From patchwork Fri Dec 8 00:52:44 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mina Almasry X-Patchwork-Id: 752906 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="t9QOWBmc" Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6977173B for ; Thu, 7 Dec 2023 16:53:22 -0800 (PST) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5d8d3271ff5so18156197b3.2 for ; Thu, 07 Dec 2023 16:53:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1701996802; x=1702601602; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=o2HtSBl/MmwRbvRf64o4B77I6D1fDAMKeKnhqiyczlI=; b=t9QOWBmcCVW9kxtBFM+wAKQVV93wS7g3VfFemYMdEeaPZtIDwMZzdTNYx8yXB2dELJ uUoHM6LgTg3AjLWp8QC1IXwDw85OxdjFidRI/lt2tlr/HJk/QvS39vK1obXn7O+1ZJp1 H/n2V05TVoCPnRYlMWUYCuMERPL5KGj9rT8kjx2TuAkqtN0ydRnXoNu+h5TAVpJzt7EO 7f6Ky8BVEYCIsU/vAbhNMCBO/yLf5jnbDivg0lx0f+1Oq1wj4QyWsILjH7kcYIwRoKqq JWa/wzNfV550kLoID3xLDOBFn/MYKtRwTBVHKYYeuKwnT+ULGRrqltG8CrpuibvotqHe mYtA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701996802; x=1702601602; 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=o2HtSBl/MmwRbvRf64o4B77I6D1fDAMKeKnhqiyczlI=; b=fK0HiUU8yaffQZUw6lnjNAMDwwwCg5fU9dsK7VHaSEdePSw6NcpgFHdWHQVvOiAk3/ lgzQ7E0xnzcTokiGdvzZ+Qu76YMGaR4CUHjDL79eltSEp1d1na2gpx9a1GbQRQbb5+5e vtU1W5BQlhL6pq14q1sqjPjWDu3/mPg9AO0u56iN68xIiBlRtzJpxpm9zDOiY7ZClkRO h8EljS/IW8S+cGpkSWs92HnE3zuhp5Lnl2oCvHhDQaAb5bPRW59r//oX5uWCc1E8WiB4 Zi032EObx0BTK/Nb6ZJibQt7X+GHkuUaVWVf4JzbHTlQRoXPKr5hSnPliJEWLUa4DFng z/CA== X-Gm-Message-State: AOJu0YyxfZw617Pfa63b4y+IOxvwBojzf7GpfVZLAPg3ruDW94PR57MA kZauDiD+G5yxTRwz3xNror4MmdkIAV2oEtZu5g== X-Google-Smtp-Source: AGHT+IGWOe8MiWAkZCA+iQLKZXfZKYY/bh9fGGE/vdscnPqlbi7pHiYt49I0HmZQtMitXM2+GWeFIEQqSaEypsCd9g== X-Received: from almasrymina.svl.corp.google.com ([2620:15c:2c4:200:f1cf:c733:235b:9fff]) (user=almasrymina job=sendgmr) by 2002:a81:af41:0:b0:5d4:1846:3121 with SMTP id x1-20020a81af41000000b005d418463121mr43133ywj.8.1701996801728; Thu, 07 Dec 2023 16:53:21 -0800 (PST) Date: Thu, 7 Dec 2023 16:52:44 -0800 In-Reply-To: <20231208005250.2910004-1-almasrymina@google.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20231208005250.2910004-1-almasrymina@google.com> X-Mailer: git-send-email 2.43.0.472.g3155946c3a-goog Message-ID: <20231208005250.2910004-14-almasrymina@google.com> Subject: [net-next v1 13/16] tcp: RX path for devmem TCP From: Mina Almasry To: Shailend Chand , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, bpf@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 , Jonathan Corbet , Jeroen de Borst , Praveen Kaligineedi , Jesper Dangaard Brouer , Ilias Apalodimas , Arnd Bergmann , David Ahern , Willem de Bruijn , Shuah Khan , Sumit Semwal , " =?utf-8?q?Christian_K=C3=B6nig?= " , Yunsheng Lin , Harshitha Ramamurthy , Shakeel Butt , Willem de Bruijn , Kaiyuan Zhang 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 --- Changes in v1: - Added dmabuf_id to dmabuf_cmsg (David/Stan). - Devmem -> dmabuf (David). - Change tcp_recvmsg_dmabuf() check to skb->dmabuf (Paolo). - Use __skb_frag_ref() & napi_pp_put_page() for refcounting (Yunsheng). RFC v3: - Fixed issue with put_cmsg() failing silently. --- include/linux/socket.h | 1 + include/net/page_pool/helpers.h | 9 ++ include/net/sock.h | 2 + include/uapi/asm-generic/socket.h | 5 + include/uapi/linux/uio.h | 10 ++ net/ipv4/tcp.c | 190 +++++++++++++++++++++++++++++- net/ipv4/tcp_ipv4.c | 8 ++ 7 files changed, 220 insertions(+), 5 deletions(-) diff --git a/include/linux/socket.h b/include/linux/socket.h index cfcb7e2c3813..fe2b9e2081bb 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/page_pool/helpers.h b/include/net/page_pool/helpers.h index 2d4e0a2c5620..e7e2e89d3663 100644 --- a/include/net/page_pool/helpers.h +++ b/include/net/page_pool/helpers.h @@ -108,6 +108,15 @@ page_pool_iov_dma_addr(const struct page_pool_iov *ppiov) ((dma_addr_t)page_pool_iov_idx(ppiov) << PAGE_SHIFT); } +static inline unsigned long +page_pool_iov_virtual_addr(const struct page_pool_iov *ppiov) +{ + struct dmabuf_genpool_chunk_owner *owner = page_pool_iov_owner(ppiov); + + return owner->base_virtual + + ((unsigned long)page_pool_iov_idx(ppiov) << PAGE_SHIFT); +} + static inline struct netdev_dmabuf_binding * page_pool_iov_binding(const struct page_pool_iov *ppiov) { diff --git