From: Laurent Vivier <lvivier@redhat.com>
To: passt-dev@passt.top
Cc: Laurent Vivier <lvivier@redhat.com>
Subject: [PATCH 06/12] udp: Pass iov_tail to udp_update_hdr4()/udp_update_hdr6()
Date: Fri, 27 Feb 2026 15:03:24 +0100 [thread overview]
Message-ID: <20260227140330.2216753-7-lvivier@redhat.com> (raw)
In-Reply-To: <20260227140330.2216753-1-lvivier@redhat.com>
Change udp_update_hdr4() and udp_update_hdr6() to take a separate
struct udphdr pointer and an iov_tail for the payload, instead of a
struct udp_payload_t pointer and an explicit data length.
This decouples the header update functions from the udp_payload_t memory
layout, which assumes all headers and data sit in a single contiguous
buffer. The vhost-user path uses virtqueue-provided scatter-gather
buffers where this assumption does not hold; passing an iov_tail lets
both the tap path and the vhost-user path share the same functions
without casting through layout-specific helpers.
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
udp.c | 65 ++++++++++++++++++++++----------------------------
udp_internal.h | 10 ++++----
udp_vu.c | 14 +++++++++--
3 files changed, 47 insertions(+), 42 deletions(-)
diff --git a/udp.c b/udp.c
index 19adda065f44..52e93e357a94 100644
--- a/udp.c
+++ b/udp.c
@@ -257,18 +257,17 @@ static void udp_iov_init(const struct ctx *c)
* @ip4h: Pre-filled IPv4 header (except for tot_len and saddr)
* @bp: Pointer to udp_payload_t 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,
- const struct flowside *toside, size_t dlen,
- bool no_udp_csum)
+size_t udp_update_hdr4(struct iphdr *ip4h, struct udphdr *uh,
+ struct iov_tail *payload,
+ const struct flowside *toside, 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 = iov_tail_size(payload) + sizeof(*uh);
size_t l3len = l4len + sizeof(*ip4h);
ASSERT(src && dst);
@@ -278,19 +277,13 @@ 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);
- if (no_udp_csum) {
- bp->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);
- }
+ uh->source = htons(toside->oport);
+ uh->dest = htons(toside->eport);
+ uh->len = htons(l4len);
+ if (no_udp_csum)
+ uh->check = 0;
+ else
+ csum_udp4(uh, *src, *dst, payload);
return l4len;
}
@@ -306,11 +299,11 @@ size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp,
*
* Return: size of IPv6 payload (UDP header + data)
*/
-size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp,
- const struct flowside *toside, size_t dlen,
- bool no_udp_csum)
+size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udphdr *uh,
+ struct iov_tail *payload,
+ const struct flowside *toside, bool no_udp_csum)
{
- uint16_t l4len = dlen + sizeof(bp->uh);
+ uint16_t l4len = iov_tail_size(payload) + sizeof(*uh);
ip6h->payload_len = htons(l4len);
ip6h->daddr = toside->eaddr.a6;
@@ -319,22 +312,17 @@ 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 = ip6h->payload_len;
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.
*/
- 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);
+ csum_udp6(uh, &toside->oaddr.a6, &toside->eaddr.a6, payload);
}
return l4len;
@@ -374,12 +362,17 @@ 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];
+ const struct iovec iov = {
+ .iov_base = bp->data,
+ .iov_len = mmh[idx].msg_len,
+ };
+ struct iov_tail payload = IOV_TAIL(&iov, 1, 0);
size_t l4len, l2len;
eth_update_mac(eh, NULL, tap_omac);
if (!inany_v4(&toside->eaddr) || !inany_v4(&toside->oaddr)) {
- l4len = udp_update_hdr6(&bm->ip6h, bp, toside,
- mmh[idx].msg_len, no_udp_csum);
+ l4len = udp_update_hdr6(&bm->ip6h, &bp->uh, &payload, toside,
+ no_udp_csum);
l2len = MAX(l4len + sizeof(bm->ip6h) + ETH_HLEN, ETH_ZLEN);
tap_hdr_update(&bm->taph, l2len);
@@ -387,8 +380,8 @@ 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,
- mmh[idx].msg_len, no_udp_csum);
+ l4len = udp_update_hdr4(&bm->ip4h, &bp->uh, &payload, toside,
+ no_udp_csum);
l2len = MAX(l4len + sizeof(bm->ip4h) + ETH_HLEN, ETH_ZLEN);
tap_hdr_update(&bm->taph, l2len);
