ifdefing inclusion of <asm/mem_access.h> in <xen/mem_access