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* [PATCH net-next v11] virtio_net: add page_pool support for buffer allocation
@ 2026-03-10 18:31 Vishwanath Seshagiri
  2026-03-13  7:51 ` Jason Wang
                   ` (3 more replies)
  0 siblings, 4 replies; 21+ messages in thread
From: Vishwanath Seshagiri @ 2026-03-10 18:31 UTC (permalink / raw)
  To: Michael S . Tsirkin, Jason Wang
  Cc: Xuan Zhuo, Eugenio Pérez, Andrew Lunn, David S . Miller,
	Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Wei,
	Matteo Croce, Ilias Apalodimas, netdev, virtualization,
	linux-kernel, kernel-team

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="y", Size: 32960 bytes --]

Use page_pool for RX buffer allocation in mergeable and small buffer
modes to enable page recycling and avoid repeated page allocator calls.
skb_mark_for_recycle() enables page reuse in the network stack.

Big packets mode is unchanged because it uses page->private for linked
list chaining of multiple pages per buffer, which conflicts with
page_pool's internal use of page->private.

Implement conditional DMA premapping using virtqueue_dma_dev():
- When non-NULL (vhost, virtio-pci): use PP_FLAG_DMA_MAP with page_pool
  handling DMA mapping, submit via virtqueue_add_inbuf_premapped()
- When NULL (VDUSE, direct physical): page_pool handles allocation only,
  submit via virtqueue_add_inbuf_ctx()

This preserves the DMA premapping optimization from commit 31f3cd4e5756b
("virtio-net: rq submits premapped per-buffer") while adding page_pool
support as a prerequisite for future zero-copy features (devmem TCP,
io_uring ZCRX).

Page pools are created in probe and destroyed in remove (not open/close),
following existing driver behavior where RX buffers remain in virtqueues
across interface state changes.

Signed-off-by: Vishwanath Seshagiri <vishs@meta.com>
---
Changes in v11:
- add_recvbuf_small: encode alloc_len and xdp_headroom in ctx via
  mergeable_len_to_ctx() so receive_small() recovers the actual buflen
  via mergeable_ctx_to_truesize() (Michael S. Tsirkin)
- receive_small_build_skb, receive_small_xdp: accept buflen parameter
  instead of recomputing it, to use the actual allocation size
- v10:
  https://lore.kernel.org/virtualization/9752a952-195d-4da3-bc7a-5a4a1f2fd2ca@meta.com/

Changes in v10:
- add_recvbuf_small: use alloc_len to avoid clobbering len; v9 feedback
  was about truesize under-accounting, not variable naming — misunderstood
  the comment in v9
- v9:
  https://lore.kernel.org/virtualization/20260302041005.1627210-1-vishs@meta.com/

Changes in v9:
- Fix virtnet_skb_append_frag() for XSK callers (Michael S. Tsirkin)
- v8:
  https://lore.kernel.org/virtualization/e824c5a3-cfe0-4d11-958f-c3ec82d11d37@meta.com/

Changes in v8:
- Remove virtnet_no_page_pool() helper, replace with direct !rq->page_pool
  checks or inlined conditions (Xuan Zhuo)
- Extract virtnet_rq_submit() helper to consolidate DMA/non-DMA buffer
  submission in add_recvbuf_small() and add_recvbuf_mergeable()
- Add skb_mark_for_recycle(nskb) for overflow frag_list skbs in
  virtnet_skb_append_frag() to ensure page_pool pages are returned to
  the pool instead of freed via put_page()
- Rebase on net-next (kzalloc_objs API)
- v7:
  https://lore.kernel.org/virtualization/20260210014305.3236342-1-vishs@meta.com/

Changes in v7:
- Replace virtnet_put_page() helper with direct page_pool_put_page()
  calls (Xuan Zhuo)
- Add virtnet_no_page_pool() helper to consolidate big_packets mode check
  (Michael S. Tsirkin)
- Add DMA sync_for_cpu for subsequent buffers in xdp_linearize_page() when
  use_page_pool_dma is set (Michael S. Tsirkin)
- Remove unused pp_params.dev assignment in non-DMA path
- Add page pool recreation in virtnet_restore_up() for freeze/restore support (Chris Mason's
Review Prompt)
- v6:
  https://lore.kernel.org/virtualization/20260208175410.1910001-1-vishs@meta.com/

Changes in v6:
- Drop page_pool_frag_offset_add() helper and switch to page_pool_alloc_va();
  page_pool_alloc_netmem() already handles internal fragmentation internally
  (Jakub Kicinski)
- v5:
  https://lore.kernel.org/virtualization/20260206002715.1885869-1-vishs@meta.com/

Benchmark results:

Configuration: pktgen TX -> tap -> vhost-net | virtio-net RX -> XDP_DROP

Small packets (64 bytes, mrg_rxbuf=off):
  1Q:  853,493 -> 868,923 pps  (+1.8%)
  2Q: 1,655,793 -> 1,696,707 pps (+2.5%)
  4Q: 3,143,375 -> 3,302,511 pps (+5.1%)
  8Q: 6,082,590 -> 6,156,894 pps (+1.2%)

Mergeable RX (64 bytes):
  1Q:   766,168 ->   814,493 pps  (+6.3%)
  2Q: 1,384,871 -> 1,670,639 pps (+20.6%)
  4Q: 2,773,081 -> 3,080,574 pps (+11.1%)
  8Q: 5,600,615 -> 6,043,891 pps  (+7.9%)

