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authorStanislav Fomichev <sdf@google.com>2023-11-27 22:03:08 +0300
committerAlexei Starovoitov <ast@kernel.org>2023-11-30 01:59:40 +0300
commit48eb03dd26304c24f03bdbb9382e89c8564e71df (patch)
treeac572d4d71fa6012c7267efc03d17c18bcb11e5c /net/xdp/xsk.c
parent341ac980eab90ac1f6c22ee9f9da83ed9604d899 (diff)
downloadlinux-48eb03dd26304c24f03bdbb9382e89c8564e71df.tar.xz
xsk: Add TX timestamp and TX checksum offload support
This change actually defines the (initial) metadata layout that should be used by AF_XDP userspace (xsk_tx_metadata). The first field is flags which requests appropriate offloads, followed by the offload-specific fields. The supported per-device offloads are exported via netlink (new xsk-flags). The offloads themselves are still implemented in a bit of a framework-y fashion that's left from my initial kfunc attempt. I'm introducing new xsk_tx_metadata_ops which drivers are supposed to implement. The drivers are also supposed to call xsk_tx_metadata_request/xsk_tx_metadata_complete in the right places. Since xsk_tx_metadata_{request,_complete} are static inline, we don't incur any extra overhead doing indirect calls. The benefit of this scheme is as follows: - keeps all metadata layout parsing away from driver code - makes it easy to grep and see which drivers implement what - don't need any extra flags to maintain to keep track of what offloads are implemented; if the callback is implemented - the offload is supported (used by netlink reporting code) Two offloads are defined right now: 1. XDP_TXMD_FLAGS_CHECKSUM: skb-style csum_start+csum_offset 2. XDP_TXMD_FLAGS_TIMESTAMP: writes TX timestamp back into metadata area upon completion (tx_timestamp field) XDP_TXMD_FLAGS_TIMESTAMP is also implemented for XDP_COPY mode: it writes SW timestamp from the skb destructor (note I'm reusing hwtstamps to pass metadata pointer). The struct is forward-compatible and can be extended in the future by appending more fields. Reviewed-by: Song Yoong Siang <yoong.siang.song@intel.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> Acked-by: Jakub Kicinski <kuba@kernel.org> Link: https://lore.kernel.org/r/20231127190319.1190813-3-sdf@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/xdp/xsk.c')
-rw-r--r--net/xdp/xsk.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index c904356e2800..e83ade32f1fd 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -571,6 +571,13 @@ static u32 xsk_get_num_desc(struct sk_buff *skb)
static void xsk_destruct_skb(struct sk_buff *skb)
{
+ struct xsk_tx_metadata_compl *compl = &skb_shinfo(skb)->xsk_meta;
+
+ if (compl->tx_timestamp) {
+ /* sw completion timestamp, not a real one */
+ *compl->tx_timestamp = ktime_get_tai_fast_ns();
+ }
+
xsk_cq_submit_locked(xdp_sk(skb->sk), xsk_get_num_desc(skb));
sock_wfree(skb);
}
@@ -655,8 +662,10 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs,
static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
struct xdp_desc *desc)
{
+ struct xsk_tx_metadata *meta = NULL;
struct net_device *dev = xs->dev;
struct sk_buff *skb = xs->skb;
+ bool first_frag = false;
int err;
if (dev->priv_flags & IFF_TX_SKB_NO_LINEAR) {
@@ -687,6 +696,8 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
kfree_skb(skb);
goto free_err;
}
+
+ first_frag = true;
} else {
int nr_frags = skb_shinfo(skb)->nr_frags;
struct page *page;
@@ -709,12 +720,35 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
skb_add_rx_frag(skb, nr_frags, page, 0, len, 0);
}
+
+ if (first_frag && desc->options & XDP_TX_METADATA) {
+ if (unlikely(xs->pool->tx_metadata_len == 0)) {
+ err = -EINVAL;
+ goto free_err;
+ }
+
+ meta = buffer - xs->pool->tx_metadata_len;
+
+ if (meta->flags & XDP_TXMD_FLAGS_CHECKSUM) {
+ if (unlikely(meta->request.csum_start +
+ meta->request.csum_offset +
+ sizeof(__sum16) > len)) {
+ err = -EINVAL;
+ goto free_err;
+ }
+
+ skb->csum_start = hr + meta->request.csum_start;
+ skb->csum_offset = meta->request.csum_offset;
+ skb->ip_summed = CHECKSUM_PARTIAL;
+ }
+ }
}
skb->dev = dev;
skb->priority = READ_ONCE(xs->sk.sk_priority);
skb->mark = READ_ONCE(xs->sk.sk_mark);
skb->destructor = xsk_destruct_skb;
+ xsk_tx_metadata_to_compl(meta, &skb_shinfo(skb)->xsk_meta);
xsk_set_destructor_arg(skb);
return skb;