[PATCH v3 0/5] libnvdimm: Cross-arch compatible namespace alignment

[PATCH v3 0/5] libnvdimm: Cross-arch compatible namespace alignment

[Dan Williams]

Changes since v2 [1]:
- Fix up a missing space in flags_show() (Jeff)

- Prompted by Jeff saying that v2 only worked for him if
  memremap_compat_align() returned PAGE_SIZE (which defeats the purpose)
  I developed a new ndctl unit test that runs through the possible
  legacy configurations that the kernel needs to support. Several changes
  fell out as a result:

  - Update nd_pfn_validate() to add more -EOPNOTSUPP cases. That error
    code indicates "Stop, the pfn looks coherent, but invalid. Do not
    proceed with exposing a raw namespace, require the user to
    investigate whether the infoblock needs to be rewritten, or the
    kernel configuration (like PAGE_SIZE) needs to change."

  - Move the validation of fsdax and devdax infoblocks to
    nd_pfn_validate() so that the presence of non-zero 'start_pad' and
    'end_trunc' can be considered in the alignment validation.

  - Fail namespace creation when the base address is misaligned. A
    non-zero-start_pad prevents dax operation due to original bug of
    ->data_offset being base address relative when it should have been
    ->start_pad relative. So, reject all base address misaligned
    namespaces in nd_pfn_init().

[1]: http://lore.kernel.org/r/158155489850.3343782.2687127373754434980.stgit@dwillia2-desk3.amr.corp.intel.com

---

Review / merge logistics notes:

Patch "libnvdimm/namespace: Enforce memremap_compat_align()" has
changed enough that it needs to be reviewed again.

Patch "mm/memremap_pages: Introduce memremap_compat_align()" still
needs a PowerPC maintainer ack for the touches to
arch/powerpc/mm/ioremap.c.

---

Aneesh reports that PowerPC requires 16MiB alignment for the address
range passed to devm_memremap_pages(), and Jeff reports that it is
possible to create a misaligned namespace which blocks future namespace
creation in that region. Both of these issues require namespace
alignment to be managed at the region level rather than padding at the
namespace level which has been a broken approach to date.

Introduce memremap_compat_align() to indicate the hard requirements of
an arch's memremap_pages() implementation. Use the maximum known
memremap_compat_align() to set the default namespace alignment for
libnvdimm. Consult that alignment when allocating free space. Finally,
allow the default region alignment to be overridden to maintain the same
namespace creation capability as previous kernels.

The ndctl unit tests, which have some misaligned namespace assumptions,
are updated to use the alignment override where necessary.

Thanks to Aneesh for early feedback and testing on this improved
alignment handling.

---

Dan Williams (5):
      mm/memremap_pages: Introduce memremap_compat_align()
      libnvdimm/pfn: Prevent raw mode fallback if pfn-infoblock valid
      libnvdimm/namespace: Enforce memremap_compat_align()
      libnvdimm/region: Introduce NDD_LABELING
      libnvdimm/region: Introduce an 'align' attribute


 arch/powerpc/Kconfig                      |    1 
 arch/powerpc/mm/ioremap.c                 |   21 +++++
 arch/powerpc/platforms/pseries/papr_scm.c |    2 
 drivers/acpi/nfit/core.c                  |    4 +
 drivers/nvdimm/dimm.c                     |    2 
 drivers/nvdimm/dimm_devs.c                |   95 +++++++++++++++++----
 drivers/nvdimm/namespace_devs.c           |   23 ++++-
 drivers/nvdimm/nd.h                       |    3 -
 drivers/nvdimm/pfn_devs.c                 |   34 ++++++-
 drivers/nvdimm/region_devs.c              |  132 ++++++++++++++++++++++++++---
 include/linux/libnvdimm.h                 |    2 
 include/linux/memremap.h                  |    8 ++
 include/linux/mmzone.h                    |    1 
 lib/Kconfig                               |    3 +
 mm/memremap.c                             |   23 +++++
 15 files changed, 307 insertions(+), 47 deletions(-)

base-commit: 11a48a5a18c63fd7621bb050228cebf13566e4d8
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[PATCH v3 1/5] mm/memremap_pages: Introduce memremap_compat_align()

[Dan Williams]

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>
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
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);
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Re: [PATCH v3 1/5] mm/memremap_pages: Introduce memremap_compat_align()

[Aneesh Kumar K.V]

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.
>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>

> 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>
> 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(-)
>
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[PATCH v3 2/5] libnvdimm/pfn: Prevent raw mode fallback if pfn-infoblock valid

[Dan Williams]

The EOPNOTSUPP return code from the pmem driver indicates that the
namespace has a configuration that may be valid, but the current kernel
does not support it. Expand this to all of the nd_pfn_validate() error
conditions after the infoblock has been verified as self consistent.

This prevents exposing the namespace to I/O when the infoblock needs to
be corrected, or the system needs to be put into a different
configuration (like changing the page size on PowerPC).

Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/pfn_devs.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index a5c25cb87116..79fe02d6f657 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -561,14 +561,14 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
 			dev_dbg(&nd_pfn->dev, "align: %lx:%lx mode: %d:%d\n",
 					nd_pfn->align, align, nd_pfn->mode,
 					mode);
-			return -EINVAL;
+			return -EOPNOTSUPP;
 		}
 	}
 
 	if (align > nvdimm_namespace_capacity(ndns)) {
 		dev_err(&nd_pfn->dev, "alignment: %lx exceeds capacity %llx\n",
 				align, nvdimm_namespace_capacity(ndns));
-		return -EINVAL;
+		return -EOPNOTSUPP;
 	}
 
