ice: change XDP RxQ frag_size from DMA write length to xdp.frame_sz

[ Upstream commit e142dc4 ]

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

This allows to trigger kernel panic, when using
XDP_ADJUST_TAIL_GROW_MULTI_BUFF xskxceiver test and changing packet size to
6912 and the requested offset to a huge value, e.g.
XSK_UMEM__MAX_FRAME_SIZE * 100.

Due to other quirks of the ZC configuration in ice, panic is not observed
in ZC mode, but tailroom growing still fails when it should not.

Use fill queue buffer truesize instead of DMA write size in XDP RxQ info.
Fix ZC mode too by using the new helper.

Fixes: 2fba7dc ("ice: Add support for XDP multi-buffer on Rx side")
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
Link: https://patch.msgid.link/20260305111253.2317394-5-larysa.zaremba@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: walking-machine

drivers/net/ethernet/intel/ice/ice_base.c

@@ -661,7 +661,6 @@ static int ice_vsi_cfg_rxq(struct ice_rx_ring *ring)
 {
 	struct device *dev = ice_pf_to_dev(ring->vsi->back);
 	u32 num_bufs = ICE_DESC_UNUSED(ring);
-	u32 rx_buf_len;
 	int err;
 
 	if (ring->vsi->type == ICE_VSI_PF || ring->vsi->type == ICE_VSI_SF ||
@@ -672,12 +671,12 @@ static int ice_vsi_cfg_rxq(struct ice_rx_ring *ring)
 			return err;
 
 		if (ring->xsk_pool) {
-			rx_buf_len =
-				xsk_pool_get_rx_frame_size(ring->xsk_pool);
+			u32 frag_size =
+				xsk_pool_get_rx_frag_step(ring->xsk_pool);
 			err = __xdp_rxq_info_reg(&ring->xdp_rxq, ring->netdev,
 						 ring->q_index,
 						 ring->q_vector->napi.napi_id,
-						 rx_buf_len);
+						 frag_size);
 			if (err)
 				return err;
 			err = xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
@@ -697,7 +696,7 @@ static int ice_vsi_cfg_rxq(struct ice_rx_ring *ring)
 			err = __xdp_rxq_info_reg(&ring->xdp_rxq, ring->netdev,
 						 ring->q_index,
 						 ring->q_vector->napi.napi_id,
-						 ring->rx_buf_len);
+						 ring->truesize);
 			if (err)
 				goto err_destroy_fq;