Re: [PATCH v3 0/5] mm/hmm/nouveau: add PMD system memory mapping

[Ralph Campbell]

On 7/10/20 12:27 PM, Jason Gunthorpe wrote:
> On Wed, Jul 01, 2020 at 03:53:47PM -0700, Ralph Campbell wrote:
> > The goal for this series is to introduce the hmm_pfn_to_map_order()
> > function. This allows a device driver to know that a given 4K PFN is
> > actually mapped by the CPU using a larger sized CPU page table entry and
> > therefore the device driver can safely map system memory using larger
> > device MMU PTEs.
> > The series is based on 5.8.0-rc3 and is intended for Jason Gunthorpe's
> > hmm tree. These were originally part of a larger series:
> > https://lore.kernel.org/linux-mm/20200619215649.32297-1-rcampbell@xxxxxxxxxx/
> >
> > Changes in v3:
> > Replaced the HMM_PFN_P[MU]D flags with hmm_pfn_to_map_order() to
> > indicate the size of the CPU mapping.
> >
> > Changes in v2:
> > Make the hmm_range_fault() API changes into a separate series and add
> >    two output flags for PMD/PUD instead of a single compund page flag as
> >    suggested by Jason Gunthorpe.
> > Make the nouveau page table changes a separate patch as suggested by
> >    Ben Skeggs.
> > Only add support for 2MB nouveau mappings initially since changing the
> > 1:1 CPU/GPU page table size assumptions requires a bigger set of changes.
> > Rebase to 5.8.0-rc3.
> >
> > Ralph Campbell (5):
> >    nouveau/hmm: fault one page at a time
> >    mm/hmm: add hmm_mapping order
> >    nouveau: fix mapping 2MB sysmem pages
> >    nouveau/hmm: support mapping large sysmem pages
> >    hmm: add tests for HMM_PFN_PMD flag
>
> Applied to hmm.git.
>
> I edited the comment for hmm_pfn_to_map_order() and added a function
> to compute the field.
>
> Thanks,
> Jason

Looks good, thanks.