From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-124.freemail.mail.aliyun.com (out30-124.freemail.mail.aliyun.com [115.124.30.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D0CD8304BDF; Mon, 9 Feb 2026 07:23:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770621789; cv=none; b=MJJ063mVeHF9JShX8rU7uydwlKQErirscvfmTpPwXskmvmVCGGazMUeGzt686VD6A+WK4uGUa+0oeZjRIiijp2ToWFafuhJMdJVJO6QFOe+6IWWSey0khhqe7VttNBIoIsWc6fnS2fJdWyl/ww2LTX6r6MdK4nHqsWXe4vydPqU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770621789; c=relaxed/simple; bh=vIQLA3sS3Q8T657Wn0NL0pbZbcsNnHudQmQtUPiqBqQ=; h=Message-ID:Subject:Date:From:To:Cc:References:In-Reply-To; b=B37viox7/MAV+wS29vsCJ+06XqMN4FNepSdrFE4/cAgiEJpm1NYOIw7vJ1RjdEH9UvhZM1atY8QAhMvZ3O7Ls6cDtJjd65UrBDy8WRPASXU3TplwB03/FJ/93AXTvT7iyuQTERd81ywVfszav1vOi7v95mf1SpenrI9NVhifwVw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=x6J+VHcX; arc=none smtp.client-ip=115.124.30.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="x6J+VHcX" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1770621785; h=Message-ID:Subject:Date:From:To; bh=uyrZHl4yXGp1b0tNQYO2Yd01r2hjapk+KZmPRyq4nY8=; b=x6J+VHcXIUzq1GpByPBmS3OzHvob2rwz8k5wps2hR17vGXEF6hX20PUOolf9d28oXxl3ankp7sF6crb29cmHWOD4jpCO/fEAbseHShGruaro+a2LABvxUP6Z61qF4pZWu6d2gSqLy3/OHNdZfqapF7m+vaPd5HNM4gkZchFXxV4= Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0Wyp2zp5_1770621783 cluster:ay36) by smtp.aliyun-inc.com; Mon, 09 Feb 2026 15:23:03 +0800 Message-ID: <1770621144.341019-1-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH v6] virtio_net: add page_pool support for buffer allocation Date: Mon, 9 Feb 2026 15:12:24 +0800 From: Xuan Zhuo To: Vishwanath Seshagiri Cc: =?utf-8?q?Eugenio_P=C3=A9rez?= , Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , David Wei , Matteo Croce , Ilias Apalodimas , netdev@vger.kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, kernel-team@meta.com, "Michael S . Tsirkin" , Jason Wang References: <20260208175410.1910001-1-vishs@meta.com> <1770602432.6451533-1-xuanzhuo@linux.alibaba.com> In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: On Sun, 8 Feb 2026 18:42:26 -0800, Vishwanath Seshagiri wrote: > On 2/8/26 6:00 PM, Xuan Zhuo wrote: > > On Sun, 8 Feb 2026 09:54:10 -0800, Vishwanath Seshagiri wrote: > >> 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 > >> --- > >> 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 | 434 +++++++++++++++++++-------------------- > >> 2 files changed, 217 insertions(+), 218 deletions(-) > >> > >> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig > >> index ac12eaf11755..f1e6b6b0a86f 100644 > >> --- a/drivers/net/Kconfig > >> +++ b/drivers/net/Kconfig > >> @@ -450,6 +450,7 @@ 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 db88dcaefb20..5055df56e4a7 100644 > >> --- a/drivers/net/virtio_net.c > >> +++ b/drivers/net/virtio_net.c > >> @@ -26,6 +26,7 @@ > >> #include > >> #include > >> #include > >> +#include > >> > >> 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 +513,13 @@ 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); > >> > >> enum virtnet_xmit_type { > >> VIRTNET_XMIT_TYPE_SKB, > >> @@ -706,15 +700,24 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask) > >> return p; > >> } > >> > >> +static void virtnet_put_page(struct receive_queue *rq, struct page *page, > >> + bool allow_direct) > >> +{ > >> + if (page_pool_page_is_pp(page)) > >> + page_pool_put_page(rq->page_pool, page, -1, allow_direct); > >> + else > >> + put_page(page); > >> +} > > > > Why we need this? > > For the caller, we should know which one should be used? > > > > This was after some feedback to unify the alloc/free path checks in v4. > But you raise a valid point - callers already know the mode via > virtnet_no_page_pool(). I can simplify this to just call > page_pool_put_page() directly, since virtnet_put_page() is only called > from paths that already checked we're using page_pool. Would you prefer > that? Based on my understanding, the big mode should directly call the Page API, while all other modes should directly call the PP API. Therefore, I believe it's better for each mode to directly invoke its respective API. > > > > > >> + > >> 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)); > >> + virtnet_put_page(rq, virt_to_head_page(buf), false); > >> else if (vi->big_packets) > >> give_pages(rq, buf); > >> else > >> - put_page(virt_to_head_page(buf)); > >> + virtnet_put_page(rq, virt_to_head_page(buf), false); > >> } > >> > >> static