Hi Wenwu,
Sorry, I missed your review.
On 5/7/22 05:20, Ma, WenwuX wrote:
-----Original Message-----
From: Maxime Coquelin <maxime.coque...@redhat.com>
Sent: 2022年5月5日 18:27
To: dev@dpdk.org; jasow...@redhat.com; Xia, Chenbo
<chenbo....@intel.com>; david.march...@redhat.com;
olivier.m...@6wind.com
Cc: sta...@dpdk.org; Maxime Coquelin <maxime.coque...@redhat.com>
Subject: [PATCH 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 advertizes 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 knwo whether it was
done before.
This patch does not advertize SCTP checksum offloading capability for now,
but it could be handled later if the need arises.
In virtio_enqueue_offload(), if RTE_MBUF_F_TX_IP_CKSUM is set, we will
performs the L3 Tx checksum, why do not we advertise IPV4 checksum offloading
capability?
Will we advertise it later?
Indeed, we have an IPv4 SW checksum fallback in Vhost library.
We could think about adding the capability, but that's not urgent I
think. Do you have a use-case where it is needed?
Regards,
Maxime
