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xdp: add multi-buff support for xdp running in generic mode

Browse source 
Similar to native xdp, do not always linearize the skb in
netif_receive_generic_xdp routine but create a non-linear xdp_buff to be
processed by the eBPF program. This allow to add multi-buffer support
for xdp running in generic mode.

Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/1044d6412b1c3e95b40d34993fd5f37cd2f319fd.1707729884.git.lorenzo@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Lorenzo Bianconi 2024-02-12 10:50:56 +01:00 committed by Jakub Kicinski
parent 4d2bb0bfe8
commit e6d5dbdd20
3 changed files with 144 additions and 19 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
include/linux/skbuff.h
View file

@ -3446,6 +3446,8 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f)
__skb_frag_ref(&skb_shinfo(skb)->frags[f]);
}
int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
struct bpf_prog *prog);
bool napi_pp_put_page(struct page *page, bool napi_safe);
static inline void

70
net/core/dev.c
View file

@ -4874,6 +4874,12 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
xdp_init_buff(xdp, frame_sz, &rxqueue->xdp_rxq);
xdp_prepare_buff(xdp, hard_start, skb_headroom(skb) - mac_len,
skb_headlen(skb) + mac_len, true);
if (skb_is_nonlinear(skb)) {
skb_shinfo(skb)->xdp_frags_size = skb->data_len;
xdp_buff_set_frags_flag(xdp);
} else {
xdp_buff_clear_frags_flag(xdp);
}
orig_data_end = xdp->data_end;
orig_data = xdp->data;
@ -4903,6 +4909,14 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
skb->len += off; /* positive on grow, negative on shrink */
}
/* XDP frag metadata (e.g. nr_frags) are updated in eBPF helpers
* (e.g. bpf_xdp_adjust_tail), we need to update data_len here.
*/
if (xdp_buff_has_frags(xdp))
skb->data_len = skb_shinfo(skb)->xdp_frags_size;
else
skb->data_len = 0;
/* check if XDP changed eth hdr such SKB needs update */
eth = (struct ethhdr *)xdp->data;
if ((orig_eth_type != eth->h_proto) ||
@ -4936,12 +4950,35 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
return act;
}
static int
netif_skb_check_for_xdp(struct sk_buff **pskb, struct bpf_prog *prog)
{
struct sk_buff *skb = *pskb;
int err, hroom, troom;
if (!skb_cow_data_for_xdp(this_cpu_read(system_page_pool), pskb, prog))
return 0;
/* In case we have to go down the path and also linearize,
* then lets do the pskb_expand_head() work just once here.
*/
hroom = XDP_PACKET_HEADROOM - skb_headroom(skb);
troom = skb->tail + skb->data_len - skb->end;
err = pskb_expand_head(skb,
hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0,
troom > 0 ? troom + 128 : 0, GFP_ATOMIC);
if (err)
return err;
return skb_linearize(skb);
}
static u32 netif_receive_generic_xdp(struct sk_buff **pskb,
struct xdp_buff *xdp,
struct bpf_prog *xdp_prog)
{
struct sk_buff *skb = *pskb;
u32 act = XDP_DROP;
u32 mac_len, act = XDP_DROP;
/* Reinjected packets coming from act_mirred or similar should
* not get XDP generic processing.
@ -4949,41 +4986,36 @@ static u32 netif_receive_generic_xdp(struct sk_buff **pskb,
if (skb_is_redirected(skb))
return XDP_PASS;
/* XDP packets must be linear and must have sufficient headroom
* of XDP_PACKET_HEADROOM bytes. This is the guarantee that also
* native XDP provides, thus we need to do it here as well.
/* XDP packets must have sufficient headroom of XDP_PACKET_HEADROOM
* bytes. This is the guarantee that also native XDP provides,
* thus we need to do it here as well.
*/
mac_len = skb->data - skb_mac_header(skb);
__skb_push(skb, mac_len);
if (skb_cloned(skb) || skb_is_nonlinear(skb) ||
skb_headroom(skb) < XDP_PACKET_HEADROOM) {
int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb);
int troom = skb->tail + skb->data_len - skb->end;
/* In case we have to go down the path and also linearize,
* then lets do the pskb_expand_head() work just once here.
*/
if (pskb_expand_head(skb,
hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0,
troom > 0 ? troom + 128 : 0, GFP_ATOMIC))
goto do_drop;
if (skb_linearize(skb))
if (netif_skb_check_for_xdp(pskb, xdp_prog))
goto do_drop;
}
act = bpf_prog_run_generic_xdp(skb, xdp, xdp_prog);
__skb_pull(*pskb, mac_len);
act = bpf_prog_run_generic_xdp(*pskb, xdp, xdp_prog);
switch (act) {
case XDP_REDIRECT:
case XDP_TX:
case XDP_PASS:
break;
default:
bpf_warn_invalid_xdp_action(skb->dev, xdp_prog, act);
bpf_warn_invalid_xdp_action((*pskb)->dev, xdp_prog, act);
fallthrough;
case XDP_ABORTED:
trace_xdp_exception(skb->dev, xdp_prog, act);
trace_xdp_exception((*pskb)->dev, xdp_prog, act);
fallthrough;
case XDP_DROP:
do_drop:
kfree_skb(skb);
kfree_skb(*pskb);
break;
}

