[PATCH net] ice: Fix logic of getting XSK pool associated with Tx queue

[Ivan Vecera <ivecera@redhat.com>]

Function ice_tx_xsk_pool() used to get XSK buffer pool associated
with XDP Tx queue returns NULL when number of ordinary Tx queues
is not equal to num_possible_cpus().

The function computes XDP Tx queue ID as an expression
`ring->q_index - vsi->num_xdp_txq` but this is wrong because
XDP Tx queues are placed after ordinary ones so the correct
formula is `ring->q_index - vsi->alloc_txq`.

Prior commit 792b2086584f ("ice: fix vsi->txq_map sizing") number
of XDP Tx queues was equal to number of ordinary Tx queues so
the bug in mentioned function was hidden.

Reproducer:
host# ethtool -L ens7f0 combined 1
host# ./xdpsock -i ens7f0 -q 0 -t -N
samples/bpf/xdpsock_user.c:kick_tx:794: errno: 6/"No such device or address"

 sock0@ens7f0:0 txonly xdp-drv
                pps         pkts        0.00
rx              0           0
tx              0           0

Fixes: 2d4238f55697 ("ice: Add support for AF_XDP")
Fixes: 792b2086584f ("ice: fix vsi->txq_map sizing")
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
 drivers/net/ethernet/intel/ice/ice.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
index b0b27bfcd7a2..d4f1874df7d0 100644
--- a/drivers/net/ethernet/intel/ice/ice.h
+++ b/drivers/net/ethernet/intel/ice/ice.h
@@ -710,7 +710,7 @@ static inline struct xsk_buff_pool *ice_tx_xsk_pool(struct ice_tx_ring *ring)
 	struct ice_vsi *vsi = ring->vsi;
 	u16 qid;
 
-	qid = ring->q_index - vsi->num_xdp_txq;
+	qid = ring->q_index - vsi->alloc_txq;
 
 	if (!ice_is_xdp_ena_vsi(vsi) || !test_bit(qid, vsi->af_xdp_zc_qps))
 		return NULL;
-- 
2.34.1