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Date: Mon, 11 Jan 2016 10:11:41 -0800
From: Tom Herbert <tom@...bertland.com>
To: Alexander Duyck <aduyck@...antis.com>
Cc: intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [next PATCH 1/4] ixgbe: Add support for generic Tx checksums
On Mon, Jan 11, 2016 at 9:53 AM, Alexander Duyck <aduyck@...antis.com> wrote:
> This patch adds support for generic Tx checksums to the ixgbe driver. It
> turns out this is actually pretty easy after going over the datasheet as we
> were doing a number of steps we didn't need to.
>
> In order to perform a Tx checksum for an L4 header we need to fill in the
> following fields in the Tx descriptor:
> MACLEN (maximum of 127), retrieved from:
> skb_network_offset()
> IPLEN (maximum of 511), retrieved from:
> skb_checksum_start_offset() - skb_network_offset()
> TUCMD.L4T indicates offset and if checksum or crc32c, based on:
> skb->csum_offset
>
> The added advantage to doing this is that we can support inner checksum
> offloads for tunnels and MPLS while still being able to transparently insert
> VLAN tags.
>
> I also took the opportunity to clean-up many of the feature flag
> configuration bits to make them a bit more consistent between drivers.
>
> Signed-off-by: Alexander Duyck <aduyck@...antis.com>
> ---
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 163 +++++++++----------------
> 1 file changed, 59 insertions(+), 104 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index 77cdaed6de90..1e3a548cc612 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -7207,103 +7207,61 @@ static int ixgbe_tso(struct ixgbe_ring *tx_ring,
> return 1;
> }
>
> +static inline bool ixgbe_ipv6_csum_is_sctp(struct sk_buff *skb)
> +{
> + unsigned int offset = 0;
> +
> + ipv6_find_hdr(skb, &offset, IPPROTO_SCTP, NULL, NULL);
> +
> + return offset == skb_checksum_start_offset(skb);
> +}
> +
> static void ixgbe_tx_csum(struct ixgbe_ring *tx_ring,
> struct ixgbe_tx_buffer *first)
> {
> struct sk_buff *skb = first->skb;
> u32 vlan_macip_lens = 0;
> - u32 mss_l4len_idx = 0;
> u32 type_tucmd = 0;
>
> if (skb->ip_summed != CHECKSUM_PARTIAL) {
> - if (!(first->tx_flags & IXGBE_TX_FLAGS_HW_VLAN) &&
> - !(first->tx_flags & IXGBE_TX_FLAGS_CC))
> +csum_failed:
> + if (!(first->tx_flags & (IXGBE_TX_FLAGS_HW_VLAN |
> + IXGBE_TX_FLAGS_CC)))
> return;
> - vlan_macip_lens = skb_network_offset(skb) <<
> - IXGBE_ADVTXD_MACLEN_SHIFT;
> - } else {
> - u8 l4_hdr = 0;
> - union {
> - struct iphdr *ipv4;
> - struct ipv6hdr *ipv6;
> - u8 *raw;
> - } network_hdr;
> - union {
> - struct tcphdr *tcphdr;
> - u8 *raw;
> - } transport_hdr;
> - __be16 frag_off;
> -
> - if (skb->encapsulation) {
> - network_hdr.raw = skb_inner_network_header(skb);
> - transport_hdr.raw = skb_inner_transport_header(skb);
> - vlan_macip_lens = skb_inner_network_offset(skb) <<
> - IXGBE_ADVTXD_MACLEN_SHIFT;
> - } else {
> - network_hdr.raw = skb_network_header(skb);
> - transport_hdr.raw = skb_transport_header(skb);
> - vlan_macip_lens = skb_network_offset(skb) <<
> - IXGBE_ADVTXD_MACLEN_SHIFT;
> - }
> -
> - /* use first 4 bits to determine IP version */
> - switch (network_hdr.ipv4->version) {
> - case IPVERSION:
> - vlan_macip_lens |= transport_hdr.raw - network_hdr.raw;
> - type_tucmd |= IXGBE_ADVTXD_TUCMD_IPV4;
> - l4_hdr = network_hdr.ipv4->protocol;
> - break;
> - case 6:
> - vlan_macip_lens |= transport_hdr.raw - network_hdr.raw;
> - l4_hdr = network_hdr.ipv6->nexthdr;
> - if (likely((transport_hdr.raw - network_hdr.raw) ==
> - sizeof(struct ipv6hdr)))
> - break;
> - ipv6_skip_exthdr(skb, network_hdr.raw - skb->data +
> - sizeof(struct ipv6hdr),
> - &l4_hdr, &frag_off);
> - if (unlikely(frag_off))
> - l4_hdr = NEXTHDR_FRAGMENT;
> - break;
> - default:
> - break;
> - }
> + goto no_csum;
> + }
>
> - switch (l4_hdr) {
> - case IPPROTO_TCP:
> - type_tucmd |= IXGBE_ADVTXD_TUCMD_L4T_TCP;
> - mss_l4len_idx = (transport_hdr.tcphdr->doff * 4) <<
> - IXGBE_ADVTXD_L4LEN_SHIFT;
> - break;
> - case IPPROTO_SCTP:
> - type_tucmd |= IXGBE_ADVTXD_TUCMD_L4T_SCTP;
> - mss_l4len_idx = sizeof(struct sctphdr) <<
> - IXGBE_ADVTXD_L4LEN_SHIFT;
> - break;
> - case IPPROTO_UDP:
> - mss_l4len_idx = sizeof(struct udphdr) <<
> - IXGBE_ADVTXD_L4LEN_SHIFT;
> + switch (skb->csum_offset) {
> + case offsetof(struct tcphdr, check):
> + type_tucmd = IXGBE_ADVTXD_TUCMD_L4T_TCP;
> + /* fall through */
> + case offsetof(struct udphdr, check):
> + break;
> + case offsetof(struct sctphdr, checksum):
> + /* validate that this is actually an SCTP request */
> + if (((first->protocol == htons(ETH_P_IP)) &&
> + (ip_hdr(skb)->protocol == IPPROTO_SCTP)) ||
> + ((first->protocol == htons(ETH_P_IPV6)) &&
> + ixgbe_ipv6_csum_is_sctp(skb))) {
> + type_tucmd = IXGBE_ADVTXD_TUCMD_L4T_SCTP;
I think we're going to have to do something different for SCTP CRC
this (and FCOE CRC) is a special case of CHECKSUM_PARTIAL that I don't
think we're always accounting for. For instance, in LCO we are always
assuming that CHECKSUM_PARTIAL refers to an IP checksum. Maybe it's
time to add a bit to ip_summed so we can define CHEKCKSUM_SCTP_CRC and
CHECKSUM_FCOE_CRC?