Mergeable RX (1500 bytes):
  1Q:   741,579 ->   785,442 pps  (+5.9%)
  2Q: 1,310,043 -> 1,534,554 pps (+17.1%)
  4Q: 2,748,700 -> 2,890,582 pps  (+5.2%)
  8Q: 5,348,589 -> 5,618,664 pps  (+5.0%)

 drivers/net/Kconfig      |   1 +
 drivers/net/virtio_net.c | 497 ++++++++++++++++++++-------------------
 2 files changed, 251 insertions(+), 247 deletions(-)

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 17108c359216..b2fd90466bab 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -452,6 +452,7 @@ config VIRTIO_NET
 	depends on VIRTIO
 	select NET_FAILOVER
 	select DIMLIB
+	select PAGE_POOL
 	help
 	  This is the virtual network driver for virtio.  It can be used with
 	  QEMU based VMMs (like KVM or Xen).  Say Y or M.
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 72d6a9c6a5a2..a85d75a7f539 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -26,6 +26,7 @@
 #include <net/netdev_rx_queue.h>
 #include <net/netdev_queues.h>
 #include <net/xdp_sock_drv.h>
+#include <net/page_pool/helpers.h>
 
 static int napi_weight = NAPI_POLL_WEIGHT;
 module_param(napi_weight, int, 0444);
@@ -290,14 +291,6 @@ struct virtnet_interrupt_coalesce {
 	u32 max_usecs;
 };
 
-/* The dma information of pages allocated at a time. */
-struct virtnet_rq_dma {
-	dma_addr_t addr;
-	u32 ref;
-	u16 len;
-	u16 need_sync;
-};
-
 /* Internal representation of a send virtqueue */
 struct send_queue {
 	/* Virtqueue associated with this send _queue */
@@ -356,8 +349,10 @@ struct receive_queue {
 	/* Average packet length for mergeable receive buffers. */
 	struct ewma_pkt_len mrg_avg_pkt_len;
 
-	/* Page frag for packet buffer allocation. */
-	struct page_frag alloc_frag;
+	struct page_pool *page_pool;
+
+	/* True if page_pool handles DMA mapping via PP_FLAG_DMA_MAP */
+	bool use_page_pool_dma;
 
 	/* RX: fragments + linear part + virtio header */
 	struct scatterlist sg[MAX_SKB_FRAGS + 2];
@@ -370,9 +365,6 @@ struct receive_queue {
 
 	struct xdp_rxq_info xdp_rxq;
 
-	/* Record the last dma info to free after new pages is allocated. */
-	struct virtnet_rq_dma *last_dma;
-
 	struct xsk_buff_pool *xsk_pool;
 
 	/* xdp rxq used by xsk */
@@ -521,11 +513,14 @@ static int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
 			       struct virtnet_rq_stats *stats);
 static void virtnet_receive_done(struct virtnet_info *vi, struct receive_queue *rq,
 				 struct sk_buff *skb, u8 flags);
-static struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
+static struct sk_buff *virtnet_skb_append_frag(struct receive_queue *rq,
+					       struct sk_buff *head_skb,
 					       struct sk_buff *curr_skb,
 					       struct page *page, void *buf,
 					       int len, int truesize);
 static void virtnet_xsk_completed(struct send_queue *sq, int num);
+static void free_unused_bufs(struct virtnet_info *vi);
+static void virtnet_del_vqs(struct virtnet_info *vi);
 
 enum virtnet_xmit_type {
 	VIRTNET_XMIT_TYPE_SKB,
@@ -709,12 +704,10 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask)
 static void virtnet_rq_free_buf(struct virtnet_info *vi,
 				struct receive_queue *rq, void *buf)
 {
-	if (vi->mergeable_rx_bufs)
-		put_page(virt_to_head_page(buf));
-	else if (vi->big_packets)
+	if (!rq->page_pool)
 		give_pages(rq, buf);
 	else
-		put_page(virt_to_head_page(buf));
+		page_pool_put_page(rq->page_pool, virt_to_head_page(buf), -1, false);
 }
 
 static void enable_rx_mode_work(struct virtnet_info *vi)
@@ -876,10 +869,16 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
 		skb = virtnet_build_skb(buf, truesize, p - buf, len);
 		if (unlikely(!skb))
 			return NULL;
+		/* Big packets mode chains pages via page->private, which is
+		 * incompatible with the way page_pool uses page->private.
+		 * Currently, big packets mode doesn't use page pools.
+		 */
+		if (!rq->page_pool) {
+			page = (struct page *)page->private;
+			if (page)
+				give_pages(rq, page);
+		}
 
-		page = (struct page *)page->private;
-		if (page)
-			give_pages(rq, page);
 		goto ok;
 	}
 
