RE: [PATCH 1/2] net: thunderx: HW TSO support for pass-2 hardware

From: Pavel Fedin
Date: Wed Dec 09 2015 - 07:05:14 EST

Hello!

> -----Original Message-----
> From: netdev-owner@xxxxxxxxxxxxxxx [mailto:netdev-owner@xxxxxxxxxxxxxxx] On Behalf Of Sunil
> Goutham
> Sent: Wednesday, December 09, 2015 2:38 PM
> To: netdev@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; p.fedin@xxxxxxxxxxx;
> Sunil.Goutham@xxxxxxxxxxxxxxxxxx; Sunil Goutham
> Subject: [PATCH 1/2] net: thunderx: HW TSO support for pass-2 hardware
>
> From: Sunil Goutham <sgoutham@xxxxxxxxxx>
>
> This adds support for offloading TCP segmentation to HW in pass-2
> revision of hardware. Both driver level SW TSO for pass1.x chips
> and HW TSO for pass-2 chip will co-exist.
>
> Signed-off-by: Sunil Goutham <sgoutham@xxxxxxxxxx>
> ---
> drivers/net/ethernet/cavium/thunder/nic.h | 12 ++++++--
> drivers/net/ethernet/cavium/thunder/nic_main.c | 11 ++-----
> drivers/net/ethernet/cavium/thunder/nicvf_main.c | 15 ++++++++-
> drivers/net/ethernet/cavium/thunder/nicvf_queues.c | 20 ++++++++++---
> drivers/net/ethernet/cavium/thunder/q_struct.h | 30 ++++++++++---------
> 5 files changed, 56 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/net/ethernet/cavium/thunder/nic.h
> b/drivers/net/ethernet/cavium/thunder/nic.h
> index 39ca674..02571f4 100644
> --- a/drivers/net/ethernet/cavium/thunder/nic.h
> +++ b/drivers/net/ethernet/cavium/thunder/nic.h
> @@ -262,9 +262,10 @@ struct nicvf {
> struct pci_dev *pdev;
> u8 vf_id;
> u8 node;
> - u8 tns_mode:1;
> - u8 sqs_mode:1;
> - u8 loopback_supported:1;
> + bool tns_mode:1;
> + bool sqs_mode:1;

These little refactors are creeping in your code without even being mentioned in the commit message, this is not good practice
IMHO. Additionally, may be turn these two flags into something like:

enum nicvf_mode {
NICVF_BYPASS,
NICVF_TNS,
NICVF_SQS
};

? Anyway, these modes are mutually exclusive.

