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rdma/mlx5_dv: stamp RoCE IPv4 TOS from SL on RTR #5

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Merged
jleeh merged 1 commit into from
Aug 28, 2026
Merged

rdma/mlx5_dv: stamp RoCE IPv4 TOS from SL on RTR #5

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29 changes: 29 additions & 0 deletions lib/rdma_provider/rdma_provider_mlx5_dv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,33 @@ struct spdk_rdma_mlx5_dv_qp {
struct ibv_qp_ex *qpex;
};

/*
* rdma_set_option(RDMA_OPTION_ID_TOS) programs SL (SQ / tx_prio). mlx5_dv
* moves the QP itself via ibv_modify_qp, so ConnectX builds the RoCEv2
* IPv4 header from the RTR AV traffic_class — which rdma_init_qp_attr
* often leaves 0. Fill TOS = SL<<5 (CS DSCP) when the AV is present and
* traffic_class is unset.
*/
static void
rdma_mlx5_dv_fill_roce_tos(struct ibv_qp_attr *qp_attr, int qp_attr_mask)
{
uint8_t sl;

if ((qp_attr_mask & IBV_QP_AV) == 0) {
return;
}
if (qp_attr->ah_attr.grh.traffic_class != 0) {
return;
}

sl = qp_attr->ah_attr.sl;
if (sl == 0) {
return;
}

qp_attr->ah_attr.grh.traffic_class = sl << 5;
}

static int
rdma_mlx5_dv_init_qpair(struct spdk_rdma_mlx5_dv_qp *mlx5_qp)
{
Expand All @@ -49,6 +76,8 @@ rdma_mlx5_dv_init_qpair(struct spdk_rdma_mlx5_dv_qp *mlx5_qp)
return rc;
}

rdma_mlx5_dv_fill_roce_tos(&qp_attr, qp_attr_mask);

rc = ibv_modify_qp(mlx5_qp->common.qp, &qp_attr, qp_attr_mask);
if (rc) {
SPDK_ERRLOG("ibv_modify_qp(IBV_QPS_RTR) failed, rc %d\n", rc);
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