From patchwork Thu Aug 10 01:57:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mina Almasry X-Patchwork-Id: 13348712 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 432BAC001E0 for ; Thu, 10 Aug 2023 01:58:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230365AbjHJB6b (ORCPT ); Wed, 9 Aug 2023 21:58:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232207AbjHJB6a (ORCPT ); Wed, 9 Aug 2023 21:58:30 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E758C6 for ; Wed, 9 Aug 2023 18:58:25 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-583fe0f84a5so6370257b3.3 for ; Wed, 09 Aug 2023 18:58:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1691632704; x=1692237504; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=A72dv4/C3nRhaaIL45Qla7D1fv5wRm/EUSGzlFwP9lc=; b=ExMQ69JxEkQEghmOjyVasRvnuhz6jC2LodZHs0V5yQ46eTTXvNsFNW4Y3Vm7mapiq1 EkHgPogZUe6tuV/HA/bG9obyt4nv21rLc90nVe1NDWLzadva4pylwBpk997/Fq9lFIYn JDoDtpud26yzjICJ9UqHXgbaytjrVPB6PxSoeqn6mOxYihp7vNnGgm62VfzX3DWsvWlB lojyqTJSfpNOBPk2xOE769LpI3SqjqGJFgAr7HFsPxe4mkBIoZuQmzUTQfpLoHNVQ3Jo PkG/Xhz4f/OMQVjAmSQB8I7CAorAkNcIQ2eioBWwrz4eGnCDMECul4hqOMVEBrxUSjpE hRxQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691632704; x=1692237504; 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=A72dv4/C3nRhaaIL45Qla7D1fv5wRm/EUSGzlFwP9lc=; b=iDUq1PVtR815uZxUg62u8iRiny1jHZaOSgYOO8n/c1dD2FBAEvRp/GrKCd2TfKDz59 qB9TNbrBbrwgNHRDQfTOwGAh+P3De8eSoTz5ipZ7XxU3S0T4kvC71dhTUZ4OjTwSAx0K sDiYbz55xxNcv6vmaPptPDiZvi1O6WxhR3ti+af6OQCc7ONZkJJsR8ogt30EpCrqs2mk woiHkmEOA8W3FS+PsePc2ByLa/Cq5oqS0AFQ46p/IrBevJbibu7GM2PG6EjJKUzYp8Gv hLj4oLqyFqCmqfogNWNr87gocWHMcY9zjs1jTkWu9wd2//JPHja1t42i8pyKFgowxWNY pLiw== X-Gm-Message-State: AOJu0YzHScF6fwamZbb/uWP/l2JbGasaSg/tu+bQxuq74Aymnx68222x nYhzWPRLEDPFdWSMAC3v+pyqk7TYmojzL8H00A== X-Google-Smtp-Source: AGHT+IHgModR+ZQzG5GYWO5cFEJqbZO8Zz/HWXObhE9KVaBkIDk3FCSw7qbAx/envuhDtjI23LEIRDR/6UkUczA98g== X-Received: from almasrymina.svl.corp.google.com ([2620:15c:2c4:200:73ad:9ed5:e067:2b9b]) (user=almasrymina job=sendgmr) by 2002:a81:af0f:0:b0:589:a997:f9ce with SMTP id n15-20020a81af0f000000b00589a997f9cemr16711ywh.2.1691632704659; Wed, 09 Aug 2023 18:58:24 -0700 (PDT) Date: Wed, 9 Aug 2023 18:57:45 -0700 In-Reply-To: <20230810015751.3297321-1-almasrymina@google.com> Mime-Version: 1.0 References: <20230810015751.3297321-1-almasrymina@google.com> X-Mailer: git-send-email 2.41.0.640.ga95def55d0-goog Message-ID: <20230810015751.3297321-10-almasrymina@google.com> Subject: [RFC PATCH v2 09/11] tcp: implement recvmsg() RX path for devmem TCP From: Mina Almasry To: netdev@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org Cc: Mina Almasry , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jesper Dangaard Brouer , Ilias Apalodimas , Arnd Bergmann , David Ahern , Willem de Bruijn , Sumit Semwal , " =?utf-8?q?Christian_K=C3=B6nig?= " , Jason Gunthorpe , Hari Ramakrishnan , Dan Williams , Andy Lutomirski , stephen@networkplumber.org, sdf@google.com, Willem de Bruijn , Kaiyuan Zhang Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org In tcp_recvmsg_locked(), detect if the skb being received by the user is a devmem skb. In this case - if the user provided the MSG_SOCK_DEVMEM flag - pass it to tcp_recvmsg_devmem() for custom handling. tcp_recvmsg_devmem() copies any data in the skb header to the linear buffer, and returns a cmsg to the user indicating the number of bytes returned in the linear buffer. tcp_recvmsg_devmem() then loops over the unaccessible devmem skb frags, and returns to the user a cmsg_devmem indicating the location of the data in the dmabuf device memory. cmsg_devmem contains this information: 1. the offset into the dmabuf where the payload starts. 'frag_offset'. 2. the size of the frag. 'frag_size'. 