[bpf-next,v2,2/9] xsk: add TX timestamp and TX checksum offload support

Commit Message

Stanislav Fomichev Sept. 14, 2023, 9:04 p.m. UTC

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_TX_METADATA_CHECKSUM: skb-style csum_start+csum_offset
2. XDP_TX_METADATA_TIMESTAMP: writes TX timestamp back into metadata
   area upon completion (tx_timestamp field)

The offloads are also implemented for copy mode:
1. Extra XDP_TX_METADATA_CHECKSUM_SW to trigger skb_checksum_help; this
   might be useful as a reference implementation and for testing
2. XDP_TX_METADATA_TIMESTAMP 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.

Signed-off-by: Stanislav Fomichev <[e-mail]>
---
 Documentation/netlink/specs/netdev.yaml | 20 +++++++
 include/linux/netdevice.h               | 27 +++++++++
 include/linux/skbuff.h                  | 14 ++++-
 include/net/xdp_sock.h                  | 80 +++++++++++++++++++++++++
 include/net/xdp_sock_drv.h              | 13 ++++
 include/net/xsk_buff_pool.h             |  6 ++
 include/uapi/linux/if_xdp.h             | 40 +++++++++++++
 include/uapi/linux/netdev.h             | 16 +++++
 net/core/netdev-genl.c                  | 12 +++-
 net/xdp/xsk.c                           | 39 ++++++++++++
 net/xdp/xsk_queue.h                     |  2 +-
 tools/include/uapi/linux/if_xdp.h       | 54 +++++++++++++++--
 tools/include/uapi/linux/netdev.h       | 15 +++++
 13 files changed, 330 insertions(+), 8 deletions(-)

Comments

kernel test robot Sept. 15, 2023, 1:29 a.m. UTC | #1

Hi Stanislav,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Stanislav-Fomichev/xsk-Support-tx_metadata_len/20230915-051153
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20230914210452.2588884-3-sdf%40google.com
patch subject: [PATCH bpf-next v2 2/9] xsk: add TX timestamp and TX checksum offload support
config: riscv-defconfig (https://download.01.org/0day-ci/archive/20230915/[e-mail]/config)
compiler: riscv64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230915/[e-mail]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[e-mail]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/

All warnings (new ones prefixed by >>):

   In file included from include/net/xdp_sock_drv.h:9,
                    from drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:44:
>> include/net/xdp_sock.h:183:52: warning: 'struct xsk_tx_metadata_comp' declared inside parameter list will not be visible outside of this definition or declaration
     183 | static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_comp *compl,
         |                                                    ^~~~~~~~~~~~~~~~~~~~


vim +183 include/net/xdp_sock.h

   182	
 > 183	static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_comp *compl,
   184						    const struct xsk_tx_metadata_ops *ops,
   185						    void *priv)
   186	{
   187	}
   188

Vinicius Costa Gomes Sept. 15, 2023, 1:30 a.m. UTC | #2

Hi,

Stanislav Fomichev <[e-mail]> writes:

