The per-protocol padding done by vu_pad() in tcp_vu.c and udp_vu.c was
only correct for single-buffer frames, and assumed the padding area always
fell within the first iov. It also relied on each caller computing the
right MAX(..., ETH_ZLEN + VNET_HLEN) size for vu_collect() and calling
vu_pad() at the right point.
Centralise padding logic into three shared vhost-user helpers instead:
- vu_collect() now ensures at least ETH_ZLEN + VNET_HLEN bytes of buffer
space are collected, so there is always room for a minimum-sized frame.
- vu_pad() replaces the old single-iov helper with a new implementation
that takes a full iovec array plus a 'skipped' byte count. It uses a
new iov_memset() helper in iov.c to zero-fill the padding area across
iovec boundaries, then calls iov_truncate() to set the logical frame
size.
- vu_flush() computes the actual frame length (accounting for
VIRTIO_NET_F_MRG_RXBUF multi-buffer frames) and passes the padded
length to vu_queue_fill().
Callers in tcp_vu.c, udp_vu.c and vu_send_single() now use the new
vu_pad() in place of the old pad-then-truncate sequences and the
MAX(..., ETH_ZLEN + VNET_HLEN) size calculations passed to vu_collect().
Centralising padding here will also ease the move to multi-iovec per
element support, since there will be a single place to update.
In vu_send_single(), fix padding, truncation and data copy to use the
requested frame size rather than the total available buffer space from
vu_collect(), which could be larger. Also add matching padding, truncation
and explicit size to vu_collect() for the DUP_ACK path in
tcp_vu_send_flag().
Signed-off-by: Laurent Vivier
---
iov.c | 26 ++++++++++++++++++
iov.h | 2 ++
tcp_vu.c | 23 ++++++----------
udp_vu.c | 10 +++----
vu_common.c | 76 ++++++++++++++++++++++++++++++++++++-----------------
vu_common.h | 2 +-
6 files changed, 92 insertions(+), 47 deletions(-)
diff --git a/iov.c b/iov.c
index 31a3f5bc29e5..34d42c7a2264 100644
--- a/iov.c
+++ b/iov.c
@@ -169,6 +169,32 @@ size_t iov_truncate(struct iovec *iov, size_t iov_cnt, size_t size)
return i;
}
+/**
+ * iov_memset() - Set bytes of an IO vector to a given value
+ * @iov: IO vector
+ * @iov_cnt: Number of elements in @iov
+ * @offset: Byte offset in the iovec at which to start
+ * @c: Byte value to fill with
+ * @length: Number of bytes to set
+ * Will write less than @length bytes if it runs out of space in
+ * the iov
+ */
+void iov_memset(const struct iovec *iov, size_t iov_cnt, size_t offset, int c,
+ size_t length)
+{
+ size_t i;
+
+ i = iov_skip_bytes(iov, iov_cnt, offset, &offset);
+
+ for ( ; i < iov_cnt && length; i++) {
+ size_t n = MIN(iov[i].iov_len - offset, length);
+
+ memset((char *)iov[i].iov_base + offset, c, n);
+ offset = 0;
+ length -= n;
+ }
+}
+
/**
* iov_tail_prune() - Remove any unneeded buffers from an IOV tail
* @tail: IO vector tail (modified)
diff --git a/iov.h b/iov.h
index b4e50b0fca5a..d295d05b3bab 100644
--- a/iov.h
+++ b/iov.h
@@ -30,6 +30,8 @@ size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt,
