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

[Philippe Mathieu-Daudé]

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.

>  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,

> +#define CSUM_TCP    0x02
> +#define CSUM_UDP    0x04

and these IP_PAYLOAD, regardless the payload protocol.

> +#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)) {
...