[V1,0/9] PCIe TPH and cache direct injection support

Message

Wei Huang May 9, 2024, 4:27 p.m. UTC

Hi All,

TPH (TLP Processing Hints) is a PCIe feature that allows endpoint devices
to provide optimization hints for requests that target memory space. These
hints, in a format called steering tag (ST), are provided in the requester's
TLP headers and allow the system hardware, including the Root Complex, to
optimize the utilization of platform resources for the requests.

Upcoming AMD hardware implement a new Cache Injection feature that leverages
TPH. Cache Injection allows PCIe endpoints to inject I/O Coherent DMA writes
directly into an L2 within the CCX (core complex) closest to the CPU core
that will consume it. The technology is targeted at applications whose
performance is sensitive to the latency of inbound writes as seen by a CPU
core. The applications include networking and storage applications.

This series implements generic TPH support in Linux. It allows STs to be
retrieved from ACPI _DSM (defined by ACPI) and used by PCIe end-point
drivers as needed. As a demo, it includes an usage example in Broadcom BNXT
driver. When running on Broadcom NICs with proper firmware, Cache Injection
shows substantial memory bandwidth saving using real-world benchmarks.

Manoj Panicker (1):
  bnxt_en: Add TPH support in BNXT driver

Michael Chan (1):
  bnxt_en: Pass NQ ID to the FW when allocating RX/RX AGG rings

Wei Huang (7):
  PCI: Introduce PCIe TPH support framework
  PCI: Add TPH related register definition
  PCI/TPH: Implement a command line option to disable TPH
  PCI/TPH: Implement a command line option to force No ST Mode
  PCI/TPH: Introduce API functions to get/set steering tags
  PCI/TPH: Retrieve steering tag from ACPI _DSM
  PCI/TPH: Add TPH documentation

 Documentation/PCI/index.rst                   |   1 +
 Documentation/PCI/tph.rst                     |  57 ++
 .../admin-guide/kernel-parameters.txt         |   2 +
 Documentation/driver-api/pci/pci.rst          |   3 +
 drivers/net/ethernet/broadcom/bnxt/bnxt.c     |  59 +-
 drivers/net/ethernet/broadcom/bnxt/bnxt.h     |   4 +
 drivers/pci/pci-driver.c                      |  12 +-
 drivers/pci/pci.c                             |  24 +
 drivers/pci/pci.h                             |   6 +
 drivers/pci/pcie/Kconfig                      |  10 +
 drivers/pci/pcie/Makefile                     |   1 +
 drivers/pci/pcie/tph.c                        | 563 ++++++++++++++++++
 drivers/pci/probe.c                           |   1 +
 drivers/vfio/pci/vfio_pci_config.c            |   7 +-
 include/linux/pci-tph.h                       |  75 +++
 include/linux/pci.h                           |   6 +
 include/uapi/linux/pci_regs.h                 |  35 +-
 17 files changed, 856 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/PCI/tph.rst
 create mode 100644 drivers/pci/pcie/tph.c
 create mode 100644 include/linux/pci-tph.h