From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: passt.top; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=aqpWdD+p; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by passt.top (Postfix) with ESMTPS id E471C5A061A for ; Mon, 16 Mar 2026 19:07:37 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773684456; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ydEMbEwA5+2dvBArG7qZfj55d05+k1w3tVy9eHkiU5k=; b=aqpWdD+pmaat5mBnOvBEIcB216Wd05Bis8ntex6DE4/+qgveXalEiXNhNXD5aaJ0Fiost4 sq+Ez4rXm4/NZ5nRy0D2jGFA/sH4O6UKH9WB/1PHk6GWNf3xQwLhleKkKp+u+naQMJQXEi 34U9GPMUEX63oedV98iJc0dHDMdImuY= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-558-EO4W18j8NUu_wm6rkYFDGw-1; Mon, 16 Mar 2026 14:07:35 -0400 X-MC-Unique: EO4W18j8NUu_wm6rkYFDGw-1 X-Mimecast-MFC-AGG-ID: EO4W18j8NUu_wm6rkYFDGw_1773684453 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 73C401956076 for ; Mon, 16 Mar 2026 18:07:33 +0000 (UTC) Received: from lenovo-t14s.redhat.com (unknown [10.44.35.65]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 7F1721800361; Mon, 16 Mar 2026 18:07:32 +0000 (UTC) From: Laurent Vivier To: passt-dev@passt.top Subject: [PATCH v3 6/8] udp_vu: Move virtqueue management from udp_vu_sock_recv() to its caller Date: Mon, 16 Mar 2026 19:07:19 +0100 Message-ID: <20260316180721.2230640-7-lvivier@redhat.com> In-Reply-To: <20260316180721.2230640-1-lvivier@redhat.com> References: <20260316180721.2230640-1-lvivier@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: ujXzVPLV9bdWmQOUmq2iEtrDenrGJD-t2AJT3qy2-ww_1773684453 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Message-ID-Hash: PWWHV2SIVXT4YNN45PYRHKB7BQOWC6IW X-Message-ID-Hash: PWWHV2SIVXT4YNN45PYRHKB7BQOWC6IW X-MailFrom: lvivier@redhat.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: Laurent Vivier X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: udp_vu_sock_recv() currently mixes two concerns: receiving data from the socket and managing virtqueue buffers (collecting, rewinding, releasing). This makes the function harder to reason about and couples socket I/O with virtqueue state. Move all virtqueue operations, vu_collect(), vu_init_elem(), vu_queue_rewind(), vu_set_vnethdr(), and the queue-readiness check, into udp_vu_sock_to_tap(), which is the only caller. This turns udp_vu_sock_recv() into a pure socket receive function that simply reads into the provided iov array and adjusts its length. Signed-off-by: Laurent Vivier --- udp_vu.c | 110 +++++++++++++++++++++++++------------------------------ 1 file changed, 49 insertions(+), 61 deletions(-) diff --git a/udp_vu.c b/udp_vu.c index 8b0de312949c..7f6561f83505 100644 --- a/udp_vu.c +++ b/udp_vu.c @@ -33,9 +33,6 @@ #include "udp_vu.h" #include "vu_common.h" -static struct iovec iov_vu [VIRTQUEUE_MAX_SIZE]; -static struct vu_virtq_element elem [VIRTQUEUE_MAX_SIZE]; - /** * udp_vu_hdrlen() - Sum size of all headers, from UDP to virtio-net * @v6: Set for IPv6 packet @@ -58,78 +55,35 @@ static size_t udp_vu_hdrlen(bool v6) /** * udp_vu_sock_recv() - Receive datagrams from socket into vhost-user buffers - * @c: Execution context * @iov: IO vector for the frame (in/out) * @cnt: Number of IO vector entries (in/out) - * @vq: virtqueue to use to receive data * @s: Socket to receive from * @v6: Set for IPv6 connections * - * Return: size of received data, 0 if the datagram - * was discarded because the virtqueue is not ready, -1 on error + * Return: size of received data, -1 on error */ -static ssize_t udp_vu_sock_recv(const struct ctx *c, struct iovec *iov, - size_t *cnt, unsigned *elem_used, - struct vu_virtq *vq, int s, bool v6) +static ssize_t udp_vu_sock_recv(struct iovec *iov, size_t *cnt, int s, bool v6) { - const struct vu_dev *vdev = c->vdev; - struct msghdr msg = { 0 }; + struct iovec msg_iov[*cnt]; + struct msghdr msg = { 0 }; struct iov_tail payload; - size_t hdrlen, iov_used; - unsigned elem_cnt; - unsigned i, j; + size_t hdrlen; ssize_t dlen; - ASSERT(!c->no_udp); - - if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) { - debug("Got UDP packet, but RX virtqueue not usable yet"); - - if (recvmsg(s, &msg, MSG_DONTWAIT) < 0) - debug_perror("Failed to discard datagram"); - - *cnt = 0; - return 0; - } - /* compute L2 header length */ hdrlen = udp_vu_hdrlen(v6); - elem_cnt = vu_collect(vdev, vq, elem, ARRAY_SIZE(elem), - iov, *cnt, &iov_used, - IP_MAX_MTU + ETH_HLEN + VNET_HLEN, NULL); - if (elem_cnt == 0) - return -1; - - ASSERT((size_t)elem_cnt == iov_used); /* one iovec per element */ - - payload = IOV_TAIL(iov, iov_used, hdrlen); + payload = IOV_TAIL(iov, *cnt, hdrlen); - struct iovec msg_iov[payload.cnt]; msg.msg_iov = msg_iov; msg.msg_iovlen = iov_tail_clone(msg.msg_iov, payload.cnt, &payload); /* read data from the socket */ dlen = recvmsg(s, &msg, 0); - if (dlen < 0) { - vu_queue_rewind(vq, elem_cnt); + if (dlen < 0) return -1; - } - - *cnt = vu_pad(iov, iov_used, 0, dlen + hdrlen); - - *elem_used = 0; - for (i = 0, j = 0; j < *cnt && i < elem_cnt; i++) { - if (j + elem[i].in_num > *cnt) - elem[i].in_num = *cnt - j; - j += elem[i].in_num; - (*elem_used)++; - } - vu_set_vnethdr(iov[0].iov_base, *elem_used); - - /* release unused buffers */ - vu_queue_rewind(vq, elem_cnt - *elem_used); + *cnt = vu_pad(iov, *cnt, 0, dlen + hdrlen); return dlen; } @@ -217,26 +171,60 @@ static void udp_vu_csum(const struct flowside *toside, */ void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx) { + static struct iovec iov_vu [VIRTQUEUE_MAX_SIZE]; + static struct vu_virtq_element elem [VIRTQUEUE_MAX_SIZE]; const struct flowside *toside = flowside_at_sidx(tosidx); bool v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr)); struct vu_dev *vdev = c->vdev; struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE]; - struct iov_tail data; int i; + ASSERT(!c->no_udp); + + if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) { + struct msghdr msg = { 0 }; + + debug("Got UDP packet, but RX virtqueue not usable yet"); + + for (i = 0; i < n; i++) { + if (recvmsg(s, &msg, MSG_DONTWAIT) < 0) + debug_perror("Failed to discard datagram"); + } + + return; + } + for (i = 0; i < n; i++) { - unsigned elem_used; + unsigned elem_used, elem_cnt, j, k; size_t iov_cnt; ssize_t dlen; - iov_cnt = ARRAY_SIZE(iov_vu); - dlen = udp_vu_sock_recv(c, iov_vu, &iov_cnt, &elem_used, vq, - s, v6); - if (dlen < 0) + elem_cnt = vu_collect(vdev, vq, elem, ARRAY_SIZE(elem), + iov_vu, ARRAY_SIZE(iov_vu), &iov_cnt, + IP_MAX_MTU + ETH_HLEN + VNET_HLEN, NULL); + if (elem_cnt == 0) + break; + + dlen = udp_vu_sock_recv(iov_vu, &iov_cnt, s, v6); + if (dlen < 0) { + vu_queue_rewind(vq, elem_cnt); break; + } + + elem_used = 0; + for (j = 0, k = 0; k < iov_cnt && j < elem_cnt; j++) { + if (k + elem[j].in_num > iov_cnt) + elem[j].in_num = iov_cnt - k; + k += elem[j].in_num; + elem_used++; + } + + /* release unused buffers */ + vu_queue_rewind(vq, elem_cnt - elem_used); if (iov_cnt > 0) { - data = IOV_TAIL(iov_vu, iov_cnt, 0); + struct iov_tail data = IOV_TAIL(iov_vu, iov_cnt, 0); + vu_set_vnethdr(iov_vu[0].iov_base, elem_used); udp_vu_prepare(c, &data, toside, dlen); if (*c->pcap) { udp_vu_csum(toside, &data); -- 2.53.0