releases/5.1.7/net-mlx5e-disable-rxhash-when-cqe-compress-is-enabled.patch

   1 From foo@baz Fri 31 May 2019 03:16:39 PM PDT
   2 From: Saeed Mahameed <saeedm@mellanox.com>
   3 Date: Thu, 23 May 2019 12:55:10 -0700
   4 Subject: net/mlx5e: Disable rxhash when CQE compress is enabled
   5
   6 From: Saeed Mahameed <saeedm@mellanox.com>
   7
   8 [ Upstream commit c0194e2d0ef0e5ce5e21a35640d23a706827ae28 ]
   9
  10 When CQE compression is enabled (Multi-host systems), compressed CQEs
  11 might arrive to the driver rx, compressed CQEs don't have a valid hash
  12 offload and the driver already reports a hash value of 0 and invalid hash
  13 type on the skb for compressed CQEs, but this is not good enough.
  14
  15 On a congested PCIe, where CQE compression will kick in aggressively,
  16 gro will deliver lots of out of order packets due to the invalid hash
  17 and this might cause a serious performance drop.
  18
  19 The only valid solution, is to disable rxhash offload at all when CQE
  20 compression is favorable (Multi-host systems).
  21
  22 Fixes: 7219ab34f184 ("net/mlx5e: CQE compression")
  23 Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
  24 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  25 ---
  26  drivers/net/ethernet/mellanox/mlx5/core/en_main.c |   13 +++++++++++++
  27  1 file changed, 13 insertions(+)
  28
  29 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
  30 +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
  31 @@ -3750,6 +3750,12 @@ static netdev_features_t mlx5e_fix_featu
  32                         netdev_warn(netdev, "Disabling LRO, not supported in legacy RQ\n");
  33         }
  34
  35 +       if (MLX5E_GET_PFLAG(params, MLX5E_PFLAG_RX_CQE_COMPRESS)) {
  36 +               features &= ~NETIF_F_RXHASH;
  37 +               if (netdev->features & NETIF_F_RXHASH)
  38 +                       netdev_warn(netdev, "Disabling rxhash, not supported when CQE compress is active\n");
  39 +       }
  40 +
  41         mutex_unlock(&priv->state_lock);
  42
  43         return features;
  44 @@ -3875,6 +3881,9 @@ int mlx5e_hwstamp_set(struct mlx5e_priv
  45         memcpy(&priv->tstamp, &config, sizeof(config));
  46         mutex_unlock(&priv->state_lock);
  47
  48 +       /* might need to fix some features */
  49 +       netdev_update_features(priv->netdev);
  50 +
  51         return copy_to_user(ifr->ifr_data, &config,
  52                             sizeof(config)) ? -EFAULT : 0;
  53  }
  54 @@ -4734,6 +4743,10 @@ static void mlx5e_build_nic_netdev(struc
  55         if (!priv->channels.params.scatter_fcs_en)
  56                 netdev->features  &= ~NETIF_F_RXFCS;
  57
  58 +       /* prefere CQE compression over rxhash */
  59 +       if (MLX5E_GET_PFLAG(&priv->channels.params, MLX5E_PFLAG_RX_CQE_COMPRESS))
  60 +               netdev->features &= ~NETIF_F_RXHASH;
  61 +
  62  #define FT_CAP(f) MLX5_CAP_FLOWTABLE(mdev, flow_table_properties_nic_receive.f)
  63         if (FT_CAP(flow_modify_en) &&
  64             FT_CAP(modify_root) &&