iommufd/selftest: Add tests for <= u8 bitmap sizes

JIRA: https://issues.redhat.com/browse/RHEL-40162
Upstream Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

commit 3333558
Author: Joao Martins <joao.m.martins@oracle.com>
Date:   Thu Jun 27 12:00:57 2024 +0100

    iommufd/selftest: Add tests for <= u8 bitmap sizes

    Add more tests for bitmaps smaller than or equal to an u8, though skip the
    tests if the IOVA buffer size is smaller than the mock page size.

    Link: https://lore.kernel.org/r/20240627110105.62325-4-joao.m.martins@oracle.com
    Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
    Reviewed-by: Kevin Tian <kevin.tian@intel.com>
    Tested-by: Matt Ochs <mochs@nvidia.com>
    Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

(cherry picked from commit 3333558)
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>

Author: snits

tools/testing/selftests/iommu/iommufd.c

@@ -1727,6 +1727,12 @@ FIXTURE_SETUP(iommufd_dirty_tracking)
 	void *vrc;
 	int rc;
 
+	if (variant->buffer_size < MOCK_PAGE_SIZE) {
+		SKIP(return,
+		     "Skipping buffer_size=%lu, less than MOCK_PAGE_SIZE=%lu",
+		     variant->buffer_size, MOCK_PAGE_SIZE);
+	}
+
 	self->fd = open("/dev/iommu", O_RDWR);
 	ASSERT_NE(-1, self->fd);
 
@@ -1779,6 +1785,18 @@ FIXTURE_TEARDOWN(iommufd_dirty_tracking)
 	teardown_iommufd(self->fd, _metadata);
 }
 
+FIXTURE_VARIANT_ADD(iommufd_dirty_tracking, domain_dirty8k)
+{
+	/* half of an u8 index bitmap */
+	.buffer_size = 8UL * 1024UL,
+};
+
+FIXTURE_VARIANT_ADD(iommufd_dirty_tracking, domain_dirty16k)
+{
+	/* one u8 index bitmap */
+	.buffer_size = 16UL * 1024UL,
+};
+
 FIXTURE_VARIANT_ADD(iommufd_dirty_tracking, domain_dirty128k)
 {
 	/* one u32 index bitmap */