diff --git a/udp_internal.h b/udp_internal.h
index 0a8fe490b07e..aca831808ab4 100644
--- a/udp_internal.h
+++ b/udp_internal.h
@@ -22,11 +22,13 @@ struct udp_payload_t {
} __attribute__ ((packed, aligned(__alignof__(unsigned int))));
#endif
-size_t udp_update_hdr4(struct iphdr *ip4h, struct udp_payload_t *bp,
- const struct flowside *toside, size_t dlen,
+size_t udp_update_hdr4(struct iphdr *ip4h, struct udphdr *uh,
+ struct iov_tail *payload,
+ const struct flowside *toside,
bool no_udp_csum);
-size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udp_payload_t *bp,
- const struct flowside *toside, size_t dlen,
+size_t udp_update_hdr6(struct ipv6hdr *ip6h, struct udphdr *uh,
+ struct iov_tail *payload,
+ const struct flowside *toside,
bool no_udp_csum);
void udp_sock_fwd(const struct ctx *c, int s, int rule_hint,
uint8_t frompif, in_port_t port, const struct timespec *now);
diff --git a/udp_vu.c b/udp_vu.c
index aefcab0b86c2..dd8904d65a38 100644
--- a/udp_vu.c
+++ b/udp_vu.c
@@ -122,21 +122,31 @@ static size_t udp_vu_prepare(const struct ctx *c, const struct iov_tail *data,
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);
+ const struct iovec payload_iov = {
+ .iov_base = bp->data,
+ .iov_len = dlen,
+ };
+ struct iov_tail payload = IOV_TAIL(&payload_iov, 1, 0);
eh->h_proto = htons(ETH_P_IP);
*iph = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_UDP);
- l4len = udp_update_hdr4(iph, bp, toside, dlen, true);
+ l4len = udp_update_hdr4(iph, &bp->uh, &payload, toside, true);
} else {
struct ipv6hdr *ip6h = vu_ip(iov[0].iov_base);
struct udp_payload_t *bp = vu_payloadv6(iov[0].iov_base);
+ const struct iovec payload_iov = {
+ .iov_base = bp->data,
+ .iov_len = dlen,
+ };
+ struct iov_tail payload = IOV_TAIL(&payload_iov, 1, 0);
eh->h_proto = htons(ETH_P_IPV6);
*ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_UDP);
- l4len = udp_update_hdr6(ip6h, bp, toside, dlen, true);
+ l4len = udp_update_hdr6(ip6h, &bp->uh, &payload, toside, true);
}
return l4len;
--
2.53.0
next prev parent reply other threads:[~2026-02-27 14:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-27 14:03 [PATCH 00/12] vhost-user,udp: Handle multiple iovec entries per virtqueue element Laurent Vivier
2026-02-27 14:03 ` [PATCH 01/12] iov: Add iov_tail_truncate() and iov_tail_zero_end() Laurent Vivier
2026-03-01 23:47 ` David Gibson
2026-02-27 14:03 ` [PATCH 02/12] vhost-user: Use ARRAY_SIZE(elem) instead of VIRTQUEUE_MAX_SIZE Laurent Vivier
2026-03-01 23:48 ` David Gibson
2026-02-27 14:03 ` [PATCH 03/12] udp_vu: Use iov_tail to manage virtqueue buffers Laurent Vivier
2026-03-02 0:03 ` David Gibson
2026-02-27 14:03 ` [PATCH 04/12] udp_vu: Move virtqueue management from udp_vu_sock_recv() to its caller Laurent Vivier
2026-03-02 0:05 ` David Gibson
2026-02-27 14:03 ` [PATCH 05/12] iov: Add IOV_PUT_HEADER() to write header data back to iov_tail Laurent Vivier
2026-03-02 0:08 ` David Gibson
2026-02-27 14:03 ` Laurent Vivier [this message]
2026-03-02 0:13 ` [PATCH 06/12] udp: Pass iov_tail to udp_update_hdr4()/udp_update_hdr6() David Gibson
2026-02-27 14:03 ` [PATCH 07/12] udp_vu: Use iov_tail in udp_vu_prepare() Laurent Vivier
2026-03-02 0:24 ` David Gibson
2026-02-27 14:03 ` [PATCH 08/12] vu_common: Pass iov_tail to vu_set_vnethdr() Laurent Vivier
2026-03-02 0:51 ` David Gibson
2026-02-27 14:03 ` [PATCH 09/12] vu_common: Accept explicit iovec counts in vu_set_element() Laurent Vivier
2026-03-02 0:54 ` David Gibson
2026-02-27 14:03 ` [PATCH 10/12] vu_common: Accept explicit iovec count per element in vu_init_elem() Laurent Vivier
2026-03-02 0:55 ` David Gibson
2026-02-27 14:03 ` [PATCH 11/12] vu_common: Prepare to use multibuffer with guest RX Laurent Vivier
2026-03-02 0:59 ` David Gibson
2026-02-27 14:03 ` [PATCH 12/12] vhost-user,udp: Use 2 iovec entries per element Laurent Vivier
2026-03-02 1:03 ` David Gibson
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