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

Dan Williams
2020-08-01T03:41:25Z

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@dwillia2-desk3.amr.corp.intel.com

---
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@arm.com), 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@oracle.com
[3]: http://lore.kernel.org/r/157309097008.1579826.12818463304589384434.stgit@dwillia2-desk3.amr.corp.intel.com
[4]: http://lore.kernel.org/r/154899811738.3165233.12325692939590944259.stgit@dwillia2-desk3.amr.corp.intel.com
[5]: http://lore.kernel.org/r/20200110190313.17144-1-joao.m.martins@oracle.com

---

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