[PATCH v2 0/8] EFI Specific Purpose Memory Support

[Dan Williams]

Changes since the initial RFC [1]
* Split the generic detection of the attribute from any policy /
  mechanism that leverages the EFI_MEMORY_SP designation (Ard).

* Various cleanups to the lib/memregion implementation (Willy)

* Rebase on v5.2-rc2

* Several fixes resulting from testing with efi_fake_mem and the
  work-in-progress patches that add HMAT support to qemu. Details in
  patch3 and patch8.

[1]: https://lore.kernel.org/lkml/155440490809.3190322.15060922240602775809.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/

---

The EFI 2.8 Specification [2] introduces the EFI_MEMORY_SP ("specific
purpose") memory attribute. This attribute bit replaces the deprecated
ACPI HMAT "reservation hint" that was introduced in ACPI 6.2 and removed
in ACPI 6.3.

Given the increasing diversity of memory types that might be advertised
to the operating system, there is a need for platform firmware to hint
which memory ranges are free for the OS to use as general purpose memory
and which ranges are intended for application specific usage. For
example, an application with prior knowledge of the platform may expect
to be able to exclusively allocate a precious / limited pool of high
bandwidth memory. Alternatively, for the general purpose case, the
operating system may want to make the memory available on a best effort
basis as a unique numa-node with performance properties by the new
CONFIG_HMEM_REPORTING [3] facility.

In support of optionally allowing either application-exclusive and
core-kernel-mm managed access to differentiated memory, claim
EFI_MEMORY_SP ranges for exposure as device-dax instances by default.
Such instances can be directly owned / mapped by a
platform-topology-aware application. Alternatively, with the new kmem
facility [4], the administrator has the option to instead designate that
those memory ranges be hot-added to the core-kernel-mm as a unique
memory numa-node. In short, allow for the decision about what software
agent manages specific-purpose memory to be made at runtime.

The patches are based on the new HMAT+HMEM_REPORTING facilities merged
for v5.2-rc1. The implementation is tested with qemu emulation of HMAT
[5] plus the efi_fake_mem facility for applying the EFI_MEMORY_SP
attribute.

[2]: https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf
[3]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e1cf33aafb84
[4]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c221c0b0308f
[5]: http://patchwork.ozlabs.org/cover/1096737/

---

Dan Williams (8):
      acpi: Drop drivers/acpi/hmat/ directory
      acpi/hmat: Skip publishing target info for nodes with no online memory
      efi: Enumerate EFI_MEMORY_SP
      x86, efi: Reserve UEFI 2.8 Specific Purpose Memory for dax
      lib/memregion: Uplevel the pmem "region" ida to a global allocator
      device-dax: Add a driver for "hmem" devices
      acpi/hmat: Register HMAT at device_initcall level
      acpi/hmat: Register "specific purpose" memory as an "hmem" device


 arch/x86/Kconfig                  |   20 +++++
 arch/x86/boot/compressed/eboot.c  |    5 +
 arch/x86/boot/compressed/kaslr.c  |    2
 arch/x86/include/asm/e820/types.h |    9 ++
 arch/x86/kernel/e820.c            |    9 ++
 arch/x86/kernel/setup.c           |    1
 arch/x86/platform/efi/efi.c       |   37 ++++++++-
 drivers/acpi/Kconfig              |   13 +++
 drivers/acpi/Makefile             |    2
 drivers/acpi/hmat.c               |  149 +++++++++++++++++++++++++++++++++----
 drivers/acpi/hmat/Kconfig         |   11 ---
 drivers/acpi/hmat/Makefile        |    2
 drivers/acpi/numa.c               |   15 +++-
 drivers/dax/Kconfig               |   27 +++++--
 drivers/dax/Makefile              |    2
 drivers/dax/hmem.c                |   58 ++++++++++++++
 drivers/firmware/efi/efi.c        |    5 +
 drivers/nvdimm/Kconfig            |    1
 drivers/nvdimm/core.c             |    1
 drivers/nvdimm/nd-core.h          |    1
 drivers/nvdimm/region_devs.c      |   13 +--
 include/linux/efi.h               |   15 ++++
 include/linux/ioport.h            |    1
 include/linux/memblock.h          |    7 ++
 include/linux/memregion.h         |   11 +++
 lib/Kconfig                       |    7 ++
 lib/Makefile                      |    1
 lib/memregion.c                   |   15 ++++
 mm/memblock.c                     |    4 +
 29 files changed, 387 insertions(+), 57 deletions(-)
 rename drivers/acpi/{hmat/hmat.c => hmat.c} (81%)
 delete mode 100644 drivers/acpi/hmat/Kconfig
 delete mode 100644 drivers/acpi/hmat/Makefile
 create mode 100644 drivers/dax/hmem.c
 create mode 100644 include/linux/memregion.h
 create mode 100644 lib/memregion.c