memory hotplug: Define memory_block_size_bytes for x86_64 with CONFIG_X86_UV

Define a version of memory_block_size_bytes for x86_64 when CONFIG_X86_UV is
set.
Signed-off-by: Robin Holt <holt@sgi.com>
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86/mm/init_64.c

@@ -51,6 +51,7 @@
 #include <asm/numa.h>
 #include <asm/cacheflush.h>
 #include <asm/init.h>
+#include <asm/uv/uv.h>
 
 static int __init parse_direct_gbpages_off(char *arg)
 {
@@ -908,6 +909,19 @@ const char *arch_vma_name(struct vm_area_struct *vma)
 	return NULL;
 }
 
+#ifdef CONFIG_X86_UV
+#define MIN_MEMORY_BLOCK_SIZE   (1 << SECTION_SIZE_BITS)
+
+unsigned long memory_block_size_bytes(void)
+{
+	if (is_uv_system()) {
+		printk(KERN_INFO "UV: memory block size 2GB\n");
+		return 2UL * 1024 * 1024 * 1024;
+	}
+	return MIN_MEMORY_BLOCK_SIZE;
+}
+#endif
+
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 /*
  * Initialise the sparsemem vmemmap using huge-pages at the PMD level.