[PATCH bpf v2 7/9] idpf: use truesize as XDP RxQ info frag_size

[Larysa Zaremba <larysa.zaremba@intel.com>]

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 idpf driver configuration lead
to negative tailroom.

To make it worse, buffer sizes are not actually uniform in idpf when
splitq is enabled, as there are several buffer queues, so rxq->rx_buf_size
is meaningless in this case.

Use rxq->truesize as a frag_size for singleq and truesize of the first bufq
in AF_XDP ZC, as there is only one. Disable growinf tail for regular
splitq.

Fixes: ac8a861f632e ("idpf: prepare structures to support XDP")
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
---
 drivers/net/ethernet/intel/idpf/xdp.c | 8 +++++++-
 drivers/net/ethernet/intel/idpf/xsk.c | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/idpf/xdp.c b/drivers/net/ethernet/intel/idpf/xdp.c
index 958d16f87424..a152c9a26976 100644
--- a/drivers/net/ethernet/intel/idpf/xdp.c
+++ b/drivers/net/ethernet/intel/idpf/xdp.c
@@ -46,11 +46,17 @@ static int __idpf_xdp_rxq_info_init(struct idpf_rx_queue *rxq, void *arg)
 {
 	const struct idpf_vport *vport = rxq->q_vector->vport;
 	bool split = idpf_is_queue_model_split(vport->rxq_model);
+	u32 frag_size = 0;
 	int err;
 
+	if (idpf_queue_has(XSK, rxq) && split)
+		frag_size = rxq->bufq_sets[0].bufq.truesize;
+	else if (!split)
+		frag_size = rxq->truesize;
+
 	err = __xdp_rxq_info_reg(&rxq->xdp_rxq, vport->netdev, rxq->idx,
 				 rxq->q_vector->napi.napi_id,
-				 rxq->rx_buf_size);
+				 frag_size);
 	if (err)
 		return err;
 
diff --git a/drivers/net/ethernet/intel/idpf/xsk.c b/drivers/net/ethernet/intel/idpf/xsk.c
index fd2cc43ab43c..febe1073b9b4 100644
--- a/drivers/net/ethernet/intel/idpf/xsk.c
+++ b/drivers/net/ethernet/intel/idpf/xsk.c
@@ -401,6 +401,7 @@ int idpf_xskfq_init(struct idpf_buf_queue *bufq)
 	bufq->pending = fq.pending;
 	bufq->thresh = fq.thresh;
 	bufq->rx_buf_size = fq.buf_len;
+	bufq->truesize = xsk_pool_get_rx_frag_step(fq.pool);
 
 	if (!idpf_xskfq_refill(bufq))
 		netdev_err(bufq->pool->netdev,
-- 
2.52.0