From 6c5aa6fc4defc2a0977a2c59e4710d50fa1e834c Mon Sep 17 00:00:00 2001 From: Denis Kirjanov Date: Mon, 29 Jun 2020 16:13:28 +0300 Subject: [PATCH] xen networking: add basic XDP support for xen-netfront The patch adds a basic XDP processing to xen-netfront driver. We ran an XDP program for an RX response received from netback driver. Also we request xen-netback to adjust data offset for bpf_xdp_adjust_head() header space for custom headers. synchronization between frontend and backend parts is done by using xenbus state switching: Reconfiguring -> Reconfigured- > Connected UDP packets drop rate using xdp program is around 310 kpps using ./pktgen_sample04_many_flows.sh and 160 kpps without the patch. Signed-off-by: Denis Kirjanov Signed-off-by: David S. Miller --- drivers/net/Kconfig | 1 + drivers/net/xen-netfront.c | 336 +++++++++++++++++++++++++++++++++++-- 2 files changed, 327 insertions(+), 10 deletions(-) diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig index 7dcb465824be..1368d1d6a114 100644 --- a/drivers/net/Kconfig +++ b/drivers/net/Kconfig @@ -495,6 +495,7 @@ config XEN_NETDEV_FRONTEND tristate "Xen network device frontend driver" depends on XEN select XEN_XENBUS_FRONTEND + select PAGE_POOL default y help This driver provides support for Xen paravirtual network diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 482c6c8b0fb7..468f3f6f1425 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -44,6 +44,9 @@ #include #include #include +#include +#include +#include #include #include @@ -102,6 +105,8 @@ 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 @@ -144,6 +149,9 @@ struct netfront_queue { struct sk_buff *rx_skbs[NET_RX_RING_SIZE]; grant_ref_t gref_rx_head; grant_ref_t grant_rx_ref[NET_RX_RING_SIZE]; + + struct page_pool *page_pool; + struct xdp_rxq_info xdp_rxq; }; struct netfront_info { @@ -159,6 +167,10 @@ struct netfront_info { struct netfront_stats __percpu *rx_stats; struct netfront_stats __percpu *tx_stats; + /* XDP state */ + bool netback_has_xdp_headroom; + bool netfront_xdp_enabled; + atomic_t rx_gso_checksum_fixup; }; @@ -265,8 +277,8 @@ static struct sk_buff *xennet_alloc_one_rx_buffer(struct netfront_queue *queue) if (unlikely(!skb)) return NULL; - page = alloc_page(GFP_ATOMIC | __GFP_NOWARN); - if (!page) { + page = page_pool_dev_alloc_pages(queue->page_pool); + if (unlikely(!page)) { kfree_skb(skb); return NULL; } @@ -560,6 +572,66 @@ static u16 xennet_select_queue(struct net_device *dev, struct sk_buff *skb, return queue_idx; } +static int xennet_xdp_xmit_one(struct net_device *dev, + struct netfront_queue *queue, + struct xdp_frame *xdpf) +{ + struct netfront_info *np = netdev_priv(dev); + struct netfront_stats *tx_stats = this_cpu_ptr(np->tx_stats); + int notify; + + xennet_make_first_txreq(queue, NULL, + virt_to_page(xdpf->data), + offset_in_page(xdpf->data), + xdpf->len); + + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&queue->tx, notify); + if (notify) + notify_remote_via_irq(queue->tx_irq); + + u64_stats_update_begin(&tx_stats->syncp); + tx_stats->bytes += xdpf->len; + tx_stats->packets++; + u64_stats_update_end(&tx_stats->syncp); + + xennet_tx_buf_gc(queue); + + return 0; +} + +static int xennet_xdp_xmit(struct net_device *dev, int n, + struct xdp_frame **frames, u32 flags) +{ + unsigned int