Avoid tweaking iovec during receive. This removes
the need to copy the vector.
Note: we already have an evil cast in work_around_broken_dhclient
and unfortunately this adds another one.
const on buf is ignored by this function anyway so arguably
this is not making things much worse.
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
hw/virtio-net.c | 45 +++++++++++++++++++++------------------------
iov.h | 8 ++++----
2 files changed, 25 insertions(+), 28 deletions(-)
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 0c5081e..6e53858 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -503,7 +503,7 @@ static int virtio_net_has_buffers(VirtIONet *n, int bufsize)
* we should provide a mechanism to disable it to avoid polluting the host
* cache.
*/
-static void work_around_broken_dhclient(struct virtio_net_hdr *hdr,
+static void work_around_broken_dhclient(const struct virtio_net_hdr *hdr,
const uint8_t *buf, size_t size)
{
if ((hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && /* missing csum */
@@ -513,31 +513,27 @@ static void work_around_broken_dhclient(struct
virtio_net_hdr *hdr,
(buf[34] == 0 && buf[35] == 67)) { /* udp.srcport == bootps */
/* FIXME this cast is evil */
net_checksum_calculate((uint8_t *)buf, size);
- hdr->flags &= ~VIRTIO_NET_HDR_F_NEEDS_CSUM;
+ ((struct virtio_net_hdr *)hdr)->flags &= ~VIRTIO_NET_HDR_F_NEEDS_CSUM;
}
}
-static int receive_header(VirtIONet *n, struct iovec *iov, int iovcnt,
- const void *buf, size_t size, size_t hdr_len)
+static int receive_header(VirtIONet *n, const struct iovec *iov, int iov_cnt,
+ const void *buf, size_t size)
{
- struct virtio_net_hdr *hdr = (struct virtio_net_hdr *)iov[0].iov_base;
int offset = 0;
- hdr->flags = 0;
- hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
-
if (n->has_vnet_hdr) {
- memcpy(hdr, buf, sizeof(*hdr));
- offset = sizeof(*hdr);
- work_around_broken_dhclient(hdr, buf + offset, size - offset);
+ work_around_broken_dhclient(buf, buf + offset, size - offset);
+ offset = sizeof(struct virtio_net_hdr);
+ iov_from_buf(iov, iov_cnt, 0, buf, offset);
+ } else {
+ struct virtio_net_hdr hdr = {
+ .flags = 0,
+ .gso_type = VIRTIO_NET_HDR_GSO_NONE
+ };
+ iov_from_buf(iov, iov_cnt, 0, &hdr, sizeof hdr);
}
- /* We only ever receive a struct virtio_net_hdr from the tapfd,
- * but we may be passing along a larger header to the guest.
- */
- iov[0].iov_base += hdr_len;
- iov[0].iov_len -= hdr_len;
-
return offset;
}
@@ -598,7 +594,8 @@ static ssize_t virtio_net_receive(NetClientState *nc, const
uint8_t *buf, size_t
{
VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
struct virtio_net_hdr_mrg_rxbuf *mhdr = NULL;
- size_t offset, i;
+ const struct iovec *sg = elem.in_sg;
+ size_t offset, i, guest_offset;
if (!virtio_net_can_receive(&n->nic->nc))
return -1;
@@ -615,7 +612,7 @@ static ssize_t virtio_net_receive(NetClientState *nc, const
uint8_t *buf, size_t
while (offset < size) {
VirtQueueElement elem;
int len, total;
- struct iovec sg[VIRTQUEUE_MAX_SIZE];
+ const struct iovec *sg = elem.in_sg;
total = 0;
@@ -640,20 +637,20 @@ static ssize_t virtio_net_receive(NetClientState *nc,
const uint8_t *buf, size_t
exit(1);
}
- memcpy(&sg, &elem.in_sg[0], sizeof(sg[0]) * elem.in_num);
-
if (i == 0) {
if (n->mergeable_rx_bufs)
mhdr = (struct virtio_net_hdr_mrg_rxbuf *)sg[0].iov_base;
offset += receive_header(n, sg, elem.in_num,
- buf + offset, size - offset,
- n->guest_hdr_len);
+ buf + offset, size - offset);
total += n->guest_hdr_len;
+ guest_offset = n->guest_hdr_len;
+ } else {
+ guest_offset = 0;
}
/* copy in packet. ugh */
- len = iov_from_buf(sg, elem.in_num, 0,
+ len = iov_from_buf(sg, elem.in_num, guest_offset,
buf + offset, size - offset);
total += len;
offset += len;
diff --git a/iov.h b/iov.h
index f0daefa..6c9fdf1 100644
--- a/iov.h
+++ b/iov.h
@@ -90,8 +90,8 @@ void iov_hexdump(const struct iovec *iov, const unsigned int
iov_cnt,
/*
* Partial copy of vector from iov to dst_iov (data is not copied).
* dst_iov overlaps iov at a specified offset.
- * size of dst_iov is at most bytes. Actual size is returned.
+ * size of dst_iov is at most bytes. dst vector count is returned.
*/
-size_t iov_cpy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
- const struct iovec *iov, unsigned int iov_cnt,
- size_t offset, size_t bytes);
+unsigned iov_cpy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
+ const struct iovec *iov, unsigned int iov_cnt,
+ size_t offset, size_t bytes);
--
MST
