and using a macro + typeof + sizeof to sanity check things, which I highly doubt is the case, this ioctl() is passing random stack data, a.k.a. garbage, to KVM. In short, drop this patch.