 	/*
@@ -581,7 +581,7 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
 	if (offset >= resource_size(&nsio->res)) {
 		dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
 				dev_name(&ndns->dev));
-		return -EBUSY;
+		return -EOPNOTSUPP;
 	}
 
 	if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
@@ -589,7 +589,7 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
 		dev_err(&nd_pfn->dev,
 				"bad offset: %#llx dax disabled align: %#lx\n",
 				offset, align);
-		return -ENXIO;
+		return -EOPNOTSUPP;
 	}
 
 	return 0;
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Re: [PATCH v3 2/5] libnvdimm/pfn: Prevent raw mode fallback if pfn-infoblock valid

[Aneesh Kumar K.V]

Dan Williams <dan.j.williams@intel.com> writes:

> The EOPNOTSUPP return code from the pmem driver indicates that the
> namespace has a configuration that may be valid, but the current kernel
> does not support it. Expand this to all of the nd_pfn_validate() error
> conditions after the infoblock has been verified as self consistent.
>
> This prevents exposing the namespace to I/O when the infoblock needs to
> be corrected, or the system needs to be put into a different
> configuration (like changing the page size on PowerPC).
>

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>

> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Cc: Jeff Moyer <jmoyer@redhat.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/nvdimm/pfn_devs.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> index a5c25cb87116..79fe02d6f657 100644
> --- a/drivers/nvdimm/pfn_devs.c
> +++ b/drivers/nvdimm/pfn_devs.c
> @@ -561,14 +561,14 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
>  			dev_dbg(&nd_pfn->dev, "align: %lx:%lx mode: %d:%d\n",
>  					nd_pfn->align, align, nd_pfn->mode,
>  					mode);
> -			return -EINVAL;
> +			return -EOPNOTSUPP;
>  		}
>  	}
>  
>  	if (align > nvdimm_namespace_capacity(ndns)) {
>  		dev_err(&nd_pfn->dev, "alignment: %lx exceeds capacity %llx\n",
>  				align, nvdimm_namespace_capacity(ndns));
> -		return -EINVAL;
> +		return -EOPNOTSUPP;
>  	}
>  
>  	/*
> @@ -581,7 +581,7 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
>  	if (offset >= resource_size(&nsio->res)) {
>  		dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
>  				dev_name(&ndns->dev));
> -		return -EBUSY;
> +		return -EOPNOTSUPP;
>  	}
>  
>  	if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
> @@ -589,7 +589,7 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
>  		dev_err(&nd_pfn->dev,
>  				"bad offset: %#llx dax disabled align: %#lx\n",
>  				offset, align);
> -		return -ENXIO;
> +		return -EOPNOTSUPP;
>  	}
>  
>  	return 0;
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[PATCH v3 3/5] libnvdimm/namespace: Enforce memremap_compat_align()

[Dan Williams]

The pmem driver on PowerPC crashes with the following signature when
instantiating misaligned namespaces that map their capacity via
memremap_pages().

    BUG: Unable to handle kernel data access at 0xc001000406000000
    Faulting instruction address: 0xc000000000090790
    NIP [c000000000090790] arch_add_memory+0xc0/0x130
    LR [c000000000090744] arch_add_memory+0x74/0x130
    Call Trace:
     arch_add_memory+0x74/0x130 (unreliable)
     memremap_pages+0x74c/0xa30
     devm_memremap_pages+0x3c/0xa0
     pmem_attach_disk+0x188/0x770
     nvdimm_bus_probe+0xd8/0x470

With the assumption that only memremap_pages() has alignment
constraints, enforce memremap_compat_align() for
pmem_should_map_pages(), nd_pfn, and nd_dax cases. This includes
preventing the creation of namespaces where the base address is
misaligned and cases there infoblock padding parameters are invalid.

Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Fixes: a3619190d62e ("libnvdimm/pfn: stop padding pmem namespaces to section alignment")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/namespace_devs.c |   12 ++++++++++++
 drivers/nvdimm/pfn_devs.c       |   26 +++++++++++++++++++++++---
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 032dc61725ff..68e89855f779 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -10,6 +10,7 @@
 #include <linux/nd.h>
 #include "nd-core.h"
 #include "pmem.h"
+#include "pfn.h"
 #include "nd.h"
 
 static void namespace_io_release(struct device *dev)
@@ -1739,6 +1740,17 @@ struct nd_namespace_common *nvdimm_namespace_common_probe(struct device *dev)
 		return ERR_PTR(-ENODEV);
 	}
 
+	if (pmem_should_map_pages(dev)) {
+		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
+		struct resource *res = &nsio->res;
+
+		if (!IS_ALIGNED(res->start | (res->end + 1),
+					memremap_compat_align())) {
+			dev_err(&ndns->dev, "%pr misaligned, unable to map\n", res);
+			return ERR_PTR(-EOPNOTSUPP);
+		}
+	}
+
 	if (is_namespace_pmem(&ndns->dev)) {
 		struct nd_namespace_pmem *nspm;
 
diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 79fe02d6f657..3bdd4b883d05 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -446,6 +446,7 @@ static bool nd_supported_alignment(unsigned long align)
 int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
 {
 	u64 checksum, offset;
+	struct resource *res;
 	enum nd_pfn_mode mode;
 	struct nd_namespace_io *nsio;
 	unsigned long align, start_pad;
@@ -578,13 +579,14 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
 	 * established.
 	 */
 	nsio = to_nd_namespace_io(&ndns->dev);
-	if (offset >= resource_size(&nsio->res)) {
+	res = &nsio->res;
+	if (offset >= resource_size(res)) {
 		dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
 				dev_name(&ndns->dev));
 		return -EOPNOTSUPP;
 	}
 
-	if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
+	if ((align && !IS_ALIGNED(res->start + offset + start_pad, align))
 			|| !IS_ALIGNED(offset, PAGE_SIZE)) {
 		dev_err(&nd_pfn->dev,
 				"bad offset: %#llx dax disabled align: %#lx\n",
@@ -592,6 +594,18 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
 		return -EOPNOTSUPP;
 	}
 
