Re: [RFC PATCH v3 3/3] VFIO Type1 IOMMU change: to support with iommu and without iommu

[Neo Jia <cjia@nvidia.com>]

On Fri, May 13, 2016 at 05:23:44PM +0800, Jike Song wrote:
> On 05/13/2016 04:31 PM, Neo Jia wrote:
> > On Fri, May 13, 2016 at 07:45:14AM +0000, Tian, Kevin wrote:
> >>
> >> We use page tracking framework, which is newly added to KVM recently,
> >> to mark RAM pages as read-only so write accesses are intercepted to 
> >> device model.
> > 
> > Yes, I am aware of that patchset from Guangrong. So far the interface are all
> > requiring struct *kvm, copied from https://lkml.org/lkml/2015/11/30/644
> > 
> > - kvm_page_track_add_page(): add the page to the tracking pool after
> >   that later specified access on that page will be tracked
> > 
> > - kvm_page_track_remove_page(): remove the page from the tracking pool,
> >   the specified access on the page is not tracked after the last user is
> >   gone
> > 
> > void kvm_page_track_add_page(struct kvm *kvm, gfn_t gfn,
> >                 enum kvm_page_track_mode mode);
> > void kvm_page_track_remove_page(struct kvm *kvm, gfn_t gfn,
> >                enum kvm_page_track_mode mode);
> > 
> > Really curious how you are going to have access to the struct kvm *kvm, or you
> > are relying on the userfaultfd to track the write faults only as part of the
> > QEMU userfault thread?
> >
> 
> Hi Neo,
> 
> For the vGPU used as a device for KVM guest, there will be interfaces
> wrapped or implemented in KVM layer, as a rival thing diverted from
> the interfaces for Xen. That is where the KVM related code supposed to be.

Hi Jike,

Is this discussed anywhere on the mailing list already? Sorry if I have missed
such conversation.

Thanks,
Neo

> 
> --
> Thanks,
> Jike