Hi Yuval-
On Oct 4, 2014, at 7:45 AM, Yuval Shaia <yuval.sh...@oracle.com> wrote:
> This enhancement suggest the usage of IB CRC instead of CSUM in IPoIB CM.
> IPoIB Connected Mode driver uses RC (Reliable Connection) which guarantees the
> corruption free delivery of the packet.
Some naïve questions:
Is this interoperable with other IPoIB implementations, such as Solaris?
Are there implications for IPv6, where checksumming is not optional?
Maybe I misunderstood what is being replaced.
What happens if IPoIB uses UD instead of RC?
When IPoIB traffic is routed off the IB fabric, isn’t end-to-end checksumming
lost because the router node has to fabricate an IP checksum that wasn’t
provided by the sender?
> InfiniBand uses 32b CRC which provides stronger data integrity protection
> compare to 16b IP Checksum.
> So, there is no added value that IP Checksum provides in the IB world.
> The proposal is to tell that network stack that IPoIB-CM supports IP Checksum
> offload.
> This enables Linux to save the time of checksum calculation of IPoIB CM
> packets.
> Network sends the IP packet without adding the IP Checksum to the header.
> On the receive side, IPoIB driver again tells the network stack that IP
> Checksum is good for the incoming packets and network stack avoids the IP
> Checksum calculations.
> During connection establishment the driver determine if the other end supports
> IB CRC as checksum.
> This is done so driver will be able to calculate checksum before transmiting
> the packet in case the other end does not support this feature.
> A support for fragmented skb is added to transmit path.
>
> Signed-off-by: Yuval Shaia <yuval.sh...@oracle.com>
> ---
> drivers/infiniband/ulp/ipoib/ipoib.h | 25 ++++++
> drivers/infiniband/ulp/ipoib/ipoib_cm.c | 117 ++++++++++++++++++++++++----
> drivers/infiniband/ulp/ipoib/ipoib_ib.c | 3 +-
> drivers/infiniband/ulp/ipoib/ipoib_main.c | 19 ++++-
> 4 files changed, 143 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h
> b/drivers/infiniband/ulp/ipoib/ipoib.h
> index 0ed9aed..6fedf83 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib.h
> +++ b/drivers/infiniband/ulp/ipoib/ipoib.h
> @@ -100,6 +100,7 @@ enum {
> IPOIB_FLAG_AUTO_MODER = 13, /*indicates moderation is running*/
> /*indicates if event handler was registered*/
> IPOIB_FLAG_EVENTS_REGISTERED = 14,
> + IPOIB_FLAG_CSUM = 15,
>
> IPOIB_MAX_BACKOFF_SECONDS = 16,
>
> @@ -192,9 +193,28 @@ struct ipoib_pmtu_update {
>
> struct ib_cm_id;
>
> +#define IPOIB_CM_PROTO_SIG 0x2211
> +#define IPOIB_CM_PROTO_VER (1UL << 12)
> +
> +static inline int ipoib_cm_check_proto_sig(u16 proto_sig)
> +{
> + return proto_sig & IPOIB_CM_PROTO_SIG;
> +};
> +
> +static inline int ipoib_cm_check_proto_ver(u16 caps)
> +{
> + return caps & IPOIB_CM_PROTO_VER;
> +};
> +
> +enum ipoib_cm_data_caps {
> + IPOIB_CM_CAPS_IBCRC_AS_CSUM = 1UL << 0,
> +};
> +
> struct ipoib_cm_data {
> __be32 qpn; /* High byte MUST be ignored on receive */
> __be32 mtu;
> + __be16 sig; /* must be IPOIB_CM_PROTO_SIG */
> + __be16 caps; /* 4 bits proto ver and 12 bits capabilities */
> };
>
> /*
> @@ -241,6 +261,7 @@ struct ipoib_cm_rx {
> int recv_count;
> u32 qpn;
> int index; /* For ring counters */
> + u16 caps;
> };
>
> struct ipoib_cm_tx {
> @@ -255,6 +276,7 @@ struct ipoib_cm_tx {
> unsigned tx_tail;
> unsigned long flags;
> u32 mtu;
> + u16 caps;
> };
>
> struct ipoib_cm_rx_buf {