@@ -925,133 +924,16 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
 	hdr = skb_vnet_common_hdr(skb);
 	memcpy(hdr, hdr_p, hdr_len);
 	if (page_to_free)
-		put_page(page_to_free);
+		page_pool_put_page(rq->page_pool, page_to_free, -1, true);
 
 	return skb;
 }
 
-static void virtnet_rq_unmap(struct receive_queue *rq, void *buf, u32 len)
-{
-	struct virtnet_info *vi = rq->vq->vdev->priv;
-	struct page *page = virt_to_head_page(buf);
-	struct virtnet_rq_dma *dma;
-	void *head;
-	int offset;
-
-	BUG_ON(vi->big_packets && !vi->mergeable_rx_bufs);
-
-	head = page_address(page);
-
-	dma = head;
-
-	--dma->ref;
-
-	if (dma->need_sync && len) {
-		offset = buf - (head + sizeof(*dma));
-
-		virtqueue_map_sync_single_range_for_cpu(rq->vq, dma->addr,
-							offset, len,
-							DMA_FROM_DEVICE);
-	}
-
-	if (dma->ref)
-		return;
-
-	virtqueue_unmap_single_attrs(rq->vq, dma->addr, dma->len,
-				     DMA_FROM_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
-	put_page(page);
-}
-
 static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx)
 {
-	struct virtnet_info *vi = rq->vq->vdev->priv;
-	void *buf;
-
-	BUG_ON(vi->big_packets && !vi->mergeable_rx_bufs);
+	BUG_ON(!rq->page_pool);
 
-	buf = virtqueue_get_buf_ctx(rq->vq, len, ctx);
-	if (buf)
-		virtnet_rq_unmap(rq, buf, *len);
-
-	return buf;
-}
-
-static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32 len)
-{
-	struct virtnet_info *vi = rq->vq->vdev->priv;
-	struct virtnet_rq_dma *dma;
-	dma_addr_t addr;
-	u32 offset;
-	void *head;
-
-	BUG_ON(vi->big_packets && !vi->mergeable_rx_bufs);
-
-	head = page_address(rq->alloc_frag.page);
-
-	offset = buf - head;
-
-	dma = head;
-
-	addr = dma->addr - sizeof(*dma) + offset;
-
-	sg_init_table(rq->sg, 1);
-	sg_fill_dma(rq->sg, addr, len);
-}
-
-static void *virtnet_rq_alloc(struct receive_queue *rq, u32 size, gfp_t gfp)
-{
-	struct page_frag *alloc_frag = &rq->alloc_frag;
-	struct virtnet_info *vi = rq->vq->vdev->priv;
-	struct virtnet_rq_dma *dma;
-	void *buf, *head;
-	dma_addr_t addr;
-
-	BUG_ON(vi->big_packets && !vi->mergeable_rx_bufs);
-
-	head = page_address(alloc_frag->page);
-
-	dma = head;
-
-	/* new pages */
-	if (!alloc_frag->offset) {
-		if (rq->last_dma) {
-			/* Now, the new page is allocated, the last dma
-			 * will not be used. So the dma can be unmapped
-			 * if the ref is 0.
-			 */
-			virtnet_rq_unmap(rq, rq->last_dma, 0);
-			rq->last_dma = NULL;
-		}
-
-		dma->len = alloc_frag->size - sizeof(*dma);
-
-		addr = virtqueue_map_single_attrs(rq->vq, dma + 1,
-						  dma->len, DMA_FROM_DEVICE, 0);
-		if (virtqueue_map_mapping_error(rq->vq, addr))
-			return NULL;
-
-		dma->addr = addr;
-		dma->need_sync = virtqueue_map_need_sync(rq->vq, addr);
-
-		/* Add a reference to dma to prevent the entire dma from
-		 * being released during error handling. This reference
-		 * will be freed after the pages are no longer used.
-		 */
-		get_page(alloc_frag->page);
-		dma->ref = 1;
-		alloc_frag->offset = sizeof(*dma);
-
-		rq->last_dma = dma;
-	}
-
-	++dma->ref;
-
-	buf = head + alloc_frag->offset;
-
-	get_page(alloc_frag->page);
-	alloc_frag->offset += size;
-
-	return buf;
+	return virtqueue_get_buf_ctx(rq->vq, len, ctx);
 }
 
 static void virtnet_rq_unmap_free_buf(struct virtqueue *vq, void *buf)
@@ -1067,9 +949,6 @@ static void virtnet_rq_unmap_free_buf(struct virtqueue *vq, void *buf)
 		return;
 	}
 
-	if (!vi->big_packets || vi->mergeable_rx_bufs)
-		virtnet_rq_unmap(rq, buf, 0);
-
 	virtnet_rq_free_buf(vi, rq, buf);
 }
 
@@ -1335,7 +1214,7 @@ static int xsk_append_merge_buffer(struct virtnet_info *vi,
 
 		truesize = len;
 
-		curr_skb  = virtnet_skb_append_frag(head_skb, curr_skb, page,
+		curr_skb  = virtnet_skb_append_frag(rq, head_skb, curr_skb, page,
 						    buf, len, truesize);
 		if (!curr_skb) {
 			put_page(page);
@@ -1771,7 +1650,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
 	return ret;
 }
 
-static void put_xdp_frags(struct xdp_buff *xdp)
+static void put_xdp_frags(struct receive_queue *rq, struct xdp_buff *xdp)
 {
 	struct skb_shared_info *shinfo;
 	struct page *xdp_page;
@@ -1781,7 +1660,7 @@ static void put_xdp_frags(struct xdp_buff *xdp)
 		shinfo = xdp_get_shared_info_from_buff(xdp);
 		for (i = 0; i < shinfo->nr_frags; i++) {
 			xdp_page = skb_frag_page(&shinfo->frags[i]);
-			put_page(xdp_page);
+			page_pool_put_page(rq->page_pool, xdp_page, -1, true);
 		}
 	}
 }
@@ -1873,7 +1752,7 @@ static struct page *xdp_linearize_page(struct net_device *dev,
 	if (page_off + *len + tailroom > PAGE_SIZE)
 		return NULL;
 
