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Subject[PATCH v2 00/22] device-dax: Support sub-dividing soft-reserved ranges
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Date
Changes since v1 [1]:

- Combine this series with "Manual definition of Soft Reserved memory
devices" [2] as the pre-requisites are required to test the device-dax
facility, the device-dax changes are part of the justification for the
numa-info reworks.

- Provide a generic version of numa data retrieval based on memblock for
arm64 rather than adding a new / empty phys_to_target_node() stub
alongside memory_add_physaddr_to_nid(). (Will)

- Fix several corner case allocation bugs and pass the unit test written
by Joao.

- Lift the restriction that a 'seed' device must be activated before a
new seed can be created. This minor sanity check was to prevent userspace
spamming devices, but it gets in the way of some of allocation
scenarios like allocating a memory-range that is guaranteed to never be
evicted due to memory-side-cache conflicts. (Iqbal)

- Add debug prints for space allocation decisions (Joao)

- Rebased on v5.8-rc2 which included resolving conflicts in the kmem
driver and memremap_pages().

[1]: http://lore.kernel.org/r/158500767138.2088294.17131646259803932461.stgit@dwillia2-desk3.amr.corp.intel.com
[2]: http://lore.kernel.org/r/158489354353.1457606.8327903161927980740.stgit@dwillia2-desk3.amr.corp.intel.com/

---

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.

Given the intersections of arm64, x86, and core memremap_pages() changes
I'd like to explore taking this through the libnvdimm tree, but that is
step 2. Any concerns with the proposed infrastructure changes
(memblock-numainfo and multi-range-memremap-pages)?

[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 (22):
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
x86: Move NUMA_KEEP_MEMINFO and related definition to x86-internals
numa: Introduce a generic memory_add_physaddr_to_nid()
memblock: Introduce a generic phys_addr_to_target_node()
arm64: Convert to generic memblock for numa-info
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

arch/arm64/Kconfig | 1
arch/arm64/mm/numa.c | 10
arch/powerpc/kvm/book3s_hv_uvmem.c | 14
arch/x86/Kconfig | 7
arch/x86/include/asm/numa.h | 8
arch/x86/kernel/e820.c | 16 +
arch/x86/mm/numa.c | 12
arch/x86/mm/numa_emulation.c | 3
arch/x86/mm/numa_internal.h | 7
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 | 6
drivers/dax/Makefile | 3
drivers/dax/bus.c | 902 ++++++++++++++++++++++++++++++--
drivers/dax/bus.h | 28 +
drivers/dax/dax-private.h | 39 +
drivers/dax/device.c | 97 ++-
drivers/dax/hmem/Makefile | 6
drivers/dax/hmem/device.c | 100 ++++
drivers/dax/hmem/hmem.c | 20 -
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 | 4
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/memblock.h | 4
include/linux/memremap.h | 11
include/linux/mm.h | 13
include/linux/numa.h | 9
include/linux/range.h | 6
kernel/resource.c | 11
mm/Kconfig | 7
mm/memblock.c | 22 +
mm/memremap.c | 300 ++++++-----
mm/page_alloc.c | 82 +++
tools/testing/nvdimm/dax-dev.c | 22 +
tools/testing/nvdimm/test/iomap.c | 2
48 files changed, 1705 insertions(+), 528 deletions(-)
create mode 100644 drivers/dax/hmem/Makefile
create mode 100644 drivers/dax/hmem/device.c
rename drivers/dax/{hmem.c => hmem/hmem.c} (74%)

base-commit: 48778464bb7d346b47157d21ffde2af6b2d39110

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