On Mon, Sep 22, 2025 at 01:49:55PM +0100, Daniel P. Berrangé wrote: > On Mon, Sep 22, 2025 at 08:15:20AM -0400, Michael S. Tsirkin wrote: > > On Mon, Sep 22, 2025 at 12:33:26PM +0100, Daniel P. Berrangé wrote: > > > On Fri, Sep 19, 2025 at 04:07:19PM -0400, Michael S. Tsirkin wrote: > > > > On Fri, Sep 19, 2025 at 04:30:53PM +0200, Christian Speich wrote: > > > > > This removes the change introduced in [1] that prevents the use of > > > > > vhost-user-device and vhost-user-device-pci on unpatched QEMU builds. > > > > > > > > > > [1]: 6275989647efb708f126eb4f880e593792301ed4 > > > > > > > > > > Signed-off-by: Christian Speich <c.spe...@avm.de> > > > > > --- > > > > > vhost-user-device and vhost-user-device-pci started out as user > > > > > creatable devices. This was changed in [1] when the vhost-user-base > > > > > was > > > > > introduced. > > > > > > > > > > The reason given is to prevent user confusion. Searching qemu-discuss > > > > > or > > > > > google for "vhost-user-device" I've seen no confused users. > > > > > > > > > > Our use case is to provide wifi emulation using > > > > > "vhost-user-device-pci", > > > > > which currently is working fine with the QEMU 9.0.2 present in Ubuntu > > > > > 24.04. With newer QEMU versions we now need to patch, distribute and > > > > > maintain our own QEMU packages, which is non-trivial. > > > > > > > > > > So I want to propose lifting this restriction to make this feature > > > > > usable without a custom QEMU. > > > > > > > > > > [1]: 6275989647efb708f126eb4f880e593792301ed4 > > > > > > > > The confusion is after someone reuses the ID you are claiming without > > > > telling anyone and then linux guests will start binding that driver to > > > > your device. > > > > > > > > > > > > We want people doing this kind of thing to *at a minimum* > > > > go ahead and register a device id with the virtio TC, > > > > but really to write and publish a spec. > > > > > > Wanting people to register a device ID is a social problem and > > > we're trying to apply a technical hammer to it, which is rarely > > > an productive approach. > > > > > > If we want to demonstrate that vhost-user-device is "risky", then > > > how about we rename it to have an 'x-' prefix and thus disclaim > > > any support for it, but none the less allow its use. Document it > > > as an experimental device, and if it breaks, users get to keep > > > both pieces. > > > > Maybe with the insecure tag you are working on? > > Sure. > > > And disable in the default config? > > Disabling in default config would retain the very problem that Christian > is trying to solve - that no distro would have the functionality available > for users.
I think his problem is that he has to patch qemu. As described, this is a developer option not an end user one. I know Red Hat will disable it anyway - we support what we ship. > With regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
