Re: [Qemu-devel] [Xen-devel] [PATCH 0/4] virtio-net: do not leak cpu mappings

[Wei Liu]

On Tue, Nov 25, 2014 at 04:28:32PM +0100, Fabio Fantoni wrote:
> Il 25/11/2014 15:42, Stefano Stabellini ha scritto:
> >Hi all,
> >this patch series fixes a cpu mapping leak in virtio-net.
> >
> >The bug is caused by virtio_net_handle_ctrl: it maps the entire out_sg
> >iov, but then modifies it and reduces it (iov_discard_front), and only
> >unmap the reduced version of the iov.
> >
> >This causes a crash when running on Xen, but the behaviour is obviously
> >incorrect without Xen too.
> >
> >The patch series fixes the issue by allowing virtio_net_handle_ctrl to
> >unmap the original out_sg iov but still call virtqueue_fill and
> >virtqueue_flush on the modified iov.
> >
> >The first three patches do not introduce any functional changes.
> 
> Thanks for these pathes, 1-2 years ago I tried to use virtio net and disks
> on xen unsuccessful and I was unable to solve it.
> When I'll have time I'll retry.
> About virtio disks can have problem similar to this or should be ok?
> About the other patches posted in link below are all not applied and should
> be only rebased or they must be fully revisioned/modified?
> http://wiki.xen.org/wiki/Virtio_On_Xen
> 

Don't use patches on that page. They are outdated.

I think Stefano's patch series intends to fix issue for HVM guest, which
might well be what you're using.  Well, I would be very surprised if you
tell me you're using PV virtio! ;-)

Wei.