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post_plugged() callback invoked after features have been queried that can handle the VERSION_1 bit being withdrawn and change ccw to fall back to revision 0 if VERSION_1 is gone.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 --- hw/s390x/virtio-ccw.c | 12 ++++++++++++ hw/virtio/virtio-bus.c | 3 +++ include/hw/virtio/virtio-bus.h | 5 +++++ 3 files changed, 20 insertions(+) diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c index fb103b7..63da303 100644 --- a/hw/s390x/virtio-ccw.c +++ b/hw/s390x/virtio-ccw.c @@ -1555,6 +1555,17 @@ static void virtio_ccw_device_plugged(DeviceState *d, Error **errp) d->hotplugged, 1); } +static void virtio_ccw_post_plugged(DeviceState *d, Error **errp) +{ + VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d); + VirtIODevice *vdev = virtio_bus_get_device(&dev->bus); + + if (!virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1)) { + /* A backend didn't support modern virtio. */ + dev->max_rev = 0; + } +} + static void virtio_ccw_device_unplugged(DeviceState *d) { VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d); @@ -1891,6 +1902,7 @@ static void virtio_ccw_bus_class_init(ObjectClass *klass, void *data) k->save_config = virtio_ccw_save_config; k->load_config = virtio_ccw_load_config; k->device_plugged = virtio_ccw_device_plugged; + k->post_plugged = virtio_ccw_post_plugged; k->device_unplugged = virtio_ccw_device_unplugged; } diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c index febda76..81c7cdd 100644 --- a/hw/virtio/virtio-bus.c +++ b/hw/virtio/virtio-bus.c @@ -56,6 +56,9 @@ void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp) assert(vdc->get_features != NULL); vdev->host_features = vdc->get_features(vdev, vdev->host_features, errp); + if (klass->post_plugged != NULL) { + klass->post_plugged(qbus->parent, errp); + } } /* Reset the virtio_bus */ 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