mm/memblock: expose only miminal interface to add/walk physmem

"physmem" in the memblock allocator is somewhat weird: it's not actually
used for allocation, it's simply information collected during boot, which
describes the unmodified physical memory map at boot time, without any
standby/hotplugged memory. It's only used on s390 and is currently the
only reason s390 keeps using CONFIG_ARCH_KEEP_MEMBLOCK.

Physmem isn't numa aware and current users don't specify any flags. Let's
hide it from the user, exposing only for_each_physmem(), and simplify. The
interface for physmem is now really minimalistic:
- memblock_physmem_add() to add ranges
- for_each_physmem() / __next_physmem_range() to walk physmem ranges

Don't place it into an __init section and don't discard it without
CONFIG_ARCH_KEEP_MEMBLOCK. As we're reusing __next_mem_range(), remove
the __meminit notifier to avoid section mismatch warnings once
CONFIG_ARCH_KEEP_MEMBLOCK is no longer used with
CONFIG_HAVE_MEMBLOCK_PHYS_MAP.

While fixing up the documentation, sneak in some related cleanups. We can
stop setting CONFIG_ARCH_KEEP_MEMBLOCK for s390 next.

Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Message-Id: <20200701141830.18749-2-david@redhat.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 24 insertions, 4 deletions

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 017fae833d4a..9d925db0d355 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -77,16 +77,12 @@ struct memblock_type {
  * @current_limit: physical address of the current allocation limit
  * @memory: usable memory regions
  * @reserved: reserved memory regions
- * @physmem: all physical memory
  */
 struct memblock {
 	bool bottom_up;  /* is bottom up direction? */
 	phys_addr_t current_limit;
 	struct memblock_type memory;
 	struct memblock_type reserved;
-#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
-	struct memblock_type physmem;
-#endif
 };
 
 extern struct memblock memblock;
@@ -145,6 +141,30 @@ void __next_reserved_mem_region(u64 *idx, phys_addr_t *out_start,
 
 void __memblock_free_late(phys_addr_t base, phys_addr_t size);
 
+#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
+static inline void __next_physmem_range(u64 *idx, struct memblock_type *type,
+					phys_addr_t *out_start,
+					phys_addr_t *out_end)
+{
+	extern struct memblock_type physmem;
+
+	__next_mem_range(idx, NUMA_NO_NODE, MEMBLOCK_NONE, &physmem, type,
+			 out_start, out_end, NULL);
+}
+
+/**
+ * for_each_physmem_range - iterate through physmem areas not included in type.
+ * @i: u64 used as loop variable
+ * @type: ptr to memblock_type which excludes from the iteration, can be %NULL
+ * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ */
+#define for_each_physmem_range(i, type, p_start, p_end)			\
+	for (i = 0, __next_physmem_range(&i, type, p_start, p_end);	\
+	     i != (u64)ULLONG_MAX;					\
+	     __next_physmem_range(&i, type, p_start, p_end))
+#endif /* CONFIG_HAVE_MEMBLOCK_PHYS_MAP */
+
 /**
  * for_each_mem_range - iterate through memblock areas from type_a and not
  * included in type_b. Or just type_a if type_b is NULL.