Re: [PATCH v9 18/29] iommufd/selftest: Add coverage for the new mmap interface

[Pranjal Shrivastava <praan@google.com>]

On Wed, Jul 09, 2025 at 10:59:10PM -0700, Nicolin Chen wrote:
> Extend the loopback test to a new mmap page.
> 
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>

Reviewed-by: Pranjal Shrivastava <praan@google.com>

> ---
>  drivers/iommu/iommufd/iommufd_test.h          |  4 +++
>  tools/testing/selftests/iommu/iommufd_utils.h |  4 +++
>  drivers/iommu/iommufd/selftest.c              | 33 ++++++++++++++++++-
>  tools/testing/selftests/iommu/iommufd.c       | 19 +++++++++++
>  4 files changed, 59 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/iommufd/iommufd_test.h b/drivers/iommu/iommufd/iommufd_test.h
> index 51cd744a354f..8fc618b2bcf9 100644
> --- a/drivers/iommu/iommufd/iommufd_test.h
> +++ b/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 */
> diff --git a/tools/testing/selftests/iommu/iommufd_utils.h b/tools/testing/selftests/iommu/iommufd_utils.h
> index 9a556f99d992..4a1b2bade018 100644
> --- a/tools/testing/selftests/iommu/iommufd_utils.h
> +++ b/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;
> diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c
> index 2189e9b119ee..8b2c44b32530 100644
> --- a/drivers/iommu/iommufd/selftest.c
> +++ b/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 = {
> diff --git a/tools/testing/selftests/iommu/iommufd.c b/tools/testing/selftests/iommu/iommufd.c
> index 73426de77675..0b21c095ca5e 100644
> --- a/tools/testing/selftests/iommu/iommufd.c
> +++ b/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)
> -- 
> 2.43.0
>