Re: [PATCH v6 12/24] vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET

Alex Williamson
2023-03-21T22:48:31Z

On Tue, 21 Mar 2023 19:20:37 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> On Tue, Mar 21, 2023 at 03:01:12PM -0600, Alex Williamson wrote:
>
> > > Though it would be nice if qemu didn't need two implementations so Yi
> > > I'd rather see a new info in this series as well and qemu can just
> > > consistently use dev_id and never bdf in iommufd mode.
> >
> > We also need to consider how libvirt determines if QEMU has the kernel
> > support it needs to pass file descriptors. It'd be a lot cleaner if
> > this aligned with the introduction of vfio cdevs.
>
> Yes, that would be much better if it was one package.
>
> But this is starting to grow and we have so many threads that need to
> progress blocked on this cdev enablement :(
>
> Could we go forward with the cdev main patches and kconfig it to
> experimental or something while the rest of the parts are completed
> and tested through qemu? ie move the vfio-pci reset enablment to after
> the cdev patches?

We need to be able to guarantee that there cannot be any significant
builds of the kernel with vfio cdev support if our intention is to stage
it for libvirt. We don't have a global EXPERIMENTAL config option any
more. Adding new code under BROKEN seems wrong. Fedora ships with
STAGING enabled. A sternly worded Kconfig entry is toothless. What is
the proposed mechanism to make this not look like a big uncompiled code
dump? Thanks,

Alex