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.