Re: [PATCH 3/3] net: checksum: Introduce fine control over checksum type

[Bin Meng]

Hi Philippe,

On Sun, Dec 6, 2020 at 7:50 PM Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
>
> Hi Ben,
>
> On 12/6/20 3:14 AM, Bin Meng wrote:
> > From: Bin Meng <bin.meng@windriver.com>
> >
> > At present net_checksum_calculate() blindly calculates all types of
> > checksums (IP, TCP, UDP). Some NICs may have a per type setting in
> > their BDs to control what checksum should be offloaded. To support
> > such hardware behavior, introduce a 'csum_flag' parameter to the
> > net_checksum_calculate() API to allow fine control over what type
> > checksum is calculated.
> >
> > Existing users of this API are updated accordingly.
> >
> > Signed-off-by: Bin Meng <bin.meng@windriver.com>
> >
> > ---
> >
> >  hw/net/allwinner-sun8i-emac.c |  2 +-
> >  hw/net/cadence_gem.c          |  2 +-
> >  hw/net/fsl_etsec/rings.c      |  8 +++-----
> >  hw/net/ftgmac100.c            | 10 +++++++++-
> >  hw/net/imx_fec.c              | 15 +++------------
> >  hw/net/virtio-net.c           |  2 +-
> >  hw/net/xen_nic.c              |  2 +-
> >  include/net/checksum.h        |  7 ++++++-
>
> When sending a such API refactor, patch is easier to
> review if you setup the scripts/git.orderfile config.

Sure. I thought I have done this before but apparently not on the
machine this series was genearated :)

>
> >  net/checksum.c                | 18 ++++++++++++++----
> >  net/filter-rewriter.c         |  4 ++--
> >  10 files changed, 41 insertions(+), 29 deletions(-)
> ...
> > diff --git a/include/net/checksum.h b/include/net/checksum.h
> > index 05a0d27..7dec37e 100644
> > --- a/include/net/checksum.h
> > +++ b/include/net/checksum.h
> > @@ -21,11 +21,16 @@
> >  #include "qemu/bswap.h"
> >  struct iovec;
> >
> > +#define CSUM_IP     0x01
>
> IMO this is IP_HEADER,

Yes, but I believe no one will misread it, no?

>
> > +#define CSUM_TCP    0x02
> > +#define CSUM_UDP    0x04
>
> and these IP_PAYLOAD, regardless the payload protocol.

We have to distinguish TCP and UDP.

>
> > +#define CSUM_ALL    (CSUM_IP | CSUM_TCP | CSUM_UDP)
>
> Maybe CSUM_HEADER / CSUM_PAYLOAD / CSUM_FULL (aka RAW?).
>
> > +
> >  uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq);
> >  uint16_t net_checksum_finish(uint32_t sum);
> >  uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
> >                               uint8_t *addrs, uint8_t *buf);
> > -void net_checksum_calculate(uint8_t *data, int length);
> > +void net_checksum_calculate(uint8_t *data, int length, int csum_flag);
> >
> >  static inline uint32_t
> >  net_checksum_add(int len, uint8_t *buf)
> > diff --git a/net/checksum.c b/net/checksum.c
> > index dabd290..70f4eae 100644
> > --- a/net/checksum.c
> > +++ b/net/checksum.c
> > @@ -57,7 +57,7 @@ uint16_t net_checksum_tcpudp(uint16_t length, uint16_t 
> > proto,
> >      return net_checksum_finish(sum);
> >  }
> >
> > -void net_checksum_calculate(uint8_t *data, int length)
> > +void net_checksum_calculate(uint8_t *data, int length, int csum_flag)
> >  {
> >      int mac_hdr_len, ip_len;
> >      struct ip_header *ip;
> > @@ -108,9 +108,11 @@ void net_checksum_calculate(uint8_t *data, int length)
> >      }
> >
> >      /* Calculate IP checksum */
> > -    stw_he_p(&ip->ip_sum, 0);
> > -    csum = net_raw_checksum((uint8_t *)ip, IP_HDR_GET_LEN(ip));
> > -    stw_be_p(&ip->ip_sum, csum);
> > +    if (csum_flag & CSUM_IP) {
> > +        stw_he_p(&ip->ip_sum, 0);
> > +        csum = net_raw_checksum((uint8_t *)ip, IP_HDR_GET_LEN(ip));
> > +        stw_be_p(&ip->ip_sum, csum);
> > +    }
> >
> >      if (IP4_IS_FRAGMENT(ip)) {
> >          return; /* a fragmented IP packet */
> > @@ -128,6 +130,10 @@ void net_checksum_calculate(uint8_t *data, int length)
> >      switch (ip->ip_p) {
> >      case IP_PROTO_TCP:
> >      {
> > +        if (!(csum_flag & CSUM_TCP)) {
> > +            return;
> > +        }
> > +
> >          tcp_header *tcp = (tcp_header *)(ip + 1);
> >
> >          if (ip_len < sizeof(tcp_header)) {
> > @@ -148,6 +154,10 @@ void net_checksum_calculate(uint8_t *data, int length)
> >      }
> >      case IP_PROTO_UDP:
> >      {
> > +        if (!(csum_flag & CSUM_UDP)) {
> > +            return;
> > +        }
> > +
> >          udp_header *udp = (udp_header *)(ip + 1);
> >
> >          if (ip_len < sizeof(udp_header)) {
> ...

Regards,
Bin