[PATCH v4 00/23] device-dax: Support sub-dividing soft-reserved ranges

From: Dan Williams
Date: Mon Aug 03 2020 - 01:18:45 EST


Changes since v3 [1]:
- Update x86 boot options documentation for 'nohmat' (Randy)

- Fixup a handful of kbuild robot reports, the most significant being
moving usage of PUD_SIZE and PMD_SIZE under
#ifdef CONFIG_TRANSPARENT_HUGEPAGE protection.

[1]: http://lore.kernel.org/r/159625229779.3040297.11363509688097221416.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

---
Merge notes:

Well, no v5.8-rc8 to line this up for v5.9, so next best is early
integration into -mm before other collisions develop.

Chatted with Justin offline and it currently appears that the missing
numa information is the fault of the platform firmware to populate all
the necessary NUMA data in the NFIT.

---
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


Documentation/x86/x86_64/boot-options.rst | 4
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 | 1046 +++++++++++++++++++++++++++--
drivers/dax/bus.h | 28 -
drivers/dax/dax-private.h | 60 +-
drivers/dax/device.c | 134 ++--
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/numa.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
44 files changed, 1825 insertions(+), 601 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