void enable_rx_mode_work(struct virtnet_info *vi) > >> @@ -876,10 +879,16 @@ 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 (vi->big_packets && !vi->mergeable_rx_bufs) { > >> + 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 +934,18 @@ 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); > >> + virtnet_put_page(rq, page_to_free, 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); > >> > >> - 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 +961,6 @@ 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 +1226,7 @@ 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 +1662,7 @@ 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 +1672,7 @@ 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); > >> + virtnet_put_page(rq, xdp_page, true); > >> } > >> } > >> } > >> @@ -1873,7 +1764,7 @@ 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; > >> > >> @@ -1897,7 +1788,7 @@ static struct page *xdp_linearize_page(struct net_device *dev, > >> off = buf - page_address(p); > >> > >> if (check_mergeable_len(dev, ctx, buflen)) { > >> - put_page(p); > >> + virtnet_put_page(rq, p, true); > >> goto err_buf; > >> } > >> > >> @@ -1905,21 +1796,21 @@ 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); > >> + virtnet_put_page(rq, p, true); > >> goto err_buf; > >> } > >> > >> memcpy(page_address(page) + page_off, > >> page_address(p) + off, buflen); > >> page_off += buflen; > >> - put_page(p); > >> + virtnet_put_page(rq, p, 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; > >> } > >> > >> @@ -1969,6 +1860,12 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev, > >> unsigned int metasize = 0; > >> u32 act; > >> > >> + if (rq->use_page_pool_dma) { > >> + int off = buf - page_address(page); > >> + > >> + page_pool_dma_sync_for_cpu(rq->page_pool, page, off, len); > >> + } > >> + > >> if (unlikely(hdr->hdr.gso_type)) > >> goto err_xdp; > >> > >> @@ -1996,7 +1893,7 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev, > >> goto err_xdp; > >> > >> buf = page_address(xdp_page); > >> - put_page(page); > >> + virtnet_put_page(rq, page, true); > >> page = xdp_page; > >> } > >> > >> @@ -2028,13 +1925,15 @@ 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); > >> + virtnet_put_page(rq, page, true); > >> xdp_xmit: > >> return NULL; > >> } > >> @@ -2056,6 +1955,12 @@ 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); > >> + > >> + page_pool_dma_sync_for_cpu(rq->page_pool, page, offset, len); > >> + } > >> + > >> len -= vi->hdr_len; > >> u64_stats_add(&stats->bytes, len); > >> > >> @@ -2082,12 +1987,14 @@ static struct sk_buff *receive_small(struct net_device *dev, > >> } > >> > >> skb = receive_small_build_skb(vi, xdp_headroom, buf, len); > >> - if (likely(skb)) > >> + if (likely(skb)) { > >> + skb_mark_for_recycle(skb); > >> return skb; > >> + } > >> > >> err: > >> u64_stats_inc(&stats->drops); > >> - put_page(page); > >> + virtnet_put_page(rq, page, true); > >> return NULL; > >> } > >> > >> @@ -2142,7 +2049,7 @@ 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); > >> + virtnet_put_page(rq, page, true); > >> } > >> } > >> > >> @@ -2253,7 +2160,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev, > >> offset = buf - page_address(page); > >> > >> if (check_mergeable_len(dev, ctx, len)) { > >> - put_page(page); > >> + virtnet_put_page(rq, page, true); > >> goto err; > >> } > >> > >> @@ -2272,7 +2179,7 @@ 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 +2244,7 @@ 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 +2254,7 @@ static void *mergeable_xdp_get_buf(struct virtnet_info *vi, > >> > >> *frame_sz = PAGE_SIZE; > >> > >> - put_page(*page); > >> + virtnet_put_page(rq, *page, true); > >> > >> *page = xdp_page; > >> > >> @@ -2393,6 +2300,8 @@ 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 +2312,10 @@ 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); > >> + virtnet_put_page(rq, page, true); > >> mergeable_buf_free(rq, num_buf, dev, stats); > >> > >> u64_stats_inc(&stats->xdp_drops); > >> @@ -2414,7 +2323,8 @@ 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) > >> @@ -2446,7 +2356,7 @@ 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); > >> + virtnet_put_page(rq, page, true); > >> skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1, > >> len, truesize); > >> } else { > >> @@ -2475,6 +2385,10 @@ 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 +2413,8 @@ 