From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) (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 CD08E249F5; Fri, 28 Jun 2024 05:48:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719553738; cv=none; b=TqLvAsWRoDCL9CXHXjFfOk+k8/G4+Bo/N4I5d7JEgKnZvl+HznwyLmCtEOSS7EC9Vc/ovYK3BqPfrrtl8R21Jl+/c9LZHmH2qgz0JC1NfWaSqqhCO/27c1mHunO2Rmazy7Yv3owGcqhBSRcwhUunR5PxzkTxbtcl76cw6Au1afk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719553738; c=relaxed/simple; bh=PtCasXHAOvOMRVdKF/jW/oHN2QvRGkd1J0RH+6x7KJI=; h=Message-ID:Subject:Date:From:To:Cc:References:In-Reply-To: Content-Type; b=u1NvicS0WyRlVaGG/CAPzWhqMAKMYI8juCmPenVeV9jWUd+M/ASm39sNuQK4bqWQCxp7weHBxIy5Ra0U9cnId+aLmAVCj0IV2A+Optj3YC7tLSLan5aMBtHFLDQJVhdQF/SWLHnJCTb3UWX2JCUYQ4OBJp0grMmfV0ZFBvqsJ7Q= 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=fPojHIyj; arc=none smtp.client-ip=115.124.30.133 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="fPojHIyj" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1719553728; h=Message-ID:Subject:Date:From:To:Content-Type; bh=VAHDm7tteOsh7ipE/Q1oWmZbyzYSsMR/7oUjqzklIwQ=; b=fPojHIyj3cow5iEGOb21prP3PK79lXl+T9UwDRRrRa5L9kjAi7Sg5PF3SNhxLYHzJbAAZGjQyZvxLr+rfmCRMqieyh0o0RYgit8VL65OlHUVeoKXLhMJNy2HMzDNi6rFdreOWiR6b4DKdUuga6W+XzmVpm7SC06nyKbud29Y3YY= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R791e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037067112;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=14;SR=0;TI=SMTPD_---0W9PEpy1_1719553727; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0W9PEpy1_1719553727) by smtp.aliyun-inc.com; Fri, 28 Jun 2024 13:48:47 +0800 Message-ID: <1719553452.932589-3-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH net-next v6 08/10] virtio_net: xsk: rx: support recv small mode Date: Fri, 28 Jun 2024 13:44:12 +0800 From: Xuan Zhuo To: Jason Wang Cc: netdev@vger.kernel.org, "Michael S. Tsirkin" , =?utf-8?q?Eugenio_P=C3=A9rez?= , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , virtualization@lists.linux.dev, bpf@vger.kernel.org References: <20240618075643.24867-1-xuanzhuo@linux.alibaba.com> <20240618075643.24867-9-xuanzhuo@linux.alibaba.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: On Fri, 28 Jun 2024 10:19:41 +0800, Jason Wang wrote: > On Tue, Jun 18, 2024 at 3:57=E2=80=AFPM Xuan Zhuo wrote: > > > > In the process: > > 1. We may need to copy data to create skb for XDP_PASS. > > 2. We may need to call xsk_buff_free() to release the buffer. > > 3. The handle for xdp_buff is difference from the buffer. > > > > If we pushed this logic into existing receive handle(merge and small), > > we would have to maintain code scattered inside merge and small (and bi= g). > > So I think it is a good choice for us to put the xsk code into an > > independent function. > > I think it's better to try to reuse the existing functions. > > More below: > > > > > Signed-off-by: Xuan Zhuo > > --- > > drivers/net/virtio_net.c | 135 ++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 133 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index 2ac5668a94ce..06608d696e2e 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -500,6 +500,10 @@ struct virtio_net_common_hdr { > > }; > > > > static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf= ); > > +static int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_b= uff *xdp, > > + struct net_device *dev, > > + unsigned int *xdp_xmit, > > + struct virtnet_rq_stats *stats); > > > > static bool is_xdp_frame(void *ptr) > > { > > @@ -1040,6 +1044,120 @@ static void sg_fill_dma(struct scatterlist *sg,= dma_addr_t addr, u32 len) > > sg->length =3D len; > > } > > > > +static struct xdp_buff *buf_to_xdp(struct virtnet_info *vi, > > + struct receive_queue *rq, void *buf,= u32 len) > > +{ > > + struct xdp_buff *xdp; > > + u32 bufsize; > > + > > + xdp =3D (struct xdp_buff *)buf; > > + > > + bufsize =3D xsk_pool_get_rx_frame_size(rq->xsk.pool) + vi->hdr_= len; > > + > > + if (unlikely(len > bufsize)) { > > + pr_debug("%s: rx error: len %u exceeds truesize %u\n", > > + vi->dev->name, len, bufsize); > > + DEV_STATS_INC(vi->dev, rx_length_errors); > > + xsk_buff_free(xdp); > > + return NULL; > > + } > > + > > + xsk_buff_set_size(xdp, len); > > + xsk_buff_dma_sync_for_cpu(xdp); > > + > > + return xdp; > > +} > > + > > +static struct sk_buff *xdp_construct_skb(struct receive_queue *rq, > > + struct xdp_buff *xdp) > > +{ > > So we have a similar caller which is receive_small_build_skb(). Any > chance to reuse that? receive_small_build_skb works with build_skb. Here we need to copy the packet from the xsk buffer to the skb buffer. So I do not think we can reuse it. > > > + unsigned int metasize =3D xdp->data - xdp->data_meta; > > + struct sk_buff *skb; > > + unsigned int size; > > + > > + size =3D xdp->data_end - xdp->data_hard_start; > > + skb =3D napi_alloc_skb(&rq->napi, size); > > + if (unlikely(!skb)) { > > + xsk_buff_free(xdp); > > + return NULL; > > + } > > + > > + skb_reserve(skb, xdp->data_meta - xdp->data_hard_start); > > + > > + size =3D xdp->data_end - xdp->data_meta; > > + memcpy(__skb_put(skb, size), xdp->data_meta, size); > > + > > + if (metasize) { > > + __skb_pull(skb, metasize); > > + skb_metadata_set(skb, metasize); > > + } > > + > > + xsk_buff_free(xdp); > > + > > + return skb; > > +} > > + > > +static struct sk_buff *virtnet_receive_xsk_small(struct net_device *de= v, struct virtnet_info *vi, > > + struct receive_queue *= rq, struct xdp_buff *xdp, > > + unsigned int *xdp_xmit, > > + struct virtnet_rq_stat= s *stats) > > +{ > > + struct bpf_prog *prog; > > + u32 ret; > > + > > + ret =3D XDP_PASS; > > + rcu_read_lock(); > > + prog =3D rcu_dereference(rq->xdp_prog); > > + if (prog) > > + ret =3D virtnet_xdp_handler(prog, xdp, dev, xdp_xmit, s= tats); > > + rcu_read_unlock(); > > + > > + switch (ret) { > > + case XDP_PASS: > > + return xdp_construct_skb(rq, xdp); > > + > > + case XDP_TX: > > + case XDP_REDIRECT: > > + return NULL; > > + > > + default: > > + /* drop packet */ > > + xsk_buff_free(xdp); > > + u64_stats_inc(&stats->drops); > > + return NULL; > > + } > > +} > > + > > +static struct sk_buff *virtnet_receive_xsk_buf(struct virtnet_info *vi= , struct receive_queue *rq, > > + void *buf, u32 len, > > + unsigned int *xdp_xmit, > > + struct virtnet_rq_stats = *stats) > > +{ > > + struct net_device *dev =3D vi->dev; > > + struct sk_buff *skb =3D NULL; > > + struct xdp_buff *xdp; > > + > > + len -=3D vi->hdr_len; > > + > > + u64_stats_add(&stats->bytes, len); > > + > > + xdp =3D buf_to_xdp(vi, rq, buf, len); > > + if (!xdp) > > + return NULL; > > + > > + if (unlikely(len < ETH_HLEN)) { > > + pr_debug("%s: short packet %i\n", dev->name, len); > > + DEV_STATS_INC(dev, rx_length_errors); > > + xsk_buff_free(xdp); > > + return NULL; > > + } > > + > > + if (!vi->mergeable_rx_bufs) > > + skb =3D virtnet_receive_xsk_small(dev, vi, rq, xdp, xdp= _xmit, stats); > > + > > + return skb; > > +} > > + > > static int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct rec= eive_queue *rq, > > struct xsk_buff_pool *pool, gfp_t gf= p) > > { > > @@ -2363,9 +2481,22 @@ static int virtnet_receive(struct receive_queue = *rq, int budget, > > void *buf; > > int i; > > > > - if (!vi->big_packets || vi->mergeable_rx_bufs) { > > - void *ctx; > > + if (rq->xsk.pool) { > > + struct sk_buff *skb; > > + > > + while (packets < budget) { > > + buf =3D virtqueue_get_buf(rq->vq, &len); > > + if (!buf) > > + break; > > > > + skb =3D virtnet_receive_xsk_buf(vi, rq, buf, le= n, xdp_xmit, &stats); > > + if (skb) > > + virtnet_receive_done(vi, rq, skb); > > + > > + packets++; > > + } > > If reusing turns out to be hard, I'd rather add new paths in receive_smal= l(). The exist function is called after virtnet_rq_get_buf(), that will do dma u= nmap. But for xsk, the dma unmap is not need. So xsk receive handle should use virtqueue_get_buf directly. Thanks. > > > + } else if (!vi->big_packets || vi->mergeable_rx_bufs) { > > + void *ctx; > > while (packets < budget && > > (buf =3D virtnet_rq_get_buf(rq, &len, &ctx))) { > > receive_buf(vi, rq, buf, len, ctx, xdp_xmit, &s= tats); > > -- > > 2.32.0.3.g01195cf9f > > > > Thanks >