[PATCH v5 0/8] Support Write-Through mapping on x86

[Toshi Kani <toshi.kani@hp.com>]

This patchset adds support of Write-Through (WT) mapping on x86.
The study below shows that using WT mapping may be useful for
non-volatile memory.

  http://www.hpl.hp.com/techreports/2012/HPL-2012-236.pdf

This patchset applies on top of the Juergen's patchset below,
which provides the basis of the PAT management.

  https://lkml.org/lkml/2014/11/3/330

All new/modified interfaces have been tested.

v5:
 - Clarified comment of why using slot 7. (Andy Lutomirski,
   Thomas Gleixner)
 - Moved [set|get]_page_memtype() to pat.c. (Thomas Gleixner)
 - Removed BUG() from set_page_memtype(). (Thomas Gleixner)

v4:
 - Added set_memory_wt() by adding WT support of regular memory.

v3:
 - Dropped the set_memory_wt() patch. (Andy Lutomirski)
 - Refactored the !pat_enabled handling. (H. Peter Anvin,
   Andy Lutomirski)
 - Added the picture of PTE encoding. (Konrad Rzeszutek Wilk)

v2:
 - Changed WT to use slot 7 of the PAT MSR. (H. Peter Anvin,
   Andy Lutomirski)
 - Changed to have conservative checks to exclude all Pentium 2, 3,
   M, and 4 families. (Ingo Molnar, Henrique de Moraes Holschuh,
   Andy Lutomirski)
 - Updated documentation to cover WT interfaces and usages.
   (Andy Lutomirski, Yigal Korman)

---
Toshi Kani (8):
  1/8 x86, mm, pat: Set WT to PA7 slot of PAT MSR
  2/8 x86, mm, pat, asm: Move [get|set]_page_memtype() to pat.c
  3/8 x86, mm, pat: Change reserve_memtype() to handle WT
  4/8 x86, mm, asm-gen: Add ioremap_wt() for WT
  5/8 x86, mm, pat: Add pgprot_writethrough() for WT
  6/8 x86, mm, pat: Refactor !pat_enable handling
  7/8 x86, mm, asm: Add WT support to set_page_memtype()
  8/8 x86, mm: Add set_memory_wt() for WT

---
 Documentation/x86/pat.txt            |  13 +-
 arch/x86/include/asm/cacheflush.h    |  75 +----------
 arch/x86/include/asm/io.h            |   2 +
 arch/x86/include/asm/pgtable_types.h |   3 +
 arch/x86/mm/init.c                   |   6 +-
 arch/x86/mm/iomap_32.c               |  12 +-
 arch/x86/mm/ioremap.c                |  26 +++-
 arch/x86/mm/pageattr.c               |  61 +++++++--
 arch/x86/mm/pat.c                    | 241 ++++++++++++++++++++++++-----------
 include/asm-generic/io.h             |   4 +
 include/asm-generic/iomap.h          |   4 +
 include/asm-generic/pgtable.h        |   4 +

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