Re: [PATCH v3 1/2] hw/net: Added plen fix for IPv6

[Jason Wang <jasowang@redhat.com>]

On 2020/7/16 上午11:53, andrew@daynix.com wrote:
> From: Andrew <andrew@daynix.com>
>
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1708065
> With network backend with 'virtual header' - there was an issue
> in 'plen' field. Overall, during TSO, 'plen' would be changed,
> but with 'vheader' this field should be set to the size of the
> payload itself instead of '0'.
>
> Signed-off-by: Andrew Melnychenko <andrew@daynix.com>


Applied.

Thanks


> ---
>   hw/net/net_tx_pkt.c | 23 +++++++++++++++++++++++
>   hw/net/net_tx_pkt.h | 14 ++++++++++++++
>   include/net/eth.h   |  1 +
>   3 files changed, 38 insertions(+)
>
> diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
> index 331c73cfc0..9560e4a49e 100644
> --- a/hw/net/net_tx_pkt.c
> +++ b/hw/net/net_tx_pkt.c
> @@ -626,6 +626,7 @@ bool net_tx_pkt_send(struct NetTxPkt *pkt, NetClientState *nc)
>   
>       if (pkt->has_virt_hdr ||
>           pkt->virt_hdr.gso_type == VIRTIO_NET_HDR_GSO_NONE) {
> +        net_tx_pkt_fix_ip6_payload_len(pkt);
>           net_tx_pkt_sendv(pkt, nc, pkt->vec,
>               pkt->payload_frags + NET_TX_PKT_PL_START_FRAG);
>           return true;
> @@ -644,3 +645,25 @@ bool net_tx_pkt_send_loopback(struct NetTxPkt *pkt, NetClientState *nc)
>   
>       return res;
>   }
> +
> +void net_tx_pkt_fix_ip6_payload_len(struct NetTxPkt *pkt)
> +{
> +    struct iovec *l2 = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
> +    if (eth_get_l3_proto(l2, 1, l2->iov_len) == ETH_P_IPV6) {
> +        struct ip6_header *ip6 = (struct ip6_header *) pkt->l3_hdr;
> +        /*
> +         * TODO: if qemu would support >64K packets - add jumbo option check
> +         * something like that:
> +         * 'if (ip6->ip6_plen == 0 && !has_jumbo_option(ip6)) {'
> +         */
> +        if (ip6->ip6_plen == 0) {
> +            if (pkt->payload_len <= ETH_MAX_IP_DGRAM_LEN) {
> +                ip6->ip6_plen = htons(pkt->payload_len);
> +            }
> +            /*
> +             * TODO: if qemu would support >64K packets
> +             * add jumbo option for packets greater then 65,535 bytes
> +             */
> +        }
> +    }
> +}
> diff --git a/hw/net/net_tx_pkt.h b/hw/net/net_tx_pkt.h
> index 212ecc62fc..4ec8bbe9bd 100644
> --- a/hw/net/net_tx_pkt.h
> +++ b/hw/net/net_tx_pkt.h
> @@ -187,4 +187,18 @@ bool net_tx_pkt_parse(struct NetTxPkt *pkt);
>   */
>   bool net_tx_pkt_has_fragments(struct NetTxPkt *pkt);
>   
> +/**
> + * Fix IPv6 'plen' field.
> + * If ipv6 payload length field is 0 - then there should be Hop-by-Hop
> + * option for packets greater than 65,535.
> + * For packets with a payload less than 65,535: fix 'plen' field.
> + * For backends with vheader, we need just one packet with proper
> + * payload size. For now, qemu drops every packet with size greater 64K
> + * (see net_tx_pkt_send()) so, there is no reason to add jumbo option to ip6
> + * hop-by-hop extension if it's missed
> + *
> + * @pkt            packet
> + */
> +void net_tx_pkt_fix_ip6_payload_len(struct NetTxPkt *pkt);
> +
>   #endif
> diff --git a/include/net/eth.h b/include/net/eth.h
> index 7f45c678e7..0671be6916 100644
> --- a/include/net/eth.h
> +++ b/include/net/eth.h
> @@ -186,6 +186,7 @@ struct tcp_hdr {
>   
>   #define ip6_nxt      ip6_ctlun.ip6_un1.ip6_un1_nxt
>   #define ip6_ecn_acc  ip6_ctlun.ip6_un3.ip6_un3_ecn
> +#define ip6_plen     ip6_ctlun.ip6_un1.ip6_un1_plen
>   
>   #define PKT_GET_ETH_HDR(p)        \
>       ((struct eth_header *)(p))