Replace direct iovec pointer arithmetic in UDP vhost-user handling with
iov_tail operations.
udp_vu_sock_recv() now takes an iov/cnt pair instead of using the
file-scoped iov_vu array, and returns the data length rather than the
iov count. Internally it uses IOV_TAIL() to create a view past the
L2/L3/L4 headers, and iov_tail_clone() to build the recvmsg() iovec,
removing the manual pointer offset and restore pattern.
udp_vu_prepare() and udp_vu_csum() take a const struct iov_tail *
instead of referencing iov_vu directly, making data flow explicit.
udp_vu_csum() uses iov_drop_header() and IOV_REMOVE_HEADER() to locate
the UDP header and payload, replacing manual offset calculations via
vu_payloadv4()/vu_payloadv6().
Signed-off-by: Laurent Vivier
---
udp_vu.c | 123 +++++++++++++++++++++++++++++++------------------------
1 file changed, 70 insertions(+), 53 deletions(-)
diff --git a/udp_vu.c b/udp_vu.c
index 5e030effa703..8b0de312949c 100644
--- a/udp_vu.c
+++ b/udp_vu.c
@@ -59,21 +59,26 @@ 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
- * @dlen: Size of received data (output)
*
- * Return: number of iov entries used to store the datagram, 0 if the datagram
+ * Return: size of received data, 0 if the datagram
* was discarded because the virtqueue is not ready, -1 on error
*/
-static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
- bool v6, ssize_t *dlen)
+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)
{
const struct vu_dev *vdev = c->vdev;
- int elem_cnt, elem_used, iov_used;
struct msghdr msg = { 0 };
- size_t iov_cnt, hdrlen;
+ struct iov_tail payload;
+ size_t hdrlen, iov_used;
+ unsigned elem_cnt;
+ unsigned i, j;
+ ssize_t dlen;
ASSERT(!c->no_udp);
@@ -83,6 +88,7 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
if (recvmsg(s, &msg, MSG_DONTWAIT) < 0)
debug_perror("Failed to discard datagram");
+ *cnt = 0;
return 0;
}
@@ -90,68 +96,70 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
hdrlen = udp_vu_hdrlen(v6);
elem_cnt = vu_collect(vdev, vq, elem, ARRAY_SIZE(elem),
- iov_vu, ARRAY_SIZE(iov_vu), &iov_cnt,
+ iov, *cnt, &iov_used,
IP_MAX_MTU + ETH_HLEN + VNET_HLEN, NULL);
if (elem_cnt == 0)
return -1;
- ASSERT((size_t)elem_cnt == iov_cnt); /* one iovec per element */
+ ASSERT((size_t)elem_cnt == iov_used); /* one iovec per element */
- /* reserve space for the headers */
- ASSERT(iov_vu[0].iov_len >= MAX(hdrlen, ETH_ZLEN + VNET_HLEN));
+ payload = IOV_TAIL(iov, iov_used, hdrlen);
- iov_vu[0].iov_base = (char *)iov_vu[0].iov_base + hdrlen;
- iov_vu[0].iov_len -= 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 */
- msg.msg_iov = iov_vu;
- msg.msg_iovlen = iov_cnt;
-
- *dlen = recvmsg(s, &msg, 0);
- if (*dlen < 0) {
+ dlen = recvmsg(s, &msg, 0);
+ if (dlen < 0) {
vu_queue_rewind(vq, elem_cnt);
return -1;
}
- /* restore the pointer to the headers address */
- iov_vu[0].iov_base = (char *)iov_vu[0].iov_base - hdrlen;
- iov_vu[0].iov_len += hdrlen;
+ *cnt = vu_pad(iov, iov_used, 0, dlen + hdrlen);
- iov_used = vu_pad(iov_vu, iov_cnt, 0, *dlen + hdrlen);
- elem_used = iov_used; /* one iovec per element */
+ *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_vu[0].iov_base, elem_used);
+ vu_set_vnethdr(iov[0].iov_base, *elem_used);
/* release unused buffers */
- vu_queue_rewind(vq, elem_cnt - elem_used);
+ vu_queue_rewind(vq, elem_cnt - *elem_used);
- return iov_used;
+ return dlen;
}
/**
* udp_vu_prepare() - Prepare the packet header
* @c: Execution context
