[PATCH V4 3/4] s390/mm: Define arch_get_mappable_range()

[Anshuman Khandual]

This overrides arch_get_mappabble_range() on s390 platform which will be
used with recently added generic framework. It modifies the existing range
check in vmem_add_mapping() using arch_get_mappable_range(). It also adds a
VM_BUG_ON() check that would ensure that mhp_range_allowed() has already
been called on the hotplug path.

Cc: Heiko Carstens <hca at linux.ibm.com>
Cc: Vasily Gorbik <gor at linux.ibm.com>
Cc: David Hildenbrand <david at redhat.com>
Cc: linux-s390 at vger.kernel.org
Cc: linux-kernel at vger.kernel.org
Acked-by: Heiko Carstens <hca at linux.ibm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual at arm.com>
---
 arch/s390/mm/init.c |  1 +
 arch/s390/mm/vmem.c | 14 +++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 73a163065b95..0e76b2127dc6 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -297,6 +297,7 @@ int arch_add_memory(int nid, u64 start, u64 size,
 	if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot))
 		return -EINVAL;
 
+	VM_BUG_ON(!mhp_range_allowed(start, size, true));
 	rc = vmem_add_mapping(start, size);
 	if (rc)
 		return rc;
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index 01f3a5f58e64..82dbf9450105 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -4,6 +4,7 @@
  *    Author(s): Heiko Carstens <heiko.carstens at de.ibm.com>
  */
 
+#include <linux/memory_hotplug.h>
 #include <linux/memblock.h>
 #include <linux/pfn.h>
 #include <linux/mm.h>
@@ -532,11 +533,22 @@ void vmem_remove_mapping(unsigned long start, unsigned long size)
 	mutex_unlock(&vmem_mutex);
 }
 
+struct range arch_get_mappable_range(void)
+{
+	struct range mhp_range;
+
+	mhp_range.start = 0;
+	mhp_range.end =  VMEM_MAX_PHYS - 1;
+	return mhp_range;
+}
+
 int vmem_add_mapping(unsigned long start, unsigned long size)
 {
+	struct range range = arch_get_mappable_range();
 	int ret;
 
-	if (start + size > VMEM_MAX_PHYS ||
+	if (start < range.start ||
+	    start + size > range.end + 1 ||
 	    start + size < start)
 		return -ERANGE;
 
-- 
2.20.1