num_queues = dev->real_num_tx_queues; + struct netfront_info *np = netdev_priv(dev); + struct netfront_queue *queue = NULL; + unsigned long irq_flags; + int drops = 0; + int i, err; + + if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) + return -EINVAL; + + queue = &np->queues[smp_processor_id() % num_queues]; + + spin_lock_irqsave(&queue->tx_lock, irq_flags); + for (i = 0; i < n; i++) { + struct xdp_frame *xdpf = frames[i]; + + if (!xdpf) + continue; + err = xennet_xdp_xmit_one(dev, queue, xdpf); + if (err) { + xdp_return_frame_rx_napi(xdpf); + drops++; + } + } + spin_unlock_irqrestore(&queue->tx_lock, irq_flags); + + return n - drops; +} + + #define MAX_XEN_SKB_FRAGS (65536 / XEN_PAGE_SIZE + 1) static netdev_tx_t xennet_start_xmit(struct sk_buff *skb, struct net_device *dev) @@ -778,23 +850,82 @@ static int xennet_get_extras(struct netfront_queue *queue, return err; } +static 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, bool *need_xdp_flush) +{ + struct xdp_frame *xdpf; + u32 len = rx->status; + u32 act = XDP_PASS; + int err; + + 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->rxq = &queue->xdp_rxq; + xdp->frame_sz = XEN_PAGE_SIZE - XDP_PACKET_HEADROOM; + + act = bpf_prog_run_xdp(prog, xdp); + switch (act) { + case XDP_TX: + get_page(pdata); + xdpf = xdp_convert_buff_to_frame(xdp); + err = xennet_xdp_xmit(queue->info->netdev, 1, &xdpf, 0); + if (unlikely(err < 0)) + trace_xdp_exception(queue->info->netdev, prog, act); + break; + case XDP_REDIRECT: + get_page(pdata); + err = xdp_do_redirect(queue->info->netdev, xdp, prog); + *need_xdp_flush = true; + if (unlikely(err)) + trace_xdp_exception(queue->info->netdev, prog, act); + break; + case XDP_PASS: + case XDP_DROP: + break; + + case XDP_ABORTED: + trace_xdp_exception(queue->info->netdev, prog, act); + break; + + default: + bpf_warn_invalid_xdp_action(act); + } + + return act; +} + static int xennet_get_responses(struct netfront_queue *queue, struct netfront_rx_info *rinfo, RING_IDX rp, - struct sk_buff_head *list) + struct sk_buff_head *list, + bool *need_xdp_flush) { struct xen_netif_rx_response *rx = &rinfo->rx; - struct xen_netif_extra_info *extras = rinfo->extras; - struct device *dev = &queue->info->netdev->dev; + int max = XEN_NETIF_NR_SLOTS_MIN + (rx->status <= RX_COPY_THRESHOLD); RING_IDX cons = queue->rx.rsp_cons; struct sk_buff *skb = xennet_get_rx_skb(queue, cons); + struct xen_netif_extra_info *extras = rinfo->extras; grant_ref_t ref = xennet_get_rx_ref(queue, cons); - int max = XEN_NETIF_NR_SLOTS_MIN + (rx->status <= RX_COPY_THRESHOLD); + struct device *dev = &queue->info->netdev->dev; + struct bpf_prog *xdp_prog; + struct xdp_buff xdp; + unsigned long ret; int slots = 1; int err = 0; - unsigned long ret; + u32 verdict; if (rx->flags & XEN_NETRXF_extra_info) { err = xennet_get_extras(queue, extras, rp); + if (!err) { + if (extras[XEN_NETIF_EXTRA_TYPE_XDP - 1].type) { + struct xen_netif_extra_info *xdp; + + xdp = &extras[XEN_NETIF_EXTRA_TYPE_XDP - 1]; + rx->offset = xdp->u.xdp.headroom; + } + } cons = queue->rx.rsp_cons; } @@ -827,9 +958,24 @@ static int xennet_get_responses(struct netfront_queue *queue, gnttab_release_grant_reference(&queue->gref_rx_head, ref); - __skb_queue_tail(list, skb); - + rcu_read_lock(); + xdp_prog = rcu_dereference(queue->xdp_prog); + if (xdp_prog) { + if (!