Re: [Intel-wired-lan] [PATCH net-next] i40e: add xdp frags support to ndo_xdp_xmit

[Lorenzo Bianconi <lorenzo.bianconi@redhat.com>]

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> 
> 
> Am 05.05.22 um 18:48 schrieb Lorenzo Bianconi:
> > Add the capability to map non-linear xdp frames in XDP_TX and ndo_xdp_xmit
> > callback.
> > 
> > Tested-by: Sarkar Tirthendu <tirthendu.sarkar@intel.com>
> > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > ---
> >   drivers/net/ethernet/intel/i40e/i40e_txrx.c | 87 +++++++++++++++------
> >   1 file changed, 62 insertions(+), 25 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> > index 7bc1174edf6b..b7967105a549 100644
> > --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> > +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> > @@ -2509,6 +2509,7 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
> >   			hard_start = page_address(rx_buffer->page) +
> >   				     rx_buffer->page_offset - offset;
> >   			xdp_prepare_buff(&xdp, hard_start, offset, size, true);
> > +			xdp_buff_clear_frags_flag(&xdp);
> >   #if (PAGE_SIZE > 4096)
> >   			/* At larger PAGE_SIZE, frame_sz depend on len size */
> >   			xdp.frame_sz = i40e_rx_frame_truesize(rx_ring, size);
> > @@ -3713,35 +3714,55 @@ u16 i40e_lan_select_queue(struct net_device *netdev,
> >   static int i40e_xmit_xdp_ring(struct xdp_frame *xdpf,
> >   			      struct i40e_ring *xdp_ring)
> >   {
> > -	u16 i = xdp_ring->next_to_use;
> > -	struct i40e_tx_buffer *tx_bi;
> > -	struct i40e_tx_desc *tx_desc;
> > +	struct skb_shared_info *sinfo = xdp_get_shared_info_from_frame(xdpf);
> > +	u8 nr_frags = unlikely(xdp_frame_has_frags(xdpf)) ? sinfo->nr_frags : 0;
> > +	u16 i = 0, index = xdp_ring->next_to_use;
> > +	struct i40e_tx_buffer *tx_head = &xdp_ring->tx_bi[index];
> > +	struct i40e_tx_buffer *tx_bi = tx_head;
> > +	struct i40e_tx_desc *tx_desc = I40E_TX_DESC(xdp_ring, index);
> >   	void *data = xdpf->data;
> >   	u32 size = xdpf->len;
> > -	dma_addr_t dma;
> > -	if (!unlikely(I40E_DESC_UNUSED(xdp_ring))) {
> > +	if (unlikely(I40E_DESC_UNUSED(xdp_ring) < 1 + nr_frags)) {
> >   		xdp_ring->tx_stats.tx_busy++;
> >   		return I40E_XDP_CONSUMED;
> >   	}
> > -	dma = dma_map_single(xdp_ring->dev, data, size, DMA_TO_DEVICE);
> > -	if (dma_mapping_error(xdp_ring->dev, dma))
> > -		return I40E_XDP_CONSUMED;
> > -	tx_bi = &xdp_ring->tx_bi[i];
> > -	tx_bi->bytecount = size;
> > -	tx_bi->gso_segs = 1;
> > -	tx_bi->xdpf = xdpf;
> > +	tx_head->bytecount = xdp_get_frame_len(xdpf);
> > +	tx_head->gso_segs = 1;
> > +	tx_head->xdpf = xdpf;
> > -	/* record length, and DMA address */
> > -	dma_unmap_len_set(tx_bi, len, size);
> > -	dma_unmap_addr_set(tx_bi, dma, dma);
> > +	for (;;) {
> > +		dma_addr_t dma;
> > -	tx_desc = I40E_TX_DESC(xdp_ring, i);
> > -	tx_desc->buffer_addr = cpu_to_le64(dma);
> > -	tx_desc->cmd_type_offset_bsz = build_ctob(I40E_TX_DESC_CMD_ICRC
> > -						  | I40E_TXD_CMD,
> > -						  0, size, 0);
> > +		dma = dma_map_single(xdp_ring->dev, data, size, DMA_TO_DEVICE);
> > +		if (dma_mapping_error(xdp_ring->dev, dma))
> > +			goto unmap;
> > +
> > +		/* record length, and DMA address */
> > +		dma_unmap_len_set(tx_bi, len, size);
> > +		dma_unmap_addr_set(tx_bi, dma, dma);
> > +
> > +		tx_desc->buffer_addr = cpu_to_le64(dma);
> > +		tx_desc->cmd_type_offset_bsz =
> > +			build_ctob(I40E_TX_DESC_CMD_ICRC, 0, size, 0);
> > +
> > +		if (++index == xdp_ring->count)
> > +			index = 0;
> > +
> > +		if (i == nr_frags)
> > +			break;
> > +
> > +		tx_bi = &xdp_ring->tx_bi[index];
> > +		tx_desc = I40E_TX_DESC(xdp_ring, index);
> > +
> > +		data = skb_frag_address(&sinfo->frags[i]);
> > +		size = skb_frag_size(&sinfo->frags[i]);
> > +		i++;
> > +	}
> > +
> > +	tx_desc->cmd_type_offset_bsz |=
> > +		cpu_to_le64(I40E_TXD_CMD << I40E_TXD_QW1_CMD_SHIFT);
> >   	/* Make certain all of the status bits have been updated
> >   	 * before next_to_watch is written.
> > @@ -3749,14 +3770,30 @@ static int i40e_xmit_xdp_ring(struct xdp_frame *xdpf,
> >   	smp_wmb();
> >   	xdp_ring->xdp_tx_active++;
> > -	i++;
> > -	if (i == xdp_ring->count)
> > -		i = 0;
> > -	tx_bi->next_to_watch = tx_desc;
> > -	xdp_ring->next_to_use = i;
> > +	tx_head->next_to_watch = tx_desc;
> > +	xdp_ring->next_to_use = index;
> >   	return I40E_XDP_TX;
> > +
> > +unmap:
> > +	for (;;) {
> > +		tx_bi = &xdp_ring->tx_bi[index];
> > +		if (dma_unmap_len(tx_bi, len))
> > +			dma_unmap_page(xdp_ring->dev,
> > +				       dma_unmap_addr(tx_bi, dma),
> > +				       dma_unmap_len(tx_bi, len),
> > +				       DMA_TO_DEVICE);
> > +		dma_unmap_len_set(tx_bi, len, 0);
> > +		if (tx_bi == tx_head)
> > +			break;
> > +
> > +		if (!index)
> > +			index += xdp_ring->count;
> > +		index--;
> > +	}
> 
> Could
> 
> ```
> do {
>         tx_bi = &xdp_ring->tx_bi[index];
>         if (dma_unmap_len(tx_bi, len))
>                 dma_unmap_page(xdp_ring->dev,
>                                dma_unmap_addr(tx_bi, dma),
>                                dma_unmap_len(tx_bi, len),
>                                DMA_TO_DEVICE);
>         dma_unmap_len_set(tx_bi, len, 0);
> 
>         if (!index)
>                 index += xdp_ring->count;
>         index--;
> } while (tx_bi != tx_head);
> ```
> 
> be used instead?

yes, it seems just a matter of test to me, doesn't it? :)

Regards,
Lorenzo

> 
> > +
> > +	return I40E_XDP_CONSUMED;
> >   }
> >   /**
> 
> 
> Kind regards,
> 
> Paul
> 

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