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

[Michael S. Tsirkin]

On Tue, Sep 15, 2020 at 04:21:56PM +0200, Stefano Garzarella wrote:
> 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 queued it but I can drop just as easily. So go ahead and send v3 pls.

> 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
> > 
> >