Re: [PATCH v12 2/4] dma-buf: add optional get_pci_tph() callback

[fengchengwen]

Acked-by: Chengwen Feng <fengcheng...@huawei.com>

On 7/16/2026 4:39 AM, Zhiping Zhang wrote:
> Add an optional dma_buf_ops.get_pci_tph callback and a
> DMA-buf importer wrapper, dma_buf_get_pci_tph().
> 
> TPH is PCIe TLP Processing Hint. 8-bit ST and 16-bit Extended ST are
> distinct PCIe TPH namespaces, so the importer requests the namespace it
> can emit and the exporter returns the matching ST/PH tuple or
> -EOPNOTSUPP.
> 
> dma_buf_get_pci_tph() is the importer entry point. It requires
> &dmabuf->resv to be held while the callback runs and returns
> -EOPNOTSUPP when the exporter does not provide PCI TPH metadata.
> 
> The first user is VFIO_DEVICE_FEATURE_DMA_BUF_TPH in vfio-pci, with
> mlx5 as the first importer.
> 
> Signed-off-by: Zhiping Zhang <zhipi...@meta.com>