91
net/core/skbuff.c
View file

@ -895,6 +895,97 @@ static bool is_pp_page(struct page *page)
return (page->pp_magic & ~0x3UL) == PP_SIGNATURE;
}
static int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
unsigned int headroom)
{
#if IS_ENABLED(CONFIG_PAGE_POOL)
u32 size, truesize, len, max_head_size, off;
struct sk_buff *skb = *pskb, *nskb;
int err, i, head_off;
void *data;
/* XDP does not support fraglist so we need to linearize
* the skb.
*/
if (skb_has_frag_list(skb))
return -EOPNOTSUPP;
max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE - headroom);
if (skb->len > max_head_size + MAX_SKB_FRAGS * PAGE_SIZE)
return -ENOMEM;
size = min_t(u32, skb->len, max_head_size);
truesize = SKB_HEAD_ALIGN(size) + headroom;
data = page_pool_dev_alloc_va(pool, &truesize);
if (!data)
return -ENOMEM;
nskb = napi_build_skb(data, truesize);
if (!nskb) {
page_pool_free_va(pool, data, true);
return -ENOMEM;
}
skb_reserve(nskb, headroom);
skb_copy_header(nskb, skb);
skb_mark_for_recycle(nskb);
err = skb_copy_bits(skb, 0, nskb->data, size);
if (err) {
consume_skb(nskb);
return err;
}
skb_put(nskb, size);
head_off = skb_headroom(nskb) - skb_headroom(skb);
skb_headers_offset_update(nskb, head_off);
off = size;
len = skb->len - off;
for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) {
struct page *page;
u32 page_off;
size = min_t(u32, len, PAGE_SIZE);
truesize = size;
page = page_pool_dev_alloc(pool, &page_off, &truesize);
if (!data) {
consume_skb(nskb);
return -ENOMEM;
}
skb_add_rx_frag(nskb, i, page, page_off, size, truesize);
err = skb_copy_bits(skb, off, page_address(page) + page_off,
size);
if (err) {
consume_skb(nskb);
return err;
}
len -= size;
off += size;
}
consume_skb(skb);
*pskb = nskb;
return 0;
#else
return -EOPNOTSUPP;
#endif
}
int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
struct bpf_prog *prog)
{
if (!prog->aux->xdp_has_frags)
return -EINVAL;
return skb_pp_cow_data(pool, pskb, XDP_PACKET_HEADROOM);
}
EXPORT_SYMBOL(skb_cow_data_for_xdp);
#if IS_ENABLED(CONFIG_PAGE_POOL)
bool napi_pp_put_page(struct page *page, bool napi_safe)
{