> @@ -558,6 +580,8 @@ void ipoib_del_neighs_by_gid(struct net_device *dev, u8
> *gid);
> extern struct workqueue_struct *ipoib_workqueue;
> extern struct workqueue_struct *ipoib_auto_moder_workqueue;
>
> +extern int cm_ibcrc_as_csum;
> +
> /* functions */
>
> int ipoib_poll(struct napi_struct *napi, int budget);
> @@ -613,6 +637,7 @@ int ipoib_mcast_stop_thread(struct net_device *dev, int
> flush);
>
> void ipoib_mcast_dev_down(struct net_device *dev);
> void ipoib_mcast_dev_flush(struct net_device *dev);
> +int ipoib_dma_map_tx(struct ib_device *ca, struct ipoib_tx_buf *tx_req);
>
> #ifdef CONFIG_INFINIBAND_IPOIB_DEBUG
> struct ipoib_mcast_iter *ipoib_mcast_iter_init(struct net_device *dev);
> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
> b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
> index db0303e..553569a 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
> +++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
> @@ -436,9 +436,16 @@ static int ipoib_cm_send_rep(struct net_device *dev,
> struct ib_cm_id *cm_id,
> struct ipoib_dev_priv *priv = netdev_priv(dev);
> struct ipoib_cm_data data = {};
> struct ib_cm_rep_param rep = {};
> + u16 caps = 0;
> +
> + caps |= IPOIB_CM_PROTO_VER;
> + if (cm_ibcrc_as_csum)
> + caps |= IPOIB_CM_CAPS_IBCRC_AS_CSUM;
>
> data.qpn = cpu_to_be32(priv->qp->qp_num);
> data.mtu = cpu_to_be32(IPOIB_CM_BUF_SIZE);
> + data.sig = cpu_to_be16(IPOIB_CM_PROTO_SIG);
> + data.caps = cpu_to_be16(caps);
>
> rep.private_data = &data;
> rep.private_data_len = sizeof data;
> @@ -458,6 +465,7 @@ static int ipoib_cm_req_handler(struct ib_cm_id *cm_id,
> struct ib_cm_event *even
> struct ipoib_cm_data *data = event->private_data;
> unsigned psn;
> int ret;
> + struct ipoib_cm_data *cm_data;
>
> ipoib_dbg(priv, "REQ arrived\n");
> p = kzalloc(sizeof *p, GFP_KERNEL);
> @@ -480,6 +488,13 @@ static int ipoib_cm_req_handler(struct ib_cm_id *cm_id,
> struct ib_cm_event *even
> goto err_qp;
> }
>
> + cm_data = (struct ipoib_cm_data *)event->private_data;
> + ipoib_dbg(priv, "Otherend sig=0x%x\n", be16_to_cpu(cm_data->sig));
> + if (ipoib_cm_check_proto_sig(be16_to_cpu(cm_data->sig)) &&
> + ipoib_cm_check_proto_ver(be16_to_cpu(cm_data->caps)))
> + p->caps = be16_to_cpu(cm_data->caps);
> + ipoib_dbg(priv, "Otherend caps=0x%x\n", p->caps);
> +
> psn = random32() & 0xffffff;
> ret = ipoib_cm_modify_rx_qp(dev, cm_id, p->qp, psn);
> if (ret)
> @@ -696,6 +711,9 @@ copied:
> if (skb->dev->priv_flags & IFF_EIPOIB_VIF)
> set_skb_oob_cb_data(skb, wc, NULL);
>
> + if (cm_ibcrc_as_csum)
> + skb->ip_summed = CHECKSUM_UNNECESSARY;
> +
> netif_receive_skb(skb);
>
> repost:
> @@ -732,14 +750,43 @@ static inline int post_send(struct ipoib_dev_priv *priv,
> return ib_post_send(tx->qp, &send_ring->tx_wr, &bad_wr);
> }
>
> +static inline int post_send_sg(struct ipoib_dev_priv *priv,
> + struct ipoib_cm_tx *tx,
> + unsigned int wr_id,
> + struct sk_buff *skb,
> + u64 mapping[MAX_SKB_FRAGS + 1],
> + struct ipoib_send_ring *send_ring)
> +{
> + struct ib_send_wr *bad_wr;
> + int i, off;
> + skb_frag_t *frags = skb_shinfo(skb)->frags;
> + int nr_frags = skb_shinfo(skb)->nr_frags;
> + if (skb_headlen(skb)) {
> + send_ring->tx_sge[0].addr = mapping[0];
> + send_ring->tx_sge[0].length = skb_headlen(skb);
> + off = 1;
> + } else
> + off = 0;
> +
> + for (i = 0; i < nr_frags; ++i) {
> + send_ring->tx_sge[i + off].addr = mapping[i + off];
> + send_ring->tx_sge[i + off].length = frags[i].size;
> + }