(rx->flags & XEN_NETRXF_more_data)) { + /* currently only a single page contains data */ + verdict = xennet_run_xdp(queue, + skb_frag_page(&skb_shinfo(skb)->frags[0]), + rx, xdp_prog, &xdp, need_xdp_flush); + if (verdict != XDP_PASS) + err = -EINVAL; + } else { + /* drop the frame */ + err = -EINVAL; + } + } + rcu_read_unlock(); next: + __skb_queue_tail(list, skb); if (!(rx->flags & XEN_NETRXF_more_data)) break; @@ -998,6 +1144,7 @@ static int xennet_poll(struct napi_struct *napi, int budget) struct sk_buff_head errq; struct sk_buff_head tmpq; int err; + bool need_xdp_flush = false; spin_lock(&queue->rx_lock); @@ -1014,7 +1161,8 @@ static int xennet_poll(struct napi_struct *napi, int budget) memcpy(rx, RING_GET_RESPONSE(&queue->rx, i), sizeof(*rx)); memset(extras, 0, sizeof(rinfo.extras)); - err = xennet_get_responses(queue, &rinfo, rp, &tmpq); + err = xennet_get_responses(queue, &rinfo, rp, &tmpq, + &need_xdp_flush); if (unlikely(err)) { err: @@ -1060,6 +1208,8 @@ static int xennet_poll(struct napi_struct *napi, int budget) i = ++queue->rx.rsp_cons; work_done++; } + if (need_xdp_flush) + xdp_do_flush(); __skb_queue_purge(&errq); @@ -1261,6 +1411,101 @@ 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) +{ + int err; + unsigned short headroom; + + headroom = xdp ? XDP_PACKET_HEADROOM : 0; + err = xenbus_printf(XBT_NIL, np->xbdev->nodename, + "xdp-headroom", "%hu", + headroom); + if (err) + pr_warn("Error writing xdp-headroom\n"); + + return err; +} + +static int xennet_xdp_set(struct net_device *dev, struct bpf_prog *prog, + struct netlink_ext_ack *extack) +{ + unsigned long max_mtu = XEN_PAGE_SIZE - XDP_PACKET_HEADROOM; + struct netfront_info *np = netdev_priv(dev); + struct bpf_prog *old_prog; + unsigned int i, err; + + if (dev->mtu > max_mtu) { + netdev_warn(dev, "XDP requires MTU less than %lu\n", max_mtu); + return -EINVAL; + } + + if (!np->netback_has_xdp_headroom) + return 0; + + xenbus_switch_state(np->xbdev, XenbusStateReconfiguring); + + err = talk_to_netback_xdp(np, prog ? NETBACK_XDP_HEADROOM_ENABLE : + NETBACK_XDP_HEADROOM_DISABLE); + if (err) + return err; + + /* avoid the race with XDP headroom adjustment */ + wait_event(module_wq, + xenbus_read_driver_state(np->xbdev->otherend) == + XenbusStateReconfigured); + np->netfront_xdp_enabled = true; + + old_prog = rtnl_dereference(np->queues[0].xdp_prog); + + 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); + + xenbus_switch_state(np->xbdev, XenbusStateConnected); + + return 0; +} + +static u32 xennet_xdp_query(struct net_device *dev) +{ + unsigned int num_queues = dev->real_num_tx_queues; + struct netfront_info *np = netdev_priv(dev); + const struct bpf_prog *xdp_prog; + struct netfront_queue *queue; + unsigned int i; + + for (i = 0; i < num_queues; ++i) { + queue = &np->queues[i]; + xdp_prog = rtnl_dereference(queue->xdp_prog); + if (xdp_prog) + return xdp_prog->aux->id; + } + + return 0; +} + +static int xennet_xdp(struct net_device *dev, struct netdev_bpf *xdp) +{ + switch (xdp->command) { + case XDP_SETUP_PROG: + return xennet_xdp_set(dev, xdp->prog, xdp->extack); + case XDP_QUERY_PROG: + xdp->prog_id = xennet_xdp_query(dev); + return 0; + default: + return -EINVAL; + } +} + static const struct net_device_ops xennet_netdev_ops = { .ndo_open = xennet_open, .ndo_stop = xennet_close, @@ -1272,6 +1517,8 @@ static const struct net_device_ops xennet_netdev_ops = { .ndo_fix_features = xennet_fix_features, .ndo_set_features = xennet_set_features, .ndo_select_queue = xennet_select_queue, + .ndo_bpf = xennet_xdp, + .ndo_xdp_xmit = xennet_xdp_xmit, #ifdef CONFIG_NET_POLL_CONTROLLER .ndo_poll_controller = xennet_poll_controller, #endif @@ -1331,6 +1578,7 @@ static struct net_device *xennet_create_dev(struct xenbus_device *dev) SET_NETDEV_DEV(netdev, &dev->dev); np->netdev = netdev; + np->netfront_xdp_enabled = false; netif_carrier_off(netdev); @@ -1419,6 +1667,8 @@ static void xennet_disconnect_backend(struct netfront_info *info) queue->rx_ring_ref = GRANT_INVALID_REF; queue->tx.sring = NULL; queue->rx.sring = NULL; + + page_pool_destroy(queue->page_pool); } } @@ -1754,6 +2004,51 @@ static void xennet_destroy_queues(struct netfront_info *info) info->queues = NULL; } + + +static int xennet_create_page_pool(struct netfront_queue *queue) +{ + int err; + struct page_pool_params pp_params = { + .order = 0, + .flags = 0, + .pool_size = NET_RX_RING_SIZE, + .nid = NUMA_NO_NODE, + .dev = &queue->info->netdev->dev, + .offset = XDP_PACKET_HEADROOM, + .max_len = XEN_PAGE_SIZE - XDP_PACKET_HEADROOM, + }; + + queue->page_pool = page_pool_create(&pp_params); + if (IS_ERR(queue->page_pool)) { + err = PTR_ERR(queue->page_pool); + queue->page_pool = NULL; + return err; + } + + err = xdp_rxq_info_reg(&queue->xdp_rxq, queue->info->netdev, + queue->id); + if (err) { + netdev_err(queue->info->netdev, "xdp_rxq_info_reg failed\n"); + goto err_free_pp; + } + + err = xdp_rxq_info_reg_mem_model(&queue->xdp_rxq, + MEM_TYPE_PAGE_POOL, queue->page_pool); + if (err) { + netdev_err(queue->info->netdev, "xdp_rxq_info_reg_mem_model failed\n"); + goto err_unregister_rxq; + } + return 0; + +err_unregister_rxq: + xdp_rxq_info_unreg(&queue->xdp_rxq); +err_free_pp: + page_pool_destroy(queue->page_pool); + queue->page_pool = NULL; + return err; +} + static int xennet_create_queues(struct netfront_info *info, unsigned int *num_queues) { @@ -1779,6 +2074,14 @@ static int xennet_create_queues(struct netfront_info *info, break; } + /* use page pool recycling instead of buddy allocator */ + ret = xennet_create_page_pool(queue); + if (ret < 0) { + dev_err(&info->xbdev->dev, "can't allocate page pool\n"); + *num_queues = i; + return ret; + } + netif_napi_add(queue->info->netdev, &queue->napi, xennet_poll, 64); if (netif_running(info->netdev)) @@ -1825,6 +2128,17 @@ static int talk_to_netback(struct xenbus_device *dev, goto out_unlocked; } + info->netback_has_xdp_headroom = xenbus_read_unsigned(info->xbdev->otherend, + "feature-xdp-headroom", 0); + if (info->netback_has_xdp_headroom) { + /* set the current xen-netfront xdp state */ + err = talk_to_netback_xdp(info, info->netfront_xdp_enabled ? + NETBACK_XDP_HEADROOM_ENABLE : + NETBACK_XDP_HEADROOM_DISABLE); + if (err) + goto out_unlocked; + } + rtnl_lock(); if (info->queues) xennet_destroy_queues(info); @@ -1959,6 +2273,8 @@ static int xennet_connect(struct net_device *dev) err = talk_to_netback(np->xbdev, np); if (err) return err; + if (np->netback_has_xdp_headroom) + pr_info("backend supports XDP headroom\n"); /* talk_to_netback() sets the correct number of queues */ num_queues = dev->real_num_tx_queues;