-	page = alloc_page(GFP_ATOMIC);
+	page = page_pool_alloc_pages(rq->page_pool, GFP_ATOMIC);
 	if (!page)
 		return NULL;
 
@@ -1896,8 +1775,12 @@ static struct page *xdp_linearize_page(struct net_device *dev,
 		p = virt_to_head_page(buf);
 		off = buf - page_address(p);
 
+		if (rq->use_page_pool_dma)
+			page_pool_dma_sync_for_cpu(rq->page_pool, p,
+						   off, buflen);
+
 		if (check_mergeable_len(dev, ctx, buflen)) {
-			put_page(p);
+			page_pool_put_page(rq->page_pool, p, -1, true);
 			goto err_buf;
 		}
 
@@ -1905,38 +1788,36 @@ static struct page *xdp_linearize_page(struct net_device *dev,
 		 * is sending packet larger than the MTU.
 		 */
 		if ((page_off + buflen + tailroom) > PAGE_SIZE) {
-			put_page(p);
+			page_pool_put_page(rq->page_pool, p, -1, true);
 			goto err_buf;
 		}
 
 		memcpy(page_address(page) + page_off,
 		       page_address(p) + off, buflen);
 		page_off += buflen;
-		put_page(p);
+		page_pool_put_page(rq->page_pool, p, -1, true);
 	}
 
 	/* Headroom does not contribute to packet length */
 	*len = page_off - XDP_PACKET_HEADROOM;
 	return page;
 err_buf:
-	__free_pages(page, 0);
+	page_pool_put_page(rq->page_pool, page, -1, true);
 	return NULL;
 }
 
 static struct sk_buff *receive_small_build_skb(struct virtnet_info *vi,
 					       unsigned int xdp_headroom,
 					       void *buf,
-					       unsigned int len)
+					       unsigned int len,
+					       unsigned int buflen)
 {
 	unsigned int header_offset;
 	unsigned int headroom;
-	unsigned int buflen;
 	struct sk_buff *skb;
 
 	header_offset = VIRTNET_RX_PAD + xdp_headroom;
 	headroom = vi->hdr_len + header_offset;
-	buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) +
-		SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
 	skb = virtnet_build_skb(buf, buflen, headroom, len);
 	if (unlikely(!skb))
@@ -1955,6 +1836,7 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
 					 void *buf,
 					 unsigned int xdp_headroom,
 					 unsigned int len,
+					 unsigned int buflen,
 					 unsigned int *xdp_xmit,
 					 struct virtnet_rq_stats *stats)
 {
@@ -1963,7 +1845,6 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
 	struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset;
 	struct page *page = virt_to_head_page(buf);
 	struct page *xdp_page;
-	unsigned int buflen;
 	struct xdp_buff xdp;
 	struct sk_buff *skb;
 	unsigned int metasize = 0;
@@ -1976,9 +1857,6 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
 	if (unlikely(hdr->hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
 		goto err_xdp;
 
-	buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) +
-		SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
-
 	if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) {
 		int offset = buf - page_address(page) + header_offset;
 		unsigned int tlen = len + vi->hdr_len;
@@ -1996,7 +1874,7 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
 			goto err_xdp;
 
 		buf = page_address(xdp_page);
-		put_page(page);
+		page_pool_put_page(rq->page_pool, page, -1, true);
 		page = xdp_page;
 	}
 
@@ -2028,13 +1906,15 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev,
 	if (metasize)
 		skb_metadata_set(skb, metasize);
 
+	skb_mark_for_recycle(skb);
+
 	return skb;
 
 err_xdp:
 	u64_stats_inc(&stats->xdp_drops);
 err:
 	u64_stats_inc(&stats->drops);
-	put_page(page);
+	page_pool_put_page(rq->page_pool, page, -1, true);
 xdp_xmit:
 	return NULL;
 }
@@ -2047,7 +1927,8 @@ static struct sk_buff *receive_small(struct net_device *dev,
 				     unsigned int *xdp_xmit,
 				     struct virtnet_rq_stats *stats)
 {
-	unsigned int xdp_headroom = (unsigned long)ctx;
+	unsigned int xdp_headroom = mergeable_ctx_to_headroom(ctx);
+	unsigned int buflen = mergeable_ctx_to_truesize(ctx);
 	struct page *page = virt_to_head_page(buf);
 	struct sk_buff *skb;
 
@@ -2056,6 +1937,13 @@ static struct sk_buff *receive_small(struct net_device *dev,
 	 */
 	buf -= VIRTNET_RX_PAD + xdp_headroom;
 
+	if (rq->use_page_pool_dma) {
+		int offset = buf - page_address(page) +
+			     VIRTNET_RX_PAD + xdp_headroom;
+
+		page_pool_dma_sync_for_cpu(rq->page_pool, page, offset, len);
+	}
+
 	len -= vi->hdr_len;
 	u64_stats_add(&stats->bytes, len);
 
@@ -2073,21 +1961,23 @@ static struct sk_buff *receive_small(struct net_device *dev,
 		xdp_prog = rcu_dereference(rq->xdp_prog);
 		if (xdp_prog) {
 			skb = receive_small_xdp(dev, vi, rq, xdp_prog, buf,
-						xdp_headroom, len, xdp_xmit,
-						stats);
+						xdp_headroom, len, buflen,
+						xdp_xmit, stats);
 			rcu_read_unlock();
 			return skb;
 		}
 		rcu_read_unlock();
 	}
 
