iommufd/selftest: Add boundary tests for veventq_depth

Test veventq_depth to cover a memory exhaustion vulnerability.

Keep veventq_depth=2 for the existing callers.

Link: https://patch.msgid.link/r/acfa370fa4e89e4626f71954bad7ad2bd64cf63b.1779408671.git.nicolinc@nvidia.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: nicolinc

tools/testing/selftests/iommu/iommufd.c

@@ -2986,11 +2986,26 @@ TEST_F(iommufd_viommu, vdevice_alloc)
 		test_err_mock_domain_replace(ENOENT, self->stdev_id,
 					     self->nested_hwpt_id);
 
+		/* Test depth lower and upper bounds (mirrors kernel cap) */
+#define VEVENTQ_MAX_DEPTH (1U << 19)
+		test_err_veventq_alloc(EINVAL, viommu_id,
+				       IOMMU_VEVENTQ_TYPE_SELFTEST, 0, NULL,
+				       NULL);
+		test_err_veventq_alloc(EINVAL, viommu_id,
+				       IOMMU_VEVENTQ_TYPE_SELFTEST,
+				       VEVENTQ_MAX_DEPTH + 1, NULL, NULL);
+		test_cmd_veventq_alloc(viommu_id, IOMMU_VEVENTQ_TYPE_SELFTEST,
+				       VEVENTQ_MAX_DEPTH, &veventq_id,
+				       &veventq_fd);
+		close(veventq_fd);
+		test_ioctl_destroy(veventq_id);
+
 		/* Allocate a vEVENTQ with veventq_depth=2 */
 		test_cmd_veventq_alloc(viommu_id, IOMMU_VEVENTQ_TYPE_SELFTEST,
-				       &veventq_id, &veventq_fd);
+				       2, &veventq_id, &veventq_fd);
 		test_err_veventq_alloc(EEXIST, viommu_id,
-				       IOMMU_VEVENTQ_TYPE_SELFTEST, NULL, NULL);
+				       IOMMU_VEVENTQ_TYPE_SELFTEST, 2, NULL,
+				       NULL);
 		/* Set vdev_id to 0x99, unset it, and set to 0x88 */
 		test_cmd_vdevice_alloc(viommu_id, dev_id, 0x99, &vdev_id);
 		test_cmd_mock_domain_replace(self->stdev_id,

tools/testing/selftests/iommu/iommufd_fail_nth.c

@@ -712,7 +712,7 @@ TEST_FAIL_NTH(basic_fail_nth, device)
 		return -1;
 
 	if (_test_cmd_veventq_alloc(self->fd, viommu_id,
-				    IOMMU_VEVENTQ_TYPE_SELFTEST, &veventq_id,
+				    IOMMU_VEVENTQ_TYPE_SELFTEST, 2, &veventq_id,
 				    &veventq_fd))
 		return -1;
 	close(veventq_fd);

tools/testing/selftests/iommu/iommufd_utils.h

@@ -1060,12 +1060,13 @@ static int _test_cmd_hw_queue_alloc(int fd, __u32 viommu_id, __u32 type,
 					      base_addr, len, out_qid))
 
 static int _test_cmd_veventq_alloc(int fd, __u32 viommu_id, __u32 type,
-				   __u32 *veventq_id, __u32 *veventq_fd)
+				   __u32 depth, __u32 *veventq_id,
+				   __u32 *veventq_fd)
 {
 	struct iommu_veventq_alloc cmd = {
 		.size = sizeof(cmd),
 		.type = type,
-		.veventq_depth = 2,
+		.veventq_depth = depth,
 		.viommu_id = viommu_id,
 	};
 	int ret;
@@ -1080,13 +1081,13 @@ static int _test_cmd_veventq_alloc(int fd, __u32 viommu_id, __u32 type,
 	return 0;
 }
 
-#define test_cmd_veventq_alloc(viommu_id, type, veventq_id, veventq_fd) \
-	ASSERT_EQ(0, _test_cmd_veventq_alloc(self->fd, viommu_id, type, \
+#define test_cmd_veventq_alloc(viommu_id, type, depth, veventq_id, veventq_fd) \
+	ASSERT_EQ(0, _test_cmd_veventq_alloc(self->fd, viommu_id, type, depth, \
 					     veventq_id, veventq_fd))
-#define test_err_veventq_alloc(_errno, viommu_id, type, veventq_id,     \
-			       veventq_fd)                              \
-	EXPECT_ERRNO(_errno,                                            \
-		     _test_cmd_veventq_alloc(self->fd, viommu_id, type, \
+#define test_err_veventq_alloc(_errno, viommu_id, type, depth, veventq_id,     \
+			       veventq_fd)                                     \
+	EXPECT_ERRNO(_errno,                                                   \
+		     _test_cmd_veventq_alloc(self->fd, viommu_id, type, depth, \
 					     veventq_id, veventq_fd))
 
 static int _test_cmd_trigger_vevents(int fd, __u32 dev_id, __u32 nvevents)