[RFC PATCH 15/73] mm/vmalloc: Add a helper to reserve a contiguous and aligned kernel virtual area

[Lai Jiangshan <jiangshanlai@gmail.com>]

From: Hou Wenlong <houwenlong.hwl@antgroup.com>

PVM needs to reserve a contiguous and aligned kernel virtual area for
the guest kernel. Therefor, add a helper to achieve this. It is a
temporary method currently, and a better method is needed in the future.

Suggested-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
 include/linux/vmalloc.h |  2 ++
 mm/vmalloc.c            | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index c720be70c8dd..1821494b51d6 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -204,6 +204,8 @@ static inline size_t get_vm_area_size(const struct vm_struct *area)
 }
 
 extern struct vm_struct *get_vm_area(unsigned long size, unsigned long flags);
+extern struct vm_struct *get_vm_area_align(unsigned long size, unsigned long align,
+					   unsigned long flags);
 extern struct vm_struct *get_vm_area_caller(unsigned long size,
 					unsigned long flags, const void *caller);
 extern struct vm_struct *__get_vm_area_caller(unsigned long size,
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d12a17fc0c17..6e4b95f24bd8 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2642,6 +2642,16 @@ struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
 				  __builtin_return_address(0));
 }
 
+struct vm_struct *get_vm_area_align(unsigned long size, unsigned long align,
+				    unsigned long flags)
+{
+	return __get_vm_area_node(size, align, PAGE_SHIFT, flags,
+				  VMALLOC_START, VMALLOC_END,
+				  NUMA_NO_NODE, GFP_KERNEL,
+				  __builtin_return_address(0));
+}
+EXPORT_SYMBOL_GPL(get_vm_area_align);
+
 struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
 				const void *caller)
 {
-- 
2.19.1.6.gb485710b