17.02.2025 17:07, Stefano Garzarella wrote:
On Mon, Feb 17, 2025 at 02:12:55PM +0100, Matias Ezequiel Vara Larsen wrote:
Use virtio_get_config_size() rather than sizeof(struct
virtio_snd_config) for the config_size in the vhost-user-snd frontend.
The frontend shall rely on device features for the size of the device
configuration space. The presence of `controls` in the config space
depends on VIRTIO_SND_F_CTLS according to the specification (v1.3):
`
5.14.4 Device Configuration Layout
...
controls
(driver-read-only) indicates a total number of all available control
elements if VIRTIO_SND_F_CTLS has been negotiated.
`
This fixes an issue introduced by commit ab0c7fb2 ("linux-headers:
update to current kvm/next") in which the optional field `controls` is
added to the virtio_snd_config structure. This breaks vhost-user-device
backends that do not implement the `controls` field.
Fixes: ab0c7fb22b ("linux-headers: update to current kvm/next")
If we want to backport this on stable branches, better to add:
Cc: qemu-sta...@nongnu.org
There's a problem with stable branches though:
static const Property vsnd_properties[] = {
DEFINE_PROP_CHR("chardev", VHostUserBase, chardev),
+ DEFINE_PROP_BIT64("controls", VHostUserBase,
+ parent_obj.host_features, VIRTIO_SND_F_CTLS, false),
};
This change introduces an incompatible change in migration stream,
it looks like. I'm not sure how to handle this for stable branches,
is there a way?
Thanks,
/mjt
