RE: [Intel-wired-lan] [RFC PATCH 1/1] Fix header clobber in IDPF with SWIOTLB enabled

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf
> Of Steve Rutherford via Intel-wired-lan
> Sent: Friday, February 27, 2026 4:00 AM
> To: Nguyen, Anthony L <anthony.l.nguyen@xxxxxxxxx>; Kitszel,
> Przemyslaw <przemyslaw.kitszel@xxxxxxxxx>; Lobakin, Aleksander
> <aleksander.lobakin@xxxxxxxxx>
> Cc: andrew+netdev@xxxxxxx; davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx;
> kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx; intel-wired-lan@xxxxxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Steve Rutherford
> <srutherford@xxxxxxxxxx>
> Subject: [Intel-wired-lan] [RFC PATCH 1/1] Fix header clobber in IDPF
> with SWIOTLB enabled
> 
> When SWIOTLB and header split are enabled, IDPF sees empty packets in
> the rx queue.
> 
> This is caused by libeth_rx_sync_for_cpu clobbering the synthesized
> header in the workaround (i.e. overflow) path. After the header is
> synthesized by idpf_rx_hsplit_wa, the sync call pulls from the empty
> SWIOTLB buffer, effectively zeroing out the buffer.
> 
> This skips the extra sync in the workaround path in most cases. The
> one exception is that it calls sync to trigger a recycle for the
> header buffer when it fails to find a header in the payload.
> 
> Signed-off-by: Steve Rutherford <srutherford@xxxxxxxxxx>


It looks like subsystem prefix idpf: is missed in subj, and Fixes tag in commit message.


> ---
>  drivers/net/ethernet/intel/idpf/idpf_txrx.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> index 3ddf7b1e85ef..b02195fa2813 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
> @@ -3007,9 +3007,14 @@ static int idpf_rx_splitq_clean(struct
> idpf_rx_queue *rxq, int budget)
>  			u64_stats_update_begin(&rxq->stats_sync);
>  			u64_stats_inc(&rxq->q_stats.hsplit_buf_ovf);
>  			u64_stats_update_end(&rxq->stats_sync);
> -		}
> 
> -		if (libeth_rx_sync_for_cpu(hdr, hdr_len)) {
> +			/* Recycle the hdr buffer if unused */
> +			if (!hdr_len)
> +				libeth_rx_sync_for_cpu(hdr, 0);
> +		} else if (!libeth_rx_sync_for_cpu(hdr, hdr_len))
> +			hdr_len = 0;
> +
> +		if (hdr_len) {
>  			skb = idpf_rx_build_skb(hdr, hdr_len);
>  			if (!skb)
>  				break;
> --
> 2.53.0.473.g4a7958ca14-goog