From: Jonathan Matthew <jonathan@d14n.org>
Subject: Re: iavf patch [1/4]: Add support of TSO
To: Yuichiro NAITO <naito.yuichiro@gmail.com>
Cc: tech@openbsd.org
Date: Tue, 20 May 2025 19:45:14 +1000

On Fri, Feb 07, 2025 at 04:20:06PM +0900, Yuichiro NAITO wrote:
> After my previous mail, iavf check-sum offload patch has been committed.
> 
> https://marc.info/?l=openbsd-tech&m=173226223303941&w=2
> 
> I rebased proceeding patches for OpenBSD current.
> I will send the patches one by one, please apply by the order of mails.
> 
> This patch enables TSO feature. There is no difference from before.
> 
> OK?

Thanks, and apologies for the delay in looking at this.
I've committed your diff with some changes to update the TCP TSO
counters as we do in other drivers.

> 
> diff --git a/sys/dev/pci/if_iavf.c b/sys/dev/pci/if_iavf.c
> index 70309635646..4d40592e41a 100644
> --- a/sys/dev/pci/if_iavf.c
> +++ b/sys/dev/pci/if_iavf.c
> @@ -82,6 +82,8 @@
>  #include <dev/pci/pcivar.h>
>  #include <dev/pci/pcidevs.h>
>  
> +#define IAVF_MAX_DMA_SEG_SIZE		((16 * 1024) - 1)
> +
>  #define I40E_MASK(mask, shift)		((mask) << (shift))
>  #define I40E_AQ_LARGE_BUF		512
>  
> @@ -388,6 +390,10 @@ struct iavf_tx_desc {
>  #define IAVF_TX_DESC_BSIZE_MASK		\
>  	(IAVF_TX_DESC_BSIZE_MAX << IAVF_TX_DESC_BSIZE_SHIFT)
>  
> +#define IAVF_TX_CTX_DESC_CMD_TSO	0x10
> +#define IAVF_TX_CTX_DESC_TLEN_SHIFT	30
> +#define IAVF_TX_CTX_DESC_MSS_SHIFT	50
> +
>  #define IAVF_TX_DESC_L2TAG1_SHIFT	48
>  #define IAVF_TX_DESC_L2TAG1_MASK	(0xffff << IAVF_TX_DESC_L2TAG1_SHIFT)
>  } __packed __aligned(16);
> @@ -899,6 +905,7 @@ iavf_attach(struct device *parent, struct device *self, void *aux)
>  	ifp->if_capabilities |= IFCAP_CSUM_IPv4 |
>  	    IFCAP_CSUM_TCPv4 | IFCAP_CSUM_UDPv4 |
>  	    IFCAP_CSUM_TCPv6 | IFCAP_CSUM_UDPv6;
> +	ifp->if_capabilities |= IFCAP_TSOv4 | IFCAP_TSOv6;
>  
>  	ifmedia_init(&sc->sc_media, 0, iavf_media_change, iavf_media_status);
>  
> @@ -1565,7 +1572,7 @@ iavf_txr_alloc(struct iavf_softc *sc, unsigned int qid)
>  		txm = &maps[i];
>  
>  		if (bus_dmamap_create(sc->sc_dmat,
> -		    IAVF_HARDMTU, IAVF_TX_PKT_DESCS, IAVF_HARDMTU, 0,
> +		    MAXMCLBYTES, IAVF_TX_PKT_DESCS, IAVF_MAX_DMA_SEG_SIZE, 0,
>  		    BUS_DMA_WAITOK | BUS_DMA_ALLOCNOW | BUS_DMA_64BIT,
>  		    &txm->txm_map) != 0)
>  			goto uncreate;
> @@ -1661,7 +1668,7 @@ iavf_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m)
>  }
>  
>  static uint64_t
> -iavf_tx_offload(struct mbuf *m)
> +iavf_tx_offload(struct mbuf *m, struct iavf_tx_ring *txr, unsigned int prod)
>  {
>  	struct ether_extracted ext;
>  	uint64_t hlen;
> @@ -1676,7 +1683,7 @@ iavf_tx_offload(struct mbuf *m)
>  #endif
>  
>  	if (!ISSET(m->m_pkthdr.csum_flags,
> -	    M_IPV4_CSUM_OUT|M_TCP_CSUM_OUT|M_UDP_CSUM_OUT))
> +	    M_IPV4_CSUM_OUT|M_TCP_CSUM_OUT|M_UDP_CSUM_OUT|M_TCP_TSO))
>  		return (offload);
>  
>  	ether_extract_headers(m, &ext);
> @@ -1708,6 +1715,32 @@ iavf_tx_offload(struct mbuf *m)
>  		    << IAVF_TX_DESC_L4LEN_SHIFT;
>  	}
>  
> +	if (ISSET(m->m_pkthdr.csum_flags, M_TCP_TSO)) {
> +		if (ext.tcp && m->m_pkthdr.ph_mss > 0) {
> +			struct iavf_tx_desc *ring, *txd;
> +			uint64_t cmd = 0, paylen, outlen;
> +
> +			hlen += ext.tcphlen;
> +
> +			/*
> +			 * The MSS should not be set to a lower value than 64
> +			 * or larger than 9668 bytes.
> +			 */
> +			outlen = MIN(9668, MAX(64, m->m_pkthdr.ph_mss));
> +			paylen = m->m_pkthdr.len - ETHER_HDR_LEN - hlen;
> +			ring = IAVF_DMA_KVA(&txr->txr_mem);
> +			txd = &ring[prod];
> +
> +			cmd |= IAVF_TX_DESC_DTYPE_CONTEXT;
> +			cmd |= IAVF_TX_CTX_DESC_CMD_TSO;
> +			cmd |= paylen << IAVF_TX_CTX_DESC_TLEN_SHIFT;
> +			cmd |= outlen << IAVF_TX_CTX_DESC_MSS_SHIFT;
> +
> +			htolem64(&txd->addr, 0);
> +			htolem64(&txd->cmd, cmd);
> +		}
> +	}
> +
>  	return offload;
>  }
>  
> @@ -1748,7 +1781,8 @@ iavf_start(struct ifqueue *ifq)
>  	mask = sc->sc_tx_ring_ndescs - 1;
>  
>  	for (;;) {
> -		if (free <= IAVF_TX_PKT_DESCS) {
> +		/* We need one extra descriptor for TSO packets. */
> +		if (free <= (IAVF_TX_PKT_DESCS + 1)) {
>  			ifq_set_oactive(ifq);
>  			break;
>  		}
> @@ -1757,11 +1791,17 @@ iavf_start(struct ifqueue *ifq)
>  		if (m == NULL)
>  			break;
>  
> -		offload = iavf_tx_offload(m);
> +		offload = iavf_tx_offload(m, txr, prod);
>  
>  		txm = &txr->txr_maps[prod];
>  		map = txm->txm_map;
>  
> +		if (ISSET(m->m_pkthdr.csum_flags, M_TCP_TSO)) {
> +			prod++;
> +			prod &= mask;
> +			free--;
> +		}
> +
>  		if (iavf_load_mbuf(sc->sc_dmat, map, m) != 0) {
>  			ifq->ifq_errors++;
>  			m_freem(m);
> 
> -- 
> Yuichiro NAITO (naito.yuichiro@gmail.com)
>