[PATCH 6.18 307/314] i40e: use xdp.frame_sz as XDP RxQ info frag_size

Sasha Levin
2026-03-10T11:30:17Z

From: Larysa Zaremba <larysa.zaremba@intel.com>

[ Upstream commit c69d22c6c46a1d792ba8af3d8d6356fdc0e6f538 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/intel/i40e/i40e_main.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index bc00bd4f439be..598739220dfb9 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));
--
2.51.0