+	if (!IS_ALIGNED(res->start + le32_to_cpu(pfn_sb->start_pad),
+				memremap_compat_align())) {
+		dev_err(&nd_pfn->dev, "resource start misaligned\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (!IS_ALIGNED(res->end + 1 - le32_to_cpu(pfn_sb->end_trunc),
+				memremap_compat_align())) {
+		dev_err(&nd_pfn->dev, "resource end misaligned\n");
+		return -EOPNOTSUPP;
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(nd_pfn_validate);
@@ -750,7 +764,13 @@ 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, SUBSECTION_SIZE);
+	align = max(nd_pfn->align, memremap_compat_align());
+	if (!IS_ALIGNED(start, memremap_compat_align())) {
+		dev_err(&nd_pfn->dev, "%s: start %pa misaligned to %#lx\n",
+				dev_name(&ndns->dev), &start,
+				memremap_compat_align());
+		return -EINVAL;
+	}
 	end_trunc = start + size - ALIGN_DOWN(start + size, align);
 	if (nd_pfn->mode == PFN_MODE_PMEM) {
 		/*
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Re: [PATCH v3 3/5] libnvdimm/namespace: Enforce memremap_compat_align()

[Aneesh Kumar K.V]

Dan Williams <dan.j.williams@intel.com> writes:

> The pmem driver on PowerPC crashes with the following signature when
> instantiating misaligned namespaces that map their capacity via
> memremap_pages().
>
>     BUG: Unable to handle kernel data access at 0xc001000406000000
>     Faulting instruction address: 0xc000000000090790
>     NIP [c000000000090790] arch_add_memory+0xc0/0x130
>     LR [c000000000090744] arch_add_memory+0x74/0x130
>     Call Trace:
>      arch_add_memory+0x74/0x130 (unreliable)
>      memremap_pages+0x74c/0xa30
>      devm_memremap_pages+0x3c/0xa0
>      pmem_attach_disk+0x188/0x770
>      nvdimm_bus_probe+0xd8/0x470
>
> With the assumption that only memremap_pages() has alignment
> constraints, enforce memremap_compat_align() for
> pmem_should_map_pages(), nd_pfn, and nd_dax cases. This includes
> preventing the creation of namespaces where the base address is
> misaligned and cases there infoblock padding parameters are invalid.
>

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>

> Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Cc: Jeff Moyer <jmoyer@redhat.com>
> Fixes: a3619190d62e ("libnvdimm/pfn: stop padding pmem namespaces to section alignment")
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/nvdimm/namespace_devs.c |   12 ++++++++++++
>  drivers/nvdimm/pfn_devs.c       |   26 +++++++++++++++++++++++---
>  2 files changed, 35 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
> index 032dc61725ff..68e89855f779 100644
> --- a/drivers/nvdimm/namespace_devs.c
> +++ b/drivers/nvdimm/namespace_devs.c
> @@ -10,6 +10,7 @@
>  #include <linux/nd.h>
>  #include "nd-core.h"
>  #include "pmem.h"
> +#include "pfn.h"
>  #include "nd.h"
>  
>  static void namespace_io_release(struct device *dev)
> @@ -1739,6 +1740,17 @@ struct nd_namespace_common *nvdimm_namespace_common_probe(struct device *dev)
>  		return ERR_PTR(-ENODEV);
>  	}

May be add a comment here that both dax/fsdax namespace details are
checked in nd_pfn_validate() so that we look at start_pad and end_trunc
while validating the namespace?

>  
> +	if (pmem_should_map_pages(dev)) {
> +		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
> +		struct resource *res = &nsio->res;
> +
> +		if (!IS_ALIGNED(res->start | (res->end + 1),
> +					memremap_compat_align())) {
> +			dev_err(&ndns->dev, "%pr misaligned, unable to map\n", res);
> +			return ERR_PTR(-EOPNOTSUPP);
> +		}
> +	}
> +
>  	if (is_namespace_pmem(&ndns->dev)) {
>  		struct nd_namespace_pmem *nspm;
>  
> diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> index 79fe02d6f657..3bdd4b883d05 100644
> --- a/drivers/nvdimm/pfn_devs.c
> +++ b/drivers/nvdimm/pfn_devs.c
> @@ -446,6 +446,7 @@ static bool nd_supported_alignment(unsigned long align)
>  int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
>  {
>  	u64 checksum, offset;
> +	struct resource *res;
>  	enum nd_pfn_mode mode;
>  	struct nd_namespace_io *nsio;
>  	unsigned long align, start_pad;
> @@ -578,13 +579,14 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
>  	 * established.
>  	 */
>  	nsio = to_nd_namespace_io(&ndns->dev);
> -	if (offset >= resource_size(&nsio->res)) {
> +	res = &nsio->res;
> +	if (offset >= resource_size(res)) {
>  		dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
>  				dev_name(&ndns->dev));
>  		return -EOPNOTSUPP;
>  	}
>  
> -	if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
> +	if ((align && !IS_ALIGNED(res->start + offset + start_pad, align))
>  			|| !IS_ALIGNED(offset, PAGE_SIZE)) {
>  		dev_err(&nd_pfn->dev,
>  				"bad offset: %#llx dax disabled align: %#lx\n",
> @@ -592,6 +594,18 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
>  		return -EOPNOTSUPP;
>  	}
>  
> +	if (!IS_ALIGNED(res->start + le32_to_cpu(pfn_sb->start_pad),
> +				memremap_compat_align())) {
> +		dev_err(&nd_pfn->dev, "resource start misaligned\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	if (!IS_ALIGNED(res->end + 1 - le32_to_cpu(pfn_sb->end_trunc),
> +				memremap_compat_align())) {
> +		dev_err(&nd_pfn->dev, "resource end misaligned\n");
> +		return -EOPNOTSUPP;
> +	}
> +
>  	return 0;
>  }
>  EXPORT_SYMBOL(nd_pfn_validate);
> @@ -750,7 +764,13 @@ 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, SUBSECTION_SIZE);
> +	align = max(nd_pfn->align, memremap_compat_align());
> +	if (!IS_ALIGNED(start, memremap_compat_align())) {
> +		dev_err(&nd_pfn->dev, "%s: start %pa misaligned to %#lx\n",
> +				dev_name(&ndns->dev), &start,
> +				memremap_compat_align());
> +		return -EINVAL;
> +	}

This validates start in case of a new namespace creation where the user
updated nd_region->align value? A comment there would help when looking
at the code later?

