Re: [PATCH] vfio: Remove VFIO_TYPE1_NESTING_IOMMU

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, May 12, 2022 at 07:57:26PM +0800, zhangfei.gao@foxmail.com wrote:
> 
> 
> On 2022/5/12 下午7:32, Jason Gunthorpe via iommu wrote:
> > On Thu, May 12, 2022 at 03:07:09PM +0800, Zhangfei Gao wrote:
> > > > > I can't help feeling a little wary about removing this until IOMMUFD
> > > > > can actually offer a functional replacement - is it in the way of
> > > > > anything upcoming?
> > > >   From an upstream perspective if someone has a patched kernel to
> > > > complete the feature, then they can patch this part in as well, we
> > > > should not carry dead code like this in the kernel and in the uapi.
> > > > 
> > > > It is not directly in the way, but this needs to get done at some
> > > > point, I'd rather just get it out of the way.
> > > We are using this interface for nested mode.
> > How are you using it? It doesn't do anything. Do you have out of tree
> > patches as well?
> 
> Yes, there are some patches out of tree, since they are pending for almost
> one year.
> 
> By the way, I am trying to test nesting mode based on iommufd, still
> requires iommu_enable_nesting,
> which is removed in this patch as well.

This is temporary.

> So can we wait for alternative patch then remove them?

Do you see a problem with patching this along with all the other
patches you need?

Jason