-	skb = receive_small_build_skb(vi, xdp_headroom, buf, len);
-	if (likely(skb))
+	skb = receive_small_build_skb(vi, xdp_headroom, buf, len, buflen);
+	if (likely(skb)) {
+		skb_mark_for_recycle(skb);
 		return skb;
+	}
 
 err:
 	u64_stats_inc(&stats->drops);
-	put_page(page);
+	page_pool_put_page(rq->page_pool, page, -1, true);
 	return NULL;
 }
 
@@ -2142,7 +2032,7 @@ static void mergeable_buf_free(struct receive_queue *rq, int num_buf,
 		}
 		u64_stats_add(&stats->bytes, len);
 		page = virt_to_head_page(buf);
-		put_page(page);
+		page_pool_put_page(rq->page_pool, page, -1, true);
 	}
 }
 
@@ -2252,8 +2142,12 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
 		page = virt_to_head_page(buf);
 		offset = buf - page_address(page);
 
+		if (rq->use_page_pool_dma)
+			page_pool_dma_sync_for_cpu(rq->page_pool, page,
+						   offset, len);
+
 		if (check_mergeable_len(dev, ctx, len)) {
-			put_page(page);
+			page_pool_put_page(rq->page_pool, page, -1, true);
 			goto err;
 		}
 
@@ -2272,7 +2166,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
 	return 0;
 
 err:
-	put_xdp_frags(xdp);
+	put_xdp_frags(rq, xdp);
 	return -EINVAL;
 }
 
@@ -2337,7 +2231,7 @@ static void *mergeable_xdp_get_buf(struct virtnet_info *vi,
 		if (*len + xdp_room > PAGE_SIZE)
 			return NULL;
 
-		xdp_page = alloc_page(GFP_ATOMIC);
+		xdp_page = page_pool_alloc_pages(rq->page_pool, GFP_ATOMIC);
 		if (!xdp_page)
 			return NULL;
 
@@ -2347,7 +2241,7 @@ static void *mergeable_xdp_get_buf(struct virtnet_info *vi,
 
 	*frame_sz = PAGE_SIZE;
 
-	put_page(*page);
+	page_pool_put_page(rq->page_pool, *page, -1, true);
 
 	*page = xdp_page;
 
@@ -2393,6 +2287,8 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
 		head_skb = build_skb_from_xdp_buff(dev, vi, &xdp, xdp_frags_truesz);
 		if (unlikely(!head_skb))
 			break;
+
+		skb_mark_for_recycle(head_skb);
 		return head_skb;
 
 	case XDP_TX:
@@ -2403,10 +2299,10 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
 		break;
 	}
 
-	put_xdp_frags(&xdp);
+	put_xdp_frags(rq, &xdp);
 
 err_xdp:
-	put_page(page);
+	page_pool_put_page(rq->page_pool, page, -1, true);
 	mergeable_buf_free(rq, num_buf, dev, stats);
 
 	u64_stats_inc(&stats->xdp_drops);
@@ -2414,7 +2310,8 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
 	return NULL;
 }
 
-static struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
+static struct sk_buff *virtnet_skb_append_frag(struct receive_queue *rq,
+					       struct sk_buff *head_skb,
 					       struct sk_buff *curr_skb,
 					       struct page *page, void *buf,
 					       int len, int truesize)
@@ -2429,6 +2326,9 @@ static struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
 		if (unlikely(!nskb))
 			return NULL;
 
+		if (head_skb->pp_recycle)
+			skb_mark_for_recycle(nskb);
+
 		if (curr_skb == head_skb)
 			skb_shinfo(curr_skb)->frag_list = nskb;
 		else
@@ -2446,7 +2346,10 @@ static struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
 
 	offset = buf - page_address(page);
 	if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
-		put_page(page);
+		if (head_skb->pp_recycle)
+			page_pool_put_page(rq->page_pool, page, -1, true);
+		else
+			put_page(page);
 		skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
 				     len, truesize);
 	} else {
@@ -2475,6 +2378,10 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	unsigned int headroom = mergeable_ctx_to_headroom(ctx);
 
 	head_skb = NULL;
+
+	if (rq->use_page_pool_dma)
+		page_pool_dma_sync_for_cpu(rq->page_pool, page, offset, len);
+
 	u64_stats_add(&stats->bytes, len - vi->hdr_len);
 
 	if (check_mergeable_len(dev, ctx, len))
@@ -2499,6 +2406,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 
 	if (unlikely(!curr_skb))
 		goto err_skb;
+
+	skb_mark_for_recycle(head_skb);
 	while (--num_buf) {
 		buf = virtnet_rq_get_buf(rq, &len, &ctx);
 		if (unlikely(!buf)) {
@@ -2513,11 +2422,17 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 		u64_stats_add(&stats->bytes, len);
 		page = virt_to_head_page(buf);
 
