Merge branch '100GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue

Tony Nguyen says:

====================
ice: xsk: reduced queue count fixes

Maciej Fijalkowski says:

this small series is supposed to fix the issues around AF_XDP usage with
reduced queue count on interface. Due to the XDP rings setup, some
configurations can result in sockets not seeing traffic flowing. More
about this in description of patch 2.

* '100GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue:
  ice: xsk: use Rx ring's XDP ring when picking NAPI context
  ice: xsk: prohibit usage of non-balanced queue id
====================

Link: https://lore.kernel.org/r/20220822163257.2382487-1-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 23 insertions, 13 deletions

diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
index cc5b85afd437..841fa149c407 100644
--- a/drivers/net/ethernet/intel/ice/ice.h
+++ b/drivers/net/ethernet/intel/ice/ice.h
@@ -684,8 +684,8 @@ static inline void ice_set_ring_xdp(struct ice_tx_ring *ring)
  * ice_xsk_pool - get XSK buffer pool bound to a ring
  * @ring: Rx ring to use
  *
- * Returns a pointer to xdp_umem structure if there is a buffer pool present,
- * NULL otherwise.
+ * Returns a pointer to xsk_buff_pool structure if there is a buffer pool
+ * present, NULL otherwise.
  */
 static inline struct xsk_buff_pool *ice_xsk_pool(struct ice_rx_ring *ring)
 {
@@ -699,23 +699,33 @@ static inline struct xsk_buff_pool *ice_xsk_pool(struct ice_rx_ring *ring)
 }
 
 /**
- * ice_tx_xsk_pool - get XSK buffer pool bound to a ring
- * @ring: Tx ring to use
+ * ice_tx_xsk_pool - assign XSK buff pool to XDP ring
+ * @vsi: pointer to VSI
+ * @qid: index of a queue to look at XSK buff pool presence
  *
- * Returns a pointer to xdp_umem structure if there is a buffer pool present,
- * NULL otherwise. Tx equivalent of ice_xsk_pool.
+ * Sets XSK buff pool pointer on XDP ring.
+ *
+ * XDP ring is picked from Rx ring, whereas Rx ring is picked based on provided
+ * queue id. Reason for doing so is that queue vectors might have assigned more
+ * than one XDP ring, e.g. when user reduced the queue count on netdev; Rx ring
+ * carries a pointer to one of these XDP rings for its own purposes, such as
+ * handling XDP_TX action, therefore we can piggyback here on the
+ * rx_ring->xdp_ring assignment that was done during XDP rings initialization.
  */
-static inline struct xsk_buff_pool *ice_tx_xsk_pool(struct ice_tx_ring *ring)
+static inline void ice_tx_xsk_pool(struct ice_vsi *vsi, u16 qid)
 {
-	struct ice_vsi *vsi = ring->vsi;
-	u16 qid;
+	struct ice_tx_ring *ring;
 
-	qid = ring->q_index - vsi->alloc_txq;
+	ring = vsi->rx_rings[qid]->xdp_ring;
+	if (!ring)
+		return;
 
-	if (!ice_is_xdp_ena_vsi(vsi) || !test_bit(qid, vsi->af_xdp_zc_qps))
-		return NULL;
+	if (!ice_is_xdp_ena_vsi(vsi) || !test_bit(qid, vsi->af_xdp_zc_qps)) {
+		ring->xsk_pool = NULL;
+		return;
+	}
 
-	return xsk_get_pool_from_qid(vsi->netdev, qid);
+	ring->xsk_pool = xsk_get_pool_from_qid(vsi->netdev, qid);
 }
 
 /**