Re: [PATCH v2] net/virtio: deduce IP length for Virtio TSO checksum

[Maxime Coquelin]

On 3/6/23 07:17, Xia, Chenbo wrote:

Hi Boleslav,

The change seems good, but patchwork is complaining about lack of .mailmap 
change.

http://mails.dpdk.org/archives/test-report/2023-March/363061.html

Guess this is your first patch? So you need to add name and email in mailmap 
file.

Thanks for the heads-up, I will update the mailmap when applying.
No need to submit a new revision.

Thanks,
Maxime

Thanks,
Chenbo

-----Original Message-----
From: Andrew Rybchenko <andrew.rybche...@oktetlabs.ru>
Sent: Friday, March 3, 2023 11:14 PM
To: Boleslav Stankevich <boleslav.stankev...@oktetlabs.ru>; dev@dpdk.org
Cc: sta...@dpdk.org; Maxime Coquelin <maxime.coque...@redhat.com>; Xia,
Chenbo <chenbo....@intel.com>
Subject: Re: [PATCH v2] net/virtio: deduce IP length for Virtio TSO
checksum

Cc Maxime and Chenbo

On 3/3/23 14:19, 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: sta...@dpdk.org

Signed-off-by: Boleslav Stankevich <boleslav.stankev...@oktetlabs.ru>
Reviewed-by: Andrew Rybchenko <andrew.rybche...@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;