On Mon, 2021-04-19 at 09:23 +0200, Kurt Kanzenbach wrote:
> When using native XDP with the igb driver, the XDP frame data doesn't
> point to
> the beginning of the packet. It's off by 16 bytes. Everything works
> as expected
> with XDP skb mode.
>
> Actually these 16 bytes are used to store the packet timestamps.
> Therefore, pull
> the timestamp before executing any XDP operations and adjust all
> other code
> accordingly. The igc driver does it like that as well.
>
> Tested with Intel i210 card and AF_XDP sockets.
>
> Fixes: 9cbc948b5a20 ("igb: add XDP support")
> Signed-off-by: Kurt Kanzenbach <k...@linutronix.de>
> ---
<snip>
> @@ -8683,7 +8676,10 @@ static int igb_clean_rx_irq(struct
> igb_q_vector *q_vector, const int budget)
> while (likely(total_packets < budget)) {
> union e1000_adv_rx_desc *rx_desc;
> struct igb_rx_buffer *rx_buffer;
> + ktime_t timestamp = 0;
> + int pkt_offset = 0;
> unsigned int size;
> + void *pktbuf;
>
> /* return some buffers to hardware, one at a time is
> too slow */
> if (cleaned_count >= IGB_RX_BUFFER_WRITE) {
> @@ -8703,14 +8699,21 @@ static int igb_clean_rx_irq(struct
> igb_q_vector *q_vector, const int budget)
> dma_rmb();
>
> rx_buffer = igb_get_rx_buffer(rx_ring, size,
> &rx_buf_pgcnt);
> + pktbuf = page_address(rx_buffer->page) + rx_buffer-
> >page_offset;
> +
> + /* pull rx packet timestamp if available */
> + if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP))
> {
> + timestamp = igb_ptp_rx_pktstamp(rx_ring-
> >q_vector,
> + pktbuf);
The timestamp should be checked for failure and not adjust these values
if the timestamp was invalid.
> + pkt_offset += IGB_TS_HDR_LEN;
> + size -= IGB_TS_HDR_LEN;
> + }
