Re: [Qemu-devel] [PATCH v2 1/1] s390x/css: catch section mismatch on load

[Cornelia Huck]

On Thu, 18 May 2017 13:14:05 +0200
Halil Pasic <address@hidden> wrote:

> Prior to the virtio-ccw-2.7 machine (and commit 2a79eb1a), our virtio
> devices residing under the virtual-css bus do not have qdev_path based
> migration stream identifiers (because their qdev_path is NULL). The ids
> are instead generated when the device is registered as a composition of
> the so called idstr, which takes the vmsd name as its value, and an
> instance_id, which is which is calculated as a maximal instance_id
> registered with the same idstr plus one, or zero (if none was registered
> previously).
> 
> That means, under certain circumstances, one device might try, and even
> succeed, to load the state of a different device. This can lead to
> trouble.
> 
> Let us fail the migration if the above problem is detected during load.
> 
> How to reproduce the problem:
> 1) start qemu-system-s390x making sure you have the following devices
>    defined on your command line:
>      -device virtio-rng-ccw,id=rng1,devno=fe.0.0001
>      -device virtio-rng-ccw,id=rng2,devno=fe.0.0002
> 2) detach the devices and reattach in reverse order using the monitor:
>      (qemu) device_del rng1
>      (qemu) device_del rng2
>      (qemu) device_add virtio-rng-ccw,id=rng2,devno=fe.0.0002
>      (qemu) device_add virtio-rng-ccw,id=rng1,devno=fe.0.0001
> 3) save the state of the vm into a temporary file and quit QEMU:
>      (qemu) migrate "exec:gzip -c > /tmp/tmp_vmstate.gz"
>      (qemu) q
> 4) use your command line from step 1 with
>      -incoming "exec:gzip -c -d /tmp/tmp_vmstate.gz"
>    appended to reproduce the problem (while trying to to load the saved vm)
> 
> CC: address@hidden
> Signed-off-by: Halil Pasic <address@hidden>
> Reviewed-by: Dong Jia Shi <address@hidden>

Hum, missed that one for my pull request, sorry.

Reviewed-by: Cornelia Huck <address@hidden>

Christian, can you please pick for the next set of s390x patches?