> 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_TX_METADATA_CHECKSUM: skb-style csum_start+csum_offset
> 2. XDP_TX_METADATA_TIMESTAMP: writes TX timestamp back into metadata
>    area upon completion (tx_timestamp field)
>
> The offloads are also implemented for copy mode:
> 1. Extra XDP_TX_METADATA_CHECKSUM_SW to trigger skb_checksum_help; this
>    might be useful as a reference implementation and for testing
> 2. XDP_TX_METADATA_TIMESTAMP 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.
>
> Signed-off-by: Stanislav Fomichev <[e-mail]>
> ---
>  Documentation/netlink/specs/netdev.yaml | 20 +++++++
>  include/linux/netdevice.h               | 27 +++++++++
>  include/linux/skbuff.h                  | 14 ++++-
>  include/net/xdp_sock.h                  | 80 +++++++++++++++++++++++++
>  include/net/xdp_sock_drv.h              | 13 ++++
>  include/net/xsk_buff_pool.h             |  6 ++
>  include/uapi/linux/if_xdp.h             | 40 +++++++++++++
>  include/uapi/linux/netdev.h             | 16 +++++
>  net/core/netdev-genl.c                  | 12 +++-
>  net/xdp/xsk.c                           | 39 ++++++++++++
>  net/xdp/xsk_queue.h                     |  2 +-
>  tools/include/uapi/linux/if_xdp.h       | 54 +++++++++++++++--
>  tools/include/uapi/linux/netdev.h       | 15 +++++
>  13 files changed, 330 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
> index 1c7284fd535b..9002b37b7676 100644
> --- a/Documentation/netlink/specs/netdev.yaml
> +++ b/Documentation/netlink/specs/netdev.yaml
> @@ -42,6 +42,19 @@ name: netdev
>          doc:
>            This feature informs if netdev implements non-linear XDP buffer
>            support in ndo_xdp_xmit callback.
> +  -
> +    type: flags
> +    name: xsk-flags
> +    render-max: true
> +    entries:
> +      -
> +        name: tx-timestamp
> +        doc:
> +          HW timestamping egress packets is supported by the driver.
> +      -
> +        name: tx-checksum
> +        doc:
> +          L3 checksum HW offload is supported by the driver.
>  
>  attribute-sets:
>    -
> @@ -68,6 +81,12 @@ name: netdev
>          type: u32
>          checks:
>            min: 1
> +      -
> +        name: xsk-features
> +        doc: Bitmask of enabled AF_XDP features.
> +        type: u64
> +        enum: xsk-flags
> +        enum-as-flags: true
>  
>  operations:
>    list:
> @@ -84,6 +103,7 @@ name: netdev
>              - ifindex
>              - xdp-features
>              - xdp-zc-max-segs
> +            - xsk-features
>        dump:
>          reply: *dev-all
>      -
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 0896aaa91dd7..3f02aaa30590 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -1647,6 +1647,31 @@ struct net_device_ops {
>  						    struct netlink_ext_ack *extack);
>  };
>  
> +/*
> + * This structure defines the AF_XDP TX metadata hooks for network devices.
> + * The following hooks can be defined; unless noted otherwise, they are
> + * optional and can be filled with a null pointer.
> + *
> + * int (*tmo_request_timestamp)(void *priv)
> + *     This function is called when AF_XDP frame requested egress timestamp.
> + *
> + * int (*tmo_fill_timestamp)(void *priv)
> + *     This function is called when AF_XDP frame, that had requested
> + *     egress timestamp, received a completion. The hook needs to return
> + *     the actual HW timestamp.
> + *
> + * int (*tmo_request_checksum)(u16 csum_start, u16 csum_offset, void *priv)
> + *     This function is called when AF_XDP frame requested HW checksum
> + *     offload. csum_start indicates position where checksumming should start.
> + *     csum_offset indicates position where checksum should be stored.
> + *
> + */
> +struct xsk_tx_metadata_ops {
> +	void	(*tmo_request_timestamp)(void *priv);
> +	u64	(*tmo_fill_timestamp)(void *priv);
> +	void	(*tmo_request_checksum)(u16 csum_start, u16 csum_offset, void *priv);
> +};
> +
>  /**
>   * enum netdev_priv_flags - &struct net_device priv_flags
>   *
> @@ -1835,6 +1860,7 @@ enum netdev_ml_priv_type {
>   *	@netdev_ops:	Includes several pointers to callbacks,
>   *			if one wants to override the ndo_*() functions
>   *	@xdp_metadata_ops:	Includes pointers to XDP metadata callbacks.
> + *	@xsk_tx_metadata_ops:	Includes pointers to AF_XDP TX metadata callbacks.
>   *	@ethtool_ops:	Management operations
>   *	@l3mdev_ops:	Layer 3 master device operations
>   *	@ndisc_ops:	Includes callbacks for different IPv6 neighbour
> @@ -2091,6 +2117,7 @@ struct net_device {
>  	unsigned long long	priv_flags;
>  	const struct net_device_ops *netdev_ops;
>  	const struct xdp_metadata_ops *xdp_metadata_ops;
> +	const struct xsk_tx_metadata_ops *xsk_tx_metadata_ops;
>  	int			ifindex;
>  	unsigned short		gflags;
>  	unsigned short		hard_header_len;
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 4174c4b82d13..444d35dcd690 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -566,6 +566,15 @@ struct ubuf_info_msgzc {
>  int mm_account_pinned_pages(struct mmpin *mmp, size_t size);
>  void mm_unaccount_pinned_pages(struct mmpin *mmp);
>  
> +/* Preserve some data across TX submission and completion.
> + *
> + * Note, this state is stored in the driver. Extending the layout
> + * might need some special care.
> + */
> +struct xsk_tx_metadata_compl {
> +	__u64 *tx_timestamp;
> +};
> +
>  /* This data is invariant across clones and lives at
>   * the end of the header data, ie. at skb->end.
>   */
> @@ -578,7 +587,10 @@ struct skb_shared_info {
>  	/* Warning: this field is not always filled in (UFO)! */
>  	unsigned short	gso_segs;
>  	struct sk_buff	*frag_list;
> -	struct skb_shared_hwtstamps hwtstamps;
> +	union {
> +		struct skb_shared_hwtstamps hwtstamps;
> +		struct xsk_tx_metadata_compl xsk_meta;
> +	};
>  	unsigned int	gso_type;
>  	u32		tskey;
>  
> diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
> index 10993a05d220..c438c614a8d0 100644
> --- a/include/net/xdp_sock.h
> +++ b/include/net/xdp_sock.h
> @@ -90,6 +90,74 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
>  int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp);
>  void __xsk_map_flush(void);
>  
> +/**
> + *  xsk_tx_metadata_to_compl - Save enough relevant metadata information
> + *  to perform tx completion in the future.
> + *  @meta: pointer to AF_XDP metadata area
> + *  @compl: pointer to output struct xsk_tx_metadata_to_compl
> + *
> + *  This function should be called by the networking device when
> + *  it prepares AF_XDP egress packet. The value of @compl should be stored
> + *  and passed to xsk_tx_metadata_complete upon TX completion.
> + */
> +static inline void xsk_tx_metadata_to_compl(struct xsk_tx_metadata *meta,
> +					    struct xsk_tx_metadata_compl *compl)

One of my systems didn't have the config XDP_SOCKETS enabled, and found
some issues:

This function is not defined when XDP_SOCKETS is disabled, got a
compilation error.

