On Tue, Aug 26, 2014 at 04:06:17PM +0800, zhanghailiang wrote: > For all NICs(except virtio-net) emulated by qemu, > Such as e1000, rtl8139, pcnet and ne2k_pci, > Qemu can still receive packets when VM is not running. > > If this happened in *migration's* last PAUSE VM stage, but > before the end of the migration, the new receiving packets will possibly dirty > parts of RAM which has been cached in *iovec*(will be sent asynchronously) and > dirty parts of new RAM which will be missed. > This will lead serious network fault in VM. > > To avoid this, we forbid receiving packets in generic net code when > VM is not running. > > Bug reproduction steps: > (1) Start a VM which configured at least one NIC > (2) In VM, open several Terminal and do *Ping IP -i 0.1* > (3) Migrate the VM repeatedly between two Hosts > And the *PING* command in VM will very likely fail with message: > 'Destination HOST Unreachable', the NIC in VM will stay unavailable unless you > run 'service network restart' > > Signed-off-by: zhanghailiang <zhang.zhanghaili...@huawei.com> > --- > v4: > - The action of flush queued packets is unnecessary, remove this. > (Thanks for the help of Jason Wang and Stefan). > > v3: > - change the 'vmstate' to 'vm_running' > > v2: > - remove the superfluous check of nc->received_disabled > --- > > net/net.c | 7 +++++++ > 1 file changed, 7 insertions(+)
Thanks, applied to my net tree: https://github.com/stefanha/qemu/commits/net Stefan
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