From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-101.freemail.mail.aliyun.com (out30-101.freemail.mail.aliyun.com [115.124.30.101]) (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 2E8D52C6BB; Mon, 1 Jul 2024 08:34:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.101 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719822853; cv=none; b=sw+mF4YYwNH3KmGxe4/v+gf1F2QD/fuPlipF12F5n2Tmx+iR7thnDMDkr552ktAtBPFY+nQ6CznPRO6PsT0558eXsochFuvh/alHF6dY1Ddzu56X9TxL4sdIe2JhF5Bl/qCqQUMe+W62iPS+zha79mASdDgC3JvqMqkjdLVVf5s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719822853; c=relaxed/simple; bh=SmGnTvi342t5TCdhjNotrThgx8/jX4Rp7taYTTQ1w6o=; h=Message-ID:Subject:Date:From:To:Cc:References:In-Reply-To: Content-Type; b=FCKYZNuUtnWv82BbtrUBMpf4hYrJa9s+QuEpeV0dAxlycJ6MXIXlI0gHF3SwdhRCBFSEok3BMJN+KoAhnvLSQ4JubtAvQfW6CBtvbg3twEHVt0yW3jSM5tm2ZgElAo9PqQIyrdzWTIVUuS85HVA36VVBtjn/kO3AYjOi1t5g6F4= 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=Re9Nxr3K; arc=none smtp.client-ip=115.124.30.101 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="Re9Nxr3K" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1719822847; h=Message-ID:Subject:Date:From:To:Content-Type; bh=MsAbrXcJVgnrPuf5AVodtEAEdIJ5iFRLnptm0WXC8VA=; b=Re9Nxr3KH6KgDU605KuQBKGZ0tmiDF7HosGVQ5gBs1XQVM94Igal94H9WHkgw8Ha6vG9VFO+ToKtORImFvLbuAqVnaE6IjJ9gVrU6jpl0mvf1EV7Dk2YkqIcZOhng2PQOETmA4uIKJ54NUa6at9AD5uRnekI7f6B5Gnzok0D4/Q= 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-contentspam033045075189;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=14;SR=0;TI=SMTPD_---0W9cLjqx_1719822846; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0W9cLjqx_1719822846) by smtp.aliyun-inc.com; Mon, 01 Jul 2024 16:34:06 +0800 Message-ID: <1719822753.9386358-1-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH net-next v6 08/10] virtio_net: xsk: rx: support recv small mode Date: Mon, 1 Jul 2024 16:32:33 +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> <1719553452.932589-3-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 Mon, 1 Jul 2024 11:25:37 +0800, Jason Wang wrote: > On Mon, Jul 1, 2024 at 11:20=E2=80=AFAM Jason Wang = wrote: > > > > On Fri, Jun 28, 2024 at 1:48=E2=80=AFPM Xuan Zhuo wrote: > > > > > > 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 sm= all), > > > > > we would have to maintain code scattered inside merge and small (= and big). > > > > > 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, voi= d *buf); > > > > > +static int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct= xdp_buff *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 scatterlis= t *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 *r= q, > > > > > + 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. > > > > RIght. > > > > > > > > Here we need to copy the packet from the xsk buffer to the skb buffer. > > > So I do not think we can reuse it. > > > > > > > Let's rename this to xsk_construct_skb() ? > > > > > > > > > > > > > > + 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_devi= ce *dev, struct virtnet_info *vi, > > > > > + struct receive_q= ueue *rq, struct xdp_buff *xdp, > > > > > + unsigned int *xd= p_xmit, > > > > > + struct virtnet_r= q_stats *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_x= mit, stats); > > > > > + 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_in= fo *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, xd= p, xdp_xmit, stats); > > > > > + > > > > > + return skb; > > > > > +} > > > > > + > > > > > static int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, stru= ct receive_queue *rq, > > > > > struct xsk_buff_pool *pool, gf= p_t gfp) > > > > > { > > > > > @@ -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, b= uf, len, 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 receiv= e_small(). > > > > > > The exist function is called after virtnet_rq_get_buf(), that will do= dma unmap. > > > But for xsk, the dma unmap is not need. So xsk receive handle should = use > > > virtqueue_get_buf directly. > > > > Probably but if it's just virtnet_rq_get_buf() we can simply did: > > > > static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, voi= d **ctx) > > { > > void *buf; > > > > buf =3D virtqueue_get_buf_ctx(rq->vq, len, ctx); > > if (buf && rq->xsk.pool) > > virtnet_rq_unmap(rq, buf, *len); > > > > return buf; > > } > > Or maybe it would be much more clearer if we did: > > static int virtnet_receive() > { > > if (rq->xsk.pool) > virtnet_receive_xsk() > else > virtnet_receive_xxx() > ... > } I like this. Thanks. > > Thanks > > > > > Thanks > > > > > > > > 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_xm= it, &stats); > > > > > -- > > > > > 2.32.0.3.g01195cf9f > > > > > > > > > > > > > Thanks > > > > > > > >