diff --git a/sys/dev/gve/gve_main.c b/sys/dev/gve/gve_main.c --- a/sys/dev/gve/gve_main.c +++ b/sys/dev/gve/gve_main.c @@ -196,6 +196,8 @@ gve_set_mtu(if_t ifp, uint32_t new_mtu) { struct gve_priv *priv = if_getsoftc(ifp); + const uint32_t max_problem_range = 8227; + const uint32_t min_problem_range = 7822; int err; if ((new_mtu > priv->max_mtu) || (new_mtu < ETHERMIN)) { @@ -204,6 +206,19 @@ return (EINVAL); } + /* + * When hardware LRO is enabled in DQ mode, MTUs within the range + * [7822, 8227] trigger hardware issues which cause a drastic drop + * in throughput. + */ + if (!gve_is_gqi(priv) && !gve_disable_hw_lro && + new_mtu >= min_problem_range && new_mtu <= max_problem_range) { + device_printf(priv->dev, + "Cannot set to MTU to %d within the range [%d, %d] while hardware LRO is enabled\n", + new_mtu, min_problem_range, max_problem_range); + return (EINVAL); + } + err = gve_adminq_set_mtu(priv, new_mtu); if (err == 0) { if (bootverbose)