2 files changed, 113 insertions, 0 deletions

diff --git a/include/net/xdp.h b/include/net/xdp.h
index aa24fa78cbe6..6da0e746cf75 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -337,6 +337,7 @@ void xdp_warn(const char *msg, const char *func, const int line);
 #define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
 
 struct sk_buff *xdp_build_skb_from_buff(const struct xdp_buff *xdp);
+struct sk_buff *xdp_build_skb_from_zc(struct xdp_buff *xdp);
 struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
 struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
 					   struct sk_buff *skb,
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 704203a15a18..67b53fc7191e 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -684,6 +684,118 @@ struct sk_buff *xdp_build_skb_from_buff(const struct xdp_buff *xdp)
 }
 EXPORT_SYMBOL_GPL(xdp_build_skb_from_buff);
 
+/**
+ * xdp_copy_frags_from_zc - copy frags from XSk buff to skb
+ * @skb: skb to copy frags to
+ * @xdp: XSk &xdp_buff from which the frags will be copied
+ * @pp: &page_pool backing page allocation, if available
+ *
+ * Copy all frags from XSk &xdp_buff to the skb to pass it up the stack.
+ * Allocate a new buffer for each frag, copy it and attach to the skb.
+ *
+ * Return: true on success, false on netmem allocation fail.
+ */
+static noinline bool xdp_copy_frags_from_zc(struct sk_buff *skb,
+					    const struct xdp_buff *xdp,
+					    struct page_pool *pp)
+{
+	struct skb_shared_info *sinfo = skb_shinfo(skb);
+	const struct skb_shared_info *xinfo;
+	u32 nr_frags, tsize = 0;
+	bool pfmemalloc = false;
+
+	xinfo = xdp_get_shared_info_from_buff(xdp);
+	nr_frags = xinfo->nr_frags;
+
+	for (u32 i = 0; i < nr_frags; i++) {
+		u32 len = skb_frag_size(&xinfo->frags[i]);
+		u32 offset, truesize = len;
+		netmem_ref netmem;
+
+		netmem = page_pool_dev_alloc_netmem(pp, &offset, &truesize);
+		if (unlikely(!netmem)) {
+			sinfo->nr_frags = i;
+			return false;
+		}
+
+		memcpy(__netmem_address(netmem),
+		       __netmem_address(xinfo->frags[i].netmem),
+		       LARGEST_ALIGN(len));
+		__skb_fill_netmem_desc_noacc(sinfo, i, netmem, offset, len);
+
+		tsize += truesize;
+		pfmemalloc |= netmem_is_pfmemalloc(netmem);
+	}
+
+	xdp_update_skb_shared_info(skb, nr_frags, xinfo->xdp_frags_size,
+				   tsize, pfmemalloc);
+
+	return true;
+}
+
+/**
+ * xdp_build_skb_from_zc - create an skb from XSk &xdp_buff
+ * @xdp: source XSk buff
+ *
+ * Similar to xdp_build_skb_from_buff(), but for XSk frames. Allocate an skb
+ * head, new buffer for the head, copy the data and initialize the skb fields.
+ * If there are frags, allocate new buffers for them and copy.
+ * Buffers are allocated from the system percpu pools to try recycling them.
+ * If new skb was built successfully, @xdp is returned to XSk pool's freelist.
+ * On error, it remains untouched and the caller must take care of this.
+ *
+ * Return: new &sk_buff on success, %NULL on error.
+ */
+struct sk_buff *xdp_build_skb_from_zc(struct xdp_buff *xdp)
+{
+	struct page_pool *pp = this_cpu_read(system_page_pool);
+	const struct xdp_rxq_info *rxq = xdp->rxq;
+	u32 len = xdp->data_end - xdp->data_meta;
+	u32 truesize = xdp->frame_sz;
+	struct sk_buff *skb;
+	int metalen;
+	void *data;
+
+	if (!IS_ENABLED(CONFIG_PAGE_POOL))
+		return NULL;
+
+	data = page_pool_dev_alloc_va(pp, &truesize);
+	if (unlikely(!data))
+		return NULL;
+
+	skb = napi_build_skb(data, truesize);
+	if (unlikely(!skb)) {
+		page_pool_free_va(pp, data, true);
+		return NULL;
+	}
+
+	skb_mark_for_recycle(skb);
+	skb_reserve(skb, xdp->data_meta - xdp->data_hard_start);
+
+	memcpy(__skb_put(skb, len), xdp->data_meta, LARGEST_ALIGN(len));
+
+	metalen = xdp->data - xdp->data_meta;
+	if (metalen > 0) {
+		skb_metadata_set(skb, metalen);
+		__skb_pull(skb, metalen);
+	}
+
+	skb_record_rx_queue(skb, rxq->queue_index);
+
+	if (unlikely(xdp_buff_has_frags(xdp)) &&
+	    unlikely(!xdp_copy_frags_from_zc(skb, xdp, pp))) {
+		napi_consume_skb(skb, true);
+		return NULL;
+	}
+
+	xsk_buff_free(xdp);
+
+	skb->protocol = eth_type_trans(skb, rxq->dev);
+
+	return skb;
+}
+EXPORT_SYMBOL_GPL(xdp_build_skb_from_zc);
+
 struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
 					   struct sk_buff *skb,
 					   struct net_device *dev)