[PATCH net-next v2 17/18] libeth: support native XDP and register memory model

[Alexander Lobakin <aleksander.lobakin@xxxxxxxxx>]

Expand libeth's Page Pool functionality by adding native XDP support.
This means picking the appropriate headroom and DMA direction.
Also, register all the created &page_pools as XDP memory models.
A driver then can call xdp_rxq_info_attach_page_pool() when registering
its RxQ info.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@xxxxxxxxx>
---
 include/net/libeth/rx.h                |  6 +++++-
 drivers/net/ethernet/intel/libeth/rx.c | 20 +++++++++++++++-----
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/include/net/libeth/rx.h b/include/net/libeth/rx.h
index 43574bd6612f..148be5cd822e 100644
--- a/include/net/libeth/rx.h
+++ b/include/net/libeth/rx.h
@@ -13,8 +13,10 @@
 
 /* Space reserved in front of each frame */
 #define LIBETH_SKB_HEADROOM	(NET_SKB_PAD + NET_IP_ALIGN)
+#define LIBETH_XDP_HEADROOM	(ALIGN(XDP_PACKET_HEADROOM, NET_SKB_PAD) + \
+				 NET_IP_ALIGN)
 /* Maximum headroom for worst-case calculations */
-#define LIBETH_MAX_HEADROOM	LIBETH_SKB_HEADROOM
+#define LIBETH_MAX_HEADROOM	LIBETH_XDP_HEADROOM
 /* Link layer / L2 overhead: Ethernet, 2 VLAN tags (C + S), FCS */
 #define LIBETH_RX_LL_LEN	(ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN)
 /* Maximum supported L2-L4 header length */
@@ -66,6 +68,7 @@ enum libeth_fqe_type {
  * @count: number of descriptors/buffers the queue has
  * @type: type of the buffers this queue has
  * @hsplit: flag whether header split is enabled
+ * @xdp: flag indicating whether XDP is enabled
  * @buf_len: HW-writeable length per each buffer
  * @nid: ID of the closest NUMA node with memory
  */
@@ -81,6 +84,7 @@ struct libeth_fq {
 	/* Cold fields */
 	enum libeth_fqe_type	type:2;
 	bool			hsplit:1;
+	bool			xdp:1;
 
 	u32			buf_len;
 	int			nid;
diff --git a/drivers/net/ethernet/intel/libeth/rx.c b/drivers/net/ethernet/intel/libeth/rx.c
index f20926669318..616426a2e363 100644
--- a/drivers/net/ethernet/intel/libeth/rx.c
+++ b/drivers/net/ethernet/intel/libeth/rx.c
@@ -68,7 +68,7 @@ static u32 libeth_rx_hw_len_truesize(const struct page_pool_params *pp,
 static bool libeth_rx_page_pool_params(struct libeth_fq *fq,
 				       struct page_pool_params *pp)
 {
-	pp->offset = LIBETH_SKB_HEADROOM;
+	pp->offset = fq->xdp ? LIBETH_XDP_HEADROOM : LIBETH_SKB_HEADROOM;
 	/* HW-writeable / syncable length per one page */
 	pp->max_len = LIBETH_RX_PAGE_LEN(pp->offset);
 
@@ -155,11 +155,12 @@ int libeth_rx_fq_create(struct libeth_fq *fq, struct napi_struct *napi)
 		.dev		= napi->dev->dev.parent,
 		.netdev		= napi->dev,
 		.napi		= napi,
-		.dma_dir	= DMA_FROM_DEVICE,
 	};
 	struct libeth_fqe *fqes;
 	struct page_pool *pool;
-	bool ret;
+	int ret;
+
+	pp.dma_dir = fq->xdp ? DMA_BIDIRECTIONAL : DMA_FROM_DEVICE;
 
 	if (!fq->hsplit)
 		ret = libeth_rx_page_pool_params(fq, &pp);
@@ -173,18 +174,26 @@ int libeth_rx_fq_create(struct libeth_fq *fq, struct napi_struct *napi)
 		return PTR_ERR(pool);
 
 	fqes = kvcalloc_node(fq->count, sizeof(*fqes), GFP_KERNEL, fq->nid);
-	if (!fqes)
+	if (!fqes) {
+		ret = -ENOMEM;
 		goto err_buf;
+	}
+
+	ret = xdp_reg_page_pool(pool);
+	if (ret)
+		goto err_mem;
 
 	fq->fqes = fqes;
 	fq->pp = pool;
 
 	return 0;
 
+err_mem:
+	kvfree(fqes);
 err_buf:
 	page_pool_destroy(pool);
 
-	return -ENOMEM;
+	return ret;
 }
 EXPORT_SYMBOL_NS_GPL(libeth_rx_fq_create, LIBETH);
 
@@ -194,6 +203,7 @@ EXPORT_SYMBOL_NS_GPL(libeth_rx_fq_create, LIBETH);
  */
 void libeth_rx_fq_destroy(struct libeth_fq *fq)
 {
+	xdp_unreg_page_pool(fq->pp);
 	kvfree(fq->fqes);
 	page_pool_destroy(fq->pp);
 }
-- 
2.46.2