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virtio-net: add vnet_hdr support 

With '-netdev tap,id=foo -nic model=virtio,netdev=foo' virtio-net can
detect that its peer (i.e. the tap backend) supports vnet headers
and advertise to the guest that it can send packets with partial
checksums and/or TSO packets.

One complication is that if we're migrating and the source host
supports IFF_VNET_HDR but the destination host doesn't, we can't then
stop the guest from using those features. In this scenario, we just
fail the migration.

[v2:
 - add has_vnet_hdr uint32_t field for ease of vmstate conversion
 - use qemu_error()
]

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
master
Mark McLoughlin 2009-10-22 17:43:45 +01:00 committed by Anthony Liguori
parent 2596774ad2
commit 3a330134b3
1 changed files with 44 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
hw/virtio-net.c
View File

@ -32,6 +32,7 @@ typedef struct VirtIONet
VLANClientState *vc;
QEMUTimer *tx_timer;
int tx_timer_active;
uint32_t has_vnet_hdr;
struct {
VirtQueueElement elem;
ssize_t len;
@ -120,8 +121,22 @@ static void virtio_net_reset(VirtIODevice *vdev)
memset(n->vlans, 0, MAX_VLAN >> 3);
}
static int peer_has_vnet_hdr(VirtIONet *n)
{
if (!n->vc->peer)
return 0;
if (n->vc->peer->type != NET_CLIENT_TYPE_TAP)
return 0;
n->has_vnet_hdr = tap_has_vnet_hdr(n->vc->peer);
return n->has_vnet_hdr;
}
static uint32_t virtio_net_get_features(VirtIODevice *vdev)
{
VirtIONet *n = to_virtio_net(vdev);
uint32_t features = (1 << VIRTIO_NET_F_MAC) |
(1 << VIRTIO_NET_F_MRG_RXBUF) |
(1 << VIRTIO_NET_F_STATUS) |
@ -130,6 +145,15 @@ static uint32_t virtio_net_get_features(VirtIODevice *vdev)
(1 << VIRTIO_NET_F_CTRL_VLAN) |
(1 << VIRTIO_NET_F_CTRL_RX_EXTRA);
if (peer_has_vnet_hdr(n)) {
tap_using_vnet_hdr(n->vc->peer, 1);
features |= (1 << VIRTIO_NET_F_CSUM);
features |= (1 << VIRTIO_NET_F_HOST_TSO4);
features |= (1 << VIRTIO_NET_F_HOST_TSO6);
features |= (1 << VIRTIO_NET_F_HOST_ECN);
}
return features;
}
@ -359,6 +383,11 @@ static int receive_header(VirtIONet *n, struct iovec *iov, int iovcnt,
hdr->flags = 0;
hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
if (n->has_vnet_hdr) {
memcpy(hdr, buf, sizeof(*hdr));
offset = 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.
*/
@ -378,6 +407,10 @@ static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
if (n->promisc)
return 1;
if (n->has_vnet_hdr) {
ptr += sizeof(struct virtio_net_hdr);
}
if (!memcmp(&ptr[12], vlan, sizeof(vlan))) {
int vid = be16_to_cpup((uint16_t *)(ptr + 14)) & 0xfff;
if (!(n->vlans[vid >> 5] & (1U << (vid & 0x1f))))
@ -510,7 +543,6 @@ static void virtio_net_tx_complete(VLANClientState *vc, ssize_t len)
static void virtio_net_flush_tx(VirtIONet *n, VirtQueue *vq)
{
VirtQueueElement elem;
int has_vnet_hdr = 0;
if (!(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK))
return;
@ -537,7 +569,7 @@ static void virtio_net_flush_tx(VirtIONet *n, VirtQueue *vq)
}
/* ignore the header if GSO is not supported */
if (!has_vnet_hdr) {
if (!n->has_vnet_hdr) {
out_num--;
out_sg++;
len += hdr_len;
@ -610,7 +642,7 @@ static void virtio_net_save(QEMUFile *f, void *opaque)
qemu_put_be32(f, n->mac_table.in_use);
qemu_put_buffer(f, n->mac_table.macs, n->mac_table.in_use * ETH_ALEN);
qemu_put_buffer(f, (uint8_t *)n->vlans, MAX_VLAN >> 3);
qemu_put_be32(f, 0); /* vnet-hdr placeholder */
qemu_put_be32(f, n->has_vnet_hdr);
qemu_put_byte(f, n->mac_table.multi_overflow);
qemu_put_byte(f, n->mac_table.uni_overflow);
qemu_put_byte(f, n->alluni);
@ -662,10 +694,15 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
if (version_id >= 6)
qemu_get_buffer(f, (uint8_t *)n->vlans, MAX_VLAN >> 3);
if (version_id >= 7 && qemu_get_be32(f)) {
fprintf(stderr,
"virtio-net: saved image requires vnet header support\n");
exit(1);
if (version_id >= 7) {
if (qemu_get_be32(f) && !peer_has_vnet_hdr(n)) {
qemu_error("virtio-net: saved image requires vnet_hdr=on\n");
return -1;
}
if (n->has_vnet_hdr) {
tap_using_vnet_hdr(n->vc->peer, 1);
}
}
if (version_id >= 9) {