[Intel-wired-lan] [PATCH net-next v3 0/9] igc: Add support for AF_XDP zero-copy

[Vedang Patel <vedang.patel@intel.com>]

Hi all,

This is the third version of this series which adds AF_XDP zero-copy support
to igc driver.

The main changes from v2 are:

    - In igc_clean_rx_ring(), clear large buffer bit after calling
      dma_unmap_page_attrs(). dma_unmap_page_attrs() needs the buffer
      size in order to unmap the page.
    - In igc_clean_rx_irq_zc(), the Rx hardware timestamp is needed if
      the BPF program returns XDP_PASS and the packet needs to be passed
      to the network stack.

Known issues:
    When an XDP application is running in Tx-Only mode with Zero-Copy
    enabled, it is not expected to add the frames to the fill-queue. I have
    noticed the following two issues in this scenario:
    - If XDP_USE_NEED_WAKEUP flag is not set by application, igc_poll()
      will go into infinite loop because the buffer allocation resulting
      in igc_clean_rx_irq_zc() indicating that all work is not done and NAPI
      should keep polling. This does not occur if XDP_USE_NEED_WAKEUP
      flag is set.
    - Since there are no buffers allocated by userspace for the fill
      queue, there is no memory allocated for the NIC to copy the data
      to. If the packet received is destined to the hardware queue where
      XDP application is running, no packets are received even on other
      queues.
    Both these issues can be mitigated by adding a few frames to the
    fill queue. The second issue can also be mitigated by making sure no
    packets are being received on the hardware queue where Rx is running. 

v2 is here:

    https://patchwork.ozlabs.org/project/intel-wired-lan/cover/20201223203705.78705-1-andre.guedes at intel.com/

v1 is here:

    https://patchwork.ozlabs.org/project/intel-wired-lan/cover/20201217202415.77891-1-andre.guedes at intel.com/

Thanks,
Vedang

Andre Guedes (9):
  igc: Move igc_xdp_is_enabled()
  igc: Refactor igc_xdp_run_prog()
  igc: Refactor igc_clean_rx_ring()
  igc: Refactor XDP rxq info registration
  igc: Introduce tx/rx stats helpers
  igc: Introduce igc_unmap_tx_buffer() helper
  igc: Replace IGC_TX_FLAGS_XDP flag by an enum
  igc: Enable RX via AF_XDP zero-copy
  igc: Enable TX via AF_XDP zero-copy

 drivers/net/ethernet/intel/igc/igc.h      |  33 +-
 drivers/net/ethernet/intel/igc/igc_base.h |   2 +
 drivers/net/ethernet/intel/igc/igc_main.c | 651 ++++++++++++++++++----
 drivers/net/ethernet/intel/igc/igc_xdp.c  | 107 +++-
 drivers/net/ethernet/intel/igc/igc_xdp.h  |   8 +-
 5 files changed, 674 insertions(+), 127 deletions(-)

-- 
2.17.1