forked from luck/tmp_suning_uos_patched
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>
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41e94a8513
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96601adb74
@ -27,7 +27,7 @@ config X86
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select ARCH_HAS_ELF_RANDOMIZE
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select ARCH_HAS_FAST_MULTIPLIER
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select ARCH_HAS_GCOV_PROFILE_ALL
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select ARCH_HAS_PMEM_API
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select ARCH_HAS_PMEM_API if X86_64
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select ARCH_HAS_MMIO_FLUSH
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select ARCH_HAS_SG_CHAIN
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select ARCH_HAVE_NMI_SAFE_CMPXCHG
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@ -18,8 +18,6 @@
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#include <asm/cpufeature.h>
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#include <asm/special_insns.h>
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#define ARCH_MEMREMAP_PMEM MEMREMAP_WB
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#ifdef CONFIG_ARCH_HAS_PMEM_API
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/**
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* arch_memcpy_to_pmem - copy data to persistent memory
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@ -143,18 +141,13 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size)
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__arch_wb_cache_pmem(vaddr, size);
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}
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static inline bool arch_has_wmb_pmem(void)
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static inline bool __arch_has_wmb_pmem(void)
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{
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#ifdef CONFIG_X86_64
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/*
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* We require that wmb() be an 'sfence', that is only guaranteed on
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* 64-bit builds
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*/
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return static_cpu_has(X86_FEATURE_PCOMMIT);
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#else
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return false;
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#endif
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}
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#endif /* CONFIG_ARCH_HAS_PMEM_API */
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#endif /* __ASM_X86_PMEM_H__ */
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@ -20,6 +20,7 @@
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#include <linux/sort.h>
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#include <linux/pmem.h>
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#include <linux/io.h>
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#include <asm/cacheflush.h>
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#include "nfit.h"
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/*
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@ -1371,7 +1372,7 @@ static int acpi_nfit_blk_region_enable(struct nvdimm_bus *nvdimm_bus,
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return -ENOMEM;
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}
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if (!arch_has_pmem_api() && !nfit_blk->nvdimm_flush)
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if (!arch_has_wmb_pmem() && !nfit_blk->nvdimm_flush)
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dev_warn(dev, "unable to guarantee persistence of writes\n");
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if (mmio->line_size == 0)
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@ -125,7 +125,7 @@ static struct pmem_device *pmem_alloc(struct device *dev,
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pmem->phys_addr = res->start;
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pmem->size = resource_size(res);
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if (!arch_has_pmem_api())
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if (!arch_has_wmb_pmem())
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dev_warn(dev, "unable to guarantee persistence of writes\n");
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if (!devm_request_mem_region(dev, pmem->phys_addr, pmem->size,
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@ -17,18 +17,25 @@
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#include <linux/uio.h>
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#ifdef CONFIG_ARCH_HAS_PMEM_API
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#define ARCH_MEMREMAP_PMEM MEMREMAP_WB
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#include <asm/pmem.h>
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#else
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#define ARCH_MEMREMAP_PMEM MEMREMAP_WT
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/*
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* These are simply here to enable compilation, all call sites gate
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* calling these symbols with arch_has_pmem_api() and redirect to the
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* implementation in asm/pmem.h.
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*/
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static inline bool __arch_has_wmb_pmem(void)
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{
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return false;
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}
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static inline void arch_wmb_pmem(void)
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{
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BUG();
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}
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static inline bool arch_has_wmb_pmem(void)
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{
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return false;
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}
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static inline void arch_memcpy_to_pmem(void __pmem *dst, const void *src,
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size_t n)
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{
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@ -53,7 +60,6 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size)
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* implementations for arch_memcpy_to_pmem(), arch_wmb_pmem(),
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* arch_copy_from_iter_pmem(), arch_clear_pmem() and arch_has_wmb_pmem().
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*/
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static inline void memcpy_from_pmem(void *dst, void __pmem const *src, size_t size)
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{
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memcpy(dst, (void __force const *) src, size);
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@ -64,8 +70,13 @@ static inline void memunmap_pmem(struct device *dev, void __pmem *addr)
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devm_memunmap(dev, (void __force *) addr);
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}
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static inline bool arch_has_pmem_api(void)
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{
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return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API);
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}
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/**
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* arch_has_pmem_api - true if wmb_pmem() ensures durability
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* arch_has_wmb_pmem - true if wmb_pmem() ensures durability
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*
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* For a given cpu implementation within an architecture it is possible
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* that wmb_pmem() resolves to a nop. In the case this returns
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@ -73,9 +84,9 @@ static inline void memunmap_pmem(struct device *dev, void __pmem *addr)
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* fall back to a different data consistency model, or otherwise notify
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* the user.
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*/
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static inline bool arch_has_pmem_api(void)
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static inline bool arch_has_wmb_pmem(void)
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{
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return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && arch_has_wmb_pmem();
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return arch_has_pmem_api() && __arch_has_wmb_pmem();
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}
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/*
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@ -120,13 +131,8 @@ static inline void default_clear_pmem(void __pmem *addr, size_t size)
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static inline void __pmem *memremap_pmem(struct device *dev,
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resource_size_t offset, unsigned long size)
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{
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#ifdef ARCH_MEMREMAP_PMEM
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return (void __pmem *) devm_memremap(dev, offset, size,
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ARCH_MEMREMAP_PMEM);
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#else
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return (void __pmem *) devm_memremap(dev, offset, size,
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MEMREMAP_WT);
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#endif
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}
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/**
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@ -158,8 +164,10 @@ static inline void memcpy_to_pmem(void __pmem *dst, const void *src, size_t n)
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*/
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static inline void wmb_pmem(void)
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{
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if (arch_has_pmem_api())
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if (arch_has_wmb_pmem())
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arch_wmb_pmem();
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else
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wmb();
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}
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/**
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