[dpdk-dev] [PATCH 2/2] vhost: fix IP csum not calculated

[Maxime Coquelin]

On 06/07/2017 08:41 AM, Jianfeng Tan wrote:
> There is no way to bypass IP checksum verification in Linux
> kernel, no matter skb->ip_summed is assigned as CHECKSUM_UNNECESSARY
> or CHECKSUM_PARTIAL.
> 
> So any packets with bad IP checksum will be dropped at VM IP layer.
> 
> To correct, we check this flag PKT_TX_IP_CKSUM to calculate IP csum.
> 
> Fixes: 859b480d5afd ("vhost: add guest offload setting")
> Cc: stable at dpdk.org
> 
> Cc: Yuanhan Liu <yuanhan.liu at linux.intel.com>
> Cc: Maxime Coquelin <maxime.coquelin at redhat.com>
> Cc: Jiayu Hu <jiayu.hu at intel.com>
> Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com>
> ---
>   lib/librte_vhost/virtio_net.c | 9 +++++++++
>   1 file changed, 9 insertions(+)


Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>

Thanks,
Maxime

> 
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 0a7e023..cf7c5ac 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -143,6 +143,15 @@ virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
>   		ASSIGN_UNLESS_EQUAL(net_hdr->flags, 0);
>   	}
>   
> +	/* IP cksum verification cannot be bypassed, then calculate here */
> +	if (m_buf->ol_flags & PKT_TX_IP_CKSUM) {
> +		struct ipv4_hdr *ipv4_hdr;
> +
> +		ipv4_hdr = rte_pktmbuf_mtod_offset(m_buf, struct ipv4_hdr *,
> +						   m_buf->l2_len);
> +		ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
> +	}
> +
>   	if (m_buf->ol_flags & PKT_TX_TCP_SEG) {
>   		if (m_buf->ol_flags & PKT_TX_IPV4)
>   			net_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
>