From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by mail.toke.dk (Postfix) with ESMTPS id 62602A2E6C4 for ; Wed, 4 Oct 2023 19:48:12 +0200 (CEST) Authentication-Results: mail.toke.dk; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20230601 header.b=c2D+qT89 Received: by mail-pg1-x549.google.com with SMTP id 41be03b00d2f7-57cf261194aso7794a12.3 for ; Wed, 04 Oct 2023 10:48:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1696441690; x=1697046490; darn=xdp-project.net; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=EZuTpjEB8ebzei/asemc2VF/5hqQqJ6KjjFoNoheXV0=; b=c2D+qT89TNW9WJQbX0QdTMW7llta2fhkR5BzovsSa29wFSxx+Tga6ALjvoWjGGJauD TRADVkv5KIHaCn+IfVJpGyc8lrtMGy3R8IG+YNRb51xleZDPW1+3+gm0QiJed2Sw94Go KeGPuTPoFoEPWN5S/xWGEOVb6fPWkUKzGDPmjjRUm/4W3vKeG8WCEufPHxLDMpod5z9K 516JxodiObf7AnZSTbWUoFx7oDgMQxK/lC2K464KYGtdYOkZ/tedOZKm09dEa8AdoZkK CDPptshv9eCF35N7If4IHxTz2IJQnsc/l2ETVfh+jZVRi7AUeo6EtuPsGfXozfo3gLQK 5XeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696441690; x=1697046490; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=EZuTpjEB8ebzei/asemc2VF/5hqQqJ6KjjFoNoheXV0=; b=schf0TlMeLFGLeHjwuEwHFurKI7/7QA6nuVbGU6q0YqfjKgetTxEsY0ASfKrhkzD1o 9K67nOq/Y8YA3E1Sleezg7YKiYGDvdhxL7ldQAmFF3ByAy1iDc3uYqWb938l3K+t8Kpa 4yUz08FaWhMy90EIKLxV0Jh9nMTehiqjbnve4oNORktnm9ViABkIQrhjAbfZBWzMHENn cfuJtmKPrldLgWBtus5x/oX0VKshkezJD4Qokwy+0kStQ4zmLNQSkT4JwaIh4Agm4DF4 zr8UQOwu18yKugWRzGiLo+kjmKeIs1zYN86DNh26usH55kR1DzGFVgRK4GCmOLPiVTsy Jjkg== X-Gm-Message-State: AOJu0YyUOsq3QJO2qB0orCK8lU+TtgYSl15+Tbgno81sv643OlZ26OZ5 vrjdUC0VHhDvWs0mriZr0tRytNE= X-Google-Smtp-Source: AGHT+IEgFB3LGS+IO9p8pnG7S7wfnPHQEq4r8PP5r7FJhg8QQeBegN95VNc6BUAGRbfZLGI9Uk46U2o= X-Received: from sdf.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5935]) (user=sdf job=sendgmr) by 2002:a63:6d8d:0:b0:589:36b2:a691 with SMTP id i135-20020a636d8d000000b0058936b2a691mr39586pgc.7.1696441690188; Wed, 04 Oct 2023 10:48:10 -0700 (PDT) Date: Wed, 4 Oct 2023 10:48:08 -0700 In-Reply-To: Mime-Version: 1.0 References: <20231003200522.1914523-1-sdf@google.com> <20231003200522.1914523-3-sdf@google.com> Message-ID: From: Stanislav Fomichev To: yoong.siang.song@intel.com Content-Type: text/plain; charset="utf-8" Message-ID-Hash: 6RCBLJBTJH4QMX4TA66YPWORZC2QBH4F X-Message-ID-Hash: 6RCBLJBTJH4QMX4TA66YPWORZC2QBH4F X-MailFrom: 3WqUdZQMKCUs5qst11tyr.p1zAq2-uv065Aq2-241wrp6.0r6@flex--sdf.bounces.google.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: "bpf@vger.kernel.org" , "ast@kernel.org" , "daniel@iogearbox.net" , "andrii@kernel.org" , "martin.lau@linux.dev" , "song@kernel.org" , "yhs@fb.com" , "john.fastabend@gmail.com" , "kpsingh@kernel.org" , "haoluo@google.com" , "jolsa@kernel.org" , "kuba@kernel.org" , "toke@kernel.org" , "willemb@google.com" , "dsahern@kernel.org" , magnus.karlsson@intel.com, "bjorn@kernel.org" , maciej.fijalkowski@intel.com, "hawk@kernel.org" , "netdev@vger.kernel.org" , "xdp-hints@xdp-project.net" X-Mailman-Version: 3.3.8 Precedence: list Subject: [xdp-hints] Re: [PATCH bpf-next v3 02/10] xsk: add TX timestamp and TX checksum offload support List-Id: XDP hardware hints design discussion Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On 10/04, Song, Yoong Siang wrote: > On Wednesday, October 4, 2023 4:05 AM Stanislav Fomichev wrote: > >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 > >--- > > Documentation/netlink/specs/netdev.yaml | 19 ++++++ > > 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 | 16 +++++ > > tools/net/ynl/generated/netdev-user.c | 19 ++++++ > > tools/net/ynl/generated/netdev-user.h | 3 + > > 15 files changed, 352 insertions(+), 8 deletions(-) > > > >diff --git a/Documentation/netlink/specs/netdev.yaml > >b/Documentation/netlink/specs/netdev.yaml > >index c46fcc78fc04..3735c26c8646 100644 > >--- a/Documentation/netlink/specs/netdev.yaml > >+++ b/Documentation/netlink/specs/netdev.yaml > >@@ -55,6 +55,19 @@ name: netdev > > name: hash > > doc: > > Device is capable of exposing receive packet hash via > >bpf_xdp_metadata_rx_hash(). > >+ - > >+ 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: > > - > >@@ -88,6 +101,11 @@ name: netdev > > type: u64 > > enum: xdp-rx-metadata > > enum-as-flags: true > >+ - > >+ name: xsk-features > >+ doc: Bitmask of enabled AF_XDP features. > >+ type: u64 > >+ enum: xsk-flags > > > > operations: > > list: > >@@ -105,6 +123,7 @@ name: netdev > > - xdp-features > > - xdp-zc-max-segs > > - xdp-rx-metadata-features > >+ - xsk-features > > dump: > > reply: *dev-all > > - > >diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index > >7e520c14eb8c..0e1cb026cbe5 100644 > >--- a/include/linux/netdevice.h > >+++ b/include/linux/netdevice.h > >@@ -1650,6 +1650,31 @@ 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) [..] > Should be "void" instead of "int" > > >+ * This function is called when AF_XDP frame requested egress timestamp. > >+ * > >+ * int (*tmo_fill_timestamp)(void *priv) > > Should be "u64" instead of "int" > > >+ * 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) > > Should be "void" instead of "int" Oh, good catch, will update these doc entries! > >+ * 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 > > * > >@@ -1838,6 +1863,7 @@ 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 > >@@ -2097,6 +2123,7 @@ 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 > >caa1f04106be..29427a69784d 100644 > >--- a/include/net/xdp_sock.h > >+++ b/include/net/xdp_sock.h > >@@ -92,6 +92,74 @@ 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) @@ - > >108,6 +176,18 @@ 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_compl > >*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) [..] > Suggestion from checkpatch.pl: > CHECK: Prefer using the BIT macro > > >+ > >+/* 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) > > Suggestion from checkpatch.pl: > CHECK: Prefer using the BIT macro > > >+ > >+/* 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) > > Suggestion from checkpatch.pl: > CHECK: Prefer using the BIT macro Will do! Hopefully nothing breaks, let me check...