> + bool loopback_supported:1;
> + bool hw_tso:1;
> u16 mtu;
> struct queue_set *qs;
> #define MAX_SQS_PER_VF_SINGLE_NODE 5
> @@ -489,6 +490,11 @@ static inline int nic_get_node_id(struct pci_dev *pdev)
> return ((addr >> NIC_NODE_ID_SHIFT) & NIC_NODE_ID_MASK);
> }
>
> +static inline bool pass1_silicon(struct pci_dev *pdev)
> +{
> + return pdev->revision < 8;
> +}
> +
> int nicvf_set_real_num_queues(struct net_device *netdev,
> int tx_queues, int rx_queues);
> int nicvf_open(struct net_device *netdev);
> diff --git a/drivers/net/ethernet/cavium/thunder/nic_main.c
> b/drivers/net/ethernet/cavium/thunder/nic_main.c
> index 4b7fd63..9f80de4 100644
> --- a/drivers/net/ethernet/cavium/thunder/nic_main.c
> +++ b/drivers/net/ethernet/cavium/thunder/nic_main.c
> @@ -55,11 +55,6 @@ struct nicpf {
> bool irq_allocated[NIC_PF_MSIX_VECTORS];
> };
>
> -static inline bool pass1_silicon(struct nicpf *nic)
> -{
> - return nic->pdev->revision < 8;
> -}
> -
> /* Supported devices */
> static const struct pci_device_id nic_id_table[] = {
> { PCI_DEVICE(PCI_VENDOR_ID_CAVIUM, PCI_DEVICE_ID_THUNDER_NIC_PF) },
> @@ -123,7 +118,7 @@ static void nic_send_msg_to_vf(struct nicpf *nic, int vf, union nic_mbx
> *mbx)
> * when PF writes to MBOX(1), in next revisions when
> * PF writes to MBOX(0)
> */
> - if (pass1_silicon(nic)) {
> + if (pass1_silicon(nic->pdev)) {
> /* see the comment for nic_reg_write()/nic_reg_read()
> * functions above
> */
> @@ -400,7 +395,7 @@ static void nic_config_cpi(struct nicpf *nic, struct cpi_cfg_msg *cfg)
> padd = cpi % 8; /* 3 bits CS out of 6bits DSCP */
>
> /* Leave RSS_SIZE as '0' to disable RSS */
> - if (pass1_silicon(nic)) {
> + if (pass1_silicon(nic->pdev)) {
> nic_reg_write(nic, NIC_PF_CPI_0_2047_CFG | (cpi << 3),
> (vnic << 24) | (padd << 16) |
> (rssi_base + rssi));
> @@ -470,7 +465,7 @@ static void nic_config_rss(struct nicpf *nic, struct rss_cfg_msg *cfg)
> }
>
> cpi_base = nic->cpi_base[cfg->vf_id];
> - if (pass1_silicon(nic))
> + if (pass1_silicon(nic->pdev))
> idx_addr = NIC_PF_CPI_0_2047_CFG;
> else
> idx_addr = NIC_PF_MPI_0_2047_CFG;
> diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> index dde8dc7..c24cb2a 100644
> --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> @@ -525,14 +525,22 @@ static void nicvf_snd_pkt_handler(struct net_device *netdev,
> __func__, cqe_tx->sq_qs, cqe_tx->sq_idx,
> cqe_tx->sqe_ptr, hdr->subdesc_cnt);
>
> - nicvf_put_sq_desc(sq, hdr->subdesc_cnt + 1);
> nicvf_check_cqe_tx_errs(nic, cq, cqe_tx);
> skb = (struct sk_buff *)sq->skbuff[cqe_tx->sqe_ptr];
> - /* For TSO offloaded packets only one head SKB needs to be freed */
> + /* For TSO offloaded packets only one SQE will have a valid SKB */
> if (skb) {
> + nicvf_put_sq_desc(sq, hdr->subdesc_cnt + 1);
> prefetch(skb);
> dev_consume_skb_any(skb);
> sq->skbuff[cqe_tx->sqe_ptr] = (u64)NULL;
> + } else {
> + /* In case of HW TSO, HW sends a CQE for each segment of a TSO
> + * packet instead of a single CQE for the whole TSO packet
> + * transmitted. Each of this CQE points to the same SQE, so
> + * avoid freeing same SQE multiple times.
> + */
> + if (!nic->hw_tso)
> + nicvf_put_sq_desc(sq, hdr->subdesc_cnt + 1);
> }
> }
>
> @@ -1549,6 +1557,9 @@ static int nicvf_probe(struct pci_dev *pdev, const struct pci_device_id
> *ent)
>
> netdev->vlan_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO;
>
> + if (!pass1_silicon(nic->pdev))
> + nic->hw_tso = true;
> +
> netdev->netdev_ops = &nicvf_netdev_ops;
> netdev->watchdog_timeo = NICVF_TX_TIMEOUT;
>
> diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
> b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
> index 1fbd908..b11fc09 100644
> --- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
> +++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
