Re: [Qemu-devel] [PATCH v3 00/10] virtio: avoid exit() when device enters invalid states

[Michael S. Tsirkin]

On Mon, Sep 19, 2016 at 06:07:40PM +0200, Cornelia Huck wrote:
> On Tue, 12 Apr 2016 14:25:24 +0100
> Stefan Hajnoczi <address@hidden> wrote:
> 
> > v3:
> >  * Patch 1: Fix typo and clarify commit description [Markus]
> >  * Use virtio_set_status() instead of open coding assignment [Cornelia]
> >  * Add live migration
> > 
> > v2:
> >  * Add VIRTIO_CONFIG_S_NEEDS_RESET notification for VIRTIO 1.0 [Cornelia]
> >    (Note I've sent a Linux virtio_config.h patch to get the constant added 
> > to
> >    the headers.)
> >  * Split int -> unsigned int change into separate commit [Fam]
> >  * Fix double "index" typo in commit description [Fam]
> > 
> > The virtio code calls exit() when the device enters an invalid state.  This
> > means invalid vring indices and descriptor chains kill the VM.  See the 
> > patch
> > descriptions for why this is a bad thing.
> > 
> > When the virtio device is in the broken state calls to virtqueue_pop() and
> > friends will pretend the virtqueue is empty.  This means the device will 
> > become
> > isolated from guest activity until it is reset again.
> > 
> > RFC because two things are missing:
> > 1. Live migration support (subsection for broken flag?)
> > 2. Auditing devices and replacing exit() calls there too
> > 
> > Stefan Hajnoczi (10):
> >   virtio: fix stray tab character
> >   include: update virtio_config.h Linux header
> >   virtio: stop virtqueue processing if device is broken
> >   virtio: migrate vdev->broken flag
> >   virtio: handle virtqueue_map_desc() errors
> >   virtio: handle virtqueue_get_avail_bytes() errors
> >   virtio: use unsigned int for virtqueue_get_avail_bytes() index
> >   virtio: handle virtqueue_read_next_desc() errors
> >   virtio: handle virtqueue_num_heads() errors
> >   virtio: handle virtqueue_get_head() errors
> > 
> >  hw/virtio/virtio.c                             | 223 
> > +++++++++++++++++++------
> >  include/hw/virtio/virtio.h                     |   3 +
> >  include/standard-headers/linux/virtio_config.h |   2 +
> >  3 files changed, 181 insertions(+), 47 deletions(-)
> > 
> 
> As the exit-in-virtio question has popped up several times in the
> recent past: I think we should go forward with this series, even if we
> still need to look at the individual devices. Do you have a version
> that fits on current master?

I agree.