[PATCH v2] net/virtio: deduce IP length for Virtio TSO checksum
Maxime Coquelin
maxime.coquelin at redhat.com
Mon Mar 6 15:13:18 CET 2023
On 3/3/23 12:19, Boleslav Stankevich wrote:
> The length of TSO payload could not fit into 16 bits provided by the
> IPv4 total length and IPv6 payload length fields. Thus, deduce it
> from the length of the packet.
>
> Fixes: 696573046e9 ("net/virtio: support TSO")
> Cc: stable at dpdk.org
>
> Signed-off-by: Boleslav Stankevich <boleslav.stankevich at oktetlabs.ru>
> Reviewed-by: Andrew Rybchenko <andrew.rybchenko at oktetlabs.ru>
> ---
> drivers/net/virtio/virtio_rxtx.c | 25 ++++++++++++++++---------
> 1 file changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> index 2d0afd3302..e48ff3cca7 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -404,29 +404,36 @@ virtio_tso_fix_cksum(struct rte_mbuf *m)
> if (likely(rte_pktmbuf_data_len(m) >= m->l2_len + m->l3_len +
> m->l4_len)) {
> struct rte_ipv4_hdr *iph;
> - struct rte_ipv6_hdr *ip6h;
> struct rte_tcp_hdr *th;
> - uint16_t prev_cksum, new_cksum, ip_len, ip_paylen;
> + uint16_t prev_cksum, new_cksum;
> + uint32_t ip_paylen;
> uint32_t tmp;
>
> iph = rte_pktmbuf_mtod_offset(m,
> struct rte_ipv4_hdr *, m->l2_len);
> th = RTE_PTR_ADD(iph, m->l3_len);
> +
> + /*
> + * Calculate IPv4 header checksum with current total length value
> + * (whatever it is) to have correct checksum after update on edits
> + * done by TSO.
> + */
> if ((iph->version_ihl >> 4) == 4) {
> iph->hdr_checksum = 0;
> iph->hdr_checksum = rte_ipv4_cksum(iph);
> - ip_len = iph->total_length;
> - ip_paylen = rte_cpu_to_be_16(rte_be_to_cpu_16(ip_len) -
> - m->l3_len);
> - } else {
> - ip6h = (struct rte_ipv6_hdr *)iph;
> - ip_paylen = ip6h->payload_len;
> }
>
> + /*
> + * Do not use IPv4 total length and IPv6 payload length fields to get
> + * TSO payload length since it could not fit into 16 bits.
> + */
> + ip_paylen = rte_cpu_to_be_32(rte_pktmbuf_pkt_len(m) - m->l2_len -
> + m->l3_len);
> +
> /* calculate the new phdr checksum not including ip_paylen */
> prev_cksum = th->cksum;
> tmp = prev_cksum;
> - tmp += ip_paylen;
> + tmp += (ip_paylen & 0xffff) + (ip_paylen >> 16);
> tmp = (tmp & 0xffff) + (tmp >> 16);
> new_cksum = tmp;
>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
Thanks,
Maxime
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