Commit 341ac980 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Alexei Starovoitov
Browse files

xsk: Support tx_metadata_len 



For zerocopy mode, tx_desc->addr can point to an arbitrary offset
and carry some TX metadata in the headroom. For copy mode, there
is no way currently to populate skb metadata.

Introduce new tx_metadata_len umem config option 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 mostly the same constraints as XDP:
- less than 256 bytes
- 8-byte aligned (compared to 4-byte alignment on xdp, due to 8-byte
  timestamp in the completion)
- non-zero

This data is not interpreted in any way right now.

Reviewed-by: default avatarSong Yoong Siang <yoong.siang.song@intel.com>
Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Reviewed-by: default avatarJakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20231127190319.1190813-2-sdf@google.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 40d0eb02

include/net/xdp_sock.h

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ struct xdp_umem { 
	struct user_struct *user;

	refcount_t users;

	u8 flags;

	u8 tx_metadata_len;

	bool zc;

	struct page **pgs;

	int id;

include/net/xsk_buff_pool.h

+1 −0
Original line number Diff line number Diff line
@@ -77,6 +77,7 @@ struct xsk_buff_pool { 
	u32 chunk_size;

	u32 chunk_shift;

	u32 frame_len;

	u8 tx_metadata_len; /* inherited from umem */

	u8 cached_need_wakeup;

	bool uses_need_wakeup;

	bool dma_need_sync;

include/uapi/linux/if_xdp.h

+1 −0
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ struct xdp_umem_reg { 
	__u32 chunk_size;

	__u32 headroom;

	__u32 flags;

	__u32 tx_metadata_len;

};



struct xdp_statistics {

net/xdp/xdp_umem.c

+4 −0
Original line number Diff line number Diff line
@@ -199,6 +199,9 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) 
	if (headroom >= chunk_size - XDP_PACKET_HEADROOM)

		return -EINVAL;



	if (mr->tx_metadata_len >= 256 || mr->tx_metadata_len % 8)

		return -EINVAL;



	umem->size = size;

	umem->headroom = headroom;

	umem->chunk_size = chunk_size;
@@ -207,6 +210,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) 
	umem->pgs = NULL;

	umem->user = NULL;

	umem->flags = mr->flags;

	umem->tx_metadata_len = mr->tx_metadata_len;



	INIT_LIST_HEAD(&umem->xsk_dma_list);

	refcount_set(&umem->users, 1);

net/xdp/xsk.c

+11 −1
Original line number Diff line number Diff line
@@ -1283,6 +1283,14 @@ struct xdp_umem_reg_v1 { 
	__u32 headroom;

};



struct xdp_umem_reg_v2 {

	__u64 addr; /* Start of packet data area */

	__u64 len; /* Length of packet data area */

	__u32 chunk_size;

	__u32 headroom;

	__u32 flags;

};



static int xsk_setsockopt(struct socket *sock, int level, int optname,

			  sockptr_t optval, unsigned int optlen)

{
@@ -1326,8 +1334,10 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname, 


		if (optlen < sizeof(struct xdp_umem_reg_v1))

			return -EINVAL;

		else if (optlen < sizeof(mr))

		else if (optlen < sizeof(struct xdp_umem_reg_v2))

			mr_size = sizeof(struct xdp_umem_reg_v1);

		else if (optlen < sizeof(mr))

			mr_size = sizeof(struct xdp_umem_reg_v2);



		if (copy_from_sockptr(&mr, optval, mr_size))

			return -EFAULT;