On Wed, Apr 02, 2025 at 07:23:28PM +0200, Laurent Vivier wrote:Use IOV_PEEK_HEADER() to get the ethernet header from the iovec. Move the workaround about multiple iovec array from vu_handle_tx() to tap_add_packet(). Removing the offset out of the iovec array should reduce the iovec count to 1. Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>--- iov.c | 1 - pcap.c | 1 + tap.c | 30 +++++++++++++++++++++--------- tap.h | 2 +- vu_common.c | 25 +++++-------------------- 5 files changed, 28 insertions(+), 31 deletions(-) diff --git a/iov.c b/iov.c index d96fc2ab594b..508fb6da91fb 100644 --- a/iov.c +++ b/iov.c @@ -238,7 +238,6 @@ size_t iov_tail_size(struct iov_tail *tail) * * Returns: true if the tail still contains any bytes, otherwise false */ -/* cppcheck-suppress unusedFunction */ bool iov_drop(struct iov_tail *tail, size_t len) { tail->off = tail->off + len; diff --git a/pcap.c b/pcap.c index e95aa6fe29a6..404043a27e22 100644 --- a/pcap.c +++ b/pcap.c @@ -76,6 +76,7 @@ static void pcap_frame(const struct iovec *iov, size_t iovcnt, * @pkt: Pointer to data buffer, including L2 headers * @l2len: L2 frame length */ +/* cppcheck-suppress unusedFunction */ void pcap(const char *pkt, size_t l2len) { struct iovec iov = { (char *)pkt, l2len }; diff --git a/tap.c b/tap.c index 182a1151f139..ab3effe80f89 100644 --- a/tap.c +++ b/tap.c @@ -1040,29 +1040,36 @@ void tap_handler(struct ctx *c, const struct timespec *now) /** * tap_add_packet() - Queue/capture packet, update notion of guest MAC address * @c: Execution context - * @l2len: Total L2 packet length - * @p: Packet buffer + * @data: Packet to add to the pool */ -void tap_add_packet(struct ctx *c, ssize_t l2len, char *p) +void tap_add_packet(struct ctx *c, struct iov_tail *data) { const struct ethhdr *eh; + struct ethhdr ehc; - pcap(p, l2len); + pcap_iov(data->iov, data->cnt, data->off); - eh = (struct ethhdr *)p; + eh = IOV_PEEK_HEADER(data, ehc); + if (!eh) + return; if (memcmp(c->guest_mac, eh->h_source, ETH_ALEN)) { memcpy(c->guest_mac, eh->h_source, ETH_ALEN); proto_update_l2_buf(c->guest_mac, NULL); } + iov_tail_prune(data); + ASSERT(data->cnt == 1); /* packet_add() doesn't support iovec */ + switch (ntohs(eh->h_proto)) { case ETH_P_ARP: case ETH_P_IP: - packet_add(pool_tap4, l2len, p); + packet_add(pool_tap4, data->iov[0].iov_len - data->off, + (char *)data->iov[0].iov_base + data->off); break; case ETH_P_IPV6: - packet_add(pool_tap6, l2len, p); + packet_add(pool_tap6, data->iov[0].iov_len - data->off, + (char *)data->iov[0].iov_base + data->off); break; default: break; @@ -1128,6 +1135,7 @@ static void tap_passt_input(struct ctx *c, const struct timespec *now) while (n >= (ssize_t)sizeof(uint32_t)) { uint32_t l2len = ntohl_unaligned(p); + struct iov_tail data; if (l2len < sizeof(struct ethhdr) || l2len > L2_MAX_LEN_PASST) { err("Bad frame size from guest, resetting connection"); @@ -1142,7 +1150,8 @@ static void tap_passt_input(struct ctx *c, const struct timespec *now) p += sizeof(uint32_t); n -= sizeof(uint32_t); - tap_add_packet(c, l2len, p); + data = IOV_TAIL_FROM_BUF(p, l2len, 0); + tap_add_packet(c, &data); p += l2len; n -= l2len; @@ -1186,6 +1195,8 @@ static void tap_pasta_input(struct ctx *c, const struct timespec *now) for (n = 0; n <= (ssize_t)(sizeof(pkt_buf) - L2_MAX_LEN_PASTA); n += len) { + struct iov_tail data; + len = read(c->fd_tap, pkt_buf + n, L2_MAX_LEN_PASTA); if (len == 0) { @@ -1207,7 +1218,8 @@ static void tap_pasta_input(struct ctx *c, const struct timespec *now) len > (ssize_t)L2_MAX_LEN_PASTA) continue; - tap_add_packet(c, len, pkt_buf + n); + data = IOV_TAIL_FROM_BUF(pkt_buf + n, len, 0); + tap_add_packet(c, &data); } tap_handler(c, now); diff --git a/tap.h b/tap.h index dd39fd896f4a..5034acd8ac46 100644 --- a/tap.h +++ b/tap.h @@ -119,6 +119,6 @@ void tap_sock_update_pool(void *base, size_t size); void tap_backend_init(struct ctx *c); void tap_flush_pools(void); void tap_handler(struct ctx *c, const struct timespec *now); -void tap_add_packet(struct ctx *c, ssize_t l2len, char *p); +void tap_add_packet(struct ctx *c, struct iov_tail *data); #endif /* TAP_H */ diff --git a/vu_common.c b/vu_common.c index 686a09b28c8e..e446fc4f2054 100644 --- a/vu_common.c +++ b/vu_common.c @@ -159,7 +159,6 @@ static void vu_handle_tx(struct vu_dev *vdev, int index, struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE]; struct iovec out_sg[VIRTQUEUE_MAX_SIZE]; struct vu_virtq *vq = &vdev->vq[index]; - int hdrlen = sizeof(struct virtio_net_hdr_mrg_rxbuf); int out_sg_count; int count; @@ -172,6 +171,7 @@ static void vu_handle_tx(struct vu_dev *vdev, int index, while (count < VIRTQUEUE_MAX_SIZE && out_sg_count + VU_MAX_TX_BUFFER_NB <= VIRTQUEUE_MAX_SIZE) { int ret; + struct iov_tail data; elem[count].out_num = VU_MAX_TX_BUFFER_NB; elem[count].out_sg = &out_sg[out_sg_count]; @@ -187,25 +187,10 @@ static void vu_handle_tx(struct vu_dev *vdev, int index, warn("virtio-net transmit queue contains no out buffers"); break; } - if (elem[count].out_num == 1) { - tap_add_packet(vdev->context, - elem[count].out_sg[0].iov_len - hdrlen, - (char *)elem[count].out_sg[0].iov_base + - hdrlen); - } else { - /* vnet header can be in a separate iovec */ - if (elem[count].out_num != 2) { - debug("virtio-net transmit queue contains more than one buffer ([%d]: %u)", - count, elem[count].out_num); - } else if (elem[count].out_sg[0].iov_len != (size_t)hdrlen) { - debug("virtio-net transmit queue entry not aligned on hdrlen ([%d]: %d != %zu)", - count, hdrlen, elem[count].out_sg[0].iov_len); - } else { - tap_add_packet(vdev->context, - elem[count].out_sg[1].iov_len, - (char *)elem[count].out_sg[1].iov_base); - } - } + + data = IOV_TAIL(elem[count].out_sg, elem[count].out_num, 0); + if (IOV_DROP_HEADER(&data, struct virtio_net_hdr_mrg_rxbuf)) + tap_add_packet(vdev->context, &data); count++; }-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson