| Message ID | 158328768844.2223916.3587427265166021149.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 9ffc1d19fc4a6dfcfe06c91c2861ad6d44fdd92d |
| Headers | show |
| Series | libnvdimm: Cross-arch compatible namespace alignment | expand |
Dan Williams <dan.j.williams@intel.com> writes: > The "sub-section memory hotplug" facility allows memremap_pages() users > like libnvdimm to compensate for hardware platforms like x86 that have a > section size larger than their hardware memory mapping granularity. The > compensation that sub-section support affords is being tolerant of > physical memory resources shifting by units smaller (64MiB on x86) than > the memory-hotplug section size (128 MiB). Where the platform > physical-memory mapping granularity is limited by the number and > capability of address-decode-registers in the memory controller. > > While the sub-section support allows memremap_pages() to operate on > sub-section (2MiB) granularity, the Power architecture may still > require 16MiB alignment on "!radix_enabled()" platforms. > > In order for libnvdimm to be able to detect and manage this per-arch > limitation, introduce memremap_compat_align() as a common minimum > alignment across all driver-facing memory-mapping interfaces, and let > Power override it to 16MiB in the "!radix_enabled()" case. > > The assumption / requirement for 16MiB to be a viable > memremap_compat_align() value is that Power does not have platforms > where its equivalent of address-decode-registers never hardware remaps a > persistent memory resource on smaller than 16MiB boundaries. Note that I > tried my best to not add a new Kconfig symbol, but header include > entanglements defeated the #ifndef memremap_compat_align design pattern > and the need to export it defeats the __weak design pattern for arch > overrides. > > Based on an initial patch by Aneesh. > > Link: http://lore.kernel.org/r/CAPcyv4gBGNP95APYaBcsocEa50tQj9b5h__83vgngjq3ouGX_Q@mail.gmail.com > Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > Reported-by: Jeff Moyer <jmoyer@redhat.com> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Cc: Paul Mackerras <paulus@samba.org> > Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > Signed-off-by: Dan Williams <dan.j.williams@intel.com> > --- > arch/powerpc/Kconfig | 1 + > arch/powerpc/mm/ioremap.c | 21 +++++++++++++++++++++ > drivers/nvdimm/pfn_devs.c | 2 +- > include/linux/memremap.h | 8 ++++++++ > include/linux/mmzone.h | 1 + > lib/Kconfig | 3 +++ > mm/memremap.c | 23 +++++++++++++++++++++++ > 7 files changed, 58 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index 497b7d0b2d7e..e6ffe905e2b9 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -122,6 +122,7 @@ config PPC > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_KCOV > select ARCH_HAS_HUGEPD if HUGETLB_PAGE > + select ARCH_HAS_MEMREMAP_COMPAT_ALIGN > select ARCH_HAS_MMIOWB if PPC64 > select ARCH_HAS_PHYS_TO_DMA > select ARCH_HAS_PMEM_API > diff --git a/arch/powerpc/mm/ioremap.c b/arch/powerpc/mm/ioremap.c > index fc669643ce6a..b1a0aebe8c48 100644 > --- a/arch/powerpc/mm/ioremap.c > +++ b/arch/powerpc/mm/ioremap.c > @@ -2,6 +2,7 @@ > > #include <linux/io.h> > #include <linux/slab.h> > +#include <linux/mmzone.h> > #include <linux/vmalloc.h> > #include <asm/io-workarounds.h> > > @@ -97,3 +98,23 @@ void __iomem *do_ioremap(phys_addr_t pa, phys_addr_t offset, unsigned long size, > > return NULL; > } > + > +#ifdef CONFIG_ZONE_DEVICE > +/* > + * Override the generic version in mm/memremap.c. > + * > + * With hash translation, the direct-map range is mapped with just one > + * page size selected by htab_init_page_sizes(). Consult > + * mmu_psize_defs[] to determine the minimum page size alignment. > +*/ > +unsigned long memremap_compat_align(void) > +{ > + unsigned int shift = mmu_psize_defs[mmu_linear_psize].shift; > + > + if (radix_enabled()) > + return SUBSECTION_SIZE; > + return max(SUBSECTION_SIZE, 1UL << shift); > + > +} > +EXPORT_SYMBOL_GPL(memremap_compat_align); > +#endif LGTM. Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) cheers
