Commit c69d22c6c46a for kernel

commit c69d22c6c46a1d792ba8af3d8d6356fdc0e6f538
Author: Larysa Zaremba <larysa.zaremba@intel.com>
Date:   Thu Mar 5 12:12:47 2026 +0100

    i40e: use xdp.frame_sz as XDP RxQ info frag_size

    The only user of frag_size field in XDP RxQ info is
    bpf_xdp_frags_increase_tail(). It clearly expects whole buffer size instead
    of DMA write size. Different assumptions in i40e driver configuration lead
    to negative tailroom.

    Set frag_size to the same value as frame_sz in shared pages mode, use new
    helper to set frag_size when AF_XDP ZC is active.

    Fixes: a045d2f2d03d ("i40e: set xdp_rxq_info::frag_size")
    Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
    Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
    Link: https://patch.msgid.link/20260305111253.2317394-7-larysa.zaremba@intel.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 781ec5aa814b..926d001b2150 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -3569,6 +3569,7 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)
 	u16 pf_q = vsi->base_queue + ring->queue_index;
 	struct i40e_hw *hw = &vsi->back->hw;
 	struct i40e_hmc_obj_rxq rx_ctx;
+	u32 xdp_frame_sz;
 	int err = 0;
 	bool ok;

@@ -3578,6 +3579,7 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)
 	memset(&rx_ctx, 0, sizeof(rx_ctx));

 	ring->rx_buf_len = vsi->rx_buf_len;
+	xdp_frame_sz = i40e_rx_pg_size(ring) / 2;

 	/* XDP RX-queue info only needed for RX rings exposed to XDP */
 	if (ring->vsi->type != I40E_VSI_MAIN)
@@ -3585,11 +3587,12 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)

 	ring->xsk_pool = i40e_xsk_pool(ring);
 	if (ring->xsk_pool) {
+		xdp_frame_sz = xsk_pool_get_rx_frag_step(ring->xsk_pool);
 		ring->rx_buf_len = xsk_pool_get_rx_frame_size(ring->xsk_pool);
 		err = __xdp_rxq_info_reg(&ring->xdp_rxq, ring->netdev,
 					 ring->queue_index,
 					 ring->q_vector->napi.napi_id,
-					 ring->rx_buf_len);
+					 xdp_frame_sz);
 		if (err)
 			return err;
 		err = xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
@@ -3605,7 +3608,7 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)
 		err = __xdp_rxq_info_reg(&ring->xdp_rxq, ring->netdev,
 					 ring->queue_index,
 					 ring->q_vector->napi.napi_id,
-					 ring->rx_buf_len);
+					 xdp_frame_sz);
 		if (err)
 			return err;
 		err = xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
@@ -3616,7 +3619,7 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)
 	}

 skip:
-	xdp_init_buff(&ring->xdp, i40e_rx_pg_size(ring) / 2, &ring->xdp_rxq);
+	xdp_init_buff(&ring->xdp, xdp_frame_sz, &ring->xdp_rxq);

 	rx_ctx.dbuff = DIV_ROUND_UP(ring->rx_buf_len,
 				    BIT_ULL(I40E_RXQ_CTX_DBUFF_SHIFT));