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

From: Rafael J. Wysocki
Date: Fri Sep 06 2019 - 07:37:38 EST

On 9/5/2019 1:06 AM, Dan Williams wrote:
On Mon, Sep 2, 2019 at 4:09 AM Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
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@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/

---

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@xxxxxxxxx>

for the ACPI-related changes in this series.
Thanks Rafael, is commit 5c7ed4385424 on a stable branch that Thomas
could merge, or Thomas, is this all too late for v5.4?

Yes, I've just exported the acpi-tables branch containing that commit as a stable one in the linux-pm.git tree at kernel.org.

Cheers!