RE: [RFC 15/20] vfio/pci: Add VFIO_DEVICE_[DE]ATTACH_IOASID

[Tian, Kevin]

> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Wednesday, September 22, 2021 2:04 AM
> 
> On Sun, Sep 19, 2021 at 02:38:43PM +0800, Liu Yi L wrote:
> > This patch adds interface for userspace to attach device to specified
> > IOASID.
> >
> > Note:
> > One device can only be attached to one IOASID in this version. This is
> > on par with what vfio provides today. In the future this restriction can
> > be relaxed when multiple I/O address spaces are supported per device
> 
> ?? In VFIO the container is the IOS and the container can be shared
> with multiple devices. This needs to start at about the same
> functionality.

a device can be only attached to one container. One container can be
shared by multiple devices.

a device can be only attached to one IOASID. One IOASID can be shared
by multiple devices.

it does start at the same functionality.

> 
> > +	} else if (cmd == VFIO_DEVICE_ATTACH_IOASID) {
> 
> This should be in the core code, right? There is nothing PCI specific
> here.
> 

but if you insist on a pci-wrapper attach function, we still need something
here (e.g. with .attach_ioasid() callback)?