> +{
> +	if (!meta)
> +		return;
> +
> +	if (meta->flags & XDP_TX_METADATA_TIMESTAMP)
> +		compl->tx_timestamp = &meta->completion.tx_timestamp;
> +	else
> +		compl->tx_timestamp = NULL;
> +}
> +
> +/**
> + *  xsk_tx_metadata_request - Evaluate AF_XDP TX metadata at submission
> + *  and call appropriate xsk_tx_metadata_ops operation.
> + *  @meta: pointer to AF_XDP metadata area
> + *  @ops: pointer to struct xsk_tx_metadata_ops
> + *  @priv: pointer to driver-private aread
> + *
> + *  This function should be called by the networking device when
> + *  it prepares AF_XDP egress packet.
> + */
> +static inline void xsk_tx_metadata_request(const struct xsk_tx_metadata *meta,
> +					   const struct xsk_tx_metadata_ops *ops,
> +					   void *priv)
> +{
> +	if (!meta)
> +		return;
> +
> +	if (ops->tmo_request_timestamp)
> +		if (meta->flags & XDP_TX_METADATA_TIMESTAMP)
> +			ops->tmo_request_timestamp(priv);
> +
> +	if (ops->tmo_request_checksum)
> +		if (meta->flags & XDP_TX_METADATA_CHECKSUM)
> +			ops->tmo_request_checksum(meta->csum_start, meta->csum_offset, priv);
> +}
> +
> +/**
> + *  xsk_tx_metadata_complete - Evaluate AF_XDP TX metadata at completion
> + *  and call appropriate xsk_tx_metadata_ops operation.
> + *  @compl: pointer to completion metadata produced from xsk_tx_metadata_to_compl
> + *  @ops: pointer to struct xsk_tx_metadata_ops
> + *  @priv: pointer to driver-private aread
> + *
> + *  This function should be called by the networking device upon
> + *  AF_XDP egress completion.
> + */
> +static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_compl *compl,
> +					    const struct xsk_tx_metadata_ops *ops,
> +					    void *priv)
> +{
> +	if (!compl)
> +		return;
> +
> +	*compl->tx_timestamp = ops->tmo_fill_timestamp(priv);
> +}
> +
>  #else
>  
>  static inline int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
> @@ -106,6 +174,18 @@ static inline void __xsk_map_flush(void)
>  {
>  }
>  
> +static inline void xsk_tx_metadata_request(struct xsk_tx_metadata *meta,
> +					   const struct xsk_tx_metadata_ops *ops,
> +					   void *priv)
> +{
> +}
> +
> +static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_comp *compl,

typo here: should be 'struct xsk_tx_metadata_compl'.

Just so you are aware of these (very) minor issues for the next version.

I enabled XDP_SOCKETS and will take a better look.


Cheers,

kernel test robot Sept. 15, 2023, 9:44 a.m. UTC | #3

Hi Stanislav,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Stanislav-Fomichev/xsk-Support-tx_metadata_len/20230915-051153
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20230914210452.2588884-3-sdf%40google.com
patch subject: [PATCH bpf-next v2 2/9] xsk: add TX timestamp and TX checksum offload support
config: um-allnoconfig (https://download.01.org/0day-ci/archive/20230915/[e-mail]/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230915/[e-mail]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[e-mail]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/

All warnings (new ones prefixed by >>):

   In file included from net/core/filter.c:21:
   In file included from include/linux/bpf_verifier.h:7:
   In file included from include/linux/bpf.h:31:
   In file included from include/linux/memcontrol.h:13:
   In file included from include/linux/cgroup.h:26:
   In file included from include/linux/kernel_stat.h:9:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from arch/um/include/asm/hardirq.h:5:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/um/include/asm/io.h:24:
   include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     547 |         val = __raw_readb(PCI_IOBASE + addr);
         |                           ~~~~~~~~~~ ^
   include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     560 |         val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
         |                                                         ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
      37 | #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
         |                                                   ^
   In file included from net/core/filter.c:21:
   In file included from include/linux/bpf_verifier.h:7:
   In file included from include/linux/bpf.h:31:
   In file included from include/linux/memcontrol.h:13:
   In file included from include/linux/cgroup.h:26:
   In file included from include/linux/kernel_stat.h:9:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from arch/um/include/asm/hardirq.h:5:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/um/include/asm/io.h:24:
   include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     573 |         val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
         |                                                         ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
      35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
         |                                                   ^
   In file included from net/core/filter.c:21:
   In file included from include/linux/bpf_verifier.h:7:
   In file included from include/linux/bpf.h:31:
   In file included from include/linux/memcontrol.h:13:
   In file included from include/linux/cgroup.h:26:
   In file included from include/linux/kernel_stat.h:9:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from arch/um/include/asm/hardirq.h:5:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/um/include/asm/io.h:24:
   include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     584 |         __raw_writeb(value, PCI_IOBASE + addr);
         |                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     594 |         __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
         |                                                       ~~~~~~~~~~ ^
   include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     604 |         __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
         |                                                       ~~~~~~~~~~ ^
   include/asm-generic/io.h:692:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     692 |         readsb(PCI_IOBASE + addr, buffer, count);
         |                ~~~~~~~~~~ ^
   include/asm-generic/io.h:700:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     700 |         readsw(PCI_IOBASE + addr, buffer, count);
         |                ~~~~~~~~~~ ^
   include/asm-generic/io.h:708:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     708 |         readsl(PCI_IOBASE + addr, buffer, count);
         |                ~~~~~~~~~~ ^
   include/asm-generic/io.h:717:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     717 |         writesb(PCI_IOBASE + addr, buffer, count);
         |                 ~~~~~~~~~~ ^
   include/asm-generic/io.h:726:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     726 |         writesw(PCI_IOBASE + addr, buffer, count);
         |                 ~~~~~~~~~~ ^
   include/asm-generic/io.h:735:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
     735 |         writesl(PCI_IOBASE + addr, buffer, count);
         |                 ~~~~~~~~~~ ^
   In file included from net/core/filter.c:62:
>> include/net/xdp_sock.h:183:52: warning: declaration of 'struct xsk_tx_metadata_comp' will not be visible outside of this function [-Wvisibility]
     183 | static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_comp *compl,
         |                                                    ^
   13 warnings generated.


vim +183 include/net/xdp_sock.h

   182	
 > 183	static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_comp *compl,
   184						    const struct xsk_tx_metadata_ops *ops,
   185						    void *priv)
   186	{
   187	}
   188

