i40e, xsk: Migrate to new MEM_TYPE_XSK_BUFF_POOL

Remove MEM_TYPE_ZERO_COPY in favor of the new MEM_TYPE_XSK_BUFF_POOL
APIs. The AF_XDP zero-copy rx_bi ring is now simply a struct xdp_buff
pointer.

v4->v5: Fixed "warning: Excess function parameter 'bi' description in
        'i40e_construct_skb_zc'". (Jakub)

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: intel-wired-lan@lists.osuosl.org
Link: https://lore.kernel.org/bpf/20200520192103.355233-9-bjorn.topel@gmail.com

Author: Björn Töpel

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -3266,21 +3266,19 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)
 		ret = i40e_alloc_rx_bi_zc(ring);
 		if (ret)
 			return ret;
-		ring->rx_buf_len = ring->xsk_umem->chunk_size_nohr -
-				   XDP_PACKET_HEADROOM;
+		ring->rx_buf_len = xsk_umem_get_rx_frame_size(ring->xsk_umem);
 		/* For AF_XDP ZC, we disallow packets to span on
 		 * multiple buffers, thus letting us skip that
 		 * handling in the fast-path.
 		 */
 		chain_len = 1;
-		ring->zca.free = i40e_zca_free;
 		ret = xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
-						 MEM_TYPE_ZERO_COPY,
-						 &ring->zca);
+						 MEM_TYPE_XSK_BUFF_POOL,
+						 NULL);
 		if (ret)
 			return ret;
 		dev_info(&vsi->back->pdev->dev,
-			 "Registered XDP mem model MEM_TYPE_ZERO_COPY on Rx ring %d\n",
+			 "Registered XDP mem model MEM_TYPE_XSK_BUFF_POOL on Rx ring %d\n",
 			 ring->queue_index);
 
 	} else {
@@ -3351,9 +3349,12 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)
 	ring->tail = hw->hw_addr + I40E_QRX_TAIL(pf_q);
 	writel(0, ring->tail);
 
-	ok = ring->xsk_umem ?
-	     i40e_alloc_rx_buffers_zc(ring, I40E_DESC_UNUSED(ring)) :
-	     !i40e_alloc_rx_buffers(ring, I40E_DESC_UNUSED(ring));
+	if (ring->xsk_umem) {
+		xsk_buff_set_rxq_info(ring->xsk_umem, &ring->xdp_rxq);
+		ok = i40e_alloc_rx_buffers_zc(ring, I40E_DESC_UNUSED(ring));
+	} else {
+		ok = !i40e_alloc_rx_buffers(ring, I40E_DESC_UNUSED(ring));
+	}
 	if (!ok) {
 		/* Log this in case the user has forgotten to give the kernel
 		 * any buffers, even later in the application.

drivers/net/ethernet/intel/i40e/i40e_txrx.h

@@ -301,12 +301,6 @@ struct i40e_rx_buffer {
 	__u16 pagecnt_bias;
 };
 
-struct i40e_rx_buffer_zc {
-	dma_addr_t dma;
-	void *addr;
-	u64 handle;
-};
-
 struct i40e_queue_stats {
 	u64 packets;
 	u64 bytes;
@@ -356,7 +350,7 @@ struct i40e_ring {
 	union {
 		struct i40e_tx_buffer *tx_bi;
 		struct i40e_rx_buffer *rx_bi;
-		struct i40e_rx_buffer_zc *rx_bi_zc;
+		struct xdp_buff **rx_bi_zc;
 	};
 	DECLARE_BITMAP(state, __I40E_RING_STATE_NBITS);
 	u16 queue_index;		/* Queue number of ring */
@@ -418,7 +412,6 @@ struct i40e_ring {
 	struct i40e_channel *ch;
 	struct xdp_rxq_info xdp_rxq;
 	struct xdp_umem *xsk_umem;
-	struct zero_copy_allocator zca; /* ZC allocator anchor */
 } ____cacheline_internodealigned_in_smp;
 
 static inline bool ring_uses_build_skb(struct i40e_ring *ring)