Re: [RFC PATCH 2/2] macvtap: TX zero copy between guest and host kernel

Michael S. Tsirkin
2010-09-15T17:36:48Z

On Wed, Sep 15, 2010 at 10:00:04AM -0700, Shirley Ma wrote:
> On Wed, 2010-09-15 at 17:39 +0200, Michael S. Tsirkin wrote:
> > In fact, I rechecked: both bridge and loopback have NETIF_F_HIGHDMA
> > set.
> > So maybe we should check NETIF_F_NETNS_LOCAL ...
> >
> > macvtap in bridged mode is interesting as well.
>
> I found that too, just wondered which flag to use is better. :)
>
> Thanks
> Shirley

At some level NETIF_F_NETNS_LOCAL makes sense: local packets
can get anywhere. OTOH one wonders whether there might be other
issues, e.g. in theory devices could hang on to frag pages
just by doing get_page. There might be other issues.
Maybe we are better off white-listing known-good drivers
with a new flag?

--
MST