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virtio: skip legacy support check on machine types less than 5.1

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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-stable@nongnu.org
Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on")
Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Suggested-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20200921122506.82515-2-sgarzare@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Stefano Garzarella 2020-09-21 14:25:03 +02:00 • committed by Michael S. Tsirkin
parent 40bc0ca924
commit d55f518248
5 changed files with 34 additions and 5 deletions
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15
hw/s390x/virtio-ccw.c
View file

@ -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");
} 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) {