On 5/1/2026 4:06 AM, Zhiping Zhang wrote:
> Query dma-buf TPH metadata when registering a dma-buf MR for peer to
> peer access and translate the raw steering tag into an mlx5 steering tag
> index. Factor mlx5_st_alloc_index() so callers that already have a raw
> steering tag can allocate the corresponding mlx5 index directly. Keep the
> DMAH path as the first priority and only fall back to dma-buf metadata when
> no DMAH is supplied.
>
> Pass the device's supported ST width (8 or 16 bit, derived from
> pdev->tph_req_type) to get_tph() so the exporter can reject tags that
> exceed the consumer's capability. Initialize ret in mlx5_st_create() so the
> cached steering-tag path returns success cleanly under clang builds.
>
> Signed-off-by: Zhiping Zhang <[email protected]>
>
> diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
> --- a/drivers/infiniband/hw/mlx5/mr.c
> +++ b/drivers/infiniband/hw/mlx5/mr.c
> @@ -46,6 +46,8 @@
> #include "data_direct.h"
> #include "dmah.h"
>
> +MODULE_IMPORT_NS("DMA_BUF");
> +
> static int mkey_max_umr_order(struct mlx5_ib_dev *dev)
> {
> if (MLX5_CAP_GEN(dev->mdev, umr_extended_translation_offset))
> @@ -899,6 +901,40 @@ static struct dma_buf_attach_ops
> mlx5_ib_dmabuf_attach_ops = {
> .invalidate_mappings = mlx5_ib_dmabuf_invalidate_cb,
> };
>
> +static void get_tph_mr_dmabuf(struct mlx5_ib_dev *dev, int fd, u16 *st_index,
> + u8 *ph)
> +{
> + struct pci_dev *pdev = dev->mdev->pdev;
> + struct dma_buf *dmabuf;
> + u16 steering_tag;
> + u8 st_width;
> + int ret;
> +
> + st_width = (pdev->tph_req_type == PCI_TPH_REQ_EXT_TPH) ? 16 : 8;
The tph_req_type is defined under CONFIG_PCIE_TPH, how about add a wrap function
to query it.
> +
> + dmabuf = dma_buf_get(fd);
> + if (IS_ERR(dmabuf))
> + return;
> +
> + if (!dmabuf->ops->get_tph)
> + goto end_dbuf_put;
> +
> + ret = dmabuf->ops->get_tph(dmabuf, &steering_tag, ph, st_width);
> + if (ret) {
> + mlx5_ib_dbg(dev, "get_tph failed (%d)\n", ret);
> + goto end_dbuf_put;
> + }
> +
> + ret = mlx5_st_alloc_index_by_tag(dev->mdev, steering_tag, st_index);
> + if (ret) {
> + *ph = MLX5_IB_NO_PH;
> + mlx5_ib_dbg(dev, "st_alloc_index_by_tag failed (%d)\n", ret);
> + }
> +
> +end_dbuf_put:
> + dma_buf_put(dmabuf);
> +}
> +
> static struct ib_mr *
> reg_user_mr_dmabuf(struct ib_pd *pd, struct device *dma_device,
> u64 offset, u64 length, u64 virt_addr,
> @@ -941,6 +977,8 @@ reg_user_mr_dmabuf(struct ib_pd *pd, struct device
> *dma_device,
> ph = dmah->ph;
> if (dmah->valid_fields & BIT(IB_DMAH_CPU_ID_EXISTS))
> st_index = mdmah->st_index;
> + } else {
> + get_tph_mr_dmabuf(dev, fd, &st_index, &ph);
> }
>
> mr = alloc_cacheable_mr(pd, &umem_dmabuf->umem, virt_addr,
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/st.c
> b/drivers/net/ethernet/mellanox/mlx5/core/lib/st.c
> --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/st.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/st.c
> @@ -29,7 +29,7 @@ struct mlx5_st *mlx5_st_create(struct mlx5_core_dev *dev)
> u8 direct_mode = 0;
> u16 num_entries;
> u32 tbl_loc;
> - int ret;
> + int ret = 0;
>
> if (!MLX5_CAP_GEN(dev, mkey_pcie_tph))
> return NULL;
> @@ -92,23 +92,18 @@ void mlx5_st_destroy(struct mlx5_core_dev *dev)
> kfree(st);
> }
>
> -int mlx5_st_alloc_index(struct mlx5_core_dev *dev, enum tph_mem_type
> mem_type,
> - unsigned int cpu_uid, u16 *st_index)
> +int mlx5_st_alloc_index_by_tag(struct mlx5_core_dev *dev, u16 tag,
> + u16 *st_index)
> {
> struct mlx5_st_idx_data *idx_data;
> struct mlx5_st *st = dev->st;
> unsigned long index;
> u32 xa_id;
> - u16 tag;
> - int ret;
> + int ret = 0;
>
> if (!st)
> return -EOPNOTSUPP;
>
> - ret = pcie_tph_get_cpu_st(dev->pdev, mem_type, cpu_uid, &tag);
> - if (ret)
> - return ret;
> -
> if (st->direct_mode) {
> *st_index = tag;
> return 0;
> @@ -152,6 +147,20 @@ int mlx5_st_alloc_index(struct mlx5_core_dev *dev, enum
> tph_mem_type mem_type,
> mutex_unlock(&st->lock);
> return ret;
> }
> +EXPORT_SYMBOL_GPL(mlx5_st_alloc_index_by_tag);
> +
> +int mlx5_st_alloc_index(struct mlx5_core_dev *dev, enum tph_mem_type
> mem_type,
> + unsigned int cpu_uid, u16 *st_index)
> +{
> + u16 tag;
> + int ret;
> +
> + ret = pcie_tph_get_cpu_st(dev->pdev, mem_type, cpu_uid, &tag);
> + if (ret)
> + return ret;
> +
> + return mlx5_st_alloc_index_by_tag(dev, tag, st_index);
> +}
> EXPORT_SYMBOL_GPL(mlx5_st_alloc_index);
>
> int mlx5_st_dealloc_index(struct mlx5_core_dev *dev, u16 st_index)
> diff --git a/include/linux/mlx5/driver.h b/include/linux/mlx5/driver.h
> --- a/include/linux/mlx5/driver.h
> +++ b/include/linux/mlx5/driver.h
> @@ -1166,10 +1166,17 @@ int mlx5_dm_sw_icm_dealloc(struct mlx5_core_dev *dev,
> enum mlx5_sw_icm_type type
> u64 length, u16 uid, phys_addr_t addr, u32 obj_id);
>
> #ifdef CONFIG_PCIE_TPH
> +int mlx5_st_alloc_index_by_tag(struct mlx5_core_dev *dev, u16 tag,
> + u16 *st_index);
> int mlx5_st_alloc_index(struct mlx5_core_dev *dev, enum tph_mem_type
> mem_type,
> unsigned int cpu_uid, u16 *st_index);
> int mlx5_st_dealloc_index(struct mlx5_core_dev *dev, u16 st_index);
> #else
> +static inline int mlx5_st_alloc_index_by_tag(struct mlx5_core_dev *dev,
> + u16 tag, u16 *st_index)
> +{
> + return -EOPNOTSUPP;
> +}
> static inline int mlx5_st_alloc_index(struct mlx5_core_dev *dev,
> enum tph_mem_type mem_type,
> unsigned int cpu_uid, u16 *st_index)
>
>
