iommufd/selftest: Add coverage for the new mmap interface

Extend the loopback test to a new mmap page.

Link: https://patch.msgid.link/r/b02b1220c955c3cf9ea5dd9fe9349ab1b4f8e20b.1752126748.git.nicolinc@nvidia.com
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: nicolinc

drivers/iommu/iommufd/iommufd_test.h

@@ -232,12 +232,16 @@ struct iommu_hwpt_invalidate_selftest {
  *                                (IOMMU_VIOMMU_TYPE_SELFTEST)
  * @in_data: Input random data from user space
  * @out_data: Output data (matching @in_data) to user space
+ * @out_mmap_offset: The offset argument for mmap syscall
+ * @out_mmap_length: The length argument for mmap syscall
  *
  * Simply set @out_data=@in_data for a loopback test
  */
 struct iommu_viommu_selftest {
 	__u32 in_data;
 	__u32 out_data;
+	__aligned_u64 out_mmap_offset;
+	__aligned_u64 out_mmap_length;
 };
 
 /* Should not be equal to any defined value in enum iommu_viommu_invalidate_data_type */

drivers/iommu/iommufd/selftest.c

@@ -152,6 +152,9 @@ struct mock_viommu {
 	struct mock_iommu_domain *s2_parent;
 	struct mock_hw_queue *hw_queue[IOMMU_TEST_HW_QUEUE_MAX];
 	struct mutex queue_mutex;
+
+	unsigned long mmap_offset;
+	u32 *page; /* Mmap page to test u32 type of in_data */
 };
 
 static inline struct mock_viommu *to_mock_viommu(struct iommufd_viommu *viommu)
@@ -689,6 +692,10 @@ static void mock_viommu_destroy(struct iommufd_viommu *viommu)
 
 	if (refcount_dec_and_test(&mock_iommu->users))
 		complete(&mock_iommu->complete);
+	if (mock_viommu->mmap_offset)
+		iommufd_viommu_destroy_mmap(&mock_viommu->core,
+					    mock_viommu->mmap_offset);
+	free_page((unsigned long)mock_viommu->page);
 	mutex_destroy(&mock_viommu->queue_mutex);
 
 	/* iommufd core frees mock_viommu and viommu */
@@ -887,11 +894,28 @@ static int mock_viommu_init(struct iommufd_viommu *viommu,
 		if (rc)
 			return rc;
 
+		/* Allocate two pages */
+		mock_viommu->page =
+			(u32 *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
+		if (!mock_viommu->page)
+			return -ENOMEM;
+
+		rc = iommufd_viommu_alloc_mmap(&mock_viommu->core,
+					       __pa(mock_viommu->page),
+					       PAGE_SIZE * 2,
+					       &mock_viommu->mmap_offset);
+		if (rc)
+			goto err_free_page;
+
+		/* For loopback tests on both the page and out_data */
+		*mock_viommu->page = data.in_data;
 		data.out_data = data.in_data;
+		data.out_mmap_length = PAGE_SIZE * 2;
+		data.out_mmap_offset = mock_viommu->mmap_offset;
 		rc = iommu_copy_struct_to_user(
 			user_data, &data, IOMMU_VIOMMU_TYPE_SELFTEST, out_data);
 		if (rc)
-			return rc;
+			goto err_destroy_mmap;
 	}
 
 	refcount_inc(&mock_iommu->users);
@@ -900,6 +924,13 @@ static int mock_viommu_init(struct iommufd_viommu *viommu,
 
 	viommu->ops = &mock_viommu_ops;
 	return 0;
+
+err_destroy_mmap:
+	iommufd_viommu_destroy_mmap(&mock_viommu->core,
+				    mock_viommu->mmap_offset);
+err_free_page:
+	free_page((unsigned long)mock_viommu->page);
+	return rc;
 }
 
 static const struct iommu_ops mock_ops = {

tools/testing/selftests/iommu/iommufd.c

@@ -2799,6 +2799,7 @@ TEST_F(iommufd_viommu, viommu_alloc_with_data)
 	struct iommu_viommu_selftest data = {
 		.in_data = 0xbeef,
 	};
+	uint32_t *test;
 
 	if (!self->device_id)
 		SKIP(return, "Skipping test for variant no_viommu");
@@ -2807,6 +2808,24 @@ TEST_F(iommufd_viommu, viommu_alloc_with_data)
 			      IOMMU_VIOMMU_TYPE_SELFTEST, &data, sizeof(data),
 			      &self->viommu_id);
 	ASSERT_EQ(data.out_data, data.in_data);
+
+	/* Negative mmap tests -- offset and length cannot be changed */
+	test_err_mmap(ENXIO, data.out_mmap_length,
+		      data.out_mmap_offset + PAGE_SIZE);
+	test_err_mmap(ENXIO, data.out_mmap_length,
+		      data.out_mmap_offset + PAGE_SIZE * 2);
+	test_err_mmap(ENXIO, data.out_mmap_length / 2, data.out_mmap_offset);
+	test_err_mmap(ENXIO, data.out_mmap_length * 2, data.out_mmap_offset);
+
+	/* Now do a correct mmap for a loopback test */
+	test = mmap(NULL, data.out_mmap_length, PROT_READ | PROT_WRITE,
+		    MAP_SHARED, self->fd, data.out_mmap_offset);
+	ASSERT_NE(MAP_FAILED, test);
+	ASSERT_EQ(data.in_data, *test);
+
+	/* The owner of the mmap region should be blocked */
+	EXPECT_ERRNO(EBUSY, _test_ioctl_destroy(self->fd, self->viommu_id));
+	munmap(test, data.out_mmap_length);
 }
 
 TEST_F(iommufd_viommu, vdevice_alloc)

tools/testing/selftests/iommu/iommufd_utils.h

@@ -56,6 +56,10 @@ static unsigned long PAGE_SIZE;
 #define offsetofend(TYPE, MEMBER) \
 	(offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER))
 
+#define test_err_mmap(_errno, length, offset)                                 \
+	EXPECT_ERRNO(_errno, (long)mmap(NULL, length, PROT_READ | PROT_WRITE, \
+					MAP_SHARED, self->fd, offset))
+
 static inline void *memfd_mmap(size_t length, int prot, int flags, int *mfd_p)
 {
 	int mfd_flags = (flags & MAP_HUGETLB) ? MFD_HUGETLB : 0;