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Message-ID: <c93dce1f78bd383c117311e4d53e2766264f6759.1706451150.git.lorenzo@kernel.org>
Date: Sun, 28 Jan 2024 15:20:39 +0100
From: Lorenzo Bianconi <lorenzo@...nel.org>
To: netdev@...r.kernel.org
Cc: lorenzo.bianconi@...hat.com,
davem@...emloft.net,
kuba@...nel.org,
edumazet@...gle.com,
pabeni@...hat.com,
bpf@...r.kernel.org,
toke@...hat.com,
willemdebruijn.kernel@...il.com,
jasowang@...hat.com,
sdf@...gle.com,
hawk@...nel.org,
ilias.apalodimas@...aro.org
Subject: [PATCH v6 net-next 3/5] xdp: add multi-buff support for xdp running in generic mode
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.
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
net/core/dev.c | 152 ++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 133 insertions(+), 19 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 960f39ac5e33..19f92ba90e49 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4862,6 +4862,12 @@ 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;
@@ -4891,6 +4897,14 @@ 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) ||
@@ -4924,12 +4938,117 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
return act;
}
+#if IS_ENABLED(CONFIG_PAGE_POOL)
+static int
+netif_skb_segment_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
+ struct bpf_prog *prog)
+{
+ 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) || !prog->aux->xdp_has_frags)
+ return -EOPNOTSUPP;
+
+ max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE - XDP_PACKET_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) + XDP_PACKET_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, XDP_PACKET_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;
+}
+#endif
+
+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 IS_ENABLED(CONFIG_PAGE_POOL)
+ if (!netif_skb_segment_for_xdp(this_cpu_read(page_pool), pskb, prog))
+ return 0;
+#endif
+
+ /* 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.
@@ -4937,41 +5056,36 @@ 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;
}
--
2.43.0
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