>  	end_trunc = start + size - ALIGN_DOWN(start + size, align);
>  	if (nd_pfn->mode == PFN_MODE_PMEM) {
>  		/*
> _______________________________________________
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Re: [PATCH v3 3/5] libnvdimm/namespace: Enforce memremap_compat_align()

[Dan Williams]

On Mon, Mar 2, 2020 at 4:09 AM Aneesh Kumar K.V
<aneesh.kumar@linux.ibm.com> wrote:
>
> Dan Williams <dan.j.williams@intel.com> writes:
>
> > The pmem driver on PowerPC crashes with the following signature when
> > instantiating misaligned namespaces that map their capacity via
> > memremap_pages().
> >
> >     BUG: Unable to handle kernel data access at 0xc001000406000000
> >     Faulting instruction address: 0xc000000000090790
> >     NIP [c000000000090790] arch_add_memory+0xc0/0x130
> >     LR [c000000000090744] arch_add_memory+0x74/0x130
> >     Call Trace:
> >      arch_add_memory+0x74/0x130 (unreliable)
> >      memremap_pages+0x74c/0xa30
> >      devm_memremap_pages+0x3c/0xa0
> >      pmem_attach_disk+0x188/0x770
> >      nvdimm_bus_probe+0xd8/0x470
> >
> > With the assumption that only memremap_pages() has alignment
> > constraints, enforce memremap_compat_align() for
> > pmem_should_map_pages(), nd_pfn, and nd_dax cases. This includes
> > preventing the creation of namespaces where the base address is
> > misaligned and cases there infoblock padding parameters are invalid.
> >
>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>
> > Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> > Cc: Jeff Moyer <jmoyer@redhat.com>
> > Fixes: a3619190d62e ("libnvdimm/pfn: stop padding pmem namespaces to section alignment")
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> > ---
> >  drivers/nvdimm/namespace_devs.c |   12 ++++++++++++
> >  drivers/nvdimm/pfn_devs.c       |   26 +++++++++++++++++++++++---
> >  2 files changed, 35 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
> > index 032dc61725ff..68e89855f779 100644
> > --- a/drivers/nvdimm/namespace_devs.c
> > +++ b/drivers/nvdimm/namespace_devs.c
> > @@ -10,6 +10,7 @@
> >  #include <linux/nd.h>
> >  #include "nd-core.h"
> >  #include "pmem.h"
> > +#include "pfn.h"
> >  #include "nd.h"
> >
> >  static void namespace_io_release(struct device *dev)
> > @@ -1739,6 +1740,17 @@ struct nd_namespace_common *nvdimm_namespace_common_probe(struct device *dev)
> >               return ERR_PTR(-ENODEV);
> >       }
>
> May be add a comment here that both dax/fsdax namespace details are
> checked in nd_pfn_validate() so that we look at start_pad and end_trunc
> while validating the namespace?
>
> >
> > +     if (pmem_should_map_pages(dev)) {
> > +             struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
> > +             struct resource *res = &nsio->res;
> > +
> > +             if (!IS_ALIGNED(res->start | (res->end + 1),
> > +                                     memremap_compat_align())) {
> > +                     dev_err(&ndns->dev, "%pr misaligned, unable to map\n", res);
> > +                     return ERR_PTR(-EOPNOTSUPP);
> > +             }
> > +     }
> > +
> >       if (is_namespace_pmem(&ndns->dev)) {
> >               struct nd_namespace_pmem *nspm;
> >
> > diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> > index 79fe02d6f657..3bdd4b883d05 100644
> > --- a/drivers/nvdimm/pfn_devs.c
> > +++ b/drivers/nvdimm/pfn_devs.c
> > @@ -446,6 +446,7 @@ static bool nd_supported_alignment(unsigned long align)
> >  int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
> >  {
> >       u64 checksum, offset;
> > +     struct resource *res;
> >       enum nd_pfn_mode mode;
> >       struct nd_namespace_io *nsio;
> >       unsigned long align, start_pad;
> > @@ -578,13 +579,14 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
> >        * established.
> >        */
> >       nsio = to_nd_namespace_io(&ndns->dev);
> > -     if (offset >= resource_size(&nsio->res)) {
> > +     res = &nsio->res;
> > +     if (offset >= resource_size(res)) {
> >               dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
> >                               dev_name(&ndns->dev));
> >               return -EOPNOTSUPP;
> >       }
> >
> > -     if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
> > +     if ((align && !IS_ALIGNED(res->start + offset + start_pad, align))
> >                       || !IS_ALIGNED(offset, PAGE_SIZE)) {
> >               dev_err(&nd_pfn->dev,
> >                               "bad offset: %#llx dax disabled align: %#lx\n",
> > @@ -592,6 +594,18 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
> >               return -EOPNOTSUPP;
> >       }
> >
> > +     if (!IS_ALIGNED(res->start + le32_to_cpu(pfn_sb->start_pad),
> > +                             memremap_compat_align())) {
> > +             dev_err(&nd_pfn->dev, "resource start misaligned\n");
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> > +     if (!IS_ALIGNED(res->end + 1 - le32_to_cpu(pfn_sb->end_trunc),
> > +                             memremap_compat_align())) {
> > +             dev_err(&nd_pfn->dev, "resource end misaligned\n");
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> >       return 0;
> >  }
> >  EXPORT_SYMBOL(nd_pfn_validate);
> > @@ -750,7 +764,13 @@ 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, SUBSECTION_SIZE);
> > +     align = max(nd_pfn->align, memremap_compat_align());
> > +     if (!IS_ALIGNED(start, memremap_compat_align())) {
> > +             dev_err(&nd_pfn->dev, "%s: start %pa misaligned to %#lx\n",
> > +                             dev_name(&ndns->dev), &start,
> > +                             memremap_compat_align());
> > +             return -EINVAL;
> > +     }
>
> This validates start in case of a new namespace creation where the user
> updated nd_region->align value? A comment there would help when looking
> at the code later?