size_t offset, void *buf, size_t bytes);
size_t iov_size(const struct iovec *iov, size_t iov_cnt);
size_t iov_truncate(struct iovec *iov, size_t iov_cnt, size_t size);
+void iov_memset(const struct iovec *iov, size_t iov_cnt, size_t offset, int c,
+ size_t length);
/*
* DOC: Theory of Operation, struct iov_tail
diff --git a/tcp_vu.c b/tcp_vu.c
index d470ab54bcea..80464d450fc9 100644
--- a/tcp_vu.c
+++ b/tcp_vu.c
@@ -72,12 +72,12 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
struct vu_dev *vdev = c->vdev;
struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
struct vu_virtq_element flags_elem[2];
- size_t optlen, hdrlen, l2len;
struct ipv6hdr *ip6h = NULL;
struct iphdr *ip4h = NULL;
struct iovec flags_iov[2];
struct tcp_syn_opts *opts;
struct iov_tail payload;
+ size_t optlen, hdrlen;
struct tcphdr *th;
struct ethhdr *eh;
uint32_t seq;
@@ -89,7 +89,7 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
elem_cnt = vu_collect(vdev, vq, &flags_elem[0], 1,
&flags_iov[0], 1, NULL,
- MAX(hdrlen + sizeof(*opts), ETH_ZLEN + VNET_HLEN), NULL);
+ hdrlen + sizeof(*opts), NULL);
if (elem_cnt != 1)
return -1;
@@ -131,7 +131,7 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
return ret;
}
- iov_truncate(&flags_iov[0], 1, hdrlen + optlen);
+ vu_pad(&flags_iov[0], 1, 0, hdrlen + optlen);
payload = IOV_TAIL(flags_elem[0].in_sg, 1, hdrlen);
if (flags & KEEPALIVE)
@@ -140,9 +140,6 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
tcp_fill_headers(c, conn, eh, ip4h, ip6h, th, &payload,
NULL, seq, !*c->pcap);
- l2len = optlen + hdrlen - VNET_HLEN;
- vu_pad(&flags_elem[0].in_sg[0], l2len);
-
if (*c->pcap)
pcap_iov(&flags_elem[0].in_sg[0], 1, VNET_HLEN);
nb_ack = 1;
@@ -150,10 +147,11 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
if (flags & DUP_ACK) {
elem_cnt = vu_collect(vdev, vq, &flags_elem[1], 1,
&flags_iov[1], 1, NULL,
- flags_elem[0].in_sg[0].iov_len, NULL);
+ hdrlen + optlen, NULL);
if (elem_cnt == 1 &&
flags_elem[1].in_sg[0].iov_len >=
flags_elem[0].in_sg[0].iov_len) {
+ vu_pad(&flags_iov[1], 1, 0, hdrlen + optlen);
memcpy(flags_elem[1].in_sg[0].iov_base,
flags_elem[0].in_sg[0].iov_base,
flags_elem[0].in_sg[0].iov_len);
@@ -213,7 +211,7 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
ARRAY_SIZE(elem) - elem_cnt,
&iov_vu[DISCARD_IOV_NUM + iov_used],
VIRTQUEUE_MAX_SIZE - iov_used, &in_num,
- MAX(MIN(mss, fillsize) + hdrlen, ETH_ZLEN + VNET_HLEN),
+ MIN(mss, fillsize) + hdrlen,
&frame_size);
if (cnt == 0)
break;
@@ -225,6 +223,7 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
/* reserve space for headers in iov */
iov = &elem[elem_cnt].in_sg[0];
ASSERT(iov->iov_len >= hdrlen);
+
iov->iov_base = (char *)iov->iov_base + hdrlen;
iov->iov_len -= hdrlen;
head[(*head_cnt)++] = elem_cnt;
@@ -249,8 +248,7 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
if (!peek_offset_cap)
ret -= already_sent;
- /* adjust iov number and length of the last iov */
- i = iov_truncate(&iov_vu[DISCARD_IOV_NUM], iov_used, ret);
