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

From: Ralph Campbell <rcampbell@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: <linux-rdma@vger.kernel.org>, <linux-mm@kvack.org>,
	<nouveau@lists.freedesktop.org>,
	<linux-kselftest@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	Jerome Glisse <jglisse@redhat.com>,
	"John Hubbard" <jhubbard@nvidia.com>,
	Christoph Hellwig <hch@lst.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Shuah Khan <shuah@kernel.org>, Ben Skeggs <bskeggs@redhat.com>
Subject: Re: [PATCH v3 0/5] mm/hmm/nouveau: add PMD system memory mapping
Date: Fri, 10 Jul 2020 13:13:46 -0700	[thread overview]
Message-ID: <886151ff-c8e7-7b49-cc8d-c0e32fdc770b@nvidia.com> (raw)
In-Reply-To: <20200710192704.GA2128670@nvidia.com>

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@nvidia.com/
>>
>> 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.