Re: [PATCH v5 00/10] EFI Specific Purpose Memory Support

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Friday, August 30, 2019 3:52:18 AM CEST Dan Williams wrote:
> Changes since v4 [1]:
> - Rename the facility from "Application Reserved" to "Soft Reserved" to
>   better reflect how the memory is treated. While the spec talks about
>   "specific / application purpose" memory the expected kernel behavior is
>   to make a best effort at reserving the memory from general purpose
>   allocations.
> 
> - Add a new efi=nosoftreserve option to disable consideration of the
>   EFI_MEMORY_SP attribute at boot time. This is also motivated by
>   Christoph's initial feedback of allowing the kernel to opt-out of the
>   policy whims of the platform BIOS implementation.
> 
> - Update the KASLR implementation to exclude soft-reserved memory
>   including the case where soft-reserved memory is specified via the
>   efi_fake_mem= attribute-override command-line option.
> 
> - Move the memregion allocator to its own object file. v4 had it in
>   kernel/resource.c which caused compile errors on Sparc. I otherwise
>   could not find an appropriate place to stash it.
> 
> - Rebase on a merge of tip/master and rafael/linux-next since the series
>   collides with changes in both those trees.
> 
> [1]: https://lore.kernel.org/r/156140036490.2951909.1837804994781523185.stgit@dwillia2-desk3.amr.corp.intel.com/
> 
> ---
> 
> Thomas, Rafael,
> 
> This happens to collide with both your trees. I think the content
> warrants going through the x86 tree, but would need to publish commit:
> 
> 5c7ed4385424 HMAT: Skip publishing target info for nodes with no online memory
> 
> ...in Rafael's tree as a stable id for -tip to pull in, but I'm also
> open to other options. I've retained Dave's reviewed-by from v4.
> 
> ---
> 
> 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 "soft reserved" and assigned to a
> device-dax instance 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 soft-reserved memory to be made at runtime.
> 
> The patches build 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. Specific details on reproducing the test configuration are in
> patch 10.
> 
> [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 (10):
>       acpi/numa: Establish a new drivers/acpi/numa/ directory
>       efi: Enumerate EFI_MEMORY_SP
>       x86, efi: Push EFI_MEMMAP check into leaf routines
>       x86, efi: Reserve UEFI 2.8 Specific Purpose Memory for dax
>       x86, efi: Add efi_fake_mem support for EFI_MEMORY_SP
>       lib: Uplevel the pmem "region" ida to a global allocator
>       dax: Fix alloc_dax_region() compile warning
>       device-dax: Add a driver for "hmem" devices
>       acpi/numa/hmat: Register HMAT at device_initcall level
>       acpi/numa/hmat: Register "soft reserved" memory as an "hmem" device
> 
> 
>  Documentation/admin-guide/kernel-parameters.txt |   19 +++
>  arch/x86/Kconfig                                |   21 ++++
>  arch/x86/boot/compressed/eboot.c                |    7 +
>  arch/x86/boot/compressed/kaslr.c                |   50 +++++++-
>  arch/x86/include/asm/e820/types.h               |    8 +
>  arch/x86/include/asm/efi-stub.h                 |   11 ++
>  arch/x86/include/asm/efi.h                      |   17 +++
>  arch/x86/kernel/e820.c                          |   12 ++
>  arch/x86/kernel/setup.c                         |   19 ++-
>  arch/x86/platform/efi/efi.c                     |   56 +++++++++
>  arch/x86/platform/efi/quirks.c                  |    3 +
>  drivers/acpi/Kconfig                            |    9 --
>  drivers/acpi/Makefile                           |    3 -
>  drivers/acpi/hmat/Makefile                      |    2 
>  drivers/acpi/numa/Kconfig                       |    8 +
>  drivers/acpi/numa/Makefile                      |    3 +
>  drivers/acpi/numa/hmat.c                        |  138 +++++++++++++++++++++--
>  drivers/acpi/numa/srat.c                        |    0 
>  drivers/dax/Kconfig                             |   27 ++++-
>  drivers/dax/Makefile                            |    2 
>  drivers/dax/bus.c                               |    2 
>  drivers/dax/bus.h                               |    2 
>  drivers/dax/dax-private.h                       |    2 
>  drivers/dax/hmem.c                              |   57 ++++++++++
>  drivers/firmware/efi/Makefile                   |    5 +
>  drivers/firmware/efi/efi.c                      |    8 +
>  drivers/firmware/efi/esrt.c                     |    3 +
>  drivers/firmware/efi/fake_mem.c                 |   26 ++--
>  drivers/firmware/efi/fake_mem.h                 |   10 ++
>  drivers/firmware/efi/libstub/efi-stub-helper.c  |   12 ++
>  drivers/firmware/efi/x86-fake_mem.c             |   69 ++++++++++++
>  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                             |    4 -
>  include/linux/ioport.h                          |    1 
>  include/linux/memregion.h                       |   23 ++++
>  lib/Kconfig                                     |    3 +
>  lib/Makefile                                    |    1 
>  lib/memregion.c                                 |   18 +++
>  41 files changed, 584 insertions(+), 93 deletions(-)
>  create mode 100644 arch/x86/include/asm/efi-stub.h
>  delete mode 100644 drivers/acpi/hmat/Makefile
>  rename drivers/acpi/{hmat/Kconfig => numa/Kconfig} (70%)
>  create mode 100644 drivers/acpi/numa/Makefile
>  rename drivers/acpi/{hmat/hmat.c => numa/hmat.c} (85%)
>  rename drivers/acpi/{numa.c => numa/srat.c} (100%)
>  create mode 100644 drivers/dax/hmem.c
>  create mode 100644 drivers/firmware/efi/fake_mem.h
>  create mode 100644 drivers/firmware/efi/x86-fake_mem.c
>  create mode 100644 include/linux/memregion.h
>  create mode 100644 lib/memregion.c
> 

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

for the ACPI-related changes in this series.