From: Dan Williams <dan.j.williams@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "Felix Kuehling" <felix.kuehling@amd.com>,
"Sierra Guiza, Alejandro (Alex)" <alex.sierra@amd.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Linux MM" <linux-mm@kvack.org>,
"Ralph Campbell" <rcampbell@nvidia.com>,
linux-ext4 <linux-ext4@vger.kernel.org>,
linux-xfs <linux-xfs@vger.kernel.org>,
"amd-gfx list" <amd-gfx@lists.freedesktop.org>,
"Maling list - DRI developers" <dri-devel@lists.freedesktop.org>,
"Jason Gunthorpe" <jgg@nvidia.com>,
"Jérôme Glisse" <jglisse@redhat.com>
Subject: Re: [PATCH v1 03/14] mm: add iomem vma selection for memory migration
Date: Thu, 2 Sep 2021 11:07:28 -0700 [thread overview]
Message-ID: <CAPcyv4gCbZikp1k+f3FA5HusSW8gGkpCAxzR70eKEASLcnMCRA@mail.gmail.com> (raw)
In-Reply-To: <20210902081826.GA16283@lst.de>
On Thu, Sep 2, 2021 at 1:18 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Wed, Sep 01, 2021 at 11:40:43AM -0400, Felix Kuehling wrote:
> > >>> It looks like I'm totally misunderstanding what you are adding here
> > >>> then. Why do we need any special treatment at all for memory that
> > >>> has normal struct pages and is part of the direct kernel map?
> > >> The pages are like normal memory for purposes of mapping them in CPU
> > >> page tables and for coherent access from the CPU.
> > > That's the user page tables. What about the kernel direct map?
> > > If there is a normal kernel struct page backing there really should
> > > be no need for the pgmap.
> >
> > I'm not sure. The physical address ranges are in the UEFI system address
> > map as special-purpose memory. Does Linux create the struct pages and
> > kernel direct map for that without a pgmap call? I didn't see that last
> > time I went digging through that code.
>
> So doing some googling finds a patch from Dan that claims to hand EFI
> special purpose memory to the device dax driver. But when I try to
> follow the version that got merged it looks it is treated simply as an
> MMIO region to be claimed by drivers, which would not get a struct page.
>
> Dan, did I misunderstand how E820_TYPE_SOFT_RESERVED works?
The original implementation of "soft reserve" support depended on the
combination of the EFI special purpose memory type and the ACPI HMAT
to define the device ranges. The requirement for ACPI HMAT was relaxed
later with commit:
5ccac54f3e12 ACPI: HMAT: attach a device for each soft-reserved range
The expectation is that system software policy can then either use the
device interface, assign a portion of the reservation back to the page
allocator, ignore the reservation altogether. Is this discussion
asking for a way to assign this memory to the GPU driver to manage?
device-dax already knows how to hand off to the page-allocator, seems
reasonable for it to be able to hand-off to another driver.
next prev parent reply other threads:[~2021-09-02 18:07 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-25 3:48 [PATCH v1 00/14] Add MEMORY_DEVICE_PUBLIC for CPU-accessible coherent device memory Alex Sierra
2021-08-25 3:48 ` [PATCH v1 01/14] ext4/xfs: add page refcount helper Alex Sierra
2021-08-25 7:35 ` Christoph Hellwig
2021-08-25 15:09 ` Theodore Ts'o
2021-08-25 15:49 ` Darrick J. Wong
2021-08-25 3:48 ` [PATCH v1 02/14] mm: remove extra ZONE_DEVICE struct page refcount Alex Sierra
2021-08-25 7:35 ` Christoph Hellwig
2021-08-25 11:15 ` Vlastimil Babka
2021-08-25 17:49 ` Ralph Campbell
2021-08-27 11:26 ` Vlastimil Babka
2021-08-25 3:48 ` [PATCH v1 03/14] mm: add iomem vma selection for memory migration Alex Sierra
2021-08-25 7:40 ` Christoph Hellwig
2021-08-25 7:46 ` Christoph Hellwig
2021-08-25 18:24 ` Sierra Guiza, Alejandro (Alex)
2021-08-26 22:27 ` Felix Kuehling
2021-08-30 8:28 ` Christoph Hellwig
2021-08-30 17:04 ` Felix Kuehling
2021-09-01 8:29 ` Christoph Hellwig
2021-09-01 15:40 ` Felix Kuehling
2021-09-01 22:03 ` Dave Chinner
2021-09-01 23:07 ` Felix Kuehling
2021-09-02 1:14 ` Dave Chinner
2021-09-09 4:55 ` Felix Kuehling
2021-09-02 8:18 ` Christoph Hellwig
2021-09-02 18:07 ` Dan Williams [this message]
2021-09-09 4:02 ` Felix Kuehling
2021-08-25 14:24 ` Felix Kuehling
2021-08-25 3:48 ` [PATCH v1 04/14] mm: add zone device public type memory support Alex Sierra
2021-08-25 3:48 ` [PATCH v1 05/14] drm/amdkfd: ref count init for device pages Alex Sierra
2021-08-25 14:34 ` Felix Kuehling
2021-08-25 3:48 ` [PATCH v1 06/14] drm/amdkfd: add SPM support for SVM Alex Sierra
2021-08-25 14:45 ` Felix Kuehling
2021-08-25 3:48 ` [PATCH v1 07/14] drm/amdkfd: public type as sys mem on migration to ram Alex Sierra
2021-08-25 3:48 ` [PATCH v1 08/14] mm: add public type support to migrate_vma helpers Alex Sierra
2021-08-25 7:47 ` Christoph Hellwig
2021-08-25 3:48 ` [PATCH v1 09/14] mm: call pgmap->ops->page_free for DEVICE_PUBLIC pages Alex Sierra
2021-08-25 7:46 ` Christoph Hellwig
2021-08-25 3:48 ` [PATCH v1 10/14] lib: test_hmm add ioctl to get zone device type Alex Sierra
2021-08-25 3:48 ` [PATCH v1 11/14] lib: test_hmm add module param for " Alex Sierra
2021-08-25 3:48 ` [PATCH v1 12/14] lib: add support for device public type in test_hmm Alex Sierra
2021-08-25 3:48 ` [PATCH v1 13/14] tools: update hmm-test to support device public type Alex Sierra
2021-08-25 3:48 ` [PATCH v1 14/14] tools: update test_hmm script to support SP config Alex Sierra
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