Commit 6c5aa6fc authored by Denis Kirjanov's avatar Denis Kirjanov Committed by David S. Miller

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: default avatarDenis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2cef30d7
......@@ -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
......
......@@ -44,6 +44,9 @@
#include <linux/mm.h>
#include <linux/slab.h>
#include <net/ip.h>
#include <linux/bpf.h>
#include <net/page_pool.h>
#include <linux/bpf_trace.h>
#include <xen/xen.h>
#include <xen/xenbus.h>
......@@ -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;
......
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