Yeah, sounds good will respin with those updates.
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[PATCH v3 4/5] libnvdimm/region: Introduce NDD_LABELING

[Dan Williams]

The NDD_ALIASING flag is used to indicate where pmem capacity might
alias with blk capacity and require labeling. It is also used to
indicate whether the DIMM supports labeling. Separate this latter
capability into its own flag so that the NDD_ALIASING flag is scoped to
true aliased configurations.

To my knowledge aliased configurations only exist in the ACPI spec,
there are no known platforms that ship this support in production.

This clarity allows namespace-capacity alignment constraints around
interleave-ways to be relaxed.

Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Link: https://lore.kernel.org/r/158041477856.3889308.4212605617834097674.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/powerpc/platforms/pseries/papr_scm.c |    2 +-
 drivers/acpi/nfit/core.c                  |    4 +++-
 drivers/nvdimm/dimm.c                     |    2 +-
 drivers/nvdimm/dimm_devs.c                |    9 +++++----
 drivers/nvdimm/namespace_devs.c           |    2 +-
 drivers/nvdimm/nd.h                       |    2 +-
 drivers/nvdimm/region_devs.c              |   10 +++++-----
 include/linux/libnvdimm.h                 |    2 ++
 8 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 0b4467e378e5..589858cb3203 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -328,7 +328,7 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 	}
 
 	dimm_flags = 0;
-	set_bit(NDD_ALIASING, &dimm_flags);
+	set_bit(NDD_LABELING, &dimm_flags);
 
 	p->nvdimm = nvdimm_create(p->bus, p, NULL, dimm_flags,
 				  PAPR_SCM_DIMM_CMD_MASK, 0, NULL);
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index a3320f93616d..71d7f2aa1b12 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2026,8 +2026,10 @@ static int acpi_nfit_register_dimms(struct acpi_nfit_desc *acpi_desc)
 			continue;
 		}
 
-		if (nfit_mem->bdw && nfit_mem->memdev_pmem)
+		if (nfit_mem->bdw && nfit_mem->memdev_pmem) {
 			set_bit(NDD_ALIASING, &flags);
+			set_bit(NDD_LABELING, &flags);
+		}
 
 		/* collate flags across all memdevs for this dimm */
 		list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
diff --git a/drivers/nvdimm/dimm.c b/drivers/nvdimm/dimm.c
index 64776ed15bb3..7d4ddc4d9322 100644
--- a/drivers/nvdimm/dimm.c
+++ b/drivers/nvdimm/dimm.c
@@ -99,7 +99,7 @@ static int nvdimm_probe(struct device *dev)
 	if (ndd->ns_current >= 0) {
 		rc = nd_label_reserve_dpa(ndd);
 		if (rc == 0)
-			nvdimm_set_aliasing(dev);
+			nvdimm_set_labeling(dev);
 	}
 	nvdimm_bus_unlock(dev);
 
diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index 94ea6dba6b4f..39a61a514746 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -32,7 +32,7 @@ int nvdimm_check_config_data(struct device *dev)
 
 	if (!nvdimm->cmd_mask ||
 	    !test_bit(ND_CMD_GET_CONFIG_DATA, &nvdimm->cmd_mask)) {
-		if (test_bit(NDD_ALIASING, &nvdimm->flags))
+		if (test_bit(NDD_LABELING, &nvdimm->flags))
 			return -ENXIO;
 		else
 			return -ENOTTY;
@@ -173,11 +173,11 @@ int nvdimm_set_config_data(struct nvdimm_drvdata *ndd, size_t offset,
 	return rc;
 }
 
-void nvdimm_set_aliasing(struct device *dev)
+void nvdimm_set_labeling(struct device *dev)
 {
 	struct nvdimm *nvdimm = to_nvdimm(dev);
 
-	set_bit(NDD_ALIASING, &nvdimm->flags);
+	set_bit(NDD_LABELING, &nvdimm->flags);
 }
 
 void nvdimm_set_locked(struct device *dev)
@@ -312,8 +312,9 @@ static ssize_t flags_show(struct device *dev,
 {
 	struct nvdimm *nvdimm = to_nvdimm(dev);
 
-	return sprintf(buf, "%s%s\n",
+	return sprintf(buf, "%s%s%s\n",
 			test_bit(NDD_ALIASING, &nvdimm->flags) ? "alias " : "",
+			test_bit(NDD_LABELING, &nvdimm->flags) ? "label " : "",
 			test_bit(NDD_LOCKED, &nvdimm->flags) ? "lock " : "");
 }
 static DEVICE_ATTR_RO(flags);
diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 68e89855f779..2388598ce1a2 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -2533,7 +2533,7 @@ static int init_active_labels(struct nd_region *nd_region)
 		if (!ndd) {
 			if (test_bit(NDD_LOCKED, &nvdimm->flags))
 				/* fail, label data may be unreadable */;
-			else if (test_bit(NDD_ALIASING, &nvdimm->flags))
+			else if (test_bit(NDD_LABELING, &nvdimm->flags))
 				/* fail, labels needed to disambiguate dpa */;
 			else
 				return 0;
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index c9f6a5b5253a..ca39abe29c7c 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -252,7 +252,7 @@ int nvdimm_set_config_data(struct nvdimm_drvdata *ndd, size_t offset,
 		void *buf, size_t len);
 long nvdimm_clear_poison(struct device *dev, phys_addr_t phys,
 		unsigned int len);
-void nvdimm_set_aliasing(struct device *dev);
+void nvdimm_set_labeling(struct device *dev);
 void nvdimm_set_locked(struct device *dev);
 void nvdimm_clear_locked(struct device *dev);
 int nvdimm_security_setup_events(struct device *dev);
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index a19e535830d9..a5fc6e4c56ff 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -195,16 +195,16 @@ EXPORT_SYMBOL_GPL(nd_blk_region_set_provider_data);
 int nd_region_to_nstype(struct nd_region *nd_region)
 {
 	if (is_memory(&nd_region->dev)) {
-		u16 i, alias;
+		u16 i, label;
 