Stanislav Fomichev Sept. 15, 2023, 4:25 p.m. UTC | #4

On Thu, Sep 14, 2023 at 6:30 PM Vinicius Costa Gomes
<[e-mail]> wrote:
>
> Hi,
>
> Stanislav Fomichev <[e-mail]> writes:
>
> > 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_TX_METADATA_CHECKSUM: skb-style csum_start+csum_offset
> > 2. XDP_TX_METADATA_TIMESTAMP: writes TX timestamp back into metadata
> >    area upon completion (tx_timestamp field)
> >
> > The offloads are also implemented for copy mode:
> > 1. Extra XDP_TX_METADATA_CHECKSUM_SW to trigger skb_checksum_help; this
> >    might be useful as a reference implementation and for testing
> > 2. XDP_TX_METADATA_TIMESTAMP 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.
> >
> > Signed-off-by: Stanislav Fomichev <[e-mail]>
> > ---
> >  Documentation/netlink/specs/netdev.yaml | 20 +++++++
> >  include/linux/netdevice.h               | 27 +++++++++
> >  include/linux/skbuff.h                  | 14 ++++-
> >  include/net/xdp_sock.h                  | 80 +++++++++++++++++++++++++
> >  include/net/xdp_sock_drv.h              | 13 ++++
> >  include/net/xsk_buff_pool.h             |  6 ++
> >  include/uapi/linux/if_xdp.h             | 40 +++++++++++++
> >  include/uapi/linux/netdev.h             | 16 +++++
> >  net/core/netdev-genl.c                  | 12 +++-
> >  net/xdp/xsk.c                           | 39 ++++++++++++
> >  net/xdp/xsk_queue.h                     |  2 +-
> >  tools/include/uapi/linux/if_xdp.h       | 54 +++++++++++++++--
> >  tools/include/uapi/linux/netdev.h       | 15 +++++
> >  13 files changed, 330 insertions(+), 8 deletions(-)
> >
> > diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
> > index 1c7284fd535b..9002b37b7676 100644
> > --- a/Documentation/netlink/specs/netdev.yaml
> > +++ b/Documentation/netlink/specs/netdev.yaml
> > @@ -42,6 +42,19 @@ name: netdev
> >          doc:
> >            This feature informs if netdev implements non-linear XDP buffer
> >            support in ndo_xdp_xmit callback.
> > +  -
> > +    type: flags
> > +    name: xsk-flags
> > +    render-max: true
> > +    entries:
> > +      -
> > +        name: tx-timestamp
> > +        doc:
> > +          HW timestamping egress packets is supported by the driver.
> > +      -
> > +        name: tx-checksum
> > +        doc:
> > +          L3 checksum HW offload is supported by the driver.
> >
> >  attribute-sets:
> >    -
> > @@ -68,6 +81,12 @@ name: netdev
> >          type: u32
> >          checks:
> >            min: 1
> > +      -
> > +        name: xsk-features
> > +        doc: Bitmask of enabled AF_XDP features.
> > +        type: u64
> > +        enum: xsk-flags
> > +        enum-as-flags: true
> >
> >  operations:
> >    list:
> > @@ -84,6 +103,7 @@ name: netdev
> >              - ifindex
> >              - xdp-features
> >              - xdp-zc-max-segs
> > +            - xsk-features
> >        dump:
> >          reply: *dev-all
> >      -
> > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> > index 0896aaa91dd7..3f02aaa30590 100644
> > --- a/include/linux/netdevice.h
> > +++ b/include/linux/netdevice.h
> > @@ -1647,6 +1647,31 @@ struct net_device_ops {
> >                                                   struct netlink_ext_ack *extack);
> >  };
> >
> > +/*
> > + * This structure defines the AF_XDP TX metadata hooks for network devices.
> > + * The following hooks can be defined; unless noted otherwise, they are
> > + * optional and can be filled with a null pointer.
> > + *
> > + * int (*tmo_request_timestamp)(void *priv)
> > + *     This function is called when AF_XDP frame requested egress timestamp.
> > + *
> > + * int (*tmo_fill_timestamp)(void *priv)
> > + *     This function is called when AF_XDP frame, that had requested
> > + *     egress timestamp, received a completion. The hook needs to return
> > + *     the actual HW timestamp.
> > + *
> > + * int (*tmo_request_checksum)(u16 csum_start, u16 csum_offset, void *priv)
> > + *     This function is called when AF_XDP frame requested HW checksum
> > + *     offload. csum_start indicates position where checksumming should start.
> > + *     csum_offset indicates position where checksum should be stored.
> > + *
> > + */
> > +struct xsk_tx_metadata_ops {
> > +     void    (*tmo_request_timestamp)(void *priv);
> > +     u64     (*tmo_fill_timestamp)(void *priv);
> > +     void    (*tmo_request_checksum)(u16 csum_start, u16 csum_offset, void *priv);
> > +};
> > +
> >  /**
> >   * enum netdev_priv_flags - &struct net_device priv_flags
> >   *
> > @@ -1835,6 +1860,7 @@ enum netdev_ml_priv_type {
> >   *   @netdev_ops:    Includes several pointers to callbacks,
> >   *                   if one wants to override the ndo_*() functions
> >   *   @xdp_metadata_ops:      Includes pointers to XDP metadata callbacks.
> > + *   @xsk_tx_metadata_ops:   Includes pointers to AF_XDP TX metadata callbacks.
> >   *   @ethtool_ops:   Management operations
> >   *   @l3mdev_ops:    Layer 3 master device operations
> >   *   @ndisc_ops:     Includes callbacks for different IPv6 neighbour
> > @@ -2091,6 +2117,7 @@ struct net_device {
> >       unsigned long long      priv_flags;
> >       const struct net_device_ops *netdev_ops;
> >       const struct xdp_metadata_ops *xdp_metadata_ops;
> > +     const struct xsk_tx_metadata_ops *xsk_tx_metadata_ops;
