selftests: kvm: vmx_dirty_log_test: skip the test when VMX is not supported

vmx_dirty_log_test fails on AMD and this is no surprise as it is VMX
specific. Bail early when nested VMX is unsupported.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c

@@ -78,6 +78,8 @@ int main(int argc, char *argv[])
 	struct ucall uc;
 	bool done = false;
 
+	nested_vmx_check_supported();
+
 	/* Create VM */
 	vm = vm_create_default(VCPU_ID, 0, l1_guest_code);
 	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());