-		for (i = 0, alias = 0; i < nd_region->ndr_mappings; i++) {
+		for (i = 0, label = 0; i < nd_region->ndr_mappings; i++) {
 			struct nd_mapping *nd_mapping = &nd_region->mapping[i];
 			struct nvdimm *nvdimm = nd_mapping->nvdimm;
 
-			if (test_bit(NDD_ALIASING, &nvdimm->flags))
-				alias++;
+			if (test_bit(NDD_LABELING, &nvdimm->flags))
+				label++;
 		}
-		if (alias)
+		if (label)
 			return ND_DEVICE_NAMESPACE_PMEM;
 		else
 			return ND_DEVICE_NAMESPACE_IO;
diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index 9df091bd30ba..18da4059be09 100644
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -37,6 +37,8 @@ enum {
 	NDD_WORK_PENDING = 4,
 	/* ignore / filter NSLABEL_FLAG_LOCAL for this DIMM, i.e. no aliasing */
 	NDD_NOBLK = 5,
+	/* dimm supports namespace labels */
+	NDD_LABELING = 6,
 
 	/* need to set a limit somewhere, but yes, this is likely overkill */
 	ND_IOCTL_MAX_BUFLEN = SZ_4M,
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[PATCH v3 5/5] libnvdimm/region: Introduce an 'align' attribute

[Dan Williams]

The align attribute applies an alignment constraint for namespace
creation in a region. Whereas the 'align' attribute of a namespace
applied alignment padding via an info block, the 'align' attribute
applies alignment constraints to the free space allocation.

The default for 'align' is the maximum known memremap_compat_align()
across all archs (16MiB from PowerPC at time of writing) multiplied by
the number of interleave ways if there is blk-aliasing. The minimum is
PAGE_SIZE and allows for the creation of cross-arch incompatible
namespaces, just as previous kernels allowed, but the expectation is
cross-arch and mode-independent compatibility by default.

The regression risk with this change is limited to cases that were
dependent on the ability to create unaligned namespaces, *and* for some
reason are unable to opt-out of aligned namespaces by writing to
'regionX/align'. If such a scenario arises the default can be flipped
from opt-out to opt-in of compat-aligned namespace creation, but that is
a last resort. The kernel will otherwise continue to support existing
defined misaligned namespaces.

Unfortunately this change needs to touch several parts of the
implementation at once:

- region/available_size: expand busy extents to current align
- region/max_available_extent: expand busy extents to current align
- namespace/size: trim free space to current align

...to keep the free space accounting conforming to the dynamic align
setting.

Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Link: https://lore.kernel.org/r/158041478371.3889308.14542630147672668068.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/dimm_devs.c      |   86 +++++++++++++++++++++++----
 drivers/nvdimm/namespace_devs.c |    9 ++-
 drivers/nvdimm/nd.h             |    1 
 drivers/nvdimm/region_devs.c    |  122 ++++++++++++++++++++++++++++++++++++---
 4 files changed, 192 insertions(+), 26 deletions(-)

diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index 39a61a514746..b7b77e8d9027 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -563,6 +563,21 @@ int nvdimm_security_freeze(struct nvdimm *nvdimm)
 	return rc;
 }
 
+static unsigned long dpa_align(struct nd_region *nd_region)
+{
+	struct device *dev = &nd_region->dev;
+
+	if (dev_WARN_ONCE(dev, !is_nvdimm_bus_locked(dev),
+				"bus lock required for capacity provision\n"))
+		return 0;
+	if (dev_WARN_ONCE(dev, !nd_region->ndr_mappings || nd_region->align
+				% nd_region->ndr_mappings,
+				"invalid region align %#lx mappings: %d\n",
+				nd_region->align, nd_region->ndr_mappings))
+		return 0;
+	return nd_region->align / nd_region->ndr_mappings;
+}
+
 int alias_dpa_busy(struct device *dev, void *data)
 {
 	resource_size_t map_end, blk_start, new;
@@ -571,6 +586,7 @@ int alias_dpa_busy(struct device *dev, void *data)
 	struct nd_region *nd_region;
 	struct nvdimm_drvdata *ndd;
 	struct resource *res;
+	unsigned long align;
 	int i;
 
 	if (!is_memory(dev))
@@ -608,13 +624,21 @@ int alias_dpa_busy(struct device *dev, void *data)
 	 * Find the free dpa from the end of the last pmem allocation to
 	 * the end of the interleave-set mapping.
 	 */
+	align = dpa_align(nd_region);
+	if (!align)
+		return 0;
+
 	for_each_dpa_resource(ndd, res) {
+		resource_size_t start, end;
+
 		if (strncmp(res->name, "pmem", 4) != 0)
 			continue;
-		if ((res->start >= blk_start && res->start < map_end)
-				|| (res->end >= blk_start
-					&& res->end <= map_end)) {
-			new = max(blk_start, min(map_end + 1, res->end + 1));
+
+		start = ALIGN_DOWN(res->start, align);
+		end = ALIGN(res->end + 1, align) - 1;
+		if ((start >= blk_start && start < map_end)
+				|| (end >= blk_start && end <= map_end)) {
+			new = max(blk_start, min(map_end, end) + 1);
 			if (new != blk_start) {
 				blk_start = new;
 				goto retry;
@@ -654,6 +678,7 @@ resource_size_t nd_blk_available_dpa(struct nd_region *nd_region)
 		.res = NULL,
 	};
 	struct resource *res;
+	unsigned long align;
 
 	if (!ndd)
 		return 0;
@@ -661,10 +686,20 @@ resource_size_t nd_blk_available_dpa(struct nd_region *nd_region)
 	device_for_each_child(&nvdimm_bus->dev, &info, alias_dpa_busy);
 