> >       int                     ifindex;
> >       unsigned short          gflags;
> >       unsigned short          hard_header_len;
> > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> > index 4174c4b82d13..444d35dcd690 100644
> > --- a/include/linux/skbuff.h
> > +++ b/include/linux/skbuff.h
> > @@ -566,6 +566,15 @@ struct ubuf_info_msgzc {
> >  int mm_account_pinned_pages(struct mmpin *mmp, size_t size);
> >  void mm_unaccount_pinned_pages(struct mmpin *mmp);
> >
> > +/* Preserve some data across TX submission and completion.
> > + *
> > + * Note, this state is stored in the driver. Extending the layout
> > + * might need some special care.
> > + */
> > +struct xsk_tx_metadata_compl {
> > +     __u64 *tx_timestamp;
> > +};
> > +
> >  /* This data is invariant across clones and lives at
> >   * the end of the header data, ie. at skb->end.
> >   */
> > @@ -578,7 +587,10 @@ struct skb_shared_info {
> >       /* Warning: this field is not always filled in (UFO)! */
> >       unsigned short  gso_segs;
> >       struct sk_buff  *frag_list;
> > -     struct skb_shared_hwtstamps hwtstamps;
> > +     union {
> > +             struct skb_shared_hwtstamps hwtstamps;
> > +             struct xsk_tx_metadata_compl xsk_meta;
> > +     };
> >       unsigned int    gso_type;
> >       u32             tskey;
> >
> > diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
> > index 10993a05d220..c438c614a8d0 100644
> > --- a/include/net/xdp_sock.h
> > +++ b/include/net/xdp_sock.h
> > @@ -90,6 +90,74 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
> >  int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp);
> >  void __xsk_map_flush(void);
> >
> > +/**
> > + *  xsk_tx_metadata_to_compl - Save enough relevant metadata information
> > + *  to perform tx completion in the future.
> > + *  @meta: pointer to AF_XDP metadata area
> > + *  @compl: pointer to output struct xsk_tx_metadata_to_compl
> > + *
> > + *  This function should be called by the networking device when
> > + *  it prepares AF_XDP egress packet. The value of @compl should be stored
> > + *  and passed to xsk_tx_metadata_complete upon TX completion.
> > + */
> > +static inline void xsk_tx_metadata_to_compl(struct xsk_tx_metadata *meta,
> > +                                         struct xsk_tx_metadata_compl *compl)
>
> One of my systems didn't have the config XDP_SOCKETS enabled, and found
> some issues:
>
> This function is not defined when XDP_SOCKETS is disabled, got a
> compilation error.
>
> > +{
> > +     if (!meta)
> > +             return;
> > +
> > +     if (meta->flags & XDP_TX_METADATA_TIMESTAMP)
> > +             compl->tx_timestamp = &meta->completion.tx_timestamp;
> > +     else
> > +             compl->tx_timestamp = NULL;
> > +}
> > +
> > +/**
> > + *  xsk_tx_metadata_request - Evaluate AF_XDP TX metadata at submission
> > + *  and call appropriate xsk_tx_metadata_ops operation.
> > + *  @meta: pointer to AF_XDP metadata area
> > + *  @ops: pointer to struct xsk_tx_metadata_ops
> > + *  @priv: pointer to driver-private aread
> > + *
> > + *  This function should be called by the networking device when
> > + *  it prepares AF_XDP egress packet.
> > + */
> > +static inline void xsk_tx_metadata_request(const struct xsk_tx_metadata *meta,
> > +                                        const struct xsk_tx_metadata_ops *ops,
> > +                                        void *priv)
> > +{
> > +     if (!meta)
> > +             return;
> > +
> > +     if (ops->tmo_request_timestamp)
> > +             if (meta->flags & XDP_TX_METADATA_TIMESTAMP)
> > +                     ops->tmo_request_timestamp(priv);
> > +
> > +     if (ops->tmo_request_checksum)
> > +             if (meta->flags & XDP_TX_METADATA_CHECKSUM)
> > +                     ops->tmo_request_checksum(meta->csum_start, meta->csum_offset, priv);
> > +}
> > +
> > +/**
> > + *  xsk_tx_metadata_complete - Evaluate AF_XDP TX metadata at completion
> > + *  and call appropriate xsk_tx_metadata_ops operation.
> > + *  @compl: pointer to completion metadata produced from xsk_tx_metadata_to_compl
> > + *  @ops: pointer to struct xsk_tx_metadata_ops
> > + *  @priv: pointer to driver-private aread
> > + *
> > + *  This function should be called by the networking device upon
> > + *  AF_XDP egress completion.
> > + */
> > +static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_compl *compl,
> > +                                         const struct xsk_tx_metadata_ops *ops,
> > +                                         void *priv)
> > +{
> > +     if (!compl)
> > +             return;
> > +
> > +     *compl->tx_timestamp = ops->tmo_fill_timestamp(priv);
> > +}
> > +
> >  #else
> >
> >  static inline int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
> > @@ -106,6 +174,18 @@ static inline void __xsk_map_flush(void)
> >  {
> >  }
> >
> > +static inline void xsk_tx_metadata_request(struct xsk_tx_metadata *meta,
> > +                                        const struct xsk_tx_metadata_ops *ops,
> > +                                        void *priv)
> > +{
> > +}
> > +
> > +static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_comp *compl,
>
> typo here: should be 'struct xsk_tx_metadata_compl'.
>
> Just so you are aware of these (very) minor issues for the next version.
>
> I enabled XDP_SOCKETS and will take a better look.

Thank you, will take a look. There are a bunch of bot build errors
that look similar as well.

Patch

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index 1c7284fd535b..9002b37b7676 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -42,6 +42,19 @@  name: netdev
         doc:
           This feature informs if netdev implements non-linear XDP buffer
           support in ndo_xdp_xmit callback.
+  -
+    type: flags
+    name: xsk-flags
+    render-max: true
+    entries:
+      -
+        name: tx-timestamp
+        doc:
+          HW timestamping egress packets is supported by the driver.
+      -
+        name: tx-checksum
+        doc:
+          L3 checksum HW offload is supported by the driver.
 
 attribute-sets:
   -
@@ -68,6 +81,12 @@  name: netdev
         type: u32
         checks:
           min: 1
+      -
+        name: xsk-features
+        doc: Bitmask of enabled AF_XDP features.
+        type: u64
+        enum: xsk-flags
+        enum-as-flags: true
 
 operations:
   list:
@@ -84,6 +103,7 @@  name: netdev
             - ifindex
             - xdp-features
             - xdp-zc-max-segs
+            - xsk-features
       dump:
         reply: *dev-all
     -
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 0896aaa91dd7..3f02aaa30590 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1647,6 +1647,31 @@  struct net_device_ops {
 						    struct netlink_ext_ack *extack);
 };
 
+/*
+ * This structure defines the AF_XDP TX metadata hooks for network devices.
+ * The following hooks can be defined; unless noted otherwise, they are
+ * optional and can be filled with a null pointer.
+ *
+ * int (*tmo_request_timestamp)(void *priv)
+ *     This function is called when AF_XDP frame requested egress timestamp.
+ *
+ * int (*tmo_fill_timestamp)(void *priv)
+ *     This function is called when AF_XDP frame, that had requested
+ *     egress timestamp, received a completion. The hook needs to return
+ *     the actual HW timestamp.
+ *
+ * int (*tmo_request_checksum)(u16 csum_start, u16 csum_offset, void *priv)
+ *     This function is called when AF_XDP frame requested HW checksum
+ *     offload. csum_start indicates position where checksumming should start.
+ *     csum_offset indicates position where checksum should be stored.
+ *
+ */
+struct xsk_tx_metadata_ops {
+	void	(*tmo_request_timestamp)(void *priv);
+	u64	(*tmo_fill_timestamp)(void *priv);
+	void	(*tmo_request_checksum)(u16 csum_start, u16 csum_offset, void *priv);
+};
+
 /**
  * enum netdev_priv_flags - &struct net_device priv_flags
  *
@@ -1835,6 +1860,7 @@  enum netdev_ml_priv_type {
  *	@netdev_ops:	Includes several pointers to callbacks,
  *			if one wants to override the ndo_*() functions
  *	@xdp_metadata_ops:	Includes pointers to XDP metadata callbacks.
+ *	@xsk_tx_metadata_ops:	Includes pointers to AF_XDP TX metadata callbacks.
  *	@ethtool_ops:	Management operations
  *	@l3mdev_ops:	Layer 3 master device operations
  *	@ndisc_ops:	Includes callbacks for different IPv6 neighbour
@@ -2091,6 +2117,7 @@  struct net_device {
 	unsigned long long	priv_flags;
 	const struct net_device_ops *netdev_ops;
 	const struct xdp_metadata_ops *xdp_metadata_ops;
+	const struct xsk_tx_metadata_ops *xsk_tx_metadata_ops;
 	int			ifindex;
 	unsigned short		gflags;
 	unsigned short		hard_header_len;
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4174c4b82d13..444d35dcd690 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -566,6 +566,15 @@  struct ubuf_info_msgzc {
 int mm_account_pinned_pages(struct mmpin *mmp, size_t size);
 void mm_unaccount_pinned_pages(struct mmpin *mmp);
 
+/* Preserve some data across TX submission and completion.
+ *
+ * Note, this state is stored in the driver. Extending the layout
+ * might need some special care.
+ */
+struct xsk_tx_metadata_compl {
+	__u64 *tx_timestamp;
+};
+
 /* This data is invariant across clones and lives at
  * the end of the header data, ie. at skb->end.
  */
@@ -578,7 +587,10 @@  struct skb_shared_info {
 	/* Warning: this field is not always filled in (UFO)! */
 	unsigned short	gso_segs;
 	struct sk_buff	*frag_list;
-	struct skb_shared_hwtstamps hwtstamps;
+	union {
+		struct skb_shared_hwtstamps hwtstamps;
+		struct xsk_tx_metadata_compl xsk_meta;
+	};
 	unsigned int	gso_type;
 	u32		tskey;
 
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 10993a05d220..c438c614a8d0 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -90,6 +90,74 @@  int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
 int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp);
 void __xsk_map_flush(void);
 
+/**
+ *  xsk_tx_metadata_to_compl - Save enough relevant metadata information
+ *  to perform tx completion in the future.
+ *  @meta: pointer to AF_XDP metadata area
+ *  @compl: pointer to output struct xsk_tx_metadata_to_compl
+ *
+ *  This function should be called by the networking device when
+ *  it prepares AF_XDP egress packet. The value of @compl should be stored
+ *  and passed to xsk_tx_metadata_complete upon TX completion.
+ */
+static inline void xsk_tx_metadata_to_compl(struct xsk_tx_metadata *meta,
+					    struct xsk_tx_metadata_compl *compl)
+{
+	if (!meta)
+		return;
+
+	if (meta->flags & XDP_TX_METADATA_TIMESTAMP)
+		compl->tx_timestamp = &meta->completion.tx_timestamp;
+	else
+		compl->tx_timestamp = NULL;
+}
+
+/**
+ *  xsk_tx_metadata_request - Evaluate AF_XDP TX metadata at submission
+ *  and call appropriate xsk_tx_metadata_ops operation.
+ *  @meta: pointer to AF_XDP metadata area
+ *  @ops: pointer to struct xsk_tx_metadata_ops
+ *  @priv: pointer to driver-private aread
+ *
+ *  This function should be called by the networking device when
+ *  it prepares AF_XDP egress packet.
+ */
+static inline void xsk_tx_metadata_request(const struct xsk_tx_metadata *meta,
+					   const struct xsk_tx_metadata_ops *ops,
+					   void *priv)
+{
+	if (!meta)
+		return;
+
+	if (ops->tmo_request_timestamp)
+		if (meta->flags & XDP_TX_METADATA_TIMESTAMP)
+			ops->tmo_request_timestamp(priv);
+
+	if (ops->tmo_request_checksum)
+		if (meta->flags & XDP_TX_METADATA_CHECKSUM)
+			ops->tmo_request_checksum(meta->csum_start, meta->csum_offset, priv);
+}
+
+/**
+ *  xsk_tx_metadata_complete - Evaluate AF_XDP TX metadata at completion
+ *  and call appropriate xsk_tx_metadata_ops operation.
+ *  @compl: pointer to completion metadata produced from xsk_tx_metadata_to_compl
+ *  @ops: pointer to struct xsk_tx_metadata_ops
+ *  @priv: pointer to driver-private aread
+ *
+ *  This function should be called by the networking device upon
+ *  AF_XDP egress completion.
+ */
+static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_compl *compl,
+					    const struct xsk_tx_metadata_ops *ops,
+					    void *priv)
+{
+	if (!compl)
+		return;
+
+	*compl->tx_timestamp = ops->tmo_fill_timestamp(priv);
+}
+
 #else
 
