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Message-ID: <20230724235957.1953861-2-sdf@google.com>
Date: Mon, 24 Jul 2023 16:59:50 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: bpf@...r.kernel.org
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
martin.lau@...ux.dev, song@...nel.org, yhs@...com, john.fastabend@...il.com,
kpsingh@...nel.org, sdf@...gle.com, haoluo@...gle.com, jolsa@...nel.org,
kuba@...nel.org, toke@...nel.org, willemb@...gle.com, dsahern@...nel.org,
magnus.karlsson@...el.com, bjorn@...nel.org, maciej.fijalkowski@...el.com,
hawk@...nel.org, netdev@...r.kernel.org, xdp-hints@...-project.net
Subject: [RFC net-next v4 1/8] xsk: Support XDP_TX_METADATA_LEN
For zerocopy mode, tx_desc->addr can point to the arbitrary offset
and carry some TX metadata in the headroom. For copy mode, there
is no way currently to populate skb metadata.
Introduce new XDP_TX_METADATA_LEN that indicates how many bytes
to treat as metadata. Metadata bytes come prior to tx_desc address
(same as in RX case).
The size of the metadata has the same constraints as XDP:
- less than 256 bytes
- 4-byte aligned
- non-zero
This data is not interpreted in any way right now.
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
include/net/xdp_sock.h | 1 +
include/net/xsk_buff_pool.h | 1 +
include/uapi/linux/if_xdp.h | 1 +
net/xdp/xsk.c | 20 ++++++++++++++++++++
net/xdp/xsk_buff_pool.c | 1 +
net/xdp/xsk_queue.h | 17 ++++++++++-------
6 files changed, 34 insertions(+), 7 deletions(-)
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 1617af380162..467b9fb56827 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -51,6 +51,7 @@ struct xdp_sock {
struct list_head flush_node;
struct xsk_buff_pool *pool;
u16 queue_id;
+ u8 tx_metadata_len;
bool zc;
bool sg;
enum {
diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index b0bdff26fc88..9c31e8d1e198 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -77,6 +77,7 @@ struct xsk_buff_pool {
u32 chunk_size;
u32 chunk_shift;
u32 frame_len;
+ u8 tx_metadata_len; /* inherited from xsk_sock */
u8 cached_need_wakeup;
bool uses_need_wakeup;
bool dma_need_sync;
diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
index 8d48863472b9..b37b50102e1c 100644
--- a/include/uapi/linux/if_xdp.h
+++ b/include/uapi/linux/if_xdp.h
@@ -69,6 +69,7 @@ struct xdp_mmap_offsets {
#define XDP_UMEM_COMPLETION_RING 6
#define XDP_STATISTICS 7
#define XDP_OPTIONS 8
+#define XDP_TX_METADATA_LEN 9
struct xdp_umem_reg {
__u64 addr; /* Start of packet data area */
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 4f1e0599146e..81106e4d6e0f 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -1337,6 +1337,26 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
mutex_unlock(&xs->mutex);
return err;
}
+ case XDP_TX_METADATA_LEN:
+ {
+ int val;
+
+ if (optlen < sizeof(val))
+ return -EINVAL;
+ if (copy_from_sockptr(&val, optval, sizeof(val)))
+ return -EFAULT;
+ if (!val || val > 256 || val % 4)
+ return -EINVAL;
+
+ mutex_lock(&xs->mutex);
+ if (xs->state != XSK_READY) {
+ mutex_unlock(&xs->mutex);
+ return -EBUSY;
+ }
+ xs->tx_metadata_len = val;
+ mutex_unlock(&xs->mutex);
+ return 0;
+ }
default:
break;
}
diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index b3f7b310811e..b351732f1032 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -85,6 +85,7 @@ struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
XDP_PACKET_HEADROOM;
pool->umem = umem;
pool->addrs = umem->addrs;
+ pool->tx_metadata_len = xs->tx_metadata_len;
INIT_LIST_HEAD(&pool->free_list);
INIT_LIST_HEAD(&pool->xskb_list);
INIT_LIST_HEAD(&pool->xsk_tx_list);
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 13354a1e4280..c74a1372bcb9 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -143,15 +143,17 @@ static inline bool xp_unused_options_set(u32 options)
static inline bool xp_aligned_validate_desc(struct xsk_buff_pool *pool,
struct xdp_desc *desc)
{
- u64 offset = desc->addr & (pool->chunk_size - 1);
+ u64 addr = desc->addr - pool->tx_metadata_len;
+ u64 len = desc->len + pool->tx_metadata_len;
+ u64 offset = addr & (pool->chunk_size - 1);
if (!desc->len)
return false;
- if (offset + desc->len > pool->chunk_size)
+ if (offset + len > pool->chunk_size)
return false;
- if (desc->addr >= pool->addrs_cnt)
+ if (addr >= pool->addrs_cnt)
return false;
if (xp_unused_options_set(desc->options))
@@ -162,16 +164,17 @@ static inline bool xp_aligned_validate_desc(struct xsk_buff_pool *pool,
static inline bool xp_unaligned_validate_desc(struct xsk_buff_pool *pool,
struct xdp_desc *desc)
{
- u64 addr = xp_unaligned_add_offset_to_addr(desc->addr);
+ u64 addr = xp_unaligned_add_offset_to_addr(desc->addr) - pool->tx_metadata_len;
+ u64 len = desc->len + pool->tx_metadata_len;
if (!desc->len)
return false;
- if (desc->len > pool->chunk_size)
+ if (len > pool->chunk_size)
return false;
- if (addr >= pool->addrs_cnt || addr + desc->len > pool->addrs_cnt ||
- xp_desc_crosses_non_contig_pg(pool, addr, desc->len))
+ if (addr >= pool->addrs_cnt || addr + len > pool->addrs_cnt ||
+ xp_desc_crosses_non_contig_pg(pool, addr, len))
return false;
if (xp_unused_options_set(desc->options))
--
2.41.0.487.g6d72f3e995-goog
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