> @@ -925,7 +925,7 @@ static int nicvf_sq_subdesc_required(struct nicvf *nic, struct sk_buff
> *skb)
> {
> int subdesc_cnt = MIN_SQ_DESC_PER_PKT_XMIT;
>
> - if (skb_shinfo(skb)->gso_size) {
> + if (skb_shinfo(skb)->gso_size && !nic->hw_tso) {
> subdesc_cnt = nicvf_tso_count_subdescs(skb);
> return subdesc_cnt;
> }
> @@ -940,7 +940,7 @@ static int nicvf_sq_subdesc_required(struct nicvf *nic, struct sk_buff
> *skb)
> * First subdescriptor for every send descriptor.
> */
> static inline void
> -nicvf_sq_add_hdr_subdesc(struct snd_queue *sq, int qentry,
> +nicvf_sq_add_hdr_subdesc(struct nicvf *nic, struct snd_queue *sq, int qentry,
> int subdesc_cnt, struct sk_buff *skb, int len)
> {
> int proto;
> @@ -976,6 +976,15 @@ nicvf_sq_add_hdr_subdesc(struct snd_queue *sq, int qentry,
> break;
> }
> }
> +
> + if (nic->hw_tso && skb_shinfo(skb)->gso_size) {
> + hdr->tso = 1;
> + hdr->tso_start = skb_transport_offset(skb) + tcp_hdrlen(skb);
> + hdr->tso_max_paysize = skb_shinfo(skb)->gso_size;
> + /* For non-tunneled pkts, point this to L2 ethertype */
> + hdr->inner_l3_offset = skb_network_offset(skb) - 2;
> + nic->drv_stats.tx_tso++;
> + }
> }
>
> /* SQ GATHER subdescriptor
> @@ -1045,7 +1054,7 @@ static int nicvf_sq_append_tso(struct nicvf *nic, struct snd_queue *sq,
> data_left -= size;
> tso_build_data(skb, &tso, size);
> }
> - nicvf_sq_add_hdr_subdesc(sq, hdr_qentry,
> + nicvf_sq_add_hdr_subdesc(nic, sq, hdr_qentry,
> seg_subdescs - 1, skb, seg_len);
> sq->skbuff[hdr_qentry] = (u64)NULL;
> qentry = nicvf_get_nxt_sqentry(sq, qentry);
> @@ -1098,11 +1107,12 @@ int nicvf_sq_append_skb(struct nicvf *nic, struct sk_buff *skb)
> qentry = nicvf_get_sq_desc(sq, subdesc_cnt);
>
> /* Check if its a TSO packet */
> - if (skb_shinfo(skb)->gso_size)
> + if (skb_shinfo(skb)->gso_size && !nic->hw_tso)
> return nicvf_sq_append_tso(nic, sq, sq_num, qentry, skb);
>
> /* Add SQ header subdesc */
> - nicvf_sq_add_hdr_subdesc(sq, qentry, subdesc_cnt - 1, skb, skb->len);
> + nicvf_sq_add_hdr_subdesc(nic, sq, qentry, subdesc_cnt - 1,
> + skb, skb->len);
>
> /* Add SQ gather subdescs */
> qentry = nicvf_get_nxt_sqentry(sq, qentry);
> diff --git a/drivers/net/ethernet/cavium/thunder/q_struct.h
> b/drivers/net/ethernet/cavium/thunder/q_struct.h
> index 3c1de97..9e6d987 100644
> --- a/drivers/net/ethernet/cavium/thunder/q_struct.h
> +++ b/drivers/net/ethernet/cavium/thunder/q_struct.h
> @@ -545,25 +545,28 @@ struct sq_hdr_subdesc {
> u64 subdesc_cnt:8;
> u64 csum_l4:2;
> u64 csum_l3:1;
> - u64 rsvd0:5;
> + u64 csum_inner_l4:2;
> + u64 csum_inner_l3:1;
> + u64 rsvd0:2;
> u64 l4_offset:8;
> u64 l3_offset:8;
> u64 rsvd1:4;
> u64 tot_len:20; /* W0 */
>
> - u64 tso_sdc_cont:8;
> - u64 tso_sdc_first:8;
> - u64 tso_l4_offset:8;
> - u64 tso_flags_last:12;
> - u64 tso_flags_first:12;
> - u64 rsvd2:2;
> + u64 rsvd2:24;
> + u64 inner_l4_offset:8;
> + u64 inner_l3_offset:8;
> + u64 tso_start:8;
> + u64 rsvd3:2;
> u64 tso_max_paysize:14; /* W1 */
> #elif defined(__LITTLE_ENDIAN_BITFIELD)
> u64 tot_len:20;
> u64 rsvd1:4;
> u64 l3_offset:8;
> u64 l4_offset:8;
> - u64 rsvd0:5;
> + u64 rsvd0:2;
> + u64 csum_inner_l3:1;
> + u64 csum_inner_l4:2;
> u64 csum_l3:1;
> u64 csum_l4:2;
> u64 subdesc_cnt:8;
> @@ -574,12 +577,11 @@ struct sq_hdr_subdesc {
> u64 subdesc_type:4; /* W0 */
>
> u64 tso_max_paysize:14;
> - u64 rsvd2:2;
> - u64 tso_flags_first:12;
> - u64 tso_flags_last:12;
> - u64 tso_l4_offset:8;
> - u64 tso_sdc_first:8;
> - u64 tso_sdc_cont:8; /* W1 */
> + u64 rsvd3:2;
> + u64 tso_start:8;
> + u64 inner_l3_offset:8;
> + u64 inner_l4_offset:8;
> + u64 rsvd2:24; /* W1 */
> #endif
> };
>
> --
> 1.7.1
>

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia

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