On Mon, Sep 21, 2020 at 11:40:54AM +0200, Cornelia Huck wrote:
> On Mon, 21 Sep 2020 10:38:04 +0200
> Stefano Garzarella <sgarz...@redhat.com> wrote:
>
> > Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally
> > on") added a check that returns an error if legacy support is on, but the
> > device does not support legacy.
> >
> > Unfortunately some devices were wrongly declared legacy capable even if
> > they were not (e.g vhost-vsock).
> >
> > To avoid migration issues, we add a virtio-device property
> > (x-disable-legacy-check) to skip the legacy error, printing a warning
> > instead, for machine types < 5.1.
> >
> > Cc: qemu-sta...@nongnu.org
> > Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally
> > on")
> > Suggested-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> > Suggested-by: Cornelia Huck <coh...@redhat.com>
> > Reviewed-by: Cornelia Huck <coh...@redhat.com>
> > Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
> > ---
> > v4:
> > - fixed commit message and warning message [Cornelia]
> > v3:
> > - added virtio_legacy_check_disabled() helper
> > - moved warning where error was returned [Cornelia]
> > v2:
> > - fixed Cornelia's e-mail address
> > ---
> > include/hw/virtio/virtio.h | 2 ++
> > hw/core/machine.c | 1 +
> > hw/s390x/virtio-ccw.c | 15 ++++++++++++---
> > hw/virtio/virtio-pci.c | 14 ++++++++++++--
> > hw/virtio/virtio.c | 7 +++++++
> > 5 files changed, 34 insertions(+), 5 deletions(-)
> >
>
> (...)
>
> > diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> > index 8feb3451a0..c534cdf2e5 100644
> > --- a/hw/s390x/virtio-ccw.c
> > +++ b/hw/s390x/virtio-ccw.c
> > @@ -1122,9 +1122,18 @@ static void virtio_ccw_device_plugged(DeviceState
> > *d, Error **errp)
> > }
> >
> > if (!virtio_ccw_rev_max(dev) && !virtio_legacy_allowed(vdev)) {
> > - error_setg(errp, "Invalid value of property max_rev "
> > - "(is %d expected >= 1)", virtio_ccw_rev_max(dev));
> > - return;
> > + /*
> > + * To avoid migration issues, we allow legacy mode when legacy
> > + * check is disabled in the old machine types (< 5.1).
> > + */
> > + if (virtio_legacy_check_disabled(vdev)) {
> > + warn_report("device requires revision >= 1, but for backward "
> > + "compatibility max_revision=0 is allowed");
I forgot to mention that I changed 'max_rev' to 'max_revision' since it
is the parameter that the user can touch.
>
> Message looks good to me.
Thanks!
Stefano
>
> > + } else {
> > + error_setg(errp, "Invalid value of property max_rev "
> > + "(is %d expected >= 1)", virtio_ccw_rev_max(dev));
> > + return;
> > + }
> > }
> >
> > if (virtio_get_num_queues(vdev) > VIRTIO_QUEUE_MAX) {
>
> (...)
>
