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xsk: wire upp Tx zero-copy functions
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Here we add the functionality required to support zero-copy Tx, and
also exposes various zero-copy related functions for the netdevs.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Magnus Karlsson authored and Daniel Borkmann committed Jun 5, 2018
1 parent e3760c7 commit ac98d8a
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Showing 5 changed files with 137 additions and 11 deletions.
9 changes: 9 additions & 0 deletions include/net/xdp_sock.h
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
#include <linux/workqueue.h>
#include <linux/if_xdp.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <net/sock.h>

Expand Down Expand Up @@ -42,6 +43,8 @@ struct xdp_umem {
struct net_device *dev;
u16 queue_id;
bool zc;
spinlock_t xsk_list_lock;
struct list_head xsk_list;
};

struct xdp_sock {
Expand All @@ -53,6 +56,8 @@ struct xdp_sock {
struct list_head flush_node;
u16 queue_id;
struct xsk_queue *tx ____cacheline_aligned_in_smp;
struct list_head list;
bool zc;
/* Protects multiple processes in the control path */
struct mutex mutex;
u64 rx_dropped;
Expand All @@ -64,8 +69,12 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
void xsk_flush(struct xdp_sock *xs);
bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs);
/* Used from netdev driver */
u64 *xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr);
void xsk_umem_discard_addr(struct xdp_umem *umem);
void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries);
bool xsk_umem_consume_tx(struct xdp_umem *umem, dma_addr_t *dma, u32 *len);
void xsk_umem_consume_tx_done(struct xdp_umem *umem);
#else
static inline int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
{
Expand Down
29 changes: 27 additions & 2 deletions net/xdp/xdp_umem.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,29 @@

#define XDP_UMEM_MIN_CHUNK_SIZE 2048

void xdp_add_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
{
unsigned long flags;

spin_lock_irqsave(&umem->xsk_list_lock, flags);
list_add_rcu(&xs->list, &umem->xsk_list);
spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
}

void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
{
unsigned long flags;

if (xs->dev) {
spin_lock_irqsave(&umem->xsk_list_lock, flags);
list_del_rcu(&xs->list);
spin_unlock_irqrestore(&umem->xsk_list_lock, flags);

if (umem->zc)
synchronize_net();
}
}

int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
u32 queue_id, u16 flags)
{
Expand All @@ -35,7 +58,7 @@ int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,

dev_hold(dev);

if (dev->netdev_ops->ndo_bpf) {
if (dev->netdev_ops->ndo_bpf && dev->netdev_ops->ndo_xsk_async_xmit) {
bpf.command = XDP_QUERY_XSK_UMEM;

rtnl_lock();
Expand Down Expand Up @@ -70,7 +93,7 @@ int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
return force_zc ? -ENOTSUPP : 0; /* fail or fallback */
}

void xdp_umem_clear_dev(struct xdp_umem *umem)
static void xdp_umem_clear_dev(struct xdp_umem *umem)
{
struct netdev_bpf bpf;
int err;
Expand Down Expand Up @@ -283,6 +306,8 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
umem->npgs = size / PAGE_SIZE;
umem->pgs = NULL;
umem->user = NULL;
INIT_LIST_HEAD(&umem->xsk_list);
spin_lock_init(&umem->xsk_list_lock);

refcount_set(&umem->users, 1);

Expand Down
8 changes: 7 additions & 1 deletion net/xdp/xdp_umem.h
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Original file line number Diff line number Diff line change
Expand Up @@ -13,12 +13,18 @@ static inline char *xdp_umem_get_data(struct xdp_umem *umem, u64 addr)
return umem->pages[addr >> PAGE_SHIFT].addr + (addr & (PAGE_SIZE - 1));
}

static inline dma_addr_t xdp_umem_get_dma(struct xdp_umem *umem, u64 addr)
{
return umem->pages[addr >> PAGE_SHIFT].dma + (addr & (PAGE_SIZE - 1));
}

int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
u32 queue_id, u16 flags);
void xdp_umem_clear_dev(struct xdp_umem *umem);
bool xdp_umem_validate_queues(struct xdp_umem *umem);
void xdp_get_umem(struct xdp_umem *umem);
void xdp_put_umem(struct xdp_umem *umem);
void xdp_add_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs);
void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs);
struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr);

#endif /* XDP_UMEM_H_ */
70 changes: 63 additions & 7 deletions net/xdp/xsk.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
#include <linux/uaccess.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <net/xdp_sock.h>
#include <net/xdp.h>

Expand Down Expand Up @@ -138,6 +139,59 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
return err;
}

void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries)
{
xskq_produce_flush_addr_n(umem->cq, nb_entries);
}
EXPORT_SYMBOL(xsk_umem_complete_tx);

void xsk_umem_consume_tx_done(struct xdp_umem *umem)
{
struct xdp_sock *xs;

rcu_read_lock();
list_for_each_entry_rcu(xs, &umem->xsk_list, list) {
xs->sk.sk_write_space(&xs->sk);
}
rcu_read_unlock();
}
EXPORT_SYMBOL(xsk_umem_consume_tx_done);

bool xsk_umem_consume_tx(struct xdp_umem *umem, dma_addr_t *dma, u32 *len)
{
struct xdp_desc desc;
struct xdp_sock *xs;

rcu_read_lock();
list_for_each_entry_rcu(xs, &umem->xsk_list, list) {
if (!xskq_peek_desc(xs->tx, &desc))
continue;

if (xskq_produce_addr_lazy(umem->cq, desc.addr))
goto out;