> + send_ring->tx_wr.num_sge = nr_frags + off;
> + send_ring->tx_wr.wr_id = wr_id | IPOIB_OP_CM;
> +
> + return ib_post_send(tx->qp, &send_ring->tx_wr, &bad_wr);
> +}
> +
> void ipoib_cm_send(struct net_device *dev, struct sk_buff *skb, struct
> ipoib_cm_tx *tx)
> {
> struct ipoib_dev_priv *priv = netdev_priv(dev);
> struct ipoib_cm_tx_buf *tx_req;
> - u64 addr;
> + u64 addr = 0;
> int rc;
> struct ipoib_send_ring *send_ring;
> u16 queue_index;
> + struct ipoib_tx_buf sg_tx_req;
>
> queue_index = skb_get_queue_mapping(skb);
> send_ring = priv->send_ring + queue_index;
> @@ -768,26 +815,45 @@ void ipoib_cm_send(struct net_device *dev, struct
> sk_buff *skb, struct ipoib_cm_
> tx_req = &tx->tx_ring[tx->tx_head & (ipoib_sendq_size - 1)];
> tx_req->skb = skb;
>
> - if (skb->len < ipoib_inline_thold && !skb_shinfo(skb)->nr_frags) {
> - addr = (u64) skb->data;
> - send_ring->tx_wr.send_flags |= IB_SEND_INLINE;
> - tx_req->is_inline = 1;
> - } else {
> - addr = ib_dma_map_single(priv->ca, skb->data,
> - skb->len, DMA_TO_DEVICE);
> - if (unlikely(ib_dma_mapping_error(priv->ca, addr))) {
> - ++send_ring->stats.tx_errors;
> + /* Calculate checksum if we support ibcrc_as_csum but peer does not */
> + if ((skb->ip_summed != CHECKSUM_NONE) && cm_ibcrc_as_csum &&
> + !(tx->caps & IPOIB_CM_CAPS_IBCRC_AS_CSUM))
> + skb_checksum_help(skb);
> +
> + if (skb_shinfo(skb)->nr_frags) {
> + sg_tx_req.skb = skb;
> + if (unlikely(ipoib_dma_map_tx(priv->ca, &sg_tx_req))) {
> + ++dev->stats.tx_errors;
> dev_kfree_skb_any(skb);
> return;
> }
> -
> - tx_req->mapping = addr;
> tx_req->is_inline = 0;
> - send_ring->tx_wr.send_flags &= ~IB_SEND_INLINE;
> - }
> + rc = post_send_sg(priv, tx, tx->tx_head &
> + (ipoib_sendq_size - 1),
> + skb, sg_tx_req.mapping, send_ring);
> + } else {
> + if (skb->len < ipoib_inline_thold &&
> + !skb_shinfo(skb)->nr_frags) {
> + addr = (u64) skb->data;
> + send_ring->tx_wr.send_flags |= IB_SEND_INLINE;
> + tx_req->is_inline = 1;
> + } else {
> + addr = ib_dma_map_single(priv->ca, skb->data,
> + skb->len, DMA_TO_DEVICE);
> + if (unlikely(ib_dma_mapping_error(priv->ca, addr))) {
> + ++send_ring->stats.tx_errors;
> + dev_kfree_skb_any(skb);
> + return;
> + }
>
> - rc = post_send(priv, tx, tx->tx_head & (ipoib_sendq_size - 1),
> - addr, skb->len, send_ring);
> + tx_req->mapping = addr;
> + tx_req->is_inline = 0;
> + send_ring->tx_wr.send_flags &= ~IB_SEND_INLINE;
> + }
> +
> + rc = post_send(priv, tx, tx->tx_head & (ipoib_sendq_size - 1),
> + addr, skb->len, send_ring);
> + }
> if (unlikely(rc)) {
> ipoib_warn(priv, "%s: post_send failed, error %d queue_index:
> %d skb->len: %d\n",
> __func__, rc, queue_index, skb->len);
> @@ -1012,6 +1078,7 @@ static int ipoib_cm_rep_handler(struct ib_cm_id *cm_id,
> struct ib_cm_event *even
> struct ib_qp_attr qp_attr;
> int qp_attr_mask, ret;
> struct sk_buff *skb;
> + struct ipoib_cm_data *cm_data;
>
> p->mtu = be32_to_cpu(data->mtu);
>
> @@ -1021,6 +1088,13 @@ static int ipoib_cm_rep_handler(struct ib_cm_id
> *cm_id, struct ib_cm_event *even
> return -EINVAL;
> }
>
> + cm_data = (struct ipoib_cm_data *)event->private_data;
> + ipoib_dbg(priv, "Otherend sig=0x%x\n", be16_to_cpu(cm_data->sig));
> + if (ipoib_cm_check_proto_sig(be16_to_cpu(cm_data->sig)) &&
> + ipoib_cm_check_proto_ver(be16_to_cpu(cm_data->caps)))
> + p->caps = be16_to_cpu(cm_data->caps);
> + ipoib_dbg(priv, "Otherend caps=0x%x\n", p->caps);
> +
> qp_attr.qp_state = IB_QPS_RTR;
