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

[Laszlo Ersek]

On 09/19/16 19:51, Michael S. Tsirkin wrote:
> 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.
> 

NB, Prasad just posted a patch (v3 being the latest) that adds another
such exit(1), at my suggestion.

[Qemu-devel] [PATCH v3] virtio: add check for descriptor's mapped
                        address

So a rebase of this series should likely consider that patch as well.
(But Stefan is aware anyway.)

Thanks!
Laszlo