Commit cfe30b872058 "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: cfe30b872058 ("libnvdimm, pmem: adjust for section collisions with...") Cc: stable@vger.kernel.org Signed-off-by: Dan Williams dan.j.williams@intel.com --- drivers/nvdimm/nd-core.h | 2 + drivers/nvdimm/pfn_devs.c | 64 ++++++++++++++++++++++++------------------ drivers/nvdimm/region_devs.c | 41 +++++++++++++++++++++++++++ 3 files changed, 80 insertions(+), 27 deletions(-)

diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h index 182258f64417..d0c621b32f72 100644 --- a/drivers/nvdimm/nd-core.h +++ b/drivers/nvdimm/nd-core.h @@ -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); diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c index 24c64090169e..6f22272e8d80 100644 --- a/drivers/nvdimm/pfn_devs.c +++ b/drivers/nvdimm/pfn_devs.c @@ -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); diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index 174a418cb171..e7377f1028ef 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -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);