On Thu, Oct 28, 2021 at 4:16 AM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > On Wed, Oct 27, 2021 at 03:21:15PM +0000, Parav Pandit wrote: > > Hi Stefano, > > > > > From: Stefano Garzarella <sgarzare@xxxxxxxxxx> > > > Sent: Wednesday, October 27, 2021 8:04 PM > > > > > > Hi folks, > > > I was trying to understand if we have a way to specify which vDPA bus driver > > > (e.g. vhost-vdpa, virtio-vdpa) a device should use. > > > IIUC we don't have it, and the first registered driver is used when a new device > > > is registered. > > > > > > I was thinking if it makes sense to extend the management API to specify which > > > bus driver to use for a device. Actually, we want to support this in the first version of vDPA bus. But for some reason it was dropped. The idea is to specify the device type 'virtio' or 'vhost'. But a concern is that, it may encourage vendor to implement e.g virtio specific device (without DMA isolation). >A use case could be for example a single host > > > handling VMs and bare-metal containers, so we would have both virtio-vdpa > > > and vhost-vdpa loaded and we want to attach some devices to VMs through > > > vhost-vdpa and others to containers through virtio-vdpa. > > > > > > What do you think? > > > > > One option is, user keeps the drivers_autoprobe disabled for the vdpa bus using, > > > > $ vdpa/vdpa dev add mgmtdev vdpasim_net name vdpa0 mac 00:11:22:33:44:55 > > $ echo 0 > /sys/bus/vdpa/drivers_autoprobe > > > > And after vdpa device creation, it manually binds to the desired driver such as, > > > > $ echo vdpa0 > /sys/bus/vdpa/drivers/virtio_vdpa/bind > > Or > > $ echo vdpa0 > /sys/bus/vdpa/drivers/vhost_vdpa/bind > > > > In an case of VDUSE, it makes more sense to bind to the one of the above driver after user space has connected the use space backend to the kernel device. > > The only annoying thing is that manual bind is not validated. > E.g. if one makes a mistake and binds an incorrect device, > it just tends to crash IIRC. > Another is that it all needs to be root. I'm not sure it's worth bothering with. As discussed, switching between vendor drivers and vfio requires manually bind/unbind as well. Thanks > > -- > MST > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
