From 11380b36196c483ff5c7f800b0f7af6aa53b5657 Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Wed, 2 Dec 2015 18:31:57 +0100 Subject: virtio: handle non-virtio-1-capable backend for ccw If you run a qemu advertising VERSION_1 with an old kernel where vhost did not yet support VERSION_1, you'll end up with a device that is {modern pci|ccw revision 1} but does not advertise VERSION_1. This is not a sensible configuration and is rejected by the Linux guest drivers. To fix this, add a ->post_plugged() callback invoked after features have been queried that can handle the VERSION_1 bit being withdrawn and change ccw to fall back to revision 0 if VERSION_1 is gone. Note that pci is _not_ fixed; we'll need to rethink the approach for the next release but at least for pci it's not a regression. Signed-off-by: Cornelia Huck Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- include/hw/virtio/virtio-bus.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include') diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h index 6c3d4cb..3f2c136 100644 --- a/include/hw/virtio/virtio-bus.h +++ b/include/hw/virtio/virtio-bus.h @@ -60,6 +60,11 @@ typedef struct VirtioBusClass { */ void (*device_plugged)(DeviceState *d, Error **errp); /* + * Re-evaluate setup after feature bits have been validated + * by the device backend. + */ + void (*post_plugged)(DeviceState *d, Error **errp); + /* * transport independent exit function. * This is called by virtio-bus just before the device is unplugged. */ -- cgit v1.1