*dma = xdp_umem_get_dma(umem, desc.addr);
*len = desc.len;

xskq_discard_desc(xs->tx);
rcu_read_unlock();
return true;
}

out:
rcu_read_unlock();
return false;
}
EXPORT_SYMBOL(xsk_umem_consume_tx);

static int xsk_zc_xmit(struct sock *sk)
{
struct xdp_sock *xs = xdp_sk(sk);
struct net_device *dev = xs->dev;

return dev->netdev_ops->ndo_xsk_async_xmit(dev, xs->queue_id);
}

static void xsk_destruct_skb(struct sk_buff *skb)
{
u64 addr = (u64)(long)skb_shinfo(skb)->destructor_arg;
Expand All @@ -151,7 +205,6 @@ static void xsk_destruct_skb(struct sk_buff *skb)
static int xsk_generic_xmit(struct sock *sk, struct msghdr *m,
size_t total_len)
{
bool need_wait = !(m->msg_flags & MSG_DONTWAIT);
u32 max_batch = TX_BATCH_SIZE;
struct xdp_sock *xs = xdp_sk(sk);
bool sent_frame = false;
Expand All @@ -161,8 +214,6 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m,

if (unlikely(!xs->tx))
return -ENOBUFS;
if (need_wait)
return -EOPNOTSUPP;

mutex_lock(&xs->mutex);

Expand Down Expand Up @@ -192,7 +243,7 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m,
goto out;
}

skb = sock_alloc_send_skb(sk, len, !need_wait, &err);
skb = sock_alloc_send_skb(sk, len, 1, &err);
if (unlikely(!skb)) {
err = -EAGAIN;
goto out;
Expand Down Expand Up @@ -235,15 +286,18 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m,

static int xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
{
bool need_wait = !(m->msg_flags & MSG_DONTWAIT);
struct sock *sk = sock->sk;
struct xdp_sock *xs = xdp_sk(sk);

if (unlikely(!xs->dev))
return -ENXIO;
if (unlikely(!(xs->dev->flags & IFF_UP)))
return -ENETDOWN;
if (need_wait)
return -EOPNOTSUPP;

return xsk_generic_xmit(sk, m, total_len);
return (xs->zc) ? xsk_zc_xmit(sk) : xsk_generic_xmit(sk, m, total_len);
}

static unsigned int xsk_poll(struct file *file, struct socket *sock,
Expand Down Expand Up @@ -419,10 +473,11 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
}

xs->dev = dev;
xs->queue_id = sxdp->sxdp_queue_id;

xs->zc = xs->umem->zc;
xs->queue_id = qid;
xskq_set_umem(xs->rx, &xs->umem->props);
xskq_set_umem(xs->tx, &xs->umem->props);
xdp_add_sk_umem(xs->umem, xs);

out_unlock:
if (err)
Expand Down Expand Up @@ -660,6 +715,7 @@ static void xsk_destruct(struct sock *sk)

xskq_destroy(xs->rx);
xskq_destroy(xs->tx);
xdp_del_sk_umem(xs->umem, xs);
xdp_put_umem(xs->umem);

sk_refcnt_debug_dec(sk);
Expand Down
32 changes: 31 additions & 1 deletion net/xdp/xsk_queue.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
#include <net/xdp_sock.h>

#define RX_BATCH_SIZE 16
#define LAZY_UPDATE_THRESHOLD 128

struct xdp_ring {
u32 producer ____cacheline_aligned_in_smp;
Expand Down Expand Up @@ -61,9 +62,14 @@ static inline u32 xskq_nb_avail(struct xsk_queue *q, u32 dcnt)
return (entries > dcnt) ? dcnt : entries;
}

static inline u32 xskq_nb_free_lazy(struct xsk_queue *q, u32 producer)
{
return q->nentries - (producer - q->cons_tail);
}

static inline u32 xskq_nb_free(struct xsk_queue *q, u32 producer, u32 dcnt)
{
u32 free_entries = q->nentries - (producer - q->cons_tail);
u32 free_entries = xskq_nb_free_lazy(q, producer);

if (free_entries >= dcnt)
return free_entries;
Expand Down Expand Up @@ -123,6 +129,9 @@ static inline int xskq_produce_addr(struct xsk_queue *q, u64 addr)
{
struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;

if (xskq_nb_free(q, q->prod_tail, LAZY_UPDATE_THRESHOLD) == 0)
return -ENOSPC;

ring->desc[q->prod_tail++ & q->ring_mask] = addr;

/* Order producer and data */
Expand All @@ -132,6 +141,27 @@ static inline int xskq_produce_addr(struct xsk_queue *q, u64 addr)
return 0;
}

static inline int xskq_produce_addr_lazy(struct xsk_queue *q, u64 addr)
{
struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;

if (xskq_nb_free(q, q->prod_head, LAZY_UPDATE_THRESHOLD) == 0)
return -ENOSPC;

ring->desc[q->prod_head++ & q->ring_mask] = addr;
return 0;
}

static inline void xskq_produce_flush_addr_n(struct xsk_queue *q,
u32 nb_entries)
{
/* Order producer and data */
smp_wmb();

q->prod_tail += nb_entries;
WRITE_ONCE(q->ring->producer, q->prod_tail);
}

static inline int xskq_reserve_addr(struct xsk_queue *q)
{
if (xskq_nb_free(q, q->prod_head, 1) == 0)
Expand Down

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