libnvdimm, pmem: fix 'pfn' support for section-misaligned namespaces

The altmap for a section-misaligned namespace needs to arrange for the
base_pfn to be section-aligned.  As a result the 'reserve' region (pfns
from base that do not have a struct page) must be increased.  Otherwise
we trip the altmap validation check in __add_pages:

	if (altmap->base_pfn != phys_start_pfn
			|| vmem_altmap_offset(altmap) > nr_pages) {
		pr_warn_once("memory add fail, invalid altmap\n");
		return -EINVAL;
	}

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/nvdimm/pfn.h b/drivers/nvdimm/pfn.h
index cc243754acef..6ee707e5b279 100644
--- a/drivers/nvdimm/pfn.h
+++ b/drivers/nvdimm/pfn.h
@@ -15,6 +15,7 @@
 #define __NVDIMM_PFN_H
 
 #include <linux/types.h>
+#include <linux/mmzone.h>
 
 #define PFN_SIG_LEN 16
 #define PFN_SIG "NVDIMM_PFN_INFO\0"
@@ -32,4 +33,16 @@ struct nd_pfn_sb {
         u8 padding[4012];
         __le64 checksum;
 };
+
+#ifdef CONFIG_SPARSEMEM
+#define PFN_SECTION_ALIGN_DOWN(x) SECTION_ALIGN_DOWN(x)
+#define PFN_SECTION_ALIGN_UP(x) SECTION_ALIGN_UP(x)
+#else
+/*
+ * In this case ZONE_DEVICE=n and we will disable 'pfn' device support,
+ * but we still want pmem to compile.
+ */
+#define PFN_SECTION_ALIGN_DOWN(x) (x)
+#define PFN_SECTION_ALIGN_UP(x) (x)
+#endif
 #endif /* __NVDIMM_PFN_H */