+static unsigned int devx_umem_find_best_pgsize(struct ib_umem *umem,
+ unsigned long pgsz_bitmap)
+{
+ unsigned long page_size;
+
+ /* Don't bother checking larger page sizes as offset must be zero and
+ * total DEVX umem length must be equal to total umem length.
+ */
+ pgsz_bitmap &= GENMASK_ULL(max_t(u64, order_base_2(umem->length),
+ PAGE_SHIFT),
+ MLX5_ADAPTER_PAGE_SHIFT);
+ if (!pgsz_bitmap)
+ return 0;
+
+ page_size = ib_umem_find_best_pgoff(umem, pgsz_bitmap, U64_MAX);
+ if (!page_size)
+ return 0;
+
+ /* If the page_size is less than the CPU page size then we can use the
+ * offset and create a umem which is a subset of the page list.
+ * For larger page sizes we can't be sure the DMA list reflects the
+ * VA so we must ensure that the umem extent is exactly equal to the
+ * page list. Reduce the page size until one of these cases is true.
+ */
+ while ((ib_umem_dma_offset(umem, page_size) != 0 ||
+ (umem->length % page_size) != 0) &&
+ page_size > PAGE_SIZE)
+ page_size /= 2;
+
+ return page_size;
+}
+