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=aQDs82zJ; 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 919C75A0262 for ; Wed, 01 Apr 2026 21:23:34 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1775071413; 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=NGT6PNysqbjZE7s8NVLBE8VzC4xzrgsPrXz2RL9JTT0=; b=aQDs82zJ9TuJEuM0NSO/nuqeM0aUaNoA0yKSEqzvm+qNYNQ0rnRgXqA8ERCOSDNx93LjSm NhUyfidjh362iDdaoc04mhJEL7tYBmxy8HJrAhEljv6ZMMr7Htj/JvejgFgIp+mFYcuR2H tgqZrZG9Qr/ZVJKwFV4BlzoviD+uYOA= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-578-wIoH-wQoNOquVlD-_CrS9g-1; Wed, 01 Apr 2026 15:23:32 -0400 X-MC-Unique: wIoH-wQoNOquVlD-_CrS9g-1 X-Mimecast-MFC-AGG-ID: wIoH-wQoNOquVlD-_CrS9g_1775071411 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 840D118005B3 for ; Wed, 1 Apr 2026 19:23:31 +0000 (UTC) Received: from lenovo-t14s.redhat.corp (headnet01.pony-001.prod.iad2.dc.redhat.com [10.2.32.101]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id BBABE30001A2; Wed, 1 Apr 2026 19:23:30 +0000 (UTC) From: Laurent Vivier To: passt-dev@passt.top Subject: [PATCH v6 3/3] udp: Pass iov_tail to udp_update_hdr4()/udp_update_hdr6() Date: Wed, 1 Apr 2026 21:23:26 +0200 Message-ID: <20260401192326.1783350-4-lvivier@redhat.com> In-Reply-To: <20260401192326.1783350-1-lvivier@redhat.com> References: <20260401192326.1783350-1-lvivier@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: mR2T32Hao8DokNGbL5XIPTedfDlxC5rZ044mEGV2_m8_1775071411 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Message-ID-Hash: QQBXROD2J5HFG74DA7EPMZJAICJHY6Y7 X-Message-ID-Hash: QQBXROD2J5HFG74DA7EPMZJAICJHY6Y7 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: Change udp_update_hdr4() and udp_update_hdr6() to take an iov_tail pointing at the UDP frame instead of a contiguous udp_payload_t buffer and explicit data length. This lets vhost-user pass scatter-gather virtqueue buffers directly without an intermediate copy. The UDP header is built into a local struct udphdr and written back with IOV_PUSH_HEADER(). On the tap side, udp_tap_prepare() wraps the existing udp_payload_t in a two-element iov to match the new interface. Signed-off-by: Laurent Vivier --- iov.c | 1 - udp.c | 70 ++++++++++++++++++++++++------------------- udp_internal.h | 4 +-- udp_vu.c | 81 +++++++++++++++++++++++++++----------------------- 4 files changed, 84 insertions(+), 72 deletions(-) diff --git a/iov.c b/iov.c index 6357c477bea6..d5fb4e81a502 100644 --- a/iov.c +++ b/iov.c @@ -368,7 +368,6 @@ void *iov_peek_header_(struct iov_tail *tail, void *v, size_t len, size_t align) * * Return: number of bytes written */ -/* cppcheck-suppress unusedFunction */ size_t iov_push_header_(struct iov_tail *tail, const void *v, size_t len) { size_t l; diff --git a/udp.c b/udp.c index e113b26bc726..0035a645ded5 100644 --- a/udp.c +++ b/udp.c @@ -255,21 +255,22 @@ static void udp_iov_init(const struct ctx *c) /** * udp_update_hdr4() - Update headers for one IPv4 datagram * @ip4h: Pre-filled IPv4 header (except for tot_len and saddr) - * @bp: Pointer to udp_payload_t to update + * @payload: iov_tail with UDP payload to update * @toside: Flowside for destination side * @dlen: Length of UDP payload * @no_udp_csum: Do not set UDP checksum * * Return: size of IPv4 payload (UDP header + data) */ -size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp, +size_t udp_update_hdr4(struct iphdr *ip4h, struct iov_tail *payload, const struct flowside *toside, size_t dlen, bool no_udp_csum) { const struct in_addr *src = inany_v4(&toside->oaddr); const struct in_addr *dst = inany_v4(&toside->eaddr); - size_t l4len = dlen + sizeof(bp->uh); + size_t l4len = dlen + sizeof(struct udphdr); size_t l3len = l4len + sizeof(*ip4h); + struct udphdr uh; assert(src && dst); @@ -278,19 +279,18 @@ size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp, ip4h->saddr = src->s_addr; ip4h->check = csum_ip4_header(l3len, IPPROTO_UDP, *src, *dst); - bp->uh.source = htons(toside->oport); - bp->uh.dest = htons(toside->eport); - bp->uh.len = htons(l4len); + uh.source = htons(toside->oport); + uh.dest = htons(toside->eport); + uh.len = htons(l4len); if (no_udp_csum) { - bp->uh.check = 0; + uh.check = 0; } else { - const struct iovec iov = { - .iov_base = bp->data, - .iov_len = dlen - }; - struct iov_tail data = IOV_TAIL(&iov, 1, 0); - csum_udp4(&bp->uh, *src, *dst, &data, l4len); + struct iov_tail data = *payload; + + IOV_DROP_HEADER(&data, struct udphdr); + csum_udp4(&uh, *src, *dst, &data, l4len); } + IOV_PUSH_HEADER(payload, uh); return l4len; } @@ -299,18 +299,19 @@ size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp, * udp_update_hdr6() - Update headers for one IPv6 datagram * @ip6h: Pre-filled IPv6 header (except for payload_len and * addresses) - * @bp: Pointer to udp_payload_t to update + * @payload: iov_tail with UDP payload to update * @toside: Flowside for destination side * @dlen: Length of UDP payload * @no_udp_csum: Do not set UDP checksum * * Return: size of IPv6 payload (UDP header + data) */ -size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp, +size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct iov_tail *payload, const struct flowside *toside, size_t dlen, bool no_udp_csum) { - uint16_t l4len = dlen + sizeof(bp->uh); + uint16_t l4len = dlen + sizeof(struct udphdr); + struct udphdr uh; ip6h->payload_len = htons(l4len); ip6h->daddr = toside->eaddr.a6; @@ -319,24 +320,24 @@ size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp, ip6h->nexthdr = IPPROTO_UDP; ip6h->hop_limit = 255; - bp->uh.source = htons(toside->oport); - bp->uh.dest = htons(toside->eport); - bp->uh.len = ip6h->payload_len; + uh.source = htons(toside->oport); + uh.dest = htons(toside->eport); + uh.len = htons(l4len); if (no_udp_csum) { /* 0 is an invalid checksum for UDP IPv6 and dropped by - * the kernel stack, even if the checksum is disabled by virtio - * flags. We need to put any non-zero value here. + * the kernel stack, even if the checksum is disabled + * by virtio flags. We need to put any non-zero value + * here. */ - bp->uh.check = 0xffff; + uh.check = 0xffff; } else { - const struct iovec iov = { - .iov_base = bp->data, - .iov_len = dlen - }; - struct iov_tail data = IOV_TAIL(&iov, 1, 0); - csum_udp6(&bp->uh, &toside->oaddr.a6, &toside->eaddr.a6, &data, - l4len); + struct iov_tail data = *payload; + + IOV_DROP_HEADER(&data, struct udphdr); + csum_udp6(&uh, &toside->oaddr.a6, &toside->eaddr.a6, + &data, l4len); } + IOV_PUSH_HEADER(payload, uh); return l4len; } @@ -375,11 +376,18 @@ static void udp_tap_prepare(const struct mmsghdr *mmh, struct ethhdr *eh = (*tap_iov)[UDP_IOV_ETH].iov_base; struct udp_payload_t *bp = &udp_payload[idx]; struct udp_meta_t *bm = &udp_meta[idx]; + struct iovec iov[2]; + struct iov_tail payload = IOV_TAIL(iov, ARRAY_SIZE(iov), 0); size_t l4len, l2len; + iov[0].iov_base = &bp->uh; + iov[0].iov_len = sizeof(bp->uh); + iov[1].iov_base = bp->data; + iov[1].iov_len = mmh[idx].msg_len; + eth_update_mac(eh, NULL, tap_omac); if (!inany_v4(&toside->eaddr) || !inany_v4(&toside->oaddr)) { - l4len = udp_update_hdr6(&bm->ip6h, bp, toside, + l4len = udp_update_hdr6(&bm->ip6h, &payload, toside, mmh[idx].msg_len, no_udp_csum); l2len = MAX(l4len + sizeof(bm->ip6h) + ETH_HLEN, ETH_ZLEN); @@ -388,7 +396,7 @@ static void udp_tap_prepare(const struct mmsghdr *mmh, eh->h_proto = htons_constant(ETH_P_IPV6); (*tap_iov)[UDP_IOV_IP] = IOV_OF_LVALUE(bm->ip6h); } else { - l4len = udp_update_hdr4(&bm->ip4h, bp, toside, + l4len = udp_update_hdr4(&bm->ip4h, &payload, toside, mmh[idx].msg_len, no_udp_csum); l2len = MAX(l4len + sizeof(bm->ip4h) + ETH_HLEN, ETH_ZLEN); diff --git a/udp_internal.h b/udp_internal.h index 64e457748324..e6cbaab79519 100644 --- a/udp_internal.h +++ b/udp_internal.h @@ -25,10 +25,10 @@ struct udp_payload_t { } __attribute__ ((packed, aligned(__alignof__(unsigned int)))); #endif -size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp, +size_t udp_update_hdr4(struct iphdr *ip4h, struct iov_tail *payload, const struct flowside *toside, size_t dlen, bool no_udp_csum); -size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp, +size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct iov_tail *payload, const struct flowside *toside, size_t dlen, bool no_udp_csum); void udp_sock_fwd(const struct ctx *c, int s, int rule_hint, diff --git a/udp_vu.c b/udp_vu.c index 5608a3a96ff5..5bc9509a1b98 100644 --- a/udp_vu.c +++ b/udp_vu.c @@ -96,43 +96,53 @@ static ssize_t udp_vu_sock_recv(struct iovec *iov, size_t *cnt, int s, bool v6) /** * udp_vu_prepare() - Prepare the packet header * @c: Execution context - * @iov: IO vector for the frame (including vnet header) + * @data: IO vector tail for the frame, + * on return, points to the L3 frame * @toside: Address information for one side of the flow * @dlen: Packet data length * * Return: Layer-4 length */ -static size_t udp_vu_prepare(const struct ctx *c, const struct iovec *iov, - const struct flowside *toside, ssize_t dlen) +static size_t udp_vu_prepare(const struct ctx *c, struct iov_tail *data, + const struct flowside *toside, size_t dlen) { - struct ethhdr *eh; + bool ipv4 = inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr); + struct ethhdr eh; size_t l4len; /* ethernet header */ - eh = vu_eth(iov[0].iov_base); + memcpy(eh.h_dest, c->guest_mac, sizeof(eh.h_dest)); + memcpy(eh.h_source, c->our_tap_mac, sizeof(eh.h_source)); - memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest)); - memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source)); + if (ipv4) + eh.h_proto = htons(ETH_P_IP); + else + eh.h_proto = htons(ETH_P_IPV6); + IOV_PUSH_HEADER(data, eh); /* initialize header */ - if (inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr)) { - struct iphdr *iph = vu_ip(iov[0].iov_base); - struct udp_payload_t *bp = vu_payloadv4(iov[0].iov_base); + if (ipv4) { + struct iov_tail udp_frame; + struct iphdr iph; - eh->h_proto = htons(ETH_P_IP); + iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_UDP); - *iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_UDP); + udp_frame = *data; + IOV_DROP_HEADER(&udp_frame, struct iphdr); + l4len = udp_update_hdr4(&iph, &udp_frame, toside, dlen, true); - l4len = udp_update_hdr4(iph, bp, toside, dlen, true); + IOV_PUSH_HEADER(data, iph); } else { - struct ipv6hdr *ip6h = vu_ip(iov[0].iov_base); - struct udp_payload_t *bp = vu_payloadv6(iov[0].iov_base); + struct iov_tail udp_frame; + struct ipv6hdr ip6h; - eh->h_proto = htons(ETH_P_IPV6); + ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_UDP); - *ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_UDP); + udp_frame = *data; + IOV_DROP_HEADER(&udp_frame, struct ipv6hdr); + l4len = udp_update_hdr6(&ip6h, &udp_frame, toside, dlen, true); - l4len = udp_update_hdr6(ip6h, bp, toside, dlen, true); + IOV_PUSH_HEADER(data, ip6h); } return l4len; @@ -141,29 +151,23 @@ static size_t udp_vu_prepare(const struct ctx *c, const struct iovec *iov, /** * udp_vu_csum() - Calculate and set checksum for a UDP packet * @toside: Address information for one side of the flow - * @iov: IO vector for the frame - * @cnt: Number of IO vector entries + * @data: IO vector tail for the L3 frame * @l4len: L4 length */ -static void udp_vu_csum(const struct flowside *toside, const struct iovec *iov, - size_t cnt, size_t l4len) +static void udp_vu_csum(const struct flowside *toside, struct iov_tail *data, + size_t l4len) { const struct in_addr *src4 = inany_v4(&toside->oaddr); const struct in_addr *dst4 = inany_v4(&toside->eaddr); - char *base = iov[0].iov_base; - struct udp_payload_t *bp; - struct iov_tail data; - - if (src4 && dst4) { - bp = vu_payloadv4(base); - data = IOV_TAIL(iov, cnt, (char *)&bp->data - base); - csum_udp4(&bp->uh, *src4, *dst4, &data, l4len); - } else { - bp = vu_payloadv6(base); - data = IOV_TAIL(iov, cnt, (char *)&bp->data - base); - csum_udp6(&bp->uh, &toside->oaddr.a6, &toside->eaddr.a6, &data, - l4len); - } + struct udphdr *uh, uh_storage; + bool ipv4 = src4 && dst4; + + uh = IOV_REMOVE_HEADER(data, uh_storage); + + if (ipv4) + csum_udp4(uh, *src4, *dst4, data, l4len); + else + csum_udp6(uh, &toside->oaddr.a6, &toside->eaddr.a6, data, l4len); } /** @@ -228,9 +232,10 @@ void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx) vu_queue_rewind(vq, elem_cnt - elem_used); if (iov_cnt > 0) { - size_t l4len = udp_vu_prepare(c, iov_vu, toside, dlen); + struct iov_tail data = IOV_TAIL(iov_vu, iov_cnt, VNET_HLEN); + size_t l4len = udp_vu_prepare(c, &data, toside, dlen); if (*c->pcap) { - udp_vu_csum(toside, iov_vu, iov_cnt, l4len); + udp_vu_csum(toside, &data, l4len); pcap_iov(iov_vu, iov_cnt, VNET_HLEN, hdrlen + dlen - VNET_HLEN); } -- 2.53.0