Guest device and host netdev are peers, i.e. it's a 1:1 relation. However, we fail to enforce that:
$ qemu -nodefaults --nographic -netdev user,id=net0 -device e1000,netdev=net0 -device virtio-net-pci,netdev=net0 -monitor stdio QEMU 0.12.50 monitor - type 'help' for more information (qemu) info network Devices not on any VLAN: net0: net=10.0.2.0, restricted=n peer=virtio-net-pci.0 e1000.0: model=e1000,macaddr=52:54:00:12:34:56 peer=net0 virtio-net-pci.0: model=virtio-net-pci,macaddr=52:54:00:12:34:57 peer=net0 It's all downhill from there. Signed-off-by: Markus Armbruster <arm...@redhat.com> --- hw/qdev-properties.c | 7 +++++++ net.c | 1 + 2 files changed, 8 insertions(+), 0 deletions(-) diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c index 438eaea..24671af 100644 --- a/hw/qdev-properties.c +++ b/hw/qdev-properties.c @@ -341,6 +341,9 @@ static int parse_netdev(DeviceState *dev, Property *prop, const char *str) *ptr = qemu_find_netdev(str); if (*ptr == NULL) return -ENOENT; + if ((*ptr)->peer) { + return -EEXIST; + } return 0; } @@ -557,6 +560,10 @@ int qdev_prop_parse(DeviceState *dev, const char *name, const char *value) ret = prop->info->parse(dev, prop, value); if (ret < 0) { switch (ret) { + case -EEXIST: + fprintf(stderr, "property \"%s.%s\": \"%s\" is already in use\n", + dev->info->name, name, value); + break; default: case -EINVAL: fprintf(stderr, "property \"%s.%s\": failed to parse \"%s\"\n", diff --git a/net.c b/net.c index a1bf49f..e6c96d3 100644 --- a/net.c +++ b/net.c @@ -245,6 +245,7 @@ VLANClientState *qemu_new_net_client(NetClientInfo *info, QTAILQ_INSERT_TAIL(&vc->vlan->clients, vc, next); } else { if (peer) { + assert(!peer->peer); vc->peer = peer; peer->peer = vc; } -- 1.6.6.1