3. an opaque token 'frag_token' to return to the kernel when the buffer is to be released. The pages awaiting freeing are stored in the newly added sk->sk_user_pages, and each page passed to userspace is get_page()'d. This reference is dropped once the userspace indicates that it is done reading this page. All pages are released when the socket is destroyed. Signed-off-by: Willem de Bruijn Signed-off-by: Kaiyuan Zhang Signed-off-by: Mina Almasry --- include/linux/socket.h | 1 + include/net/sock.h | 2 + include/uapi/asm-generic/socket.h | 5 + include/uapi/linux/uio.h | 6 + net/ipv4/tcp.c | 180 +++++++++++++++++++++++++++++- net/ipv4/tcp_ipv4.c | 7 ++ 6 files changed, 196 insertions(+), 5 deletions(-) diff --git a/include/linux/socket.h b/include/linux/socket.h index 39b74d83c7c4..102733ae888d 100644 --- a/include/linux/socket.h +++ b/include/linux/socket.h @@ -326,6 +326,7 @@ struct ucred { * plain text and require encryption */ +#define MSG_SOCK_DEVMEM 0x2000000 /* Receive devmem skbs as cmsg */ #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */ #define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator in sendmsg() */ #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */ diff --git a/include/net/sock.h b/include/net/sock.h index 2eb916d1ff64..5d2a97001152 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -353,6 +353,7 @@ struct sk_filter; * @sk_txtime_unused: unused txtime flags * @ns_tracker: tracker for netns reference * @sk_bind2_node: bind node in the bhash2 table + * @sk_user_pages: xarray of pages the user is holding a reference on. */ struct sock { /* @@ -545,6 +546,7 @@ struct sock { struct rcu_head sk_rcu; netns_tracker ns_tracker; struct hlist_node sk_bind2_node; + struct xarray sk_user_pages; }; enum sk_pacing { diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h index 8ce8a39a1e5f..aacb97f16b78 100644 --- a/include/uapi/asm-generic/socket.h +++ b/include/uapi/asm-generic/socket.h @@ -135,6 +135,11 @@ #define SO_PASSPIDFD 76 #define SO_PEERPIDFD 77 +#define SO_DEVMEM_HEADER 98 +#define SCM_DEVMEM_HEADER SO_DEVMEM_HEADER +#define SO_DEVMEM_OFFSET 99 +#define SCM_DEVMEM_OFFSET SO_DEVMEM_OFFSET + #if !defined(__KERNEL__) #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__)) diff --git a/include/uapi/linux/uio.h b/include/uapi/linux/uio.h index 059b1a9147f4..ae94763b1963 100644 --- a/include/uapi/linux/uio.h +++ b/include/uapi/linux/uio.h @@ -20,6 +20,12 @@ struct iovec __kernel_size_t iov_len; /* Must be size_t (1003.1g) */ }; +struct cmsg_devmem { + __u64 frag_offset; + __u32 frag_size; + __u32 frag_token; +}; + /* * UIO_MAXIOV shall be at least 16 1003.1g (5.4.1.1) */ diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 53ec616b1fb7..7a5279b61a89 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -461,6 +461,7 @@ void tcp_init_sock(struct sock *sk) set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags); sk_sockets_allocated_inc(sk); + xa_init_flags(&sk->sk_user_pages, XA_FLAGS_ALLOC1); } EXPORT_SYMBOL(tcp_init_sock); @@ -2306,6 +2307,144 @@ static int tcp_inq_hint(struct sock *sk) return inq; } +/* On error, returns the -errno. On success, returns number of bytes sent to the + * user. May not consume all of @remaining_len. + */ +static int tcp_recvmsg_devmem(const struct sock *sk, const struct sk_buff *skb, + unsigned int offset, struct msghdr *msg, + int remaining_len) +{ + struct cmsg_devmem cmsg_devmem = { 0 }; + unsigned int start; + int i, copy, n; + int sent = 0; + int err = 0; + + do { + start = skb_headlen(skb); + + if (!skb_frags_not_readable(skb)) { + err = -ENODEV; + goto out; + } + + /* Copy header. */ + copy = start - offset; + if (copy > 0) { + copy = min(copy, remaining_len); + + n = copy_to_iter(skb->data + offset, copy, + &msg->msg_iter); + if (n != copy) { + err = -EFAULT; + goto out; + } + + offset += copy; + remaining_len -= copy; + + /* First a cmsg_devmem for # bytes copied to user + * buffer. + */ + memset(&cmsg_devmem, 0, sizeof(cmsg_devmem)); + cmsg_devmem.frag_size = copy; + err = put_cmsg(msg, SOL_SOCKET, SO_DEVMEM_HEADER, + sizeof(cmsg_devmem), &cmsg_devmem); + if (err) + goto out; + + sent += copy; + + if (remaining_len == 0) + goto out; + } + + /* after that, send information of devmem pages through a + * sequence of cmsg + */ + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + const skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; + struct page_pool_iov *ppiov; + u64 frag_offset; + u32 user_token; + int end; + + /* skb_frags_not_readable() should indicate that ALL the + * frags in this skb are unreadable page_pool_iovs. + * We're checking for that flag above, but also check + * individual pages here. If the tcp stack is not + * setting skb->devmem correctly, we still don't want to + * crash here when accessing pgmap or priv below. + */ + if (!skb_frag_page_pool_iov(frag)) { + net_err_ratelimited("Found non-devmem skb with page_pool_iov"); + err = -ENODEV; + goto out; + } + + ppiov = skb_frag_page_pool_iov(frag); + end = start + skb_frag_size(frag); + copy = end - offset; + + if (copy > 0) { + copy = min(copy, remaining_len); + + frag_offset = page_pool_iov_virtual_addr(ppiov) + + skb_frag_off(frag) + offset - + start; + cmsg_devmem.frag_offset = frag_offset; + cmsg_devmem.frag_size = copy; + err = xa_alloc((struct xarray *)&sk->sk_user_pages, + &user_token, frag->bv_page, + xa_limit_31b, GFP_KERNEL); + if (err) + goto out; + + cmsg_devmem.frag_token = user_token; + + offset += copy; + remaining_len -= copy; + + err = put_cmsg(msg, SOL_SOCKET, + SO_DEVMEM_OFFSET, + sizeof(cmsg_devmem), + &cmsg_devmem); + if (err) + goto out; + + page_pool_iov_get_many(ppiov, 1); + + sent += copy; + + if (remaining_len == 0) + goto out; + } + start = end; + } + + if (!remaining_len) + goto out; + + /* if remaining_len is not satisfied yet, we need to go to the + * next frag in the frag_list to satisfy remaining_len. + */ + skb = skb_shinfo(skb)->frag_list ?: skb->next; + + offset = offset - start; + } while (skb); + + if (remaining_len) { + err = -EFAULT; + goto out; + } + +out: + if (!sent) + sent = err; + + return sent; +} + /* * This routine copies from a sock struct into the user buffer. * @@ -2318,6 +2457,7 @@ static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len, int flags, struct scm_timestamping_internal *tss, int *cmsg_flags) { + bool last_copied_devmem, last_copied_init = false; struct tcp_sock *tp = tcp_sk(sk); int copied = 0; u32 peek_seq; @@ -2492,15 +2632,45 @@ static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len, } if (!(flags & MSG_TRUNC)) { - err = skb_copy_datagram_msg(skb, offset, msg, used); - if (err) { - /* Exception. Bailout! */ - if (!copied) - copied = -EFAULT; + if (last_copied_init && + last_copied_devmem != skb->devmem) break; + + if (!skb->devmem) { + err = skb_copy_datagram_msg(skb, offset, msg, + used); + if (err) { + /* Exception. Bailout! */ + if (!copied) + copied = -EFAULT; + break; + } + } else { + if (!(flags & MSG_SOCK_DEVMEM)) { + /* skb->devmem skbs can only be received + * with the MSG_SOCK_DEVMEM flag. + */ + if (!copied) + copied = -EFAULT; + + break; + } + + err = tcp_recvmsg_devmem(sk, skb, offset, msg, + used); + if (err <= 0) { + if (!copied) + copied = -EFAULT; + + break; + } + used = err; } } + last_copied_devmem = skb->devmem; + last_copied_init = true; + WRITE_ONCE(*seq, *seq + used); copied += used; len -= used; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index cecd5a135e64..4472b9357569 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2295,6 +2295,13 @@ static int tcp_v4_init_sock(struct sock *sk) void tcp_v4_destroy_sock(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); + struct page *page; + unsigned long index; + + xa_for_each(&sk->sk_user_pages, index, page) + page_pool_page_put_many(page, 1); + + xa_destroy(&sk->sk_user_pages); trace_tcp_destroy_sock(sk);