 static inline int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
@@ -106,6 +174,18 @@  static inline void __xsk_map_flush(void)
 {
 }
 
+static inline void xsk_tx_metadata_request(struct xsk_tx_metadata *meta,
+					   const struct xsk_tx_metadata_ops *ops,
+					   void *priv)
+{
+}
+
+static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_comp *compl,
+					    const struct xsk_tx_metadata_ops *ops,
+					    void *priv)
+{
+}
+
 #endif /* CONFIG_XDP_SOCKETS */
 
 #endif /* _LINUX_XDP_SOCK_H */
diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h
index 1f6fc8c7a84c..e2558ac3e195 100644
--- a/include/net/xdp_sock_drv.h
+++ b/include/net/xdp_sock_drv.h
@@ -165,6 +165,14 @@  static inline void *xsk_buff_raw_get_data(struct xsk_buff_pool *pool, u64 addr)
 	return xp_raw_get_data(pool, addr);
 }
 
+static inline struct xsk_tx_metadata *xsk_buff_get_metadata(struct xsk_buff_pool *pool, u64 addr)
+{
+	if (!pool->tx_metadata_len)
+		return NULL;
+
+	return xp_raw_get_data(pool, addr) - pool->tx_metadata_len;
+}
+
 static inline void xsk_buff_dma_sync_for_cpu(struct xdp_buff *xdp, struct xsk_buff_pool *pool)
 {
 	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);
@@ -324,6 +332,11 @@  static inline void *xsk_buff_raw_get_data(struct xsk_buff_pool *pool, u64 addr)
 	return NULL;
 }
 
+static inline struct xsk_tx_metadata *xsk_buff_get_metadata(struct xsk_buff_pool *pool, u64 addr)
+{
+	return NULL;
+}
+
 static inline void xsk_buff_dma_sync_for_cpu(struct xdp_buff *xdp, struct xsk_buff_pool *pool)
 {
 }
diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index 1985ffaf9b0c..97f5cc10d79e 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -33,6 +33,7 @@  struct xdp_buff_xsk {
 };
 
 #define XSK_CHECK_PRIV_TYPE(t) BUILD_BUG_ON(sizeof(t) > offsetofend(struct xdp_buff_xsk, cb))
+#define XSK_TX_COMPL_FITS(t) BUILD_BUG_ON(sizeof(struct xsk_tx_metadata_compl) > sizeof(t))
 
 struct xsk_dma_map {
 	dma_addr_t *dma_pages;
@@ -234,4 +235,9 @@  static inline u64 xp_get_handle(struct xdp_buff_xsk *xskb)
 	return xskb->orig_addr + (offset << XSK_UNALIGNED_BUF_OFFSET_SHIFT);
 }
 
+static inline bool xp_tx_metadata_enabled(const struct xsk_buff_pool *pool)
+{
+	return pool->tx_metadata_len > 0;
+}
+
 #endif /* XSK_BUFF_POOL_H_ */
diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
index 2ecf79282c26..ecfd67988283 100644
--- a/include/uapi/linux/if_xdp.h
+++ b/include/uapi/linux/if_xdp.h
@@ -106,6 +106,43 @@  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_TX_METADATA_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_TX_METADATA_CHECKSUM		(1 << 1)
+
+/* Force checksum calculation in software. Can be used for testing or
+ * working around potential HW issues. This option causes performance
+ * degradation and only works in XDP_COPY mode.
+ */
+#define XDP_TX_METADATA_CHECKSUM_SW		(1 << 2)
+
+struct xsk_tx_metadata {
+	union {
+		struct {
+			__u32 flags;
+
+			/* XDP_TX_METADATA_CHECKSUM */
+
+			/* Offset from desc->addr where checksumming should start. */
+			__u16 csum_start;
+			/* Offset from csum_start where checksum should be stored. */
+			__u16 csum_offset;
+		};
+
+		struct {
+			/* XDP_TX_METADATA_TIMESTAMP */
+			__u64 tx_timestamp;
+		} completion;
+	};
+};
+
 /* Rx/Tx descriptor */
 struct xdp_desc {
 	__u64 addr;
@@ -122,4 +159,7 @@  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 c1634b95c223..138e467a09d6 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -38,11 +38,27 @@  enum netdev_xdp_act {
 	NETDEV_XDP_ACT_MASK = 127,
 };
 
+/**
+ * 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_XSK_FEATURES,
 
 	__NETDEV_A_DEV_MAX,
 	NETDEV_A_DEV_MAX = (__NETDEV_A_DEV_MAX - 1)
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index c1aea8b756b6..2821546e08de 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -12,15 +12,25 @@  static int
 netdev_nl_dev_fill(struct net_device *netdev, struct sk_buff *rsp,
 		   const struct genl_info *info)
 {
+	u64 xsk_flags = 0;
 	void *hdr;
 
 	hdr = genlmsg_iput(rsp, info);
 	if (!hdr)
 		return -EMSGSIZE;
 
