From 48eb03dd26304c24f03bdbb9382e89c8564e71df Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Mon, 27 Nov 2023 11:03:08 -0800 Subject: 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 Signed-off-by: Stanislav Fomichev Acked-by: Jakub Kicinski Link: https://lore.kernel.org/r/20231127190319.1190813-3-sdf@google.com Signed-off-by: Alexei Starovoitov --- include/uapi/linux/if_xdp.h | 38 ++++++++++++++++++++++++++++++++++++++ include/uapi/linux/netdev.h | 16 ++++++++++++++++ 2 files changed, 54 insertions(+) (limited to 'include/uapi') diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h index 2ecf79282c26..95de66d5a26c 100644 --- a/include/uapi/linux/if_xdp.h +++ b/include/uapi/linux/if_xdp.h @@ -106,6 +106,41 @@ struct xdp_options { #define XSK_UNALIGNED_BUF_ADDR_MASK \ ((1ULL << XSK_UNALIGNED_BUF_OFFSET_SHIFT) - 1) +/* Request transmit timestamp. Upon completion, put it into tx_timestamp + * field of struct xsk_tx_metadata. + */ +#define XDP_TXMD_FLAGS_TIMESTAMP (1 << 0) + +/* Request transmit checksum offload. Checksum start position and offset + * are communicated via csum_start and csum_offset fields of struct + * xsk_tx_metadata. + */ +#define XDP_TXMD_FLAGS_CHECKSUM (1 << 1) + +/* AF_XDP offloads request. 'request' union member is consumed by the driver + * when the packet is being transmitted. 'completion' union member is + * filled by the driver when the transmit completion arrives. + */ +struct xsk_tx_metadata { + __u64 flags; + + union { + struct { + /* XDP_TXMD_FLAGS_CHECKSUM */ + + /* Offset from desc->addr where checksumming should start. */ + __u16 csum_start; + /* Offset from csum_start where checksum should be stored. */ + __u16 csum_offset; + } request; + + struct { + /* XDP_TXMD_FLAGS_TIMESTAMP */ + __u64 tx_timestamp; + } completion; + }; +}; + /* Rx/Tx descriptor */ struct xdp_desc { __u64 addr; @@ -122,4 +157,7 @@ struct xdp_desc { */ #define XDP_PKT_CONTD (1 << 0) +/* TX packet carries valid metadata. */ +#define XDP_TX_METADATA (1 << 1) + #endif /* _LINUX_IF_XDP_H */ diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h index 2943a151d4f1..48d5477a668c 100644 --- a/include/uapi/linux/netdev.h +++ b/include/uapi/linux/netdev.h @@ -53,12 +53,28 @@ enum netdev_xdp_rx_metadata { NETDEV_XDP_RX_METADATA_MASK = 3, }; +/** + * enum netdev_xsk_flags + * @NETDEV_XSK_FLAGS_TX_TIMESTAMP: HW timestamping egress packets is supported + * by the driver. + * @NETDEV_XSK_FLAGS_TX_CHECKSUM: L3 checksum HW offload is supported by the + * driver. + */ +enum netdev_xsk_flags { + NETDEV_XSK_FLAGS_TX_TIMESTAMP = 1, + NETDEV_XSK_FLAGS_TX_CHECKSUM = 2, + + /* private: */ + NETDEV_XSK_FLAGS_MASK = 3, +}; + enum { NETDEV_A_DEV_IFINDEX = 1, NETDEV_A_DEV_PAD, NETDEV_A_DEV_XDP_FEATURES, NETDEV_A_DEV_XDP_ZC_MAX_SEGS, NETDEV_A_DEV_XDP_RX_METADATA_FEATURES, + NETDEV_A_DEV_XSK_FEATURES, __NETDEV_A_DEV_MAX, NETDEV_A_DEV_MAX = (__NETDEV_A_DEV_MAX - 1) -- cgit v1.2.3