Re: [PATCH v2 1/3] docs: IOMMU user API

[Jacob Pan]

On Thu, 11 Jun 2020 17:27:27 -0700
Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> wrote:

> > 
> > But then I thought it even better if VFIO leaves the entire
> > copy_from_user() to the layer consuming it.
> >   
> OK. Sounds good, that was what Kevin suggested also. I just wasn't
> sure how much VFIO wants to inspect, I thought VFIO layer wanted to
> do a sanity check.
> 
> Anyway, I will move copy_from_user to iommu uapi layer.

Just one more point brought up by Yi when we discuss this offline.

If we move copy_from_user to iommu uapi layer, then there will be
multiple copy_from_user calls for the same data when a VFIO container
has multiple domains, devices. For bind, it might be OK. But might be
additional overhead for TLB flush request from the guest.

Thoughts?

Jacob