Re: [dpdk-dev] [DPDK] net/e1000: fix buffer overrun while i219 processing DMA transactions

["Anand H. Krishnan" <anandhkrishnan@gmail.com>]

This seems to be changing the IGB driver. Shouldn't you be changing
the em driver
rather than the igb driver?

Thanks,
Anand

On Mon, Jul 8, 2019 at 10:10 AM Xiao Zhang <xiao.zhang@intel.com> wrote:
>
> Intel® 100/200 Series Chipset platforms reduced the round-trip
> latency for the LAN Controller DMA accesses, causing in some high
> performance cases a buffer overrun while the I219 LAN Connected
> Device is processing the DMA transactions. I219LM and I219V devices
> can fall into unrecovered Tx hang under very stressfully UDP traffic
> and multiple reconnection of Ethernet cable. This Tx hang of the LAN
> Controller is only recovered if the system is rebooted. Slightly slow
> down DMA access by reducing the number of outstanding requests.
> This workaround could have an impact on TCP traffic performance
> on the platform. Disabling TSO eliminates performance loss for TCP
> traffic without a noticeable impact on CPU performance.
>
> Please, refer to I218/I219 specification update:
> https://www.intel.com/content/www/us/en/embedded/products/networking/
> ethernet-connection-i218-family-documentation.html
>
> Signed-off-by: Xiao Zhang <xiao.zhang@intel.com>
> ---
>  drivers/net/e1000/base/e1000_ich8lan.h |  1 +
>  drivers/net/e1000/igb_rxtx.c           | 16 ++++++++++++++++
>  2 files changed, 17 insertions(+)
>
> diff --git a/drivers/net/e1000/base/e1000_ich8lan.h b/drivers/net/e1000/base/e1000_ich8lan.h
> index 1f2a3f8..084eb9c 100644
> --- a/drivers/net/e1000/base/e1000_ich8lan.h
> +++ b/drivers/net/e1000/base/e1000_ich8lan.h
> @@ -134,6 +134,7 @@ POSSIBILITY OF SUCH DAMAGE.
>  #define E1000_FLASH_BASE_ADDR 0xE000 /*offset of NVM access regs*/
>  #define E1000_CTRL_EXT_NVMVS 0x3 /*NVM valid sector */
>  #define E1000_TARC0_CB_MULTIQ_3_REQ    (1 << 28 | 1 << 29)
> +#define E1000_TARC0_CB_MULTIQ_2_REQ    (1 << 29)
>  #define PCIE_ICH8_SNOOP_ALL    PCIE_NO_SNOOP_ALL
>
>  #define E1000_ICH_RAR_ENTRIES  7
> diff --git a/drivers/net/e1000/igb_rxtx.c b/drivers/net/e1000/igb_rxtx.c
> index 33eeb4e..5d45e62 100644
> --- a/drivers/net/e1000/igb_rxtx.c
> +++ b/drivers/net/e1000/igb_rxtx.c
> @@ -2627,6 +2627,22 @@ eth_igb_tx_init(struct rte_eth_dev *dev)
>
>         e1000_config_collision_dist(hw);
>
> +       /* SPT and CNP Si errata workaround to avoid data corruption */
> +       if (hw->mac.type == e1000_pch_spt) {
> +               uint32_t reg_val;
> +               reg_val = E1000_READ_REG(hw, E1000_IOSFPC);
> +               reg_val |= E1000_RCTL_RDMTS_HEX;
> +               E1000_WRITE_REG(hw, E1000_IOSFPC, reg_val);
> +
> +               /* Dropping the number of outstanding requests from
> +                * 3 to 2 in order to avoid a buffer overrun.
> +                */
> +               reg_val = E1000_READ_REG(hw, E1000_TARC(0));
> +               reg_val &= ~E1000_TARC0_CB_MULTIQ_3_REQ;
> +               reg_val |= E1000_TARC0_CB_MULTIQ_2_REQ;
> +               E1000_WRITE_REG(hw, E1000_TARC(0), reg_val);
> +       }
> +
>         /* This write will effectively turn on the transmit unit. */
>         E1000_WRITE_REG(hw, E1000_TCTL, tctl);
>  }
> --
> 2.7.4
>