[PATCH 4.14 62/67] libnvdimm, pfn: Pad pfn namespaces relative to other regions

Greg Kroah-Hartman
2018-12-11T16:08:00Z

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

commit ae86cbfef3818300f1972e52f67a93211acb0e24 upstream.

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>
Reported-by: Patrick Geary <patrickg@supermicro.com>
Tested-by: Patrick Geary <patrickg@supermicro.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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(-)

--- a/drivers/nvdimm/nd-core.h
+++ b/drivers/nvdimm/nd-core.h
@@ -105,6 +105,8 @@ resource_size_t nd_pmem_available_dpa(st
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);
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -589,14 +589,47 @@ static u64 phys_pmem_align_down(struct n
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;
@@ -628,30 +661,7 @@ static int nd_pfn_init(struct nd_pfn *nd

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);
@@ -662,7 +672,7 @@ static int nd_pfn_init(struct nd_pfn *nd
* 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);
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1112,6 +1112,47 @@ int nvdimm_has_cache(struct nd_region *n
}
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);