From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4525AC3F2CD for ; Mon, 2 Mar 2020 15:29:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 18F022084E for ; Mon, 2 Mar 2020 15:29:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727142AbgCBP3p (ORCPT ); Mon, 2 Mar 2020 10:29:45 -0500 Received: from mx2.suse.de ([195.135.220.15]:55388 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726751AbgCBP3o (ORCPT ); Mon, 2 Mar 2020 10:29:44 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 96E2CAFE8; Mon, 2 Mar 2020 15:29:42 +0000 (UTC) Subject: Re: [PATCH net-next v2] xen-netfront: add basic XDP support To: Denis Kirjanov , netdev@vger.kernel.org Cc: ilias.apalodimas@linaro.org References: <1583158874-2751-1-git-send-email-kda@linux-powerpc.org> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: Date: Mon, 2 Mar 2020 16:29:41 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <1583158874-2751-1-git-send-email-kda@linux-powerpc.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 02.03.20 15:21, Denis Kirjanov wrote: > the patch adds a basic xdo logic to the netfront driver > > XDP redirect is not supported yet > > v2: > - avoid data copying while passing to XDP > - tell xen-natback that we need the headroom space Please add the patch history below the "---" delimiter > > Signed-off-by: Denis Kirjanov > --- > drivers/net/xen-netback/common.h | 1 + > drivers/net/xen-netback/rx.c | 9 ++- > drivers/net/xen-netback/xenbus.c | 21 ++++++ > drivers/net/xen-netfront.c | 157 +++++++++++++++++++++++++++++++++++++++ > 4 files changed, 186 insertions(+), 2 deletions(-) You are modifying xen-netback sources. Please Cc the maintainers. > > diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h > index 05847eb..0750c6f 100644 > --- a/drivers/net/xen-netback/common.h > +++ b/drivers/net/xen-netback/common.h > @@ -280,6 +280,7 @@ struct xenvif { > u8 ip_csum:1; > u8 ipv6_csum:1; > u8 multicast_control:1; > + u8 xdp_enabled:1; > > /* Is this interface disabled? True when backend discovers > * frontend is rogue. > diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c > index ef58870..a110a59 100644 > --- a/drivers/net/xen-netback/rx.c > +++ b/drivers/net/xen-netback/rx.c > @@ -33,6 +33,11 @@ > #include > #include > > +static inline int xenvif_rx_xdp_offset(struct xenvif *vif) > +{ > + return (vif->xdp_enabled ? XDP_PACKET_HEADROOM : 0); > +} > + > static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue) > { > RING_IDX prod, cons; > @@ -356,7 +361,7 @@ static void xenvif_rx_data_slot(struct xenvif_queue *queue, > struct xen_netif_rx_request *req, > struct xen_netif_rx_response *rsp) > { > - unsigned int offset = 0; > + unsigned int offset = xenvif_rx_xdp_offset(queue->vif); > unsigned int flags; > > do { > @@ -389,7 +394,7 @@ static void xenvif_rx_data_slot(struct xenvif_queue *queue, > flags |= XEN_NETRXF_extra_info; > } > > - rsp->offset = 0; > + rsp->offset = xenvif_rx_xdp_offset(queue->vif); > rsp->flags = flags; > rsp->id = req->id; > rsp->status = (s16)offset; > diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c > index 286054b..81a6023 100644 > --- a/drivers/net/xen-netback/xenbus.c > +++ b/drivers/net/xen-netback/xenbus.c > @@ -393,6 +393,20 @@ static void set_backend_state(struct backend_info *be, > } > } > > +static void read_xenbus_fronetend_xdp(struct backend_info *be, > + struct xenbus_device *dev) Typo: s/fronetend/frontend/ > +{ > + struct xenvif *vif = be->vif; > + unsigned int val; > + int err; > + > + err = xenbus_scanf(XBT_NIL, dev->otherend, > + "feature-xdp", "%u", &val); > + if (err < 0) > + return; > + vif->xdp_enabled = val; > +} > + > /** > * Callback received when the frontend's state changes. > */ > @@ -417,6 +431,11 @@ static void frontend_changed(struct xenbus_device *dev, > set_backend_state(be, XenbusStateConnected); > break; > > + case XenbusStateReconfiguring: > + read_xenbus_fronetend_xdp(be, dev); > + xenbus_switch_state(dev, XenbusStateReconfigured); > + break; > + Where is the reaction to the backend being set to "Reconfigured"? > case XenbusStateClosing: > set_backend_state(be, XenbusStateClosing); > break; > @@ -935,6 +954,8 @@ static int read_xenbus_vif_flags(struct backend_info *be) > > vif->gso_mask = 0; > > + vif->xdp_enabled = 0; > + > if (xenbus_read_unsigned(dev->otherend, "feature-gso-tcpv4", 0)) > vif->gso_mask |= GSO_BIT(TCPV4); > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index 