linux_dsm_epyc7002/arch
Dan Williams 96601adb74 x86, pmem: clarify that ARCH_HAS_PMEM_API implies PMEM mapped WB
Given that a write-back (WB) mapping plus non-temporal stores is
expected to be the most efficient way to access PMEM, update the
definition of ARCH_HAS_PMEM_API to imply arch support for
WB-mapped-PMEM.  This is needed as a pre-requisite for adding PMEM to
the direct map and mapping it with struct page.

The above clarification for X86_64 means that memcpy_to_pmem() is
permitted to use the non-temporal arch_memcpy_to_pmem() rather than
needlessly fall back to default_memcpy_to_pmem() when the pcommit
instruction is not available.  When arch_memcpy_to_pmem() is not
guaranteed to flush writes out of cache, i.e. on older X86_32
implementations where non-temporal stores may just dirty cache,
ARCH_HAS_PMEM_API is simply disabled.

The default fall back for persistent memory handling remains.  Namely,
map it with the WT (write-through) cache-type and hope for the best.

arch_has_pmem_api() is updated to only indicate whether the arch
provides the proper helpers to meet the minimum "writes are visible
outside the cache hierarchy after memcpy_to_pmem() + wmb_pmem()".  Code
that cares whether wmb_pmem() actually flushes writes to pmem must now
call arch_has_wmb_pmem() directly.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
[hch: set ARCH_HAS_PMEM_API=n on x86_32]
Reviewed-by: Christoph Hellwig <hch@lst.de>
[toshi: x86_32 compile fixes]
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-08-27 19:40:59 -04:00
..
alpha mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
arc mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
arm mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h 2015-08-27 19:40:58 -04:00
arm64 mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h 2015-08-27 19:40:58 -04:00
avr32 AVR32/time: Migrate to new 'set-state' interface 2015-07-20 12:19:10 +02:00
blackfin mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
c6x mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
cris mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
frv mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
h8300 mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
hexagon mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
ia64 mm: ZONE_DEVICE for "device memory" 2015-08-27 19:40:58 -04:00
m32r m32r: Add ioreadXX/iowriteXX big-endian mmio accessors 2015-07-23 18:08:28 -07:00
m68k mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
metag mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
microblaze mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
mips Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2015-07-19 14:12:22 -07:00
mn10300 mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
nios2 mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
openrisc mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
parisc parisc: mm: Fix a memory leak related to pmd not attached to the pgd 2015-07-19 08:56:14 +02:00
powerpc mm: ZONE_DEVICE for "device memory" 2015-08-27 19:40:58 -04:00
s390 mm: ZONE_DEVICE for "device memory" 2015-08-27 19:40:58 -04:00
score mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
sh mm: ZONE_DEVICE for "device memory" 2015-08-27 19:40:58 -04:00
sparc cleanup IORESOURCE_CACHEABLE vs ioremap() 2015-08-10 23:07:06 -04:00
tile mm: ZONE_DEVICE for "device memory" 2015-08-27 19:40:58 -04:00
um mm: clean up per architecture MM hook header files 2015-07-17 16:39:53 -07:00
unicore32 mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h 2015-08-27 19:40:58 -04:00
x86 x86, pmem: clarify that ARCH_HAS_PMEM_API implies PMEM mapped WB 2015-08-27 19:40:59 -04:00
xtensa arch: introduce memremap() 2015-08-14 13:23:28 -04:00
.gitignore
Kconfig x86/fpu, sched: Introduce CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT and use it on x86 2015-07-18 03:42:51 +02:00