Re: [PATCH 0/2] KVM: MMU: support VMAs that got remap_pfn_range-ed

[Xiao Guangrong]

On 07/05/2016 08:18 PM, Paolo Bonzini wrote:
> On 05/07/2016 07:41, Neo Jia wrote:
> > On Thu, Jun 30, 2016 at 03:01:49PM +0200, Paolo Bonzini wrote:
> > > The vGPU folks would like to trap the first access to a BAR by setting
> > > vm_ops on the VMAs produced by mmap-ing a VFIO device.  The fault handler
> > > then can use remap_pfn_range to place some non-reserved pages in the VMA.
> > >
> > > KVM lacks support for this kind of non-linear VM_PFNMAP mapping, and these
> > > patches should fix this.
> >
> > Hi Paolo,
> >
> > I have tested your patches with the mediated passthru patchset that is being
> > reviewed in KVM and QEMU mailing list.
> >
> > The fault handler gets called successfully and the previously mapped memory gets
> > unmmaped correctly via unmap_mapping_range.
>
> Great, then I'll include them in 4.8.

Code is okay, but i still suspect if this implementation, fetch mmio pages in fault
handler, is needed. We'd better include these patches after the design of vfio
framework is decided.