 	/* now account for busy blk allocations in unaliased dpa */
+	align = dpa_align(nd_region);
+	if (!align)
+		return 0;
 	for_each_dpa_resource(ndd, res) {
+		resource_size_t start, end, size;
+
 		if (strncmp(res->name, "blk", 3) != 0)
 			continue;
-		info.available -= resource_size(res);
+		start = ALIGN_DOWN(res->start, align);
+		end = ALIGN(res->end + 1, align) - 1;
+		size = end - start + 1;
+		if (size >= info.available)
+			return 0;
+		info.available -= size;
 	}
 
 	return info.available;
@@ -683,19 +718,31 @@ resource_size_t nd_pmem_max_contiguous_dpa(struct nd_region *nd_region,
 	struct nvdimm_bus *nvdimm_bus;
 	resource_size_t max = 0;
 	struct resource *res;
+	unsigned long align;
 
 	/* if a dimm is disabled the available capacity is zero */
 	if (!ndd)
 		return 0;
 
+	align = dpa_align(nd_region);
+	if (!align)
+		return 0;
+
 	nvdimm_bus = walk_to_nvdimm_bus(ndd->dev);
 	if (__reserve_free_pmem(&nd_region->dev, nd_mapping->nvdimm))
 		return 0;
 	for_each_dpa_resource(ndd, res) {
+		resource_size_t start, end;
+
 		if (strcmp(res->name, "pmem-reserve") != 0)
 			continue;
-		if (resource_size(res) > max)
-			max = resource_size(res);
+		/* trim free space relative to current alignment setting */
+		start = ALIGN(res->start, align);
+		end = ALIGN_DOWN(res->end + 1, align) - 1;
+		if (end < start)
+			continue;
+		if (end - start + 1 > max)
+			max = end - start + 1;
 	}
 	release_free_pmem(nvdimm_bus, nd_mapping);
 	return max;
@@ -723,24 +770,33 @@ resource_size_t nd_pmem_available_dpa(struct nd_region *nd_region,
 	struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
 	struct resource *res;
 	const char *reason;
+	unsigned long align;
 
 	if (!ndd)
 		return 0;
 
+	align = dpa_align(nd_region);
+	if (!align)
+		return 0;
+
 	map_start = nd_mapping->start;
 	map_end = map_start + nd_mapping->size - 1;
 	blk_start = max(map_start, map_end + 1 - *overlap);
 	for_each_dpa_resource(ndd, res) {
-		if (res->start >= map_start && res->start < map_end) {
+		resource_size_t start, end;
+
+		start = ALIGN_DOWN(res->start, align);
+		end = ALIGN(res->end + 1, align) - 1;
+		if (start >= map_start && start < map_end) {
 			if (strncmp(res->name, "blk", 3) == 0)
 				blk_start = min(blk_start,
-						max(map_start, res->start));
-			else if (res->end > map_end) {
+						max(map_start, start));
+			else if (end > map_end) {
 				reason = "misaligned to iset";
 				goto err;
 			} else
-				busy += resource_size(res);
-		} else if (res->end >= map_start && res->end <= map_end) {
+				busy += end - start + 1;
+		} else if (end >= map_start && end <= map_end) {
 			if (strncmp(res->name, "blk", 3) == 0) {
 				/*
 				 * If a BLK allocation overlaps the start of
@@ -749,8 +805,8 @@ resource_size_t nd_pmem_available_dpa(struct nd_region *nd_region,
 				 */
 				blk_start = map_start;
 			} else
-				busy += resource_size(res);
-		} else if (map_start > res->start && map_start < res->end) {
+				busy += end - start + 1;
+		} else if (map_start > start && map_start < end) {
 			/* total eclipse of the mapping */
 			busy += nd_mapping->size;
 			blk_start = map_start;
@@ -760,7 +816,7 @@ resource_size_t nd_pmem_available_dpa(struct nd_region *nd_region,
 	*overlap = map_end + 1 - blk_start;
 	available = blk_start - map_start;
 	if (busy < available)
-		return available - busy;
+		return ALIGN_DOWN(available - busy, align);
 	return 0;
 
  err:
diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 2388598ce1a2..23b373bb31b3 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -542,6 +542,11 @@ static void space_valid(struct nd_region *nd_region, struct nvdimm_drvdata *ndd,
 {
 	bool is_reserve = strcmp(label_id->id, "pmem-reserve") == 0;
 	bool is_pmem = strncmp(label_id->id, "pmem", 4) == 0;
+	unsigned long align;
+
+	align = nd_region->align / nd_region->ndr_mappings;
+	valid->start = ALIGN(valid->start, align);
+	valid->end = ALIGN_DOWN(valid->end + 1, align) - 1;
 
 	if (valid->start >= valid->end)
 		goto invalid;
@@ -981,10 +986,10 @@ static ssize_t __size_store(struct device *dev, unsigned long long val)
 		return -ENXIO;
 	}
 
-	div_u64_rem(val, PAGE_SIZE * nd_region->ndr_mappings, &remainder);
+	div_u64_rem(val, nd_region->align, &remainder);
 	if (remainder) {
 		dev_dbg(dev, "%llu is not %ldK aligned\n", val,
-				(PAGE_SIZE * nd_region->ndr_mappings) / SZ_1K);
+				nd_region->align / SZ_1K);
 		return -EINVAL;
 	}
 
