linux-kernel - [PATCH v3 0/4] Support persistent memory as reserved type in e820/EFI

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Date:	Wed,  9 Mar 2016 12:46:57 -0700
From:	Toshi Kani <toshi.kani@....com>
To:	mingo@...nel.org, bp@...e.de, dan.j.williams@...el.com,
	rjw@...ysocki.net, akpm@...ux-foundation.org
Cc:	torvalds@...ux-foundation.org, linux-nvdimm@...ts.01.org,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 0/4] Support persistent memory as reserved type in e820/EFI

ACPI 6 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 adds remove_resource(), exports 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 exports insert_resource() and remove_resource().
- Patch 4 changes the ACPI nfit driver to call insert_resource() to
  insert a PMEM range from NFIT.

---
v3:
 - Drop devm_insert/remove_resource(), and export insert/remove_resource().
   (Linus Torvalds)

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: Export insert_resource and remove_resource
 4/4 ACPI: Change NFIT driver to insert new resource

---
 drivers/acpi/nfit.c    | 48 ++++++++++++++++++++++++++++++++++++++++
 include/linux/ioport.h |  1 +
 kernel/resource.c      | 60 +++++++++++++++++++++++++++++++++++++++++++-------
 3 files changed, 101 insertions(+), 8 deletions(-)