x86, memblock: Add memblock_x86_register_active_regions() and memblock_x86_hole_size()

memblock_x86_register_active_regions() will be used to fill early_node_map,
the result will be memblock.memory.region AND numa data

memblock_x86_hole_size will be used to find hole size on memblock.memory.region
with specified range.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/include/asm/memblock.h

@@ -11,4 +11,8 @@ void memblock_x86_free_range(u64 start, u64 end);
 struct range;
 int get_free_all_memory_range(struct range **rangep, int nodeid);
 
+void memblock_x86_register_active_regions(int nid, unsigned long start_pfn,
+					 unsigned long last_pfn);
+u64 memblock_x86_hole_size(u64 start, u64 end);
+
 #endif

arch/x86/mm/memblock.c

@@ -232,3 +232,69 @@ void __init memblock_x86_free_range(u64 start, u64 end)
 
 	memblock_free(start, end - start);
 }
+
+/*
+ * Finds an active region in the address range from start_pfn to last_pfn and
+ * returns its range in ei_startpfn and ei_endpfn for the memblock entry.
+ */
+static int __init memblock_x86_find_active_region(const struct memblock_region *ei,
+				  unsigned long start_pfn,
+				  unsigned long last_pfn,
+				  unsigned long *ei_startpfn,
+				  unsigned long *ei_endpfn)
+{
+	u64 align = PAGE_SIZE;
+
+	*ei_startpfn = round_up(ei->base, align) >> PAGE_SHIFT;
+	*ei_endpfn = round_down(ei->base + ei->size, align) >> PAGE_SHIFT;
+
+	/* Skip map entries smaller than a page */
+	if (*ei_startpfn >= *ei_endpfn)
+		return 0;
+
+	/* Skip if map is outside the node */
+	if (*ei_endpfn <= start_pfn || *ei_startpfn >= last_pfn)
+		return 0;
+
+	/* Check for overlaps */
+	if (*ei_startpfn < start_pfn)
+		*ei_startpfn = start_pfn;
+	if (*ei_endpfn > last_pfn)
+		*ei_endpfn = last_pfn;
+
+	return 1;
+}
+
+/* Walk the memblock.memory map and register active regions within a node */
+void __init memblock_x86_register_active_regions(int nid, unsigned long start_pfn,
+					 unsigned long last_pfn)
+{
+	unsigned long ei_startpfn;
+	unsigned long ei_endpfn;
+	struct memblock_region *r;
+
+	for_each_memblock(memory, r)
+		if (memblock_x86_find_active_region(r, start_pfn, last_pfn,
+					   &ei_startpfn, &ei_endpfn))
+			add_active_range(nid, ei_startpfn, ei_endpfn);
+}
+
+/*
+ * Find the hole size (in bytes) in the memory range.
+ * @start: starting address of the memory range to scan
+ * @end: ending address of the memory range to scan
+ */
+u64 __init memblock_x86_hole_size(u64 start, u64 end)
+{
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long last_pfn = end >> PAGE_SHIFT;
+	unsigned long ei_startpfn, ei_endpfn, ram = 0;
+	struct memblock_region *r;
+
+	for_each_memblock(memory, r)
+		if (memblock_x86_find_active_region(r, start_pfn, last_pfn,
+					   &ei_startpfn, &ei_endpfn))
+			ram += ei_endpfn - ei_startpfn;
+
+	return end - start - ((u64)ram << PAGE_SHIFT);
+}