Re: [Qemu-devel] [PATCH] e1000/rtl8139: forbid dealing with packets when VM is paused

[Michael S. Tsirkin]

On Wed, May 14, 2014 at 02:30:26PM +0200, Stefan Hajnoczi wrote:
> On Thu, May 08, 2014 at 12:51:05PM +0000, Zhanghailiang wrote:
> > > If you implement this in the net layer then that problem is easy to 
> > > resolve since
> > > we can flush all queues when the guest resumes to get packets flowing 
> > > again.
> > > 
> > Do you mean we should also listen for VM runstate changes in net layer, and 
> > when detect runstate changes back to running , we flush all queues 
> > actively? Am I misunderstanding? 
> > Or we can do it *before* qemu (exactly when it check if it can send 
> > packets) send packets to guest again, this way will be simple, but it also 
> > need know the change of runstate. Any idea? 
> 
> When the runstate changes back to running, we definitely need to flush
> queues to get packets flowing again.  I think the simplest way of doing
> that is in the net layer so individual NICs and netdevs don't have to
> duplicate this code.
> 
> Stefan

That will help with networking but not other devices.
The issue isn't limited to networking at all.
How about we stop all io threads with the vm?

That will address the issue in a generic way.

-- 
MST