[PATCH v3 00/23] device-dax: Support sub-dividing soft-reserved ranges

[Dan Williams]

Changes since v2 [1]:
- Rebase on next/master to resolve conflicts with pending mem-hotplug
  and memremap_pages() changes in -mm

- Drop attempt at a generic phys_to_target_node() implementation and
  just follow the default fallback approach taken with
  memory_add_physaddr_to_nid() (Mike)

- Fix test_hmm and other compilation fixups (Ralph)

- Integrate Joao's extensions to the device-dax sub-division interface
  (per-device align, user-directed extent allocation). (Joao)

[1]: http://lore.kernel.org/r/159457116473.754248.7879464730875147365.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

---
Merge notes:

Andrew, this series is rebased on today's next/master to resolve
conflicts with some pending patches in -mm. I'd like to take it through
your tree given the intersections with memremap_pages() and memory
hotplug. If at all possible I'd like to see it in v5.10, but I realize
time is short. Outside of the Intel identified use cases for this Joao
has identified a use case for Oracle as well.

I would have sent this earlier save for the fact I am mostly offline
tending to a newborn these days. Vishal has stepped up to take on care
and feeding of this patchset if additional review / integration fixups
are needed.

The one test feedback this wants is from Justin (justin.he@xxxxxxx), and
whether this lights up dax_kmem and now dax_hmem for him on arm64.
Otherwise, Joao has written unit tests for this in his enabling of the
daxctl userspace utility [2].

---
Cover:

The device-dax facility allows an address range to be directly mapped
through a chardev, or optionally hotplugged to the core kernel page
allocator as System-RAM. It is the mechanism for converting persistent
memory (pmem) to be used as another volatile memory pool i.e. the
current Memory Tiering hot topic on linux-mm.

In the case of pmem the nvdimm-namespace-label mechanism can sub-divide
it, but that labeling mechanism is not available / applicable to
soft-reserved ("EFI specific purpose") memory [3]. This series provides
a sysfs-mechanism for the daxctl utility to enable provisioning of
volatile-soft-reserved memory ranges.

The motivations for this facility are:

1/ Allow performance differentiated memory ranges to be split between
   kernel-managed and directly-accessed use cases.

2/ Allow physical memory to be provisioned along performance relevant
   address boundaries. For example, divide a memory-side cache [4] along
   cache-color boundaries.

3/ Parcel out soft-reserved memory to VMs using device-dax as a security
   / permissions boundary [5]. Specifically I have seen people (ab)using
   memmap=nn!ss (mark System-RAM as Persistent Memory) just to get the
   device-dax interface on custom address ranges. A follow-on for the VM
   use case is to teach device-dax to dynamically allocate 'struct page' at
   runtime to reduce the duplication of 'struct page' space in both the
   guest and the host kernel for the same physical pages.

[2]: http://lore.kernel.org/r/20200713160837.13774-11-joao.m.martins@xxxxxxxxxx
[3]: http://lore.kernel.org/r/157309097008.1579826.12818463304589384434.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[4]: http://lore.kernel.org/r/154899811738.3165233.12325692939590944259.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[5]: http://lore.kernel.org/r/20200110190313.17144-1-joao.m.martins@xxxxxxxxxx

---

Dan Williams (19):
      x86/numa: Cleanup configuration dependent command-line options
      x86/numa: Add 'nohmat' option
      efi/fake_mem: Arrange for a resource entry per efi_fake_mem instance
      ACPI: HMAT: Refactor hmat_register_target_device to hmem_register_device
      resource: Report parent to walk_iomem_res_desc() callback
      mm/memory_hotplug: Introduce default phys_to_target_node() implementation
      ACPI: HMAT: Attach a device for each soft-reserved range
      device-dax: Drop the dax_region.pfn_flags attribute
      device-dax: Move instance creation parameters to 'struct dev_dax_data'
      device-dax: Make pgmap optional for instance creation
      device-dax: Kill dax_kmem_res
      device-dax: Add an allocation interface for device-dax instances
      device-dax: Introduce 'seed' devices
      drivers/base: Make device_find_child_by_name() compatible with sysfs inputs
      device-dax: Add resize support
      mm/memremap_pages: Convert to 'struct range'
      mm/memremap_pages: Support multiple ranges per invocation
      device-dax: Add dis-contiguous resource support
      device-dax: Introduce 'mapping' devices

Joao Martins (4):
      device-dax: Make align a per-device property
      device-dax: Add an 'align' attribute
      dax/hmem: Introduce dax_hmem.region_idle parameter
      device-dax: Add a range mapping allocation attribute


 arch/powerpc/kvm/book3s_hv_uvmem.c     |   14 
 arch/x86/include/asm/numa.h            |    8 
 arch/x86/kernel/e820.c                 |   16 
 arch/x86/mm/numa.c                     |   11 
 arch/x86/mm/numa_emulation.c           |    3 
 arch/x86/xen/enlighten_pv.c            |    2 
 drivers/acpi/numa/hmat.c               |   76 --
 drivers/acpi/numa/srat.c               |    9 
 drivers/base/core.c                    |    2 
 drivers/dax/Kconfig                    |    4 
 drivers/dax/Makefile                   |    3 
 drivers/dax/bus.c                      | 1055 ++++++++++++++++++++++++++++++--
 drivers/dax/bus.h                      |   28 +
 drivers/dax/dax-private.h              |   40 +
 drivers/dax/device.c                   |  132 ++--
 drivers/dax/hmem.c                     |   56 --
 drivers/dax/hmem/Makefile              |    6 
 drivers/dax/hmem/device.c              |  100 +++
 drivers/dax/hmem/hmem.c                |   65 ++
 drivers/dax/kmem.c                     |  199 +++---
 drivers/dax/pmem/compat.c              |    2 
 drivers/dax/pmem/core.c                |   22 -
 drivers/firmware/efi/x86_fake_mem.c    |   12 
 drivers/gpu/drm/nouveau/nouveau_dmem.c |   15 
 drivers/nvdimm/badrange.c              |   26 -
 drivers/nvdimm/claim.c                 |   13 
 drivers/nvdimm/nd.h                    |    3 
 drivers/nvdimm/pfn_devs.c              |   13 
 drivers/nvdimm/pmem.c                  |   27 -
 drivers/nvdimm/region.c                |   21 -
 drivers/pci/p2pdma.c                   |   12 
 include/acpi/acpi_numa.h               |   14 
 include/linux/dax.h                    |    8 
 include/linux/memory_hotplug.h         |    5 
 include/linux/memremap.h               |   11 
 include/linux/range.h                  |    6 
 kernel/resource.c                      |   11 
 lib/test_hmm.c                         |   15 
 mm/memory_hotplug.c                    |   10 
 mm/memremap.c                          |  299 +++++----
 tools/testing/nvdimm/dax-dev.c         |   22 -
 tools/testing/nvdimm/test/iomap.c      |    2 
 42 files changed, 1810 insertions(+), 588 deletions(-)
 delete mode 100644 drivers/dax/hmem.c
 create mode 100644 drivers/dax/hmem/Makefile
 create mode 100644 drivers/dax/hmem/device.c
 create mode 100644 drivers/dax/hmem/hmem.c

base-commit: 01830e6c042e8eb6eb202e05d7df8057135b4c26