+		if (rq->use_page_pool_dma) {
+			offset = buf - page_address(page);
+			page_pool_dma_sync_for_cpu(rq->page_pool, page,
+						   offset, len);
+		}
+
 		if (check_mergeable_len(dev, ctx, len))
 			goto err_skb;
 
 		truesize = mergeable_ctx_to_truesize(ctx);
-		curr_skb  = virtnet_skb_append_frag(head_skb, curr_skb, page,
+		curr_skb  = virtnet_skb_append_frag(rq, head_skb, curr_skb, page,
 						    buf, len, truesize);
 		if (!curr_skb)
 			goto err_skb;
@@ -2527,7 +2442,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	return head_skb;
 
 err_skb:
-	put_page(page);
+	page_pool_put_page(rq->page_pool, page, -1, true);
 	mergeable_buf_free(rq, num_buf, dev, stats);
 
 err_buf:
@@ -2658,40 +2573,54 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 	virtnet_receive_done(vi, rq, skb, flags);
 }
 
-/* Unlike mergeable buffers, all buffers are allocated to the
- * same size, except for the headroom. For this reason we do
- * not need to use  mergeable_len_to_ctx here - it is enough
- * to store the headroom as the context ignoring the truesize.
+static int virtnet_rq_submit(struct receive_queue *rq, char *buf,
+			     int len, void *ctx, gfp_t gfp)
+{
+	if (rq->use_page_pool_dma) {
+		struct page *page = virt_to_head_page(buf);
+		dma_addr_t addr = page_pool_get_dma_addr(page) +
+				  (buf - (char *)page_address(page));
+
+		sg_init_table(rq->sg, 1);
+		sg_fill_dma(rq->sg, addr, len);
+		return virtqueue_add_inbuf_premapped(rq->vq, rq->sg, 1,
+						     buf, ctx, gfp);
+	}
+
+	sg_init_one(rq->sg, buf, len);
+	return virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
+}
+
+/* With page_pool, the actual allocation may exceed the requested size
+ * when the remaining page fragment can't fit another buffer. Encode
+ * the actual allocation size in ctx so build_skb() gets the correct
+ * buflen for truesize accounting.
  */
 static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
 			     gfp_t gfp)
 {
-	char *buf;
 	unsigned int xdp_headroom = virtnet_get_headroom(vi);
-	void *ctx = (void *)(unsigned long)xdp_headroom;
-	int len = vi->hdr_len + VIRTNET_RX_PAD + GOOD_PACKET_LEN + xdp_headroom;
+	unsigned int len = vi->hdr_len + VIRTNET_RX_PAD + GOOD_PACKET_LEN + xdp_headroom;
+	unsigned int alloc_len;
+	char *buf;
+	void *ctx;
 	int err;
 
 	len = SKB_DATA_ALIGN(len) +
 	      SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
-	if (unlikely(!skb_page_frag_refill(len, &rq->alloc_frag, gfp)))
-		return -ENOMEM;
-
-	buf = virtnet_rq_alloc(rq, len, gfp);
+	alloc_len = len;
+	buf = page_pool_alloc_va(rq->page_pool, &alloc_len, gfp);
 	if (unlikely(!buf))
 		return -ENOMEM;
 
 	buf += VIRTNET_RX_PAD + xdp_headroom;
 
-	virtnet_rq_init_one_sg(rq, buf, vi->hdr_len + GOOD_PACKET_LEN);
-
-	err = virtqueue_add_inbuf_premapped(rq->vq, rq->sg, 1, buf, ctx, gfp);
-	if (err < 0) {
-		virtnet_rq_unmap(rq, buf, 0);
-		put_page(virt_to_head_page(buf));
-	}
+	ctx = mergeable_len_to_ctx(alloc_len, xdp_headroom);
+	err = virtnet_rq_submit(rq, buf, vi->hdr_len + GOOD_PACKET_LEN, ctx, gfp);
 
+	if (err < 0)
+		page_pool_put_page(rq->page_pool, virt_to_head_page(buf), -1, false);
 	return err;
 }
 
@@ -2764,13 +2693,12 @@ static unsigned int get_mergeable_buf_len(struct receive_queue *rq,
 static int add_recvbuf_mergeable(struct virtnet_info *vi,
 				 struct receive_queue *rq, gfp_t gfp)
 {
-	struct page_frag *alloc_frag = &rq->alloc_frag;
 	unsigned int headroom = virtnet_get_headroom(vi);
 	unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
 	unsigned int room = SKB_DATA_ALIGN(headroom + tailroom);
-	unsigned int len, hole;
-	void *ctx;
+	unsigned int len, alloc_len;
 	char *buf;
+	void *ctx;
 	int err;
 
 	/* Extra tailroom is needed to satisfy XDP's assumption. This
@@ -2779,39 +2707,22 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
 	 */
 	len = get_mergeable_buf_len(rq, &rq->mrg_avg_pkt_len, room);
 
-	if (unlikely(!skb_page_frag_refill(len + room, alloc_frag, gfp)))
-		return -ENOMEM;
-
-	if (!alloc_frag->offset && len + room + sizeof(struct virtnet_rq_dma) > alloc_frag->size)
-		len -= sizeof(struct virtnet_rq_dma);
-
-	buf = virtnet_rq_alloc(rq, len + room, gfp);
+	alloc_len = len + room;
+	buf = page_pool_alloc_va(rq->page_pool, &alloc_len, gfp);
 	if (unlikely(!buf))
 		return -ENOMEM;
 
 	buf += headroom; /* advance address leaving hole at front of pkt */
-	hole = alloc_frag->size - alloc_frag->offset;
-	if (hole < len + room) {
-		/* To avoid internal fragmentation, if there is very likely not
-		 * enough space for another buffer, add the remaining space to
-		 * the current buffer.
-		 * XDP core assumes that frame_size of xdp_buff and the length
-		 * of the frag are PAGE_SIZE, so we disable the hole mechanism.
-		 */
-		if (!headroom)
-			len += hole;
-		alloc_frag->offset += hole;
-	}
 
