Commit ae86cbfe authored by Dan Williams's avatar Dan Williams
Browse files

libnvdimm, pfn: Pad pfn namespaces relative to other regions 

Commit cfe30b87 "libnvdimm, pmem: adjust for section collisions with
'System RAM'" enabled Linux to workaround occasions where platform
firmware arranges for "System RAM" and "Persistent Memory" to collide
within a single section boundary. Unfortunately, as reported in this
issue [1], platform firmware can inflict the same collision between
persistent memory regions.

The approach of interrogating iomem_resource does not work in this
case because platform firmware may merge multiple regions into a single
iomem_resource range. Instead provide a method to interrogate regions
that share the same parent bus.

This is a stop-gap until the core-MM can grow support for hotplug on
sub-section boundaries.

[1]: https://github.com/pmem/ndctl/issues/76



Fixes: cfe30b87 ("libnvdimm, pmem: adjust for section collisions with...")
Cc: <stable@vger.kernel.org>
Reported-by: default avatarPatrick Geary <patrickg@supermicro.com>
Tested-by: default avatarPatrick Geary <patrickg@supermicro.com>
Reviewed-by: default avatarVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent e3f5df76

drivers/nvdimm/nd-core.h

+2 −0
Original line number Diff line number Diff line
@@ -111,6 +111,8 @@ resource_size_t nd_pmem_available_dpa(struct nd_region *nd_region, 
		struct nd_mapping *nd_mapping, resource_size_t *overlap);

resource_size_t nd_blk_available_dpa(struct nd_region *nd_region);

resource_size_t nd_region_available_dpa(struct nd_region *nd_region);

int nd_region_conflict(struct nd_region *nd_region, resource_size_t start,

		resource_size_t size);

resource_size_t nvdimm_allocated_dpa(struct nvdimm_drvdata *ndd,

		struct nd_label_id *label_id);

int alias_dpa_busy(struct device *dev, void *data);

drivers/nvdimm/pfn_devs.c

+37 −27
Original line number Diff line number Diff line
@@ -649,14 +649,47 @@ static u64 phys_pmem_align_down(struct nd_pfn *nd_pfn, u64 phys) 
			ALIGN_DOWN(phys, nd_pfn->align));

}



/*

 * Check if pmem collides with 'System RAM', or other regions when

 * section aligned.  Trim it accordingly.

 */

static void trim_pfn_device(struct nd_pfn *nd_pfn, u32 *start_pad, u32 *end_trunc)

{

	struct nd_namespace_common *ndns = nd_pfn->ndns;

	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

	struct nd_region *nd_region = to_nd_region(nd_pfn->dev.parent);

	const resource_size_t start = nsio->res.start;

	const resource_size_t end = start + resource_size(&nsio->res);

	resource_size_t adjust, size;



	*start_pad = 0;

	*end_trunc = 0;



	adjust = start - PHYS_SECTION_ALIGN_DOWN(start);

	size = resource_size(&nsio->res) + adjust;

	if (region_intersects(start - adjust, size, IORESOURCE_SYSTEM_RAM,

				IORES_DESC_NONE) == REGION_MIXED

			|| nd_region_conflict(nd_region, start - adjust, size))

		*start_pad = PHYS_SECTION_ALIGN_UP(start) - start;



	/* Now check that end of the range does not collide. */

	adjust = PHYS_SECTION_ALIGN_UP(end) - end;

	size = resource_size(&nsio->res) + adjust;

	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,

				IORES_DESC_NONE) == REGION_MIXED

			|| !IS_ALIGNED(end, nd_pfn->align)

			|| nd_region_conflict(nd_region, start, size + adjust))

		*end_trunc = end - phys_pmem_align_down(nd_pfn, end);

}



static int nd_pfn_init(struct nd_pfn *nd_pfn)

{

	u32 dax_label_reserve = is_nd_dax(&nd_pfn->dev) ? SZ_128K : 0;

	struct nd_namespace_common *ndns = nd_pfn->ndns;

	u32 start_pad = 0, end_trunc = 0;

	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

	resource_size_t start, size;

	struct nd_namespace_io *nsio;

	struct nd_region *nd_region;

	u32 start_pad, end_trunc;

	struct nd_pfn_sb *pfn_sb;

	unsigned long npfns;

	phys_addr_t offset;
@@ -688,30 +721,7 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn) 


	memset(pfn_sb, 0, sizeof(*pfn_sb));



	/*

	 * Check if pmem collides with 'System RAM' when section aligned and

	 * trim it accordingly

	 */

	nsio = to_nd_namespace_io(&ndns->dev);

	start = PHYS_SECTION_ALIGN_DOWN(nsio->res.start);

	size = resource_size(&nsio->res);

	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,

				IORES_DESC_NONE) == REGION_MIXED) {

		start = nsio->res.start;

		start_pad = PHYS_SECTION_ALIGN_UP(start) - start;

	}



	start = nsio->res.start;

	size = PHYS_SECTION_ALIGN_UP(start + size) - start;

	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,

				IORES_DESC_NONE) == REGION_MIXED

			|| !IS_ALIGNED(start + resource_size(&nsio->res),

				nd_pfn->align)) {

		size = resource_size(&nsio->res);

		end_trunc = start + size - phys_pmem_align_down(nd_pfn,

				start + size);

	}



	trim_pfn_device(nd_pfn, &start_pad, &end_trunc);

	if (start_pad + end_trunc)

		dev_info(&nd_pfn->dev, "%s alignment collision, truncate %d bytes\n",

				dev_name(&ndns->dev), start_pad + end_trunc);
@@ -722,7 +732,7 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn) 
	 * implementation will limit the pfns advertised through

	 * ->direct_access() to those that are included in the memmap.

	 */

	start += start_pad;

	start = nsio->res.start + start_pad;

	size = resource_size(&nsio->res);

	npfns = PFN_SECTION_ALIGN_UP((size - start_pad - end_trunc - SZ_8K)

			/ PAGE_SIZE);

drivers/nvdimm/region_devs.c

+41 −0
Original line number Diff line number Diff line
@@ -1184,6 +1184,47 @@ int nvdimm_has_cache(struct nd_region *nd_region) 
}

EXPORT_SYMBOL_GPL(nvdimm_has_cache);



struct conflict_context {

	struct nd_region *nd_region;

	resource_size_t start, size;

};



static int region_conflict(struct device *dev, void *data)

{

	struct nd_region *nd_region;

	struct conflict_context *ctx = data;

	resource_size_t res_end, region_end, region_start;



	if (!is_memory(dev))

		return 0;



	nd_region = to_nd_region(dev);

	if (nd_region == ctx->nd_region)

		return 0;



	res_end = ctx->start + ctx->size;

	region_start = nd_region->ndr_start;

	region_end = region_start + nd_region->ndr_size;

	if (ctx->start >= region_start && ctx->start < region_end)

		return -EBUSY;

	if (res_end > region_start && res_end <= region_end)

		return -EBUSY;

	return 0;

}



int nd_region_conflict(struct nd_region *nd_region, resource_size_t start,

		resource_size_t size)

{

	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&nd_region->dev);

	struct conflict_context ctx = {

		.nd_region = nd_region,

		.start = start,

		.size = size,

	};



	return device_for_each_child(&nvdimm_bus->dev, &ctx, region_conflict);

}



void __exit nd_region_devs_exit(void)

{

	ida_destroy(&region_ida);

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