Re: [PATCH v3 05/12] vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET

Jason Gunthorpe
2023-04-05T16:46:15Z

On Wed, Apr 05, 2023 at 09:36:46AM -0600, Alex Williamson wrote:

> > If we don't support singletion dev_set hot-reset, noiommu devices in cdev
> > path shall fail the hot-reset if empty-fd array is provided. But we may just
> > document that empty-fd array does not work for noiommu. User should
> > use the device fd array.
>
> I don't see any replies to my comment on 08/12 where I again question
> why we need an empty array option.

I was pressing we'd do empty-fd only and not do the device fd array at
all since it is such an ugly fit for the use cases we have.

But it is such a minor detail if you don't want it then take it out.

> This singleton dev-set notion seems equally unjustified. Do we just
> need to deal with hot-reset being unsupported for no-iommu devices
> with iommufd?

It was to support no-iommu, if you want to de-support it then it can
go away too. AFAIK dpdk doesn't use this feature and it is the only
user we know of that has support for no-iommu so it is probably safe.

Jason