482c6c8..db8a280 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -44,6 +44,8 @@ > #include > #include > #include > +#include > +#include > > #include > #include > @@ -102,6 +104,8 @@ struct netfront_queue { > char name[QUEUE_NAME_SIZE]; /* DEVNAME-qN */ > struct netfront_info *info; > > + struct bpf_prog __rcu *xdp_prog; > + > struct napi_struct napi; > > /* Split event channels support, tx_* == rx_* when using > @@ -778,6 +782,40 @@ static int xennet_get_extras(struct netfront_queue *queue, > return err; > } > > +u32 xennet_run_xdp(struct netfront_queue *queue, struct page *pdata, > + struct xen_netif_rx_response *rx, struct bpf_prog *prog, > + struct xdp_buff *xdp) > +{ > + u32 len = rx->status; > + u32 act = XDP_PASS; > + > + xdp->data_hard_start = page_address(pdata); > + xdp->data = xdp->data_hard_start + XDP_PACKET_HEADROOM; > + xdp_set_data_meta_invalid(xdp); > + xdp->data_end = xdp->data + len; > + xdp->handle = 0; > + > + act = bpf_prog_run_xdp(prog, xdp); > + switch (act) { > + case XDP_PASS: > + case XDP_TX: > + case XDP_DROP: > + break; > + > + case XDP_ABORTED: > + trace_xdp_exception(queue->info->netdev, prog, act); > + break; > + > + default: > + bpf_warn_invalid_xdp_action(act); > + } > + > + if (act != XDP_PASS && act != XDP_TX) > + xdp->data_hard_start = NULL; > + > + return act; > +} > + > static int xennet_get_responses(struct netfront_queue *queue, > struct netfront_rx_info *rinfo, RING_IDX rp, > struct sk_buff_head *list) > @@ -792,6 +830,9 @@ static int xennet_get_responses(struct netfront_queue *queue, > int slots = 1; > int err = 0; > unsigned long ret; > + struct bpf_prog *xdp_prog; > + struct xdp_buff xdp; > + u32 verdict; > > if (rx->flags & XEN_NETRXF_extra_info) { > err = xennet_get_extras(queue, extras, rp); > @@ -827,6 +868,22 @@ static int xennet_get_responses(struct netfront_queue *queue, > > gnttab_release_grant_reference(&queue->gref_rx_head, ref); > > + rcu_read_lock(); > + xdp_prog = rcu_dereference(queue->xdp_prog); > + if (xdp_prog) { > + /* currently only a single page contains data */ > + WARN_ON_ONCE(skb_shinfo(skb)->nr_frags != 1); > + verdict = xennet_run_xdp(queue, > + skb_frag_page(&skb_shinfo(skb)->frags[0]), > + rx, xdp_prog, &xdp); > + > + if (verdict != XDP_PASS && verdict != XDP_TX) { > + err = -EINVAL; > + goto next; > + } > + > + } > + rcu_read_unlock(); > __skb_queue_tail(list, skb); > > next: > @@ -1261,6 +1318,105 @@ static void xennet_poll_controller(struct net_device *dev) > } > #endif > > +#define NETBACK_XDP_HEADROOM_DISABLE 0 > +#define NETBACK_XDP_HEADROOM_ENABLE 1 > + > +static int talk_to_netback_xdp(struct netfront_info *np, int xdp) > +{ > + struct xenbus_transaction xbt; > + const char *message; > + int err; > + > +again: > + err = xenbus_transaction_start(&xbt); > + if (err) { > + xenbus_dev_fatal(np->xbdev, err, "starting transaction"); > + goto out; > + } > + > + err = xenbus_printf(xbt, np->xbdev->nodename, "feature-xdp", "%d", xdp); > + if (err) { > + message = "writing feature-xdp"; > + goto abort_transaction; > + } > + > + err = xenbus_transaction_end(xbt, 0); > + if (err) { > + if (err == -EAGAIN) > + goto again; Writing a single node to Xenstore doesn't need a transaction. > + } > + > + return 0; > + > +abort_transaction: > + xenbus_dev_fatal(np->xbdev, err, "%s", message); > + xenbus_transaction_end(xbt, 1); > +out: > + return err; > +} > + > +static int xennet_xdp_set(struct net_device *dev, struct bpf_prog *prog, > + struct netlink_ext_ack *extack) > +{ > + struct netfront_info *np = netdev_priv(dev); > + struct bpf_prog *old_prog; > + unsigned int i, err; > + > + old_prog = rtnl_dereference(np->queues[0].xdp_prog); > + if (!old_prog && !prog) > + return 0; > + > + if (prog) > + bpf_prog_add(prog, dev->real_num_tx_queues); > + > + for (i = 0; i < dev->real_num_tx_queues; ++i) > + rcu_assign_pointer(np->queues[i].xdp_prog, prog); > + > + if (old_prog) > + for (i = 0; i < dev->real_num_tx_queues; ++i) > + bpf_prog_put(old_prog); > + > + err = talk_to_netback_xdp(np, old_prog ? NETBACK_XDP_HEADROOM_DISABLE: > + NETBACK_XDP_HEADROOM_ENABLE); > + if (err) > + return err; > + > + xenbus_switch_state(np->xbdev, XenbusStateReconfiguring); What is happening in case the backend doesn't support XDP? Is it really a good idea to communicate xdp_set via a frontend state change? This will be rather slow. OTOH I have no idea how often this might happen. Juergen