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index ca39abe29c7c..c4d69c1cce55 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -146,6 +146,7 @@ struct nd_region {
 	struct device *btt_seed;
 	struct device *pfn_seed;
 	struct device *dax_seed;
+	unsigned long align;
 	u16 ndr_mappings;
 	u64 ndr_size;
 	u64 ndr_start;
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index a5fc6e4c56ff..bf239e783940 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -216,21 +216,25 @@ int nd_region_to_nstype(struct nd_region *nd_region)
 }
 EXPORT_SYMBOL(nd_region_to_nstype);
 
-static ssize_t size_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
+static unsigned long long region_size(struct nd_region *nd_region)
 {
-	struct nd_region *nd_region = to_nd_region(dev);
-	unsigned long long size = 0;
-
-	if (is_memory(dev)) {
-		size = nd_region->ndr_size;
+	if (is_memory(&nd_region->dev)) {
+		return nd_region->ndr_size;
 	} else if (nd_region->ndr_mappings == 1) {
 		struct nd_mapping *nd_mapping = &nd_region->mapping[0];
 
-		size = nd_mapping->size;
+		return nd_mapping->size;
 	}
 
-	return sprintf(buf, "%llu\n", size);
+	return 0;
+}
+
+static ssize_t size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_region *nd_region = to_nd_region(dev);
+
+	return sprintf(buf, "%llu\n", region_size(nd_region));
 }
 static DEVICE_ATTR_RO(size);
 
@@ -529,6 +533,55 @@ static ssize_t read_only_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(read_only);
 
+static ssize_t align_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_region *nd_region = to_nd_region(dev);
+
+	return sprintf(buf, "%#lx\n", nd_region->align);
+}
+
+static ssize_t align_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct nd_region *nd_region = to_nd_region(dev);
+	unsigned long val, dpa;
+	u32 remainder;
+	int rc;
+
+	rc = kstrtoul(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	if (!nd_region->ndr_mappings)
+		return -ENXIO;
+
+	/*
+	 * Ensure space-align is evenly divisible by the region
+	 * interleave-width because the kernel typically has no facility
+	 * to determine which DIMM(s), dimm-physical-addresses, would
+	 * contribute to the tail capacity in system-physical-address
+	 * space for the namespace.
+	 */
+	dpa = val;
+	remainder = do_div(dpa, nd_region->ndr_mappings);
+	if (!is_power_of_2(dpa) || dpa < PAGE_SIZE
+			|| val > region_size(nd_region) || remainder)
+		return -EINVAL;
+
+	/*
+	 * Given that space allocation consults this value multiple
+	 * times ensure it does not change for the duration of the
+	 * allocation.
+	 */
+	nvdimm_bus_lock(dev);
+	nd_region->align = val;
+	nvdimm_bus_unlock(dev);
+
+	return len;
+}
+static DEVICE_ATTR_RW(align);
+
 static ssize_t region_badblocks_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
@@ -571,6 +624,7 @@ static DEVICE_ATTR_RO(persistence_domain);
 
 static struct attribute *nd_region_attributes[] = {
 	&dev_attr_size.attr,
+	&dev_attr_align.attr,
 	&dev_attr_nstype.attr,
 	&dev_attr_mappings.attr,
 	&dev_attr_btt_seed.attr,
@@ -626,6 +680,19 @@ static umode_t region_visible(struct kobject *kobj, struct attribute *a, int n)
 		return a->mode;
 	}
 
+	if (a == &dev_attr_align.attr) {
+		int i;
+
+		for (i = 0; i < nd_region->ndr_mappings; i++) {
+			struct nd_mapping *nd_mapping = &nd_region->mapping[i];
+			struct nvdimm *nvdimm = nd_mapping->nvdimm;
+
+			if (test_bit(NDD_LABELING, &nvdimm->flags))
+				return a->mode;
+		}
+		return 0;
+	}
+
 	if (a != &dev_attr_set_cookie.attr
 			&& a != &dev_attr_available_size.attr)
 		return a->mode;
@@ -935,6 +1002,42 @@ void nd_region_release_lane(struct nd_region *nd_region, unsigned int lane)
 }
 EXPORT_SYMBOL(nd_region_release_lane);
 
+/*
+ * PowerPC requires this alignment for memremap_pages(). All other archs
+ * should be ok with SUBSECTION_SIZE (see memremap_compat_align()).
+ */
+#define MEMREMAP_COMPAT_ALIGN_MAX SZ_16M
+
+static unsigned long default_align(struct nd_region *nd_region)
+{
+	unsigned long align, per_mapping;
+	int i, mappings;
+	u32 remainder;
+
+	if (is_nd_blk(&nd_region->dev))
+		align = PAGE_SIZE;
+	else
+		align = MEMREMAP_COMPAT_ALIGN_MAX;
+
+	for (i = 0; i < nd_region->ndr_mappings; i++) {
+		struct nd_mapping *nd_mapping = &nd_region->mapping[i];
+		struct nvdimm *nvdimm = nd_mapping->nvdimm;
+
+		if (test_bit(NDD_ALIASING, &nvdimm->flags)) {
+			align = MEMREMAP_COMPAT_ALIGN_MAX;
+			break;
+		}
+	}
+
+	mappings = max_t(u16, 1, nd_region->ndr_mappings);
+	per_mapping = align;
+	remainder = do_div(per_mapping, mappings);
+	if (remainder)
+		align *= mappings;
+
+	return align;
+}
+
 static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
 		struct nd_region_desc *ndr_desc,
 		const struct device_type *dev_type, const char *caller)
@@ -1039,6 +1142,7 @@ static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
 	dev->of_node = ndr_desc->of_node;
 	nd_region->ndr_size = resource_size(ndr_desc->res);
 	nd_region->ndr_start = ndr_desc->res->start;
+	nd_region->align = default_align(nd_region);
 	if (ndr_desc->flush)
 		nd_region->flush = ndr_desc->flush;
 	else
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