+ i = vu_pad(&iov_vu[DISCARD_IOV_NUM], iov_used, hdrlen, ret);
/* adjust head count */
while (*head_cnt > 0 && head[*head_cnt - 1] >= i)
@@ -446,7 +444,6 @@ int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
size_t frame_size = iov_size(iov, buf_cnt);
bool push = i == head_cnt - 1;
ssize_t dlen;
- size_t l2len;
ASSERT(frame_size >= hdrlen);
@@ -460,10 +457,6 @@ int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
tcp_vu_prepare(c, conn, iov, buf_cnt, &check, !*c->pcap, push);
- /* Pad first/single buffer only, it's at least ETH_ZLEN long */
- l2len = dlen + hdrlen - VNET_HLEN;
- vu_pad(iov, l2len);
-
if (*c->pcap)
pcap_iov(iov, buf_cnt, VNET_HLEN);
diff --git a/udp_vu.c b/udp_vu.c
index acc18d375a0f..5e030effa703 100644
--- a/udp_vu.c
+++ b/udp_vu.c
@@ -73,8 +73,7 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
const struct vu_dev *vdev = c->vdev;
int elem_cnt, elem_used, iov_used;
struct msghdr msg = { 0 };
- size_t hdrlen, l2len;
- size_t iov_cnt;
+ size_t iov_cnt, hdrlen;
ASSERT(!c->no_udp);
@@ -100,6 +99,7 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
/* reserve space for the headers */
ASSERT(iov_vu[0].iov_len >= MAX(hdrlen, ETH_ZLEN + VNET_HLEN));
+
iov_vu[0].iov_base = (char *)iov_vu[0].iov_base + hdrlen;
iov_vu[0].iov_len -= hdrlen;
@@ -117,13 +117,9 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
iov_vu[0].iov_base = (char *)iov_vu[0].iov_base - hdrlen;
iov_vu[0].iov_len += hdrlen;
- iov_used = iov_truncate(iov_vu, iov_cnt, *dlen + hdrlen);
+ iov_used = vu_pad(iov_vu, iov_cnt, 0, *dlen + hdrlen);
elem_used = iov_used; /* one iovec per element */
- /* pad frame to 60 bytes: first buffer is at least ETH_ZLEN long */
- l2len = *dlen + hdrlen - VNET_HLEN;
- vu_pad(&iov_vu[0], l2len);
-
vu_set_vnethdr(iov_vu[0].iov_base, elem_used);
/* release unused buffers */
diff --git a/vu_common.c b/vu_common.c
index d5fca9e52004..4ba407f6faf7 100644
--- a/vu_common.c
+++ b/vu_common.c
@@ -74,6 +74,7 @@ int vu_collect(const struct vu_dev *vdev, struct vu_virtq *vq,
size_t current_iov = 0;
int elem_cnt = 0;
+ size = MAX(size, ETH_ZLEN + VNET_HLEN); /* Ethernet minimum size */
while (current_size < size && elem_cnt < max_elem &&
current_iov < max_in_sg) {
int ret;
@@ -113,6 +114,25 @@ int vu_collect(const struct vu_dev *vdev, struct vu_virtq *vq,
return elem_cnt;
}
+/**
+ * vu_pad() - Pad short frames to minimum Ethernet length and truncate iovec
+ * @iov: Pointer to iovec array
+ * @cnt: Number of entries in @iov
+ * @skipped: Bytes already accounted for in the frame but not in @iov
+ * @size: Data length in @iov
+ *
+ * Return: number of iovec entries after truncation
+ */
+size_t vu_pad(struct iovec *iov, size_t cnt, size_t skipped, size_t size)
+{
+ if (skipped + size < ETH_ZLEN + VNET_HLEN) {
+ iov_memset(iov, cnt, size, 0,
+ ETH_ZLEN + VNET_HLEN - (skipped + size));
+ }
+
+ return iov_truncate(iov, cnt, size);
+}
+
/**
* vu_set_vnethdr() - set virtio-net headers
* @vnethdr: Address of the header to set
@@ -137,12 +157,32 @@ void vu_set_vnethdr(struct virtio_net_hdr_mrg_rxbuf *vnethdr, int num_buffers)
void vu_flush(const struct vu_dev *vdev, struct vu_virtq *vq,
struct vu_virtq_element *elem, int elem_cnt)
{
- int i;
-
- for (i = 0; i < elem_cnt; i++) {
- size_t elem_size = iov_size(elem[i].in_sg, elem[i].in_num);
-
- vu_queue_fill(vdev, vq, &elem[i], elem_size, i);
+ int i, j, num_elements;
+
+ for (i = 0; i < elem_cnt; i += num_elements) {
+ const struct virtio_net_hdr_mrg_rxbuf *vnethdr;
+ size_t len, padding, elem_size;
+
+ vnethdr = elem[i].in_sg[0].iov_base;
+ num_elements = le16toh(vnethdr->num_buffers);
+
+ len = 0;
+ for (j = 0; j < num_elements - 1; j++) {
+ elem_size = iov_size(elem[i + j].in_sg,
+ elem[i + j].in_num);
+ vu_queue_fill(vdev, vq, &elem[i + j],
+ elem_size, i + j);
+ len += elem_size;
+ }
+ /* pad the last element to have an Ethernet minimum size */
+ elem_size = iov_size(elem[i + j].in_sg, elem[i + j].in_num);
+ if (ETH_ZLEN + VNET_HLEN > len + elem_size)
+ padding = ETH_ZLEN + VNET_HLEN - (len + elem_size);
+ else
+ padding = 0;
+
+ vu_queue_fill(vdev, vq, &elem[i + j], elem_size + padding,
+ i + j);
}
vu_queue_flush(vdev, vq, elem_cnt);
@@ -261,38 +301,26 @@ int vu_send_single(const struct ctx *c, const void *buf, size_t size)
goto err;
}
+ in_num = vu_pad(in_sg, in_num, 0, size);
+
vu_set_vnethdr(in_sg[0].iov_base, elem_cnt);
- total -= VNET_HLEN;
+ size -= VNET_HLEN;
/* copy data from the buffer to the iovec */
- iov_from_buf(in_sg, in_num, VNET_HLEN, buf, total);
+ iov_from_buf(in_sg, in_num, VNET_HLEN, buf, size);
if (*c->pcap)
pcap_iov(in_sg, in_num, VNET_HLEN);
vu_flush(vdev, vq, elem, elem_cnt);
- trace("vhost-user sent %zu", total);
+ trace("vhost-user sent %zu", size);
- return total;
+ return size;
err:
for (i = 0; i < elem_cnt; i++)
vu_queue_detach_element(vq);
return -1;
}
-
-/**
- * vu_pad() - Pad 802.3 frame to minimum length (60 bytes) if needed
- * @iov: Buffer in iovec array where end of 802.3 frame is stored
- * @l2len: Layer-2 length already filled in frame
- */
-void vu_pad(struct iovec *iov, size_t l2len)
-{
- if (l2len >= ETH_ZLEN)
- return;
-
- memset((char *)iov->iov_base + iov->iov_len, 0, ETH_ZLEN - l2len);
- iov->iov_len += ETH_ZLEN - l2len;
-}
diff --git a/vu_common.h b/vu_common.h
index 6c31630e8712..73cc6ea9949b 100644
--- a/vu_common.h
+++ b/vu_common.h
@@ -39,12 +39,12 @@ int vu_collect(const struct vu_dev *vdev, struct vu_virtq *vq,
struct vu_virtq_element *elem, int max_elem,
struct iovec *in_sg, size_t max_in_sg, size_t *in_num,
size_t size, size_t *collected);
+size_t vu_pad(struct iovec *iov, size_t cnt, size_t skipped, size_t size);
void vu_set_vnethdr(struct virtio_net_hdr_mrg_rxbuf *vnethdr, int num_buffers);
void vu_flush(const struct vu_dev *vdev, struct vu_virtq *vq,
struct vu_virtq_element *elem, int elem_cnt);
void vu_kick_cb(struct vu_dev *vdev, union epoll_ref ref,
const struct timespec *now);
int vu_send_single(const struct ctx *c, const void *buf, size_t size);
-void vu_pad(struct iovec *iov, size_t l2len);
#endif /* VU_COMMON_H */
--
2.53.0