-	virtnet_rq_init_one_sg(rq, buf, len);
+	if (!headroom)
+		len = alloc_len - room;
 
 	ctx = mergeable_len_to_ctx(len + room, headroom);
-	err = virtqueue_add_inbuf_premapped(rq->vq, rq->sg, 1, buf, ctx, gfp);
-	if (err < 0) {
-		virtnet_rq_unmap(rq, buf, 0);
-		put_page(virt_to_head_page(buf));
-	}
 
+	err = virtnet_rq_submit(rq, buf, len, ctx, gfp);
+
+	if (err < 0)
+		page_pool_put_page(rq->page_pool, virt_to_head_page(buf), -1, false);
 	return err;
 }
 
@@ -2963,7 +2874,7 @@ static int virtnet_receive_packets(struct virtnet_info *vi,
 	int packets = 0;
 	void *buf;
 
-	if (!vi->big_packets || vi->mergeable_rx_bufs) {
+	if (rq->page_pool) {
 		void *ctx;
 		while (packets < budget &&
 		       (buf = virtnet_rq_get_buf(rq, &len, &ctx))) {
@@ -3128,7 +3039,10 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
 		return err;
 
 	err = xdp_rxq_info_reg_mem_model(&vi->rq[qp_index].xdp_rxq,
-					 MEM_TYPE_PAGE_SHARED, NULL);
+					 vi->rq[qp_index].page_pool ?
+						MEM_TYPE_PAGE_POOL :
+						MEM_TYPE_PAGE_SHARED,
+					 vi->rq[qp_index].page_pool);
 	if (err < 0)
 		goto err_xdp_reg_mem_model;
 
@@ -3168,6 +3082,82 @@ static void virtnet_update_settings(struct virtnet_info *vi)
 		vi->duplex = duplex;
 }
 
+static int virtnet_create_page_pools(struct virtnet_info *vi)
+{
+	int i, err;
+
+	if (vi->big_packets && !vi->mergeable_rx_bufs)
+		return 0;
+
+	for (i = 0; i < vi->max_queue_pairs; i++) {
+		struct receive_queue *rq = &vi->rq[i];
+		struct page_pool_params pp_params = { 0 };
+		struct device *dma_dev;
+
+		if (rq->page_pool)
+			continue;
+
+		if (rq->xsk_pool)
+			continue;
+
+		pp_params.order = 0;
+		pp_params.pool_size = virtqueue_get_vring_size(rq->vq);
+		pp_params.nid = dev_to_node(vi->vdev->dev.parent);
+		pp_params.netdev = vi->dev;
+		pp_params.napi = &rq->napi;
+
+		/* Use page_pool DMA mapping if backend supports DMA API.
+		 * DMA_SYNC_DEV is needed for non-coherent archs on recycle.
+		 */
+		dma_dev = virtqueue_dma_dev(rq->vq);
+		if (dma_dev) {
+			pp_params.dev = dma_dev;
+			pp_params.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV;
+			pp_params.dma_dir = DMA_FROM_DEVICE;
+			pp_params.max_len = PAGE_SIZE;
+			pp_params.offset = 0;
+			rq->use_page_pool_dma = true;
+		} else {
+			/* No DMA API (e.g., VDUSE): page_pool for allocation only. */
+			pp_params.flags = 0;
+			rq->use_page_pool_dma = false;
+		}
+
+		rq->page_pool = page_pool_create(&pp_params);
+		if (IS_ERR(rq->page_pool)) {
+			err = PTR_ERR(rq->page_pool);
+			rq->page_pool = NULL;
+			goto err_cleanup;
+		}
+	}
+	return 0;
+
+err_cleanup:
+	while (--i >= 0) {
+		struct receive_queue *rq = &vi->rq[i];
+
+		if (rq->page_pool) {
+			page_pool_destroy(rq->page_pool);
+			rq->page_pool = NULL;
+		}
+	}
+	return err;
+}
+
+static void virtnet_destroy_page_pools(struct virtnet_info *vi)
+{
+	int i;
+
+	for (i = 0; i < vi->max_queue_pairs; i++) {
+		struct receive_queue *rq = &vi->rq[i];
+
+		if (rq->page_pool) {
+			page_pool_destroy(rq->page_pool);
+			rq->page_pool = NULL;
+		}
+	}
+}
+
 static int virtnet_open(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
@@ -5715,6 +5705,10 @@ static int virtnet_restore_up(struct virtio_device *vdev)
 	if (err)
 		return err;
 
+	err = virtnet_create_page_pools(vi);
+	if (err)
+		goto err_del_vqs;
+
 	virtio_device_ready(vdev);
 
 	enable_rx_mode_work(vi);
@@ -5724,12 +5718,24 @@ static int virtnet_restore_up(struct virtio_device *vdev)
 		err = virtnet_open(vi->dev);
 		rtnl_unlock();
 		if (err)
-			return err;
+			goto err_destroy_pools;
 	}
 
 	netif_tx_lock_bh(vi->dev);
 	netif_device_attach(vi->dev);
 	netif_tx_unlock_bh(vi->dev);
+	return 0;
+
+err_destroy_pools:
+	virtio_reset_device(vdev);
+	free_unused_bufs(vi);
+	virtnet_destroy_page_pools(vi);
+	virtnet_del_vqs(vi);
+	return err;
+
+err_del_vqs:
+	virtio_reset_device(vdev);
+	virtnet_del_vqs(vi);
 	return err;
 }
 
@@ -5857,7 +5863,7 @@ static int virtnet_xsk_pool_enable(struct net_device *dev,
 	/* In big_packets mode, xdp cannot work, so there is no need to
 	 * initialize xsk of rq.
 	 */
-	if (vi->big_packets && !vi->mergeable_rx_bufs)
+	if (!vi->rq[qid].page_pool)
 		return -ENOENT;
 
 	if (qid >= vi->curr_queue_pairs)
@@ -6287,17 +6293,6 @@ static void free_receive_bufs(struct virtnet_info *vi)
 	rtnl_unlock();
 }
 
-static void free_receive_page_frags(struct virtnet_info *vi)
-{
-	int i;
-	for (i = 0; i < vi->max_queue_pairs; i++)
-		if (vi->rq[i].alloc_frag.page) {
-			if (vi->rq[i].last_dma)
-				virtnet_rq_unmap(&vi->rq[i], vi->rq[i].last_dma, 0);
-			put_page(vi->rq[i].alloc_frag.page);
-		}
-}
-
 static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
 {
 	struct virtnet_info *vi = vq->vdev->priv;
@@ -6401,7 +6396,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 	vqs_info = kzalloc_objs(*vqs_info, total_vqs);
 	if (!vqs_info)
 		goto err_vqs_info;
-	if (!vi->big_packets || vi->mergeable_rx_bufs) {
+	if (vi->mergeable_rx_bufs || !vi->big_packets) {
 		ctx = kzalloc_objs(*ctx, total_vqs);
 		if (!ctx)
 			goto err_ctx;
@@ -6441,10 +6436,8 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 		vi->rq[i].min_buf_len = mergeable_min_buf_len(vi, vi->rq[i].vq);
 		vi->sq[i].vq = vqs[txq2vq(i)];
 	}
-
 	/* run here: ret == 0. */
 
-
 err_find:
 	kfree(ctx);
 err_ctx:
@@ -6945,6 +6938,14 @@ static int virtnet_probe(struct virtio_device *vdev)
 			goto free;
 	}
 
+	/* Create page pools for receive queues.
+	 * Page pools are created at probe time so they can be used
+	 * with premapped DMA addresses throughout the device lifetime.
+	 */
+	err = virtnet_create_page_pools(vi);
+	if (err)
+		goto free_irq_moder;
+
 #ifdef CONFIG_SYSFS
 	if (vi->mergeable_rx_bufs)
 		dev->sysfs_rx_queue_group = &virtio_net_mrg_rx_group;
@@ -6958,7 +6959,7 @@ static int virtnet_probe(struct virtio_device *vdev)
 		vi->failover = net_failover_create(vi->dev);
 		if (IS_ERR(vi->failover)) {
 			err = PTR_ERR(vi->failover);
-			goto free_vqs;
+			goto free_page_pools;
 		}
 	}
 
@@ -7075,9 +7076,11 @@ static int virtnet_probe(struct virtio_device *vdev)
 	unregister_netdev(dev);
 free_failover:
 	net_failover_destroy(vi->failover);
-free_vqs:
+free_page_pools:
+	virtnet_destroy_page_pools(vi);
+free_irq_moder:
+	virtnet_free_irq_moder(vi);
 	virtio_reset_device(vdev);
-	free_receive_page_frags(vi);
 	virtnet_del_vqs(vi);
 free:
 	free_netdev(dev);
@@ -7102,7 +7105,7 @@ static void remove_vq_common(struct virtnet_info *vi)
 
 	free_receive_bufs(vi);
 
-	free_receive_page_frags(vi);
+	virtnet_destroy_page_pools(vi);
 
 	virtnet_del_vqs(vi);
 }
-- 
2.52.0


^ permalink raw reply related	[flat|nested] 21+ messages in thread
end of thread, other threads:[~2026-03-24  8:20 UTC | newest]

Thread overview: 21+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-03-10 18:31 [PATCH net-next v11] virtio_net: add page_pool support for buffer allocation Vishwanath Seshagiri
2026-03-13  7:51 ` Jason Wang
2026-03-13  9:26   ` Vishwanath Seshagiri
2026-03-16  7:41     ` Jason Wang
2026-03-13 16:50   ` Vishwanath Seshagiri
2026-03-16  7:35     ` Jason Wang
2026-03-16  9:56 ` Michael S. Tsirkin
2026-03-16 10:43   ` Michael S. Tsirkin
2026-03-16 11:57     ` Vishwanath Seshagiri
2026-03-16 12:04       ` Michael S. Tsirkin
2026-03-17  2:30 ` patchwork-bot+netdevbpf
2026-03-23 15:01 ` Omar Elghoul
2026-03-23 15:52   ` Michael S. Tsirkin
2026-03-23 16:54     ` Omar Elghoul
2026-03-23 17:10       ` Michael S. Tsirkin
2026-03-23 16:58     ` Michael S. Tsirkin
2026-03-23 17:09       ` Omar Elghoul
2026-03-23 17:50         ` Vishwanath Seshagiri
2026-03-23 23:37           ` Michael S. Tsirkin
2026-03-24  0:34       ` Jason Wang
2026-03-24  8:20       ` Aithal, Srikanth

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