| Message ID | 20230420104622.12504-8-ljrcore@126.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: selftests: Add tests for pmu event filter | expand |
On Thu, Apr 20, 2023, Jinrong Liang wrote: > From: Jinrong Liang <cloudliang@tencent.com> > > From: Jinrong Liang <cloudliang@tencent.com> > > 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@tencent.com> > --- > .../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.
Sean Christopherson <seanjc@google.com> 于2023年5月25日周四 07:50写道： > > On Thu, Apr 20, 2023, Jinrong Liang wrote: > > From: Jinrong Liang <cloudliang@tencent.com> > > > > From: Jinrong Liang <cloudliang@tencent.com> > > > > 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@tencent.com> > > --- > > .../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. Thank you for letting us know about the issues with the patch. I will drop the patch as suggested. Would you advise me to prepare version 3 to remove this patch?
On Thu, May 25, 2023, Jinrong Liang wrote: > Sean Christopherson <seanjc@google.com> 于2023年5月25日周四 07:50写道： > > > +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. > > Thank you for letting us know about the issues with the patch. I will > drop the patch as suggested. Would you advise me to prepare version 3 > to remove this patch? More comments on the other patches are incoming, please hold off on v3 until then.
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); + + return run_vcpu_to_sync(vcpu); +} + static void test_fixed_ctr_action_and_bitmap(struct kvm_vcpu *vcpu, uint8_t fixed_ctr_idx, uint8_t max_fixed_num) @@ -918,6 +936,11 @@ static void test_fixed_ctr_action_and_bitmap(struct kvm_vcpu *vcpu, TEST_ASSERT(expected == !!count, "Fixed event filter does not work as expected."); + + /* Test incompatible event filter works as expected. */ + count = test_incompatible_filter(vcpu, actions[i], bitmap); + TEST_ASSERT(expected == !!count, + "Incompatible filter does not work as expected."); } } }