Re: [PATCH v2 0/3] vhost-vsock: force virtio version 1

[Stefano Garzarella]

Hi Michael,
if you haven't queued the series, maybe I can send a v3 to solve
migration issues, otherwise I can send a new series.

I would like to force virtio 1 only on machine types newer than 5.0,
otherwise the migration will fail.

@Cornelia, @David, do you think it makes sense?

Thanks,
Stefano

On Wed, Aug 19, 2020 at 04:38:48PM +0200, Stefano Garzarella wrote:
> v2:
>    - Fixed commit message in patche 1 and 2 [Cornelia]
>    - Added Cornelia's R-b tags in all patches
> 
> v1: https://lists.gnu.org/archive/html/qemu-devel/2020-08/msg04373.html
> 
> Recenlty changes in QEMU 5.1 requires to set 'disable-legacy=on'
> on vhost-vsock-pci and vhost-user-vsock-pci devices:
> 
>     $ ./qemu-system-x86_64 ... -device vhost-vsock-pci,guest-cid=5
>         qemu-system-x86_64: -device vhost-vsock-pci,guest-cid=5:
>         device is modern-only, use disable-legacy=on
> 
> As discussed with Cornelia [1], this series force virtio version 1
> to vhost-vsock-pci, vhost-user-vsock-pci, and vhost-vsock-ccw devices.
> 
> virtio-vsock was introduced after the release of VIRTIO 1.0 specifications,
> so it should be 'modern-only'.
> In addition Cornelia verified that forcing a legacy mode on vhost-vsock-pci
> device using x86-64 host and s390x guest, so with different endianness,
> produces strange behaviours.
> 
> About migration, QEMU 5.1 already requires that the source and destination
> specify 'disable-legacy=on', otherwise the migration fails in this way:
>     qemu-system-x86_64: get_pci_config_device: Bad config data: i=0x2 read: 
> 12 device: 53 cmask: ff wmask: 0 w1cmask:0
>     qemu-system-x86_64: Failed to load PCIDevice:config
>     qemu-system-x86_64: Failed to load virtio-vhost_vsock:virtio
>     qemu-system-x86_64: error while loading state for instance 0x0 of device 
> '0000:00:03.0/virtio-vhost_vsock'
>     qemu-system-x86_64: load of migration failed: Invalid argument
> 
> With this series applied there is the same requirements. Alternatively
> we have to detach and re-attach the device manually.
> 
> Thanks,
> Stefano
> 
> [1] https://lists.nongnu.org/archive/html/qemu-devel/2020-08/msg02515.html
> 
> Stefano Garzarella (3):
>   vhost-vsock-pci: force virtio version 1
>   vhost-user-vsock-pci: force virtio version 1
>   vhost-vsock-ccw: force virtio version 1
> 
>  hw/s390x/vhost-vsock-ccw.c       | 2 ++
>  hw/virtio/vhost-user-vsock-pci.c | 2 +-
>  hw/virtio/vhost-vsock-pci.c      | 2 +-
>  3 files changed, 4 insertions(+), 2 deletions(-)
> 
> -- 
> 2.26.2
> 
>