> break;
> - default:
> - if (unlikely(net_ratelimit())) {
> - dev_warn(tx_ring->dev,
> - "partial checksum, version=%d, l4 proto=%x\n",
> - network_hdr.ipv4->version, l4_hdr);
> - }
> - skb_checksum_help(skb);
> - goto no_csum;
> }
> -
> - /* update TX checksum flag */
> - first->tx_flags |= IXGBE_TX_FLAGS_CSUM;
> + /* fall through */
> + default:
> + skb_checksum_help(skb);
> + goto csum_failed;
> }
>
> + /* update TX checksum flag */
> + first->tx_flags |= IXGBE_TX_FLAGS_CSUM;
> + vlan_macip_lens = skb_checksum_start_offset(skb) -
> + skb_network_offset(skb);
> no_csum:
> /* vlan_macip_lens: MACLEN, VLAN tag */
> + vlan_macip_lens |= skb_network_offset(skb) << IXGBE_ADVTXD_MACLEN_SHIFT;
> vlan_macip_lens |= first->tx_flags & IXGBE_TX_FLAGS_VLAN_MASK;
>
> - ixgbe_tx_ctxtdesc(tx_ring, vlan_macip_lens, 0,
> - type_tucmd, mss_l4len_idx);
> + ixgbe_tx_ctxtdesc(tx_ring, vlan_macip_lens, 0, type_tucmd, 0);
> }
>
> #define IXGBE_SET_FLAG(_input, _flag, _result) \
> @@ -9012,40 +8970,37 @@ skip_sriov:
>
> #endif
> netdev->features = NETIF_F_SG |
> - NETIF_F_IP_CSUM |
> - NETIF_F_IPV6_CSUM |
> - NETIF_F_HW_VLAN_CTAG_TX |
> - NETIF_F_HW_VLAN_CTAG_RX |
> NETIF_F_TSO |
> NETIF_F_TSO6 |
> NETIF_F_RXHASH |
> - NETIF_F_RXCSUM;
> -
> - netdev->hw_features = netdev->features | NETIF_F_HW_L2FW_DOFFLOAD;
> + NETIF_F_RXCSUM |
> + NETIF_F_HW_CSUM |
> + NETIF_F_SCTP_CRC |
> + NETIF_F_HW_VLAN_CTAG_TX |
> + NETIF_F_HW_VLAN_CTAG_RX;
>
> - switch (adapter->hw.mac.type) {
> - case ixgbe_mac_82599EB:
> - case ixgbe_mac_X540:
> - case ixgbe_mac_X550:
> - case ixgbe_mac_X550EM_x:
> + if (hw->mac.type >= ixgbe_mac_82599EB)
> netdev->features |= NETIF_F_SCTP_CRC;
> - netdev->hw_features |= NETIF_F_SCTP_CRC |
> - NETIF_F_NTUPLE;
> - break;
> - default:
> - break;
> - }
>
> - netdev->hw_features |= NETIF_F_RXALL;
> + /* copy netdev features into list of user selectable features */
> + netdev->hw_features |= netdev->features;
> + netdev->hw_features |= NETIF_F_RXALL |
> + NETIF_F_HW_L2FW_DOFFLOAD;
> +
> + if (hw->mac.type >= ixgbe_mac_82599EB)
> + netdev->hw_features |= NETIF_F_NTUPLE;
> +
> + /* set this bit last since it cannot be part of hw_features */
> netdev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;
>
> - netdev->vlan_features |= NETIF_F_TSO;
> - netdev->vlan_features |= NETIF_F_TSO6;
> - netdev->vlan_features |= NETIF_F_IP_CSUM;
> - netdev->vlan_features |= NETIF_F_IPV6_CSUM;
> - netdev->vlan_features |= NETIF_F_SG;
> + netdev->vlan_features |= NETIF_F_SG |
> + NETIF_F_TSO |
> + NETIF_F_TSO6 |
> + NETIF_F_HW_CSUM |
> + NETIF_F_SCTP_CRC;
>
> - netdev->hw_enc_features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
> + netdev->mpls_features |= NETIF_F_HW_CSUM;
> + netdev->hw_enc_features |= NETIF_F_HW_CSUM;
>
> netdev->priv_flags |= IFF_UNICAST_FLT;
> netdev->priv_flags |= IFF_SUPP_NOFCS;
>
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