Add tests which validate dma map/unmap at the end of address space. Add
negative test cases for checking that overflowing ioctl args fail with
the expected errno.

Signed-off-by: Alex Mastro <amastro@fb.com>
---
 .../testing/selftests/vfio/vfio_dma_mapping_test.c | 89 ++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/tools/testing/selftests/vfio/vfio_dma_mapping_test.c b/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
index a38966e8e5a6..2c38bc17232e 100644
--- a/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
+++ b/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
@@ -112,6 +112,8 @@ FIXTURE_VARIANT_ADD_ALL_IOMMU_MODES(anonymous, 0, 0);
 FIXTURE_VARIANT_ADD_ALL_IOMMU_MODES(anonymous_hugetlb_2mb, SZ_2M, MAP_HUGETLB | MAP_HUGE_2MB);
 FIXTURE_VARIANT_ADD_ALL_IOMMU_MODES(anonymous_hugetlb_1gb, SZ_1G, MAP_HUGETLB | MAP_HUGE_1GB);
 
+#undef FIXTURE_VARIANT_ADD_IOMMU_MODE
+
 FIXTURE_SETUP(vfio_dma_mapping_test)
 {
 	self->device = vfio_pci_device_init(device_bdf, variant->iommu_mode);
@@ -195,6 +197,93 @@ TEST_F(vfio_dma_mapping_test, dma_map_unmap)
 	ASSERT_TRUE(!munmap(region.vaddr, size));
 }
 
+FIXTURE(vfio_dma_map_limit_test) {
+	struct vfio_pci_device *device;
+	struct vfio_dma_region region;
+	size_t mmap_size;
+};
+
+FIXTURE_VARIANT(vfio_dma_map_limit_test) {
+	const char *iommu_mode;
+};
+
+#define FIXTURE_VARIANT_ADD_IOMMU_MODE(_iommu_mode)			       \
+FIXTURE_VARIANT_ADD(vfio_dma_map_limit_test, _iommu_mode) {		       \
+	.iommu_mode = #_iommu_mode,					       \
+}
+
+FIXTURE_VARIANT_ADD_ALL_IOMMU_MODES();
+
+#undef FIXTURE_VARIANT_ADD_IOMMU_MODE
+
+FIXTURE_SETUP(vfio_dma_map_limit_test)
+{
+	u64 region_size = getpagesize();
+	/*
+	 * Over-allocate mmap by double the size to provide enough backing vaddr
+	 * for overflow tests
+	 */
+	self->mmap_size = 2 * region_size;
+	struct vfio_dma_region *region = &self->region;
+
+	self->device = vfio_pci_device_init(device_bdf, variant->iommu_mode);
+	region->vaddr = mmap(NULL, self->mmap_size, PROT_READ | PROT_WRITE,
+			     MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	ASSERT_NE(region->vaddr, MAP_FAILED);
+
+	/* One page prior to the end of address space */
+	region->iova = ~(iova_t)0 & ~(region_size - 1);
+	region->size = region_size;
+}
+
+FIXTURE_TEARDOWN(vfio_dma_map_limit_test)
+{
+	vfio_pci_device_cleanup(self->device);
+	ASSERT_EQ(munmap(self->region.vaddr, self->mmap_size), 0);
+}
+
+TEST_F(vfio_dma_map_limit_test, unmap_range)
+{
+	struct vfio_dma_region *region = &self->region;
+	u64 unmapped;
+	int rc;
+
+	vfio_pci_dma_map(self->device, region);
+	ASSERT_EQ(region->iova, to_iova(self->device, region->vaddr));
+
+	rc = __vfio_pci_dma_unmap(self->device, region, &unmapped);
+	ASSERT_EQ(rc, 0);
+	ASSERT_EQ(unmapped, region->size);
+}
+
+TEST_F(vfio_dma_map_limit_test, unmap_all)
+{
+	struct vfio_dma_region *region = &self->region;
+	u64 unmapped;
+	int rc;
+
+	vfio_pci_dma_map(self->device, region);
+	ASSERT_EQ(region->iova, to_iova(self->device, region->vaddr));
+
+	rc = __vfio_pci_dma_unmap_all(self->device, &unmapped);
+	ASSERT_EQ(rc, 0);
+	ASSERT_EQ(unmapped, region->size);
+}
+
+TEST_F(vfio_dma_map_limit_test, overflow)
+{
+	struct vfio_dma_region *region = &self->region;
+	int rc;
+
+	region->size = self->mmap_size;
+
+	rc = __vfio_pci_dma_map(self->device, region);
+	ASSERT_EQ(rc, -EOVERFLOW);
+
+	rc = __vfio_pci_dma_unmap(self->device, region, NULL);
+	ASSERT_EQ(rc, -EOVERFLOW);
+}
+
 int main(int argc, char *argv[])
 {
 	device_bdf = vfio_selftests_get_bdf(&argc, argv);

-- 
2.47.3

On 2025-10-27 10:33 AM, Alex Mastro wrote:
> Add tests which validate dma map/unmap at the end of address space. Add
> negative test cases for checking that overflowing ioctl args fail with
> the expected errno.
> 
> Signed-off-by: Alex Mastro <amastro@fb.com>

Reviewed-by: David Matlack <dmatlack@google.com>

> +FIXTURE_SETUP(vfio_dma_map_limit_test)
> +{
> +	u64 region_size = getpagesize();

nit: Add a blank line after variable declarations.

> +	/*
> +	 * Over-allocate mmap by double the size to provide enough backing vaddr
> +	 * for overflow tests
> +	 */
> +	self->mmap_size = 2 * region_size;
> +	struct vfio_dma_region *region = &self->region;

nit: Declare variables at the beginning of blocks.