On Wed, May 6, 2026 at 12:04 AM fengchengwen <[email protected]> wrote:
>
> >
> 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.
>
Good catch!
so the direct dereference here will break the build when TPH is
disabled. I'll add a small
wrapper in include/linux/pci-tph.h alongside the existing helpers, e.g.:
#ifdef CONFIG_PCIE_TPH
u8 pcie_tph_get_st_width(struct pci_dev *pdev);
#else
static inline u8 pcie_tph_get_st_width(struct pci_dev *pdev) { return 0; }
#endif
with the implementation
in drivers/pci/pcie/tph.c returning 16 for PCI_TPH_REQ_EXT_TPH and 8 otherwise.
Then get_tph_mr_dmabuf() becomes:
st_width = pcie_tph_get_st_width(pdev);
if (!st_width)
goto end_dbuf_put;
which also gives us a clean early-out when TPH isn't supported on the
device. Will fix in v3.
Thanks,
Zhiping
