aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorCornelia Huck <cornelia.huck@de.ibm.com>2015-12-02 18:31:57 +0100
committerMichael S. Tsirkin <mst@redhat.com>2015-12-02 19:34:11 +0200
commit11380b36196c483ff5c7f800b0f7af6aa53b5657 (patch)
tree616f8cd145d8c08199f51ba39d9cae715c6d5b9a
parent6d0b908a628a7086fa855c68b217cc1e2a5c4c19 (diff)
downloadqemu-11380b36196c483ff5c7f800b0f7af6aa53b5657.tar.gz
qemu-11380b36196c483ff5c7f800b0f7af6aa53b5657.tar.xz
qemu-11380b36196c483ff5c7f800b0f7af6aa53b5657.zip
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post_plugged() callback invoked after features have been queried that can handle the VERSION_1 bit being withdrawn and change ccw to fall back to revision 0 if VERSION_1 is gone.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 <cornelia.huck@de.ibm.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
-rw-r--r--hw/s390x/virtio-ccw.c12
-rw-r--r--hw/virtio/virtio-bus.c3
-rw-r--r--include/hw/virtio/virtio-bus.h5
3 files changed, 20 insertions, 0 deletions
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index fb103b78a..63da30386 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 febda76b9..81c7cdd50 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 6c3d4cb19..3f2c1363d 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.
*/