+	if (netdev->xsk_tx_metadata_ops) {
+		if (netdev->xsk_tx_metadata_ops->tmo_fill_timestamp)
+			xsk_flags |= NETDEV_XSK_FLAGS_TX_TIMESTAMP;
+		if (netdev->xsk_tx_metadata_ops->tmo_request_checksum)
+			xsk_flags |= NETDEV_XSK_FLAGS_TX_CHECKSUM;
+	}
+
 	if (nla_put_u32(rsp, NETDEV_A_DEV_IFINDEX, netdev->ifindex) ||
 	    nla_put_u64_64bit(rsp, NETDEV_A_DEV_XDP_FEATURES,
-			      netdev->xdp_features, NETDEV_A_DEV_PAD)) {
+			      netdev->xdp_features, NETDEV_A_DEV_PAD) ||
+	    nla_put_u64_64bit(rsp, NETDEV_A_DEV_XSK_FEATURES,
+			      xsk_flags, NETDEV_A_DEV_PAD)) {
 		genlmsg_cancel(rsp, hdr);
 		return -EINVAL;
 	}
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 5e479869ede1..44cc4f8560d3 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -543,6 +543,13 @@  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);
 }
@@ -627,8 +634,10 @@  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) {
@@ -659,6 +668,8 @@  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;
@@ -681,12 +692,40 @@  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_TX_METADATA_CHECKSUM) {
+				if (unlikely(meta->csum_start + meta->csum_offset +
+					     sizeof(__sum16) > len)) {
+					err = -EINVAL;
+					goto free_err;
+				}
+
+				skb->csum_start = hr + meta->csum_start;
+				skb->csum_offset = meta->csum_offset;
+				skb->ip_summed = CHECKSUM_PARTIAL;
+
+				if (unlikely(meta->flags & XDP_TX_METADATA_CHECKSUM_SW)) {
+					err = skb_checksum_help(skb);
+					if (err)
+						goto free_err;
+				}
+			}
+		}
 	}
 
 	skb->dev = dev;
 	skb->priority = 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;
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index c74a1372bcb9..6f2d1621c992 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -137,7 +137,7 @@  static inline bool xskq_cons_read_addr_unchecked(struct xsk_queue *q, u64 *addr)
 
 static inline bool xp_unused_options_set(u32 options)
 {
-	return options & ~XDP_PKT_CONTD;
+	return options & ~(XDP_PKT_CONTD | XDP_TX_METADATA);
 }
 
 static inline bool xp_aligned_validate_desc(struct xsk_buff_pool *pool,
diff --git a/tools/include/uapi/linux/if_xdp.h b/tools/include/uapi/linux/if_xdp.h
index 34411a2e5b6c..53ceaae10dd1 100644
--- a/tools/include/uapi/linux/if_xdp.h
+++ b/tools/include/uapi/linux/if_xdp.h
@@ -26,11 +26,11 @@ 
  */
 #define XDP_USE_NEED_WAKEUP (1 << 3)
 /* By setting this option, userspace application indicates that it can
- * handle multiple descriptors per packet thus enabling xsk core to split
+ * handle multiple descriptors per packet thus enabling AF_XDP to split
  * multi-buffer XDP frames into multiple Rx descriptors. Without this set
- * such frames will be dropped by xsk.
+ * such frames will be dropped.
  */
-#define XDP_USE_SG     (1 << 4)
+#define XDP_USE_SG	(1 << 4)
 
 /* Flags for xsk_umem_config flags */
 #define XDP_UMEM_UNALIGNED_CHUNK_FLAG (1 << 0)
@@ -106,6 +106,43 @@  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 union xsk_tx_metadata.
+ */
+#define XDP_TX_METADATA_TIMESTAMP		(1 << 0)
+
+/* Request transmit checksum offload. Checksum start position and offset
+ * are communicated via csum_start and csum_offset fields of union
+ * xsk_tx_metadata.
+ */
+#define XDP_TX_METADATA_CHECKSUM		(1 << 1)
+
+/* Force checksum calculation in software. Can be used for testing or
+ * working around potential HW issues. This option causes performance
+ * degradation and only works in XDP_COPY mode.
+ */
+#define XDP_TX_METADATA_CHECKSUM_SW		(1 << 2)
+
+struct xsk_tx_metadata {
+	union {
+		struct {
+			__u32 flags;
+
+			/* XDP_TX_METADATA_CHECKSUM */
+
+			/* Offset from desc->addr where checksumming should start. */
+			__u16 csum_start;
+			/* Offset from csum_start where checksum should be stored. */
+			__u16 csum_offset;
+		};
+
+		struct {
+			/* XDP_TX_METADATA_TIMESTAMP */
+			__u64 tx_timestamp;
+		} completion;
+	};
+};
+
 /* Rx/Tx descriptor */
 struct xdp_desc {
 	__u64 addr;
@@ -113,9 +150,16 @@  struct xdp_desc {
 	__u32 options;
 };
 
-/* Flag indicating packet constitutes of multiple buffers*/
+/* UMEM descriptor is __u64 */
+
+/* Flag indicating that the packet continues with the buffer pointed out by the
+ * next frame in the ring. The end of the packet is signalled by setting this
+ * bit to zero. For single buffer packets, every descriptor has 'options' set
+ * to 0 and this maintains backward compatibility.
+ */
 #define XDP_PKT_CONTD (1 << 0)
 
-/* UMEM descriptor is __u64 */
+/* TX packet carries valid metadata. */
+#define XDP_TX_METADATA (1 << 1)
 
 #endif /* _LINUX_IF_XDP_H */
diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h
index c1634b95c223..e8fdc530dcc9 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -38,11 +38,26 @@  enum netdev_xdp_act {
 	NETDEV_XDP_ACT_MASK = 127,
 };
 
+/**
+ * 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,
+
+	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_XSK_FEATURES,
 
 	__NETDEV_A_DEV_MAX,
 	NETDEV_A_DEV_MAX = (__NETDEV_A_DEV_MAX - 1)