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 497b7d0b2d7e..e6ffe905e2b9 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -122,6 +122,7 @@ config PPC select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_KCOV select ARCH_HAS_HUGEPD if HUGETLB_PAGE + select ARCH_HAS_MEMREMAP_COMPAT_ALIGN select ARCH_HAS_MMIOWB if PPC64 select ARCH_HAS_PHYS_TO_DMA select ARCH_HAS_PMEM_API diff --git a/arch/powerpc/mm/ioremap.c b/arch/powerpc/mm/ioremap.c index fc669643ce6a..b1a0aebe8c48 100644 --- a/arch/powerpc/mm/ioremap.c +++ b/arch/powerpc/mm/ioremap.c @@ -2,6 +2,7 @@ #include <linux/io.h> #include <linux/slab.h> +#include <linux/mmzone.h> #include <linux/vmalloc.h> #include <asm/io-workarounds.h> @@ -97,3 +98,23 @@ void __iomem *do_ioremap(phys_addr_t pa, phys_addr_t offset, unsigned long size, return NULL; } + +#ifdef CONFIG_ZONE_DEVICE +/* + * Override the generic version in mm/memremap.c. + * + * With hash translation, the direct-map range is mapped with just one + * page size selected by htab_init_page_sizes(). Consult + * mmu_psize_defs[] to determine the minimum page size alignment. +*/ +unsigned long memremap_compat_align(void) +{ + unsigned int shift = mmu_psize_defs[mmu_linear_psize].shift; + + if (radix_enabled()) + return SUBSECTION_SIZE; + return max(SUBSECTION_SIZE, 1UL << shift); + +} +EXPORT_SYMBOL_GPL(memremap_compat_align); +#endif diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c index b94f7a7e94b8..a5c25cb87116 100644 --- a/drivers/nvdimm/pfn_devs.c +++ b/drivers/nvdimm/pfn_devs.c @@ -750,7 +750,7 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn) start = nsio->res.start; size = resource_size(&nsio->res); npfns = PHYS_PFN(size - SZ_8K); - align = max(nd_pfn->align, (1UL << SUBSECTION_SHIFT)); + align = max(nd_pfn->align, SUBSECTION_SIZE); end_trunc = start + size - ALIGN_DOWN(start + size, align); if (nd_pfn->mode == PFN_MODE_PMEM) { /* diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 6fefb09af7c3..8af1cbd8f293 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -132,6 +132,7 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn, unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); +unsigned long memremap_compat_align(void); #else static inline void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) @@ -165,6 +166,12 @@ static inline void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns) { } + +/* when memremap_pages() is disabled all archs can remap a single page */ +static inline unsigned long memremap_compat_align(void) +{ + return PAGE_SIZE; +} #endif /* CONFIG_ZONE_DEVICE */ static inline void put_dev_pagemap(struct dev_pagemap *pgmap) @@ -172,4 +179,5 @@ static inline void put_dev_pagemap(struct dev_pagemap *pgmap) if (pgmap) percpu_ref_put(pgmap->ref); } + #endif /* _LINUX_MEMREMAP_H_ */ diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 462f6873905a..6b77f7239af5 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1170,6 +1170,7 @@ static inline unsigned long section_nr_to_pfn(unsigned long sec) #define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK) #define SUBSECTION_SHIFT 21 +#define SUBSECTION_SIZE (1UL << SUBSECTION_SHIFT) #define PFN_SUBSECTION_SHIFT (SUBSECTION_SHIFT - PAGE_SHIFT) #define PAGES_PER_SUBSECTION (1UL << PFN_SUBSECTION_SHIFT) diff --git a/lib/Kconfig b/lib/Kconfig index bc7e56370129..5d53f9609c25 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -615,6 +615,9 @@ config ARCH_HAS_PMEM_API config MEMREGION bool +config ARCH_HAS_MEMREMAP_COMPAT_ALIGN + bool + # use memcpy to implement user copies for nommu architectures config UACCESS_MEMCPY bool diff --git a/mm/memremap.c b/mm/memremap.c index 09b5b7adc773..3e7afaf05639 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -7,6 +7,7 @@ #include <linux/mm.h> #include <linux/pfn_t.h> #include <linux/swap.h> +#include <linux/mmzone.h> #include <linux/swapops.h> #include <linux/types.h> #include <linux/wait_bit.h> @@ -14,6 +15,28 @@ static DEFINE_XARRAY(pgmap_array); +/* + * The memremap() and memremap_pages() interfaces are alternately used + * to map persistent memory namespaces. These interfaces place different + * constraints on the alignment and size of the mapping (namespace). + * memremap() can map individual PAGE_SIZE pages. memremap_pages() can + * only map subsections (2MB), and at least one architecture (PowerPC) + * the minimum mapping granularity of memremap_pages() is 16MB. + * + * The role of memremap_compat_align() is to communicate the minimum + * arch supported alignment of a namespace such that it can freely + * switch modes without violating the arch constraint. Namely, do not + * allow a namespace to be PAGE_SIZE aligned since that namespace may be + * reconfigured into a mode that requires SUBSECTION_SIZE alignment. + */ +#ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN +unsigned long memremap_compat_align(void) +{ + return SUBSECTION_SIZE; +} +EXPORT_SYMBOL_GPL(memremap_compat_align); +#endif + #ifdef CONFIG_DEV_PAGEMAP_OPS DEFINE_STATIC_KEY_FALSE(devmap_managed_key); EXPORT_SYMBOL(devmap_managed_key);