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)) { > >> @@ -2517,7 +2433,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > >> 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 +2443,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > >> return head_skb; > >> > >> err_skb: > >> - put_page(page); > >> + virtnet_put_page(rq, page, true); > >> mergeable_buf_free(rq, num_buf, dev, stats); > >> > >> err_buf: > >> @@ -2666,32 +2582,41 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, > >> 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; > >> + struct page *page; > >> + dma_addr_t addr; > >> + char *buf; > >> 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); > >> + buf = page_pool_alloc_va(rq->page_pool, &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); > >> + if (rq->use_page_pool_dma) { > >> + page = virt_to_head_page(buf); > >> + addr = page_pool_get_dma_addr(page) + > >> + (buf - (char *)page_address(page)); > >> > >> - 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)); > >> + sg_init_table(rq->sg, 1); > >> + sg_fill_dma(rq->sg, addr, vi->hdr_len + GOOD_PACKET_LEN); > >> + err = virtqueue_add_inbuf_premapped(rq->vq, rq->sg, 1, > >> + buf, ctx, gfp); > >> + } else { > >> + sg_init_one(rq->sg, buf, vi->hdr_len + GOOD_PACKET_LEN); > >> + err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, > >> + buf, ctx, gfp); > >> } > >> > >> + if (err < 0) > >> + page_pool_put_page(rq->page_pool, virt_to_head_page(buf), > >> + -1, false); > >> return err; > >> } > >> > >> @@ -2764,13 +2689,14 @@ 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; > >> + struct page *page; > >> + dma_addr_t addr; > >> char *buf; > >> + void *ctx; > >> int err; > >> > >> /* Extra tailroom is needed to satisfy XDP's assumption. This > >> @@ -2779,39 +2705,36 @@ 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)); > >> + > >> + if (rq->use_page_pool_dma) { > >> + page = virt_to_head_page(buf); > >> + 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); > >> + err = virtqueue_add_inbuf_premapped(rq->vq, rq->sg, 1, > >> + buf, ctx, gfp); > >> + } else { > >> + sg_init_one(rq->sg, buf, len); > >> + err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, > >> + buf, ctx, gfp); > >> } > >> > >> + if (err < 0) > >> + page_pool_put_page(rq->page_pool, virt_to_head_page(buf), > >> + -1, false); > >> return err; > >> } > >> > >> @@ -3128,7 +3051,10 @@ 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 +3094,81 @@ 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->mergeable_rx_bufs && vi->big_packets) > >> + 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; > >> + > >> + /* Check if backend supports DMA API (e.g., vhost, virtio-pci). > >> + * If so, use page_pool's DMA mapping for premapped buffers. > >> + * Otherwise (e.g., VDUSE), page_pool only handles allocation. > >> + */ > >> + dma_dev = virtqueue_dma_dev(rq->vq); > >> + if (dma_dev) { > >> + pp_params.dev = dma_dev; > >> + pp_params.flags = PP_FLAG_DMA_MAP; > >> + pp_params.dma_dir = DMA_FROM_DEVICE; > >> + rq->use_page_pool_dma = true; > >> + } else { > >> + pp_params.dev = vi->vdev->dev.parent; > >> + pp_params.flags = 0; > >> + rq->use_page_pool_dma = false; > > > > Can the page pool handles dma with vi->vdev->dev.parent? > > No, we cannot use the page_pool DMA with vi->vdev->dev.parent in VDUSE > case because VDUSE uses its own address translation. virtqueue_dma_dev() > returns NULL, virtio doesn't use standard DMA API at all. Now that I > think about it, setting pp_params.dev in this branch is unnecessary > since it is never accessed. I can remove it, if you prefer. If that's the case, then it is indeed a bit troublesome. I don't know if VDUSE has a better solution. What I don't like is use_page_pool_dma -- it introduces many branches into the code, making it more chaotic. We may need to look for a better unified solution. Thanks. > > > > > > Thanks. > > > >> + } > >> + > >> + 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); > >> @@ -6287,17 +6288,6 @@ 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; > >> @@ -6441,10 +6431,8 @@ 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 +6933,14 @@ 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 +6954,7 @@ 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 +7071,11 @@ 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 +7100,7 @@ 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); > >> } > >> -- > >> 2.47.3 > >> >