diff options
author | Dan Williams <dan.j.williams@intel.com> | 2015-08-24 18:29:38 -0400 |
---|---|---|
committer | Dan Williams <dan.j.williams@intel.com> | 2015-08-27 19:40:59 -0400 |
commit | 96601adb745186ccbcf5b078d4756f13381ec2af (patch) | |
tree | 1dff922da6a102e55978278c8ad078f30a7384b8 /include | |
parent | 41e94a851304f7acac840adec4004f8aeee53ad4 (diff) | |
download | op-kernel-dev-96601adb745186ccbcf5b078d4756f13381ec2af.zip op-kernel-dev-96601adb745186ccbcf5b078d4756f13381ec2af.tar.gz |
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>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/pmem.h | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/include/linux/pmem.h b/include/linux/pmem.h index a9d84bf..85f810b3 100644 --- a/include/linux/pmem.h +++ b/include/linux/pmem.h @@ -17,16 +17,23 @@ #include <linux/uio.h> #ifdef CONFIG_ARCH_HAS_PMEM_API +#define ARCH_MEMREMAP_PMEM MEMREMAP_WB #include <asm/pmem.h> #else -static inline void arch_wmb_pmem(void) +#define ARCH_MEMREMAP_PMEM MEMREMAP_WT +/* + * These are simply here to enable compilation, all call sites gate + * calling these symbols with arch_has_pmem_api() and redirect to the + * implementation in asm/pmem.h. + */ +static inline bool __arch_has_wmb_pmem(void) { - BUG(); + return false; } -static inline bool arch_has_wmb_pmem(void) +static inline void arch_wmb_pmem(void) { - return false; + BUG(); } static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src, @@ -53,7 +60,6 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size) * implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(), * arch_copy_from_iter_pmem(), arch_clear_pmem() and arch_has_wmb_pmem(). */ - static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size) { memcpy(dst, (void __force const *) src, size); @@ -64,8 +70,13 @@ static inline void memunmap_pmem(struct device *dev, void __pmem *addr) devm_memunmap(dev, (void __force *) addr); } +static inline bool arch_has_pmem_api(void) +{ + return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API); +} + /** - * arch_has_pmem_api - true if wmb_pmem() ensures durability + * arch_has_wmb_pmem - true if wmb_pmem() ensures durability * * For a given cpu implementation within an architecture it is possible * that wmb_pmem() resolves to a nop. In the case this returns @@ -73,9 +84,9 @@ static inline void memunmap_pmem(struct device *dev, void __pmem *addr) * fall back to a different data consistency model, or otherwise notify * the user. */ -static inline bool arch_has_pmem_api(void) +static inline bool arch_has_wmb_pmem(void) { - return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && arch_has_wmb_pmem(); + return arch_has_pmem_api() && __arch_has_wmb_pmem(); } /* @@ -120,13 +131,8 @@ static inline void default_clear_pmem(void __pmem *addr, size_t size) static inline void __pmem *memremap_pmem(struct device *dev, resource_size_t offset, unsigned long size) { -#ifdef ARCH_MEMREMAP_PMEM return (void __pmem *) devm_memremap(dev, offset, size, ARCH_MEMREMAP_PMEM); -#else - return (void __pmem *) devm_memremap(dev, offset, size, - MEMREMAP_WT); -#endif } /** @@ -158,8 +164,10 @@ static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n) */ static inline void wmb_pmem(void) { - if (arch_has_pmem_api()) + if (arch_has_wmb_pmem()) arch_wmb_pmem(); + else + wmb(); } /** |