Hi Maxime,
> -----Original Message-----
> From: Maxime Coquelin <maxime.coque...@redhat.com>
> Sent: Wednesday, June 8, 2022 8:50 PM
> To: dev@dpdk.org; jasow...@redhat.com; Xia, Chenbo <chenbo....@intel.com>;
> david.march...@redhat.com; Matz, Olivier <olivier.m...@6wind.com>; Ma,
> WenwuX <wenwux...@intel.com>; Zhang, Yuying <yuying.zh...@intel.com>;
> Singh, Aman Deep <aman.deep.si...@intel.com>
> Cc: Maxime Coquelin <maxime.coque...@redhat.com>
> Subject: [PATCH v2 6/6] net/vhost: perform SW checksum in Tx path
>
> Virtio specification supports guest checksum offloading
> for L4, which is enabled with VIRTIO_NET_F_GUEST_CSUM
> feature negotiation. However, the Vhost PMD does not
> advertise Tx checksum offload capabilities.
>
> Advertising these offload capabilities at the ethdev level
> is not enough, because we could still end-up with the
> application enabling these offloads while the guest not
> negotiating it.
>
> This patch advertises the Tx checksum offload capabilities,
> and introduces a compatibility layer to cover the case
> VIRTIO_NET_F_GUEST_CSUM has not been negotiated but the
> application does configure the Tx checksum offloads. This
> function performs the L4 Tx checksum in SW for UDP and TCP.
> Compared to Rx SW checksum, the Tx SW checksum function
> needs to compute the pseudo-header checksum, as we cannot
> know whether it was done before.
>
> This patch does not advertise SCTP checksum offloading
> capability for now, but it could be handled later if the
> need arises.
>
> Reported-by: Jason Wang <jasow...@redhat.com>
> Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
> ---
> drivers/net/vhost/rte_eth_vhost.c | 62 +++++++++++++++++++++++++++++++
> 1 file changed, 62 insertions(+)
>
> diff --git a/drivers/net/vhost/rte_eth_vhost.c
> b/drivers/net/vhost/rte_eth_vhost.c
> index 42f0d52ebc..d75d256040 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -92,6 +92,7 @@ struct pmd_internal {
> rte_atomic32_t started;
> bool vlan_strip;
> bool rx_sw_csum;
> + bool tx_sw_csum;
> };
>
> struct internal_list {
> @@ -283,8 +284,10 @@ vhost_dev_csum_configure(struct rte_eth_dev *eth_dev)
> {
> struct pmd_internal *internal = eth_dev->data->dev_private;
> const struct rte_eth_rxmode *rxmode = ð_dev->data-
> >dev_conf.rxmode;
> + const struct rte_eth_txmode *txmode = ð_dev->data-
> >dev_conf.txmode;
>
> internal->rx_sw_csum = false;
> + internal->tx_sw_csum = false;
>
> /* SW checksum is not compatible with legacy mode */
> if (!(internal->flags & RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS))
> @@ -297,6 +300,56 @@ vhost_dev_csum_configure(struct rte_eth_dev *eth_dev)
> internal->rx_sw_csum = true;
> }
> }
> +
> + if (!(internal->features & (1ULL << VIRTIO_NET_F_GUEST_CSUM))) {
> + if (txmode->offloads &
> + (RTE_ETH_TX_OFFLOAD_UDP_CKSUM |
> RTE_ETH_TX_OFFLOAD_TCP_CKSUM)) {
> + VHOST_LOG(NOTICE, "Tx csum will be done in SW, may
> impact performance.");
Missing \n
With above fixed:
Reviewed-by: Chenbo Xia <chenbo....@intel.com>
> + internal->tx_sw_csum = true;
> + }
> + }
> +}
> +
> +static void
> +vhost_dev_tx_sw_csum(struct rte_mbuf *mbuf)
> +{
> + uint32_t hdr_len;
> + uint16_t csum = 0, csum_offset;
> +
> + switch (mbuf->ol_flags & RTE_MBUF_F_TX_L4_MASK) {
> + case RTE_MBUF_F_TX_L4_NO_CKSUM:
> + return;
> + case RTE_MBUF_F_TX_TCP_CKSUM:
> + csum_offset = offsetof(struct rte_tcp_hdr, cksum);
> + break;
> + case RTE_MBUF_F_TX_UDP_CKSUM:
> + csum_offset = offsetof(struct rte_udp_hdr, dgram_cksum);
> + break;
> + default:
> + /* Unsupported packet type. */
> + return;
> + }
> +
> + hdr_len = mbuf->l2_len + mbuf->l3_len;
> + csum_offset += hdr_len;
> +
> + /* Prepare the pseudo-header checksum */
> + if (rte_net_intel_cksum_prepare(mbuf) < 0)
> + return;
> +
> + if (rte_raw_cksum_mbuf(mbuf, hdr_len, rte_pktmbuf_pkt_len(mbuf) -
> hdr_len, &csum) < 0)
> + return;
> +
> + csum = ~csum;
> + /* See RFC768 */
> + if (unlikely((mbuf->packet_type & RTE_PTYPE_L4_UDP) && csum == 0))
> + csum = 0xffff;
> +
> + if (rte_pktmbuf_data_len(mbuf) >= csum_offset + 1)
> + *rte_pktmbuf_mtod_offset(mbuf, uint16_t *, csum_offset) = csum;
> +
> + mbuf->ol_flags &= ~RTE_MBUF_F_TX_L4_MASK;
> + mbuf->ol_flags |= RTE_MBUF_F_TX_L4_NO_CKSUM;
> }
>
> static void
> @@ -423,6 +476,10 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs,
> uint16_t nb_bufs)
> }
> }
>
> + if (r->internal->tx_sw_csum)
> + vhost_dev_tx_sw_csum(m);
> +
> +
> bufs[nb_send] = m;
> ++nb_send;
> }
> @@ -1267,6 +1324,11 @@ eth_dev_info(struct rte_eth_dev *dev,
>
> dev_info->tx_offload_capa = RTE_ETH_TX_OFFLOAD_MULTI_SEGS |
> RTE_ETH_TX_OFFLOAD_VLAN_INSERT;
> + if (internal->flags & RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS) {
> + dev_info->tx_offload_capa |= RTE_ETH_TX_OFFLOAD_UDP_CKSUM |
> + RTE_ETH_TX_OFFLOAD_TCP_CKSUM;
> + }
> +
> dev_info->rx_offload_capa = RTE_ETH_RX_OFFLOAD_VLAN_STRIP;
> if (internal->flags & RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS) {
> dev_info->rx_offload_capa |= RTE_ETH_RX_OFFLOAD_UDP_CKSUM |
> --
> 2.35.3
