[PATCH v2 0/4] Support persistent memory as reserved type in e820/EFI

Toshi Kani
2016-03-02T21:58:19Z

ACPI 6.0 defines persistent memory (PMEM) ranges in multiple
firmware interfaces, e820, EFI, and ACPI NFIT table. This EFI
change, however, leads to hit a bug in the grub bootloader, which
treats EFI_PERSISTENT_MEMORY type as regular memory and corrupts
stored user data [1].

Therefore, BIOS may set generic reserved type in e820 and EFI
to cover PMEM ranges. The kernel can initialize PMEM ranges
from ACPI NFIT table alone.

This scheme cause a problem in the iomem table, though. On x86,
for instance, e820_reserve_resources() initializes top-level entries
(iomem_resource.child) from the e820 table at early boot-time.
This creates "reserved" entry for a PMEM range, which does not allow
region_intersects() to check with PMEM type.

This patch-set introduces devm_insert/remove_resource(), and changes
the NFIT driver to insert a PMEM entry to the iomem table.

[1] https://lists.gnu.org/archive/html/grub-devel/2015-11/msg00209.html

Patch 1 fixes __request_region() to handle inheritance of attribute
properly. This patch is independent from this series.

Patch 2 adds remove_resource() interface.

Patch 3 adds devm_insert_resource() and devm_remove_resouce().

Patch 4 changes the ACPI nfit driver to call devm_insert_resource() to
insert a PMEM range from NFIT.

---
v2:
- Change the NFIT driver to call insert_resource() to insert a PMEM entry
when necessary. (Dan Williams)
- The NFIT driver still needs to allow unloading. (Dan Williams)

---
This patch-set is based on the tip tree, which has the following patchset.
https://lkml.org/lkml/2016/1/26/886

---
Toshi Kani (4):
1/4 resource: Change __request_region to inherit from immediate parent
2/4 resource: Add remove_resource interface
3/4 resource: Add device-managed insert/remove_resource()
4/4 ACPI: Change NFIT driver to insert new resource

---
drivers/acpi/nfit.c | 30 ++++++++++++
include/linux/ioport.h | 6 +++
kernel/resource.c | 127 +++++++++++++++++++++++++++++++++++++++++++++----
3 files changed, 155 insertions(+), 8 deletions(-)