a/include/net/sock.h b/include/net/sock.h index 1d6931caf0c3..01029c855c1b 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..25a2f5255f52 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_LINEAR 98 +#define SCM_DEVMEM_LINEAR SO_DEVMEM_LINEAR +#define SO_DEVMEM_DMABUF 99 +#define SCM_DEVMEM_DMABUF SO_DEVMEM_DMABUF + #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..ad92e37699da 100644 --- a/include/uapi/linux/uio.h +++ b/include/uapi/linux/uio.h @@ -20,6 +20,16 @@ struct iovec __kernel_size_t iov_len; /* Must be size_t (1003.1g) */ }; +struct dmabuf_cmsg { + __u64 frag_offset; /* offset into the dmabuf where the frag starts. + */ + __u32 frag_size; /* size of the frag. */ + __u32 frag_token; /* token representing this frag for + * DEVMEM_DONTNEED. + */ + __u32 dmabuf_id; /* dmabuf id this frag belongs to. */ +}; + /* * 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 5a3135e93d3d..088b2b48bee0 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); @@ -2303,6 +2304,155 @@ 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_dmabuf(const struct sock *sk, const struct sk_buff *skb, + unsigned int offset, struct msghdr *msg, + int remaining_len) +{ + struct dmabuf_cmsg dmabuf_cmsg = { 0 }; + unsigned int start; + int i, copy, n; + int sent = 0; + int err = 0; + + do { + start = skb_headlen(skb); + + if (!skb->dmabuf) { + 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 dmabuf_cmsg for # bytes copied to user + * buffer. + */ + memset(&dmabuf_cmsg, 0, sizeof(dmabuf_cmsg)); + dmabuf_cmsg.frag_size = copy; + err = put_cmsg(msg, SOL_SOCKET, SO_DEVMEM_LINEAR, + sizeof(dmabuf_cmsg), &dmabuf_cmsg); + if (err || msg->msg_flags & MSG_CTRUNC) { + msg->msg_flags &= ~MSG_CTRUNC; + if (!err) + err = -ETOOSMALL; + goto out; + } + + sent += copy; + + if (remaining_len == 0) + goto out; + } + + /* after that, send information of dmabuf pages through a + * sequence of cmsg + */ + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; + struct page_pool_iov *ppiov; + u64 frag_offset; + u32 user_token; + int end; + + /* skb->dmabuf should indicate that ALL the frags in + * this skb are dmabuf page_pool_iovs. We're checking + * for that flag above, but also check individual frags + * here. If the tcp stack is not setting skb->dmabuf + * 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-dmabuf 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; + dmabuf_cmsg.frag_offset = frag_offset; + dmabuf_cmsg.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; + + dmabuf_cmsg.frag_token = user_token; + dmabuf_cmsg.dmabuf_id = page_pool_iov_binding_id(ppiov); + + offset += copy; + remaining_len -= copy; + + err = put_cmsg(msg, SOL_SOCKET, + SO_DEVMEM_DMABUF, + sizeof(dmabuf_cmsg), + &dmabuf_cmsg); + if (err || msg->msg_flags & MSG_CTRUNC) { + msg->msg_flags &= ~MSG_CTRUNC; + xa_erase((struct xarray *)&sk->sk_user_pages, + user_token); + if (!err) + err = -ETOOSMALL; + goto out; + } + + __skb_frag_ref(frag); + + 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. * @@ -2316,6 +2466,7 @@ static int tcp_recvmsg_locked(struct sock *sk, struct msghdr *msg, size_t len, int *cmsg_flags) { struct tcp_sock *tp = tcp_sk(sk); + int last_copied_dmabuf = -1; /* uninitialized */ int copied = 0; u32 peek_seq; u32 *seq; @@ -2493,15 +2644,44 @@ 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_dmabuf != -1 && + last_copied_dmabuf != skb->dmabuf) break; + + if (!skb->dmabuf) { + 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->dmabuf skbs can only be received + * with the MSG_SOCK_DEVMEM flag. + */ + if (!copied) + copied = -EFAULT; + + break; + } + + err = tcp_recvmsg_dmabuf(sk, skb, offset, msg, + used); + if (err <= 0) { + if (!copied) + copied = -EFAULT; + + break; + } + used = err; } } + last_copied_dmabuf = skb->dmabuf; + WRITE_ONCE(*seq, *seq + used); copied += used; len -= used; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 86cc6d36f818..986398cc2f65 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2501,6 +2501,14 @@ static void tcp_md5sig_info_free_rcu(struct rcu_head *head) 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) + if (WARN_ON_ONCE(!napi_pp_put_page(page, false))) + page_pool_page_put_many(page, 1); + + xa_destroy(&sk->sk_user_pages); trace_tcp_destroy_sock(sk);