bnxt_en: Fix XDP RX path

The XDP program can change the starting address of the RX data buffer and
this information needs to be passed back from bnxt_rx_xdp() to
bnxt_rx_pkt() for the XDP_PASS case so that the SKB can point correctly
to the modified buffer address.  Add back the data_ptr parameter to
bnxt_rx_xdp() to make this work.

Fixes: b231c3f3 ("bnxt: refactor bnxt_rx_xdp to separate xdp_init_buff/xdp_prepare_buff")
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -1940,7 +1940,7 @@ static int bnxt_rx_pkt(struct bnxt *bp, struct bnxt_cp_ring_info *cpr,
 	}
 
 	if (xdp_active) {
-		if (bnxt_rx_xdp(bp, rxr, cons, xdp, data, &len, event)) {
+		if (bnxt_rx_xdp(bp, rxr, cons, xdp, data, &data_ptr, &len, event)) {
 			rc = 1;
 			goto next_rx;
 		}

drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c

@@ -222,7 +222,8 @@ void bnxt_xdp_buff_frags_free(struct bnxt_rx_ring_info *rxr,
  * false   - packet should be passed to the stack.
  */
 bool bnxt_rx_xdp(struct bnxt *bp, struct bnxt_rx_ring_info *rxr, u16 cons,
-		 struct xdp_buff xdp, struct page *page, unsigned int *len, u8 *event)
+		 struct xdp_buff xdp, struct page *page, u8 **data_ptr,
+		 unsigned int *len, u8 *event)
 {
 	struct bpf_prog *xdp_prog = READ_ONCE(rxr->xdp_prog);
 	struct bnxt_tx_ring_info *txr;
@@ -255,8 +256,10 @@ bool bnxt_rx_xdp(struct bnxt *bp, struct bnxt_rx_ring_info *rxr, u16 cons,
 		*event &= ~BNXT_RX_EVENT;
 
 	*len = xdp.data_end - xdp.data;
-	if (orig_data != xdp.data)
+	if (orig_data != xdp.data) {
 		offset = xdp.data - xdp.data_hard_start;
+		*data_ptr = xdp.data_hard_start + offset;
+	}
 
 	switch (act) {
 	case XDP_PASS:

drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.h

@@ -18,8 +18,8 @@ struct bnxt_sw_tx_bd *bnxt_xmit_bd(struct bnxt *bp,
 				   struct xdp_buff *xdp);
 void bnxt_tx_int_xdp(struct bnxt *bp, struct bnxt_napi *bnapi, int nr_pkts);
 bool bnxt_rx_xdp(struct bnxt *bp, struct bnxt_rx_ring_info *rxr, u16 cons,
-		 struct xdp_buff xdp, struct page *page, unsigned int *len,
-		 u8 *event);
+		 struct xdp_buff xdp, struct page *page, u8 **data_ptr,
+		 unsigned int *len, u8 *event);
 int bnxt_xdp(struct net_device *dev, struct netdev_bpf *xdp);
 int bnxt_xdp_xmit(struct net_device *dev, int num_frames,
 		  struct xdp_frame **frames, u32 flags);