On Fri, Jul 07, 2023 at 12:30:01PM -0700, Stanislav Fomichev wrote:
> +
> +static int mlx5e_devtx_request_l4_checksum(const struct devtx_ctx *_ctx,
> + u16 csum_start, u16 csum_offset)
> +{
> + const struct mlx5e_devtx_ctx *ctx = (void *)_ctx;
> + struct mlx5_wqe_eth_seg *eseg;
> +
> + if (unlikely(!ctx->wqe))
> + return -ENODATA;
> +
> + eseg = &ctx->wqe->eth;
> +
> + switch (csum_offset) {
> + case sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct udphdr, check):
> + case sizeof(struct ethhdr) + sizeof(struct ipv6hdr) + offsetof(struct udphdr, check):
> + /* Looks like HW/FW is doing parsing, so offsets are largely ignored. */
> + eseg->cs_flags = MLX5_ETH_WQE_L3_CSUM | MLX5_ETH_WQE_L4_CSUM;
> + break;
> + default:
> + return -EINVAL;
> + }
I think this proves my point: csum is not generalizable even across veth and mlx5.
Above is a square peg that tries to fit csum_start/offset api (that makes sense from SW pov)
into HW that has different ideas about csum-ing.
Here is what mlx5 does:
mlx5e_txwqe_build_eseg_csum(struct mlx5e_txqsq *sq, struct sk_buff *skb,
struct mlx5e_accel_tx_state *accel,
struct mlx5_wqe_eth_seg *eseg)
{
if (unlikely(mlx5e_ipsec_txwqe_build_eseg_csum(sq, skb, eseg)))
return;
if (likely(skb->ip_summed == CHECKSUM_PARTIAL)) {
eseg->cs_flags = MLX5_ETH_WQE_L3_CSUM;
if (skb->encapsulation) {
eseg->cs_flags |= MLX5_ETH_WQE_L3_INNER_CSUM |
MLX5_ETH_WQE_L4_INNER_CSUM;
sq->stats->csum_partial_inner++;
} else {
eseg->cs_flags |= MLX5_ETH_WQE_L4_CSUM;
sq->stats->csum_partial++;
}
How would you generalize that into csum api that will work across NICs ?
My answer stands: you cannot.
My proposal again:
add driver specifc kfuncs and hooks for things like csum.
Kuba,
since you nacked driver specific stuff please suggest a way to unblock this stalemate.