+ * @data: IO vector tail for the 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,
+static size_t udp_vu_prepare(const struct ctx *c, const struct iov_tail *data,
const struct flowside *toside, ssize_t dlen)
{
+ const struct iovec *iov = data->iov;
struct ethhdr *eh;
size_t l4len;
/* ethernet header */
- eh = vu_eth(iov_vu[0].iov_base);
+ 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));
/* initialize header */
if (inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr)) {
- struct iphdr *iph = vu_ip(iov_vu[0].iov_base);
- struct udp_payload_t *bp = vu_payloadv4(iov_vu[0].iov_base);
+ struct iphdr *iph = vu_ip(iov[0].iov_base);
+ struct udp_payload_t *bp = vu_payloadv4(iov[0].iov_base);
eh->h_proto = htons(ETH_P_IP);
@@ -159,8 +167,8 @@ static size_t udp_vu_prepare(const struct ctx *c,
l4len = udp_update_hdr4(iph, bp, toside, dlen, true);
} else {
- struct ipv6hdr *ip6h = vu_ip(iov_vu[0].iov_base);
- struct udp_payload_t *bp = vu_payloadv6(iov_vu[0].iov_base);
+ struct ipv6hdr *ip6h = vu_ip(iov[0].iov_base);
+ struct udp_payload_t *bp = vu_payloadv6(iov[0].iov_base);
eh->h_proto = htons(ETH_P_IPV6);
@@ -175,25 +183,29 @@ static size_t udp_vu_prepare(const struct ctx *c,
/**
* udp_vu_csum() - Calculate and set checksum for a UDP packet
* @toside: Address information for one side of the flow
- * @iov_used: Number of used iov_vu items
+ * @data: IO vector tail for the frame (including vnet header)
*/
-static void udp_vu_csum(const struct flowside *toside, int iov_used)
+static void udp_vu_csum(const struct flowside *toside,
+ const struct iov_tail *data)
{
const struct in_addr *src4 = inany_v4(&toside->oaddr);
const struct in_addr *dst4 = inany_v4(&toside->eaddr);
- char *base = iov_vu[0].iov_base;
- struct udp_payload_t *bp;
- struct iov_tail data;
+ struct iov_tail payload = *data;
+ struct udphdr *uh, uh_storage;
+ bool ipv4 = src4 && dst4;
+
+ IOV_DROP_HEADER(&payload, struct virtio_net_hdr_mrg_rxbuf);
+ IOV_DROP_HEADER(&payload, struct ethhdr);
+ if (ipv4)
+ IOV_DROP_HEADER(&payload, struct iphdr);
+ else
+ IOV_DROP_HEADER(&payload, struct ipv6hdr);
+ uh = IOV_REMOVE_HEADER(&payload, uh_storage);
- if (src4 && dst4) {
- bp = vu_payloadv4(base);
- data = IOV_TAIL(iov_vu, iov_used, (char *)&bp->data - base);
- csum_udp4(&bp->uh, *src4, *dst4, &data);
- } else {
- bp = vu_payloadv6(base);
- data = IOV_TAIL(iov_vu, iov_used, (char *)&bp->data - base);
- csum_udp6(&bp->uh, &toside->oaddr.a6, &toside->eaddr.a6, &data);
- }
+ if (ipv4)
+ csum_udp4(uh, *src4, *dst4, &payload);
+ else
+ csum_udp6(uh, &toside->oaddr.a6, &toside->eaddr.a6, &payload);
}
/**
@@ -209,23 +221,28 @@ void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t 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;
for (i = 0; i < n; i++) {
+ unsigned elem_used;
+ size_t iov_cnt;
ssize_t dlen;
- int iov_used;
- iov_used = udp_vu_sock_recv(c, vq, s, v6, &dlen);
- if (iov_used < 0)
+ iov_cnt = ARRAY_SIZE(iov_vu);
+ dlen = udp_vu_sock_recv(c, iov_vu, &iov_cnt, &elem_used, vq,
+ s, v6);
+ if (dlen < 0)
break;
- if (iov_used > 0) {
- udp_vu_prepare(c, toside, dlen);
+ if (iov_cnt > 0) {
+ data = IOV_TAIL(iov_vu, iov_cnt, 0);
+ udp_vu_prepare(c, &data, toside, dlen);
if (*c->pcap) {
- udp_vu_csum(toside, iov_used);
- pcap_iov(iov_vu, iov_used, VNET_HLEN);
+ udp_vu_csum(toside, &data);
+ pcap_iov(data.iov, data.cnt, VNET_HLEN);
}
- vu_flush(vdev, vq, elem, iov_used);
+ vu_flush(vdev, vq, elem, elem_used);
}
}
}
--
2.53.0