Hi
> -----Original Message-----
> From: David Marchand <david.march...@redhat.com>
> Sent: Friday, October 15, 2021 16:10
> To: Li, Xiaoyun <xiaoyun...@intel.com>
> Cc: Yigit, Ferruh <ferruh.yi...@intel.com>; dev <dev@dpdk.org>; dpdk stable
> <sta...@dpdk.org>
> Subject: Re: [dpdk-dev] [PATCH] app/testpmd: fix l4 sw csum over multi
> segments
>
> Hello,
>
> On Fri, Oct 15, 2021 at 7:27 AM Xiaoyun Li <xiaoyun...@intel.com> wrote:
> >
> > In csum forwarding mode, software UDP/TCP csum calculation only takes
> > the first segment into account while using the whole packet length so
> > the calculation will read invalid memory region with multi-segments
> > packets and will get wrong value.
> > This patch fixes this issue.
> >
> > Fixes: af75078fece3 ("first public release")
> > Cc: sta...@dpdk.org
> >
> > Signed-off-by: Xiaoyun Li <xiaoyun...@intel.com>
> > ---
> > app/test-pmd/csumonly.c | 31 +++++++++++++++++++++++--------
> > 1 file changed, 23 insertions(+), 8 deletions(-)
> >
> > diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c index
> > 090797318a..5df3be0a6f 100644
> > --- a/app/test-pmd/csumonly.c
> > +++ b/app/test-pmd/csumonly.c
> > @@ -18,7 +18,7 @@
> > #include <rte_log.h>
> > #include <rte_debug.h>
> > #include <rte_cycles.h>
> > -#include <rte_memory.h>
> > +#include <rte_malloc.h>
>
> This include caught my eye.
>
>
> > #include <rte_memcpy.h>
> > #include <rte_launch.h>
> > #include <rte_eal.h>
> > @@ -56,6 +56,11 @@
> > #define GRE_SUPPORTED_FIELDS (GRE_CHECKSUM_PRESENT |
> GRE_KEY_PRESENT |\
> > GRE_SEQUENCE_PRESENT)
> >
> > +/* When UDP or TCP or outer UDP csum offload is off, sw l4 csum is needed
> */
> > +#define UDP_TCP_CSUM (DEV_TX_OFFLOAD_UDP_CKSUM |\
> > + DEV_TX_OFFLOAD_TCP_CKSUM |\
> > + DEV_TX_OFFLOAD_OUTER_UDP_CKSUM)
> > +
> > /* We cannot use rte_cpu_to_be_16() on a constant in a switch/case */
> > #if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN #define _htons(x)
> > ((uint16_t)((((x) & 0x00ffU) << 8) | (((x) & 0xff00U) >> 8))) @@
> > -602,12 +607,8 @@ process_outer_cksums(void *outer_l3_hdr, struct
> testpmd_offload_info *info,
> > /* do not recalculate udp cksum if it was 0 */
> > if (udp_hdr->dgram_cksum != 0) {
> > udp_hdr->dgram_cksum = 0;
> > - if (info->outer_ethertype == _htons(RTE_ETHER_TYPE_IPV4))
> > - udp_hdr->dgram_cksum =
> > - rte_ipv4_udptcp_cksum(ipv4_hdr, udp_hdr);
> > - else
> > - udp_hdr->dgram_cksum =
> > - rte_ipv6_udptcp_cksum(ipv6_hdr, udp_hdr);
> > + udp_hdr->dgram_cksum = get_udptcp_checksum(outer_l3_hdr,
> > + udp_hdr,
> > + info->outer_ethertype);
> > }
> >
> > return ol_flags;
> > @@ -802,6 +803,7 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
> > struct rte_mbuf *m, *p;
> > struct rte_ether_hdr *eth_hdr;
> > void *l3_hdr = NULL, *outer_l3_hdr = NULL; /* can be IPv4 or
> > IPv6 */
> > + uint8_t *l3_buf = NULL;
> > void **gro_ctx;
> > uint16_t gro_pkts_num;
> > uint8_t gro_enable;
> > @@ -877,7 +879,19 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
> > rte_ether_addr_copy(&ports[fs->tx_port].eth_addr,
> > ð_hdr->src_addr);
> > parse_ethernet(eth_hdr, &info);
> > - l3_hdr = (char *)eth_hdr + info.l2_len;
> > + /* When sw csum is needed, multi-segs needs a buf to contain
> > + * the whole packet for later UDP/TCP csum calculation.
> > + */
> > + if (m->nb_segs > 1 && !(tx_ol_flags & PKT_TX_TCP_SEG) &&
> > + !(tx_offloads & UDP_TCP_CSUM)) {
> > + l3_buf = rte_zmalloc("csum l3_buf",
> > + info.pkt_len - info.l2_len,
> > + RTE_CACHE_LINE_SIZE);
>
> Rather than call a dyn allocation in datapath, can't we have a static buffer
> on
> the stack?
I wanted to do that. But the issue only happens when it's a large packet. Each
hw has its own limitation on max packet size but it grows fast.
I'm not sure how large array should I use. 64K? Since total length in IP hdr is
16 bit.
BRs
Xiaoyun
>
>
> > + rte_pktmbuf_read(m, info.l2_len,
> > + info.pkt_len - info.l2_len,
> > l3_buf);
> > + l3_hdr = l3_buf;
> > + } else
> > + l3_hdr = (char *)eth_hdr + info.l2_len;
> >
> > /* check if it's a supported tunnel */
> > if (txp->parse_tunnel) { @@ -1051,6 +1065,7 @@
> > pkt_burst_checksum_forward(struct fwd_stream *fs)
> > printf("tx: flags=%s", buf);
> > printf("\n");
> > }
> > + rte_free(l3_buf);
> > }
> >
> > if (unlikely(gro_enable)) {
> > --
> > 2.25.1
> >
>
>
> --
> David Marchand
