Linux v6.13 introduced the PCIe TLP Processing Hints (TPH) feature for direct cache injection. As described in the relevant patch set [1], direct cache injection in supported hardware allows optimal platform resource utilization for specific requests on the PCIe bus. This feature is currently available only for kernel device drivers. However, user space applications, especially those whose performance is sensitive to the latency of inbound writes as seen by a CPU core, may benefit from using this information (E.g., DPDK cache stashing RFC [2] or an HPC application running in a VM). For such applications to enable and configure TPH on PCIe devices, this RFC proposes a new VFIO ioctl. [1] lore.kernel.org/linux-pci/20241002165954.128085-1-wei.huang2@xxxxxxx [2] inbox.dpdk.org/dev/20241021015246.304431-2-wathsala.vithanage@xxxxxxx V1->V2: * Rewrite as a VFIO IOCTL * Add missing padding for structs * Increase maximum steering tags per IOCTL to 2048 Wathsala Vithanage (1): vfio/pci: add PCIe TPH device ioctl drivers/vfio/pci/vfio_pci_core.c | 153 +++++++++++++++++++++++++++++++ include/uapi/linux/vfio.h | 83 +++++++++++++++++ 2 files changed, 236 insertions(+) -- 2.43.0