> ret = ib_cm_init_qp_attr(cm_id, &qp_attr, &qp_attr_mask);
> if (ret) {
> @@ -1105,6 +1179,9 @@ static struct ib_qp *ipoib_cm_create_tx_qp(struct
> net_device *dev, struct ipoib_
>
> spin_unlock_irqrestore(&priv->lock, flags);
>
> + if (dev->features & NETIF_F_SG)
> + attr.cap.max_send_sge = MAX_SKB_FRAGS + 1;
> +
> return ib_create_qp(priv->pd, &attr);
> }
>
> @@ -1116,9 +1193,16 @@ static int ipoib_cm_send_req(struct net_device *dev,
> struct ipoib_dev_priv *priv = netdev_priv(dev);
> struct ipoib_cm_data data = {};
> struct ib_cm_req_param req = {};
> + u16 caps = 0;
> +
> + caps |= IPOIB_CM_PROTO_VER;
> + if (cm_ibcrc_as_csum)
> + caps |= IPOIB_CM_CAPS_IBCRC_AS_CSUM;
>
> data.qpn = cpu_to_be32(priv->qp->qp_num);
> data.mtu = cpu_to_be32(IPOIB_CM_BUF_SIZE);
> + data.sig = cpu_to_be16(IPOIB_CM_PROTO_SIG);
> + data.caps = cpu_to_be16(caps);
>
> req.primary_path = pathrec;
> req.alternate_path = NULL;
> @@ -1594,7 +1678,6 @@ static void ipoib_cm_stale_task(struct work_struct
> *work)
> spin_unlock_irq(&priv->lock);
> }
>
> -
> static ssize_t show_mode(struct device *d, struct device_attribute *attr,
> char *buf)
> {
> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> index 9e7d824..28f36dd 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> +++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> @@ -349,8 +349,7 @@ repost:
> "for buf %d\n", wr_id);
> }
>
> -static int ipoib_dma_map_tx(struct ib_device *ca,
> - struct ipoib_tx_buf *tx_req)
> +int ipoib_dma_map_tx(struct ib_device *ca, struct ipoib_tx_buf *tx_req)
> {
> struct sk_buff *skb = tx_req->skb;
> u64 *mapping = tx_req->mapping;
> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c
> b/drivers/infiniband/ulp/ipoib/ipoib_main.c
> index dcf18df..b17c7ab 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
> +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
> @@ -69,6 +69,12 @@ module_param_named(debug_level, ipoib_debug_level, int,
> 0644);
> MODULE_PARM_DESC(debug_level, "Enable debug tracing if > 0 (default: 0)
> (0-1)");
> #endif
>
> +int cm_ibcrc_as_csum;
> +
> +module_param_named(cm_ibcrc_as_csum, cm_ibcrc_as_csum, int, 0444);
> +MODULE_PARM_DESC(cm_ibcrc_as_csum, "Indicates whether to utilize IB-CRC as "
> + "CSUM in connected mode,(default: 0)");
> +
> struct ipoib_path_iter {
> struct net_device *dev;
> struct ipoib_path path;
> @@ -195,7 +201,12 @@ static netdev_features_t ipoib_fix_features(struct
> net_device *dev, netdev_featu
> struct ipoib_dev_priv *priv = netdev_priv(dev);
>
> if (test_bit(IPOIB_FLAG_ADMIN_CM, &priv->flags))
> - features &= ~(NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO);
> + if (cm_ibcrc_as_csum && (test_bit(IPOIB_FLAG_CSUM,
> + &priv->flags)))
> + dev->features |= NETIF_F_IP_CSUM | NETIF_F_SG;
> + else
> + features &= ~(NETIF_F_SG | NETIF_F_IP_CSUM |
> + NETIF_F_TSO);
>
> return features;
> }
> @@ -249,7 +260,11 @@ int ipoib_set_mode(struct net_device *dev, const char
> *buf)
>
> send_ring = priv->send_ring;
> for (i = 0; i < priv->num_tx_queues; i++) {
> - send_ring->tx_wr.send_flags &= ~IB_SEND_IP_CSUM;
> + if (cm_ibcrc_as_csum && (test_bit(IPOIB_FLAG_CSUM,
> + &priv->flags)))
> + send_ring->tx_wr.send_flags |= IB_SEND_IP_CSUM;
> + else
> + send_ring->tx_wr.send_flags &= ~IB_SEND_IP_CSUM;
> send_ring++;
> }
>
> --
> 1.7.1
>
> --
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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