[PATCH] libnvdimm, e820: Register all pmem resources

From: Dan Williams
Date: Sat Jun 02 2018 - 15:29:11 EST


There is currently a mismatch between the resources that will trigger
the e820_pmem driver to register/load and the resources that will
actually be surfaced as pmem ranges. register_e820_pmem() uses
walk_iomem_res_desc() which includes children and siblings. In contrast,
e820_pmem_probe() only considers top level resources. For example the
following resource tree results in the driver being loaded, but no
resources being registered:

398000000000-39bfffffffff : PCI Bus 0000:ae
39be00000000-39bf07ffffff : PCI Bus 0000:af
39be00000000-39beffffffff : 0000:af:00.0
39be10000000-39beffffffff : Persistent Memory (legacy)

Fix this up to allow definitions of "legacy" pmem ranges anywhere in
system-physical address space. Not that it is a recommended or safe to
define a pmem range in PCI space, but it is useful for debug /
experimentation, and the restriction on being a top-level resource was
arbitrary.

Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/nvdimm/e820.c | 41 ++++++++++++++++++++++-------------------
kernel/resource.c | 1 +
2 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/drivers/nvdimm/e820.c b/drivers/nvdimm/e820.c
index 6f9a6ffd7cde..521eaf53a52a 100644
--- a/drivers/nvdimm/e820.c
+++ b/drivers/nvdimm/e820.c
@@ -38,12 +38,27 @@ static int e820_range_to_nid(resource_size_t addr)
}
#endif

+static int e820_register_one(struct resource *res, void *data)
+{
+ struct nd_region_desc ndr_desc;
+ struct nvdimm_bus *nvdimm_bus = data;
+
+ memset(&ndr_desc, 0, sizeof(ndr_desc));
+ ndr_desc.res = res;
+ ndr_desc.attr_groups = e820_pmem_region_attribute_groups;
+ ndr_desc.numa_node = e820_range_to_nid(res->start);
+ set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
+ if (!nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc))
+ return -ENXIO;
+ return 0;
+}
+
static int e820_pmem_probe(struct platform_device *pdev)
{
static struct nvdimm_bus_descriptor nd_desc;
struct device *dev = &pdev->dev;
struct nvdimm_bus *nvdimm_bus;
- struct resource *p;
+ int rc = -ENXIO;

nd_desc.attr_groups = e820_pmem_attribute_groups;
nd_desc.provider_name = "e820";
@@ -53,27 +68,15 @@ static int e820_pmem_probe(struct platform_device *pdev)
goto err;
platform_set_drvdata(pdev, nvdimm_bus);

- for (p = iomem_resource.child; p ; p = p->sibling) {
- struct nd_region_desc ndr_desc;
-
- if (p->desc != IORES_DESC_PERSISTENT_MEMORY_LEGACY)
- continue;
-
- memset(&ndr_desc, 0, sizeof(ndr_desc));
- ndr_desc.res = p;
- ndr_desc.attr_groups = e820_pmem_region_attribute_groups;
- ndr_desc.numa_node = e820_range_to_nid(p->start);
- set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
- if (!nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc))
- goto err;
- }
-
+ rc = walk_iomem_res_desc(IORES_DESC_PERSISTENT_MEMORY_LEGACY,
+ IORESOURCE_MEM, 0, -1, nvdimm_bus, e820_register_one);
+ if (rc)
+ goto err;
return 0;
-
- err:
+err:
nvdimm_bus_unregister(nvdimm_bus);
dev_err(dev, "failed to register legacy persistent memory ranges\n");
- return -ENXIO;
+ return rc;
}

static struct platform_driver e820_pmem_driver = {
diff --git a/kernel/resource.c b/kernel/resource.c
index 2af6c03858b9..b85f59e8a4b8 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -448,6 +448,7 @@ int walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start,

return __walk_iomem_res_desc(&res, desc, false, arg, func);
}
+EXPORT_SYMBOL_GPL(walk_iomem_res_desc);

/*
* This function calls the @func callback against all memory ranges of type