Hi Parav, I tried your mlx4-patch together with SMC on s390x, but it failed. The SMC-R code tries to send 44 bytes as inline in 1 sge. I wonder about a length check with 16 bytes, which probably explains the failure. See my question below in the patch: On 03/12/2017 09:20 PM, Parav Pandit wrote: > Hi Ursula, > >> -----Original Message----- >> From: linux-rdma-owner@xxxxxxxxxxxxxxx [mailto:linux-rdma- >> owner@xxxxxxxxxxxxxxx] On Behalf Of Ursula Braun >> Sent: Thursday, March 9, 2017 3:54 AM >> To: Eli Cohen <eli@xxxxxxxxxxxx>; Matan Barak <matanb@xxxxxxxxxxxx> >> Cc: Saeed Mahameed <saeedm@xxxxxxxxxxxx>; Leon Romanovsky >> <leonro@xxxxxxxxxxxx>; linux-rdma@xxxxxxxxxxxxxxx >> Subject: Re: Fwd: mlx5_ib_post_send panic on s390x >> >> >> >> On 03/06/2017 02:08 PM, Eli Cohen wrote: >>>>> >>>>> The problem seems to be caused by the usage of plain memcpy in >> set_data_inl_seg(). >>>>> The address provided by SMC-code in struct ib_send_wr *wr is an >>>>> address belonging to an area mapped with the ib_dma_map_single() >>>>> call. On s390x those kind of addresses require extra access functions (see >> arch/s390/include/asm/io.h). >>>>> >>> >>> By definition, when you are posting a send request with inline, the address >> must be mapped to the cpu so plain memcpy should work. >>> >> In the past I run SMC-R with Connect X3 cards. The mlx4 driver does not seem to >> contain extra coding for IB_SEND_INLINE flag for ib_post_send. Does this mean >> for SMC-R to run on Connect X3 cards the IB_SEND_INLINE flag is ignored, and >> thus I needed the ib_dma_map_single() call for the area used with >> ib_post_send()? Does this mean I should stay away from the IB_SEND_INLINE >> flag, if I want to run the same SMC-R code with both, Connect X3 cards and >> Connect X4 cards? >> > I had encountered the same kernel panic that you mentioned last week on ConnectX-4 adapters with smc-r on x86_64. > Shall I submit below fix to netdev mailing list? > I have tested above change. I also have optimization that avoids dma mapping for wr_tx_dma_addr. > > - lnk->wr_tx_sges[i].addr = > - lnk->wr_tx_dma_addr + i * SMC_WR_BUF_SIZE; > + lnk->wr_tx_sges[i].addr = (uintptr_t)(lnk->wr_tx_bufs + i); > > I also have fix for processing IB_SEND_INLINE in mlx4 driver on little older kernel base. > I have attached below. I can rebase my kernel and provide fix in mlx5_ib driver. > Let me know. > > Regards, > Parav Pandit > > diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c > index a2e4ca5..0d984f5 100644 > --- a/drivers/infiniband/hw/mlx4/qp.c > +++ b/drivers/infiniband/hw/mlx4/qp.c > @@ -2748,6 +2748,7 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, > unsigned long flags; > int nreq; > int err = 0; > + int inl = 0; > unsigned ind; > int uninitialized_var(stamp); > int uninitialized_var(size); > @@ -2958,30 +2959,97 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, > default: > break; > } > + if (wr->send_flags & IB_SEND_INLINE && wr->num_sge) { > + struct mlx4_wqe_inline_seg *seg; > + void *addr; > + int len, seg_len; > + int num_seg; > + int off, to_copy; > + > + inl = 0; > + > + seg = wqe; > + wqe += sizeof *seg; > + off = ((uintptr_t) wqe) & (MLX4_INLINE_ALIGN - 1); > + num_seg = 0; > + seg_len = 0; > + > + for (i = 0; i < wr->num_sge; ++i) { > + addr = (void *) (uintptr_t) wr->sg_list[i].addr; > + len = wr->sg_list[i].length; > + inl += len; > + > + if (inl > 16) { > + inl = 0; > + err = ENOMEM; > + *bad_wr = wr; > + goto out; > + } SMC-R fails due to this check. inl is 44 here. Why is 16 a limit for IB_SEND_INLINE data? The SMC-R code calls ib_create_qp() with max_inline_data=44. And the function does not seem to return an error. > > - /* > - * Write data segments in reverse order, so as to > - * overwrite cacheline stamp last within each > - * cacheline. This avoids issues with WQE > - * prefetching. > - */ > + while (len >= MLX4_INLINE_ALIGN - off) { > + to_copy = MLX4_INLINE_ALIGN - off; > + memcpy(wqe, addr, to_copy); > + len -= to_copy; > + wqe += to_copy; > + addr += to_copy; > + seg_len += to_copy; > + wmb(); /* see comment below */ > + seg->byte_count = htonl(MLX4_INLINE_SEG | seg_len); > + seg_len = 0; > + seg = wqe; > + wqe += sizeof *seg; > + off = sizeof *seg; > + ++num_seg; > + } > > - dseg = wqe; > - dseg += wr->num_sge - 1; > - size += wr->num_sge * (sizeof (struct mlx4_wqe_data_seg) / 16); > + memcpy(wqe, addr, len); > + wqe += len; > + seg_len += len; > + off += len; > + } > > - /* Add one more inline data segment for ICRC for MLX sends */ > - if (unlikely(qp->mlx4_ib_qp_type == MLX4_IB_QPT_SMI || > - qp->mlx4_ib_qp_type == MLX4_IB_QPT_GSI || > - qp->mlx4_ib_qp_type & > - (MLX4_IB_QPT_PROXY_SMI_OWNER | MLX4_IB_QPT_TUN_SMI_OWNER))) { > - set_mlx_icrc_seg(dseg + 1); > - size += sizeof (struct mlx4_wqe_data_seg) / 16; > - } > + if (seg_len) { > + ++num_seg; > + /* > + * Need a barrier here to make sure > + * all the data is visible before the > + * byte_count field is set. Otherwise > + * the HCA prefetcher could grab the > + * 64-byte chunk with this inline > + * segment and get a valid (!= > + * 0xffffffff) byte count but stale > + * data, and end up sending the wrong > + * data. > + */ > + wmb(); > + seg->byte_count = htonl(MLX4_INLINE_SEG | seg_len); > + } > > - for (i = wr->num_sge - 1; i >= 0; --i, --dseg) > - set_data_seg(dseg, wr->sg_list + i); > + size += (inl + num_seg * sizeof (*seg) + 15) / 16; > + } else { > + /* > + * Write data segments in reverse order, so as to > + * overwrite cacheline stamp last within each > + * cacheline. This avoids issues with WQE > + * prefetching. > + */ > + > + dseg = wqe; > + dseg += wr->num_sge - 1; > + size += wr->num_sge * (sizeof (struct mlx4_wqe_data_seg) / 16); > + > + /* Add one more inline data segment for ICRC for MLX sends */ > + if (unlikely(qp->mlx4_ib_qp_type == MLX4_IB_QPT_SMI || > + qp->mlx4_ib_qp_type == MLX4_IB_QPT_GSI || > + qp->mlx4_ib_qp_type & > + (MLX4_IB_QPT_PROXY_SMI_OWNER | MLX4_IB_QPT_TUN_SMI_OWNER))) { > + set_mlx_icrc_seg(dseg + 1); > + size += sizeof (struct mlx4_wqe_data_seg) / 16; > + } > > + for (i = wr->num_sge - 1; i >= 0; --i, --dseg) > + set_data_seg(dseg, wr->sg_list + i); > + } > /* > * Possibly overwrite stamping in cacheline with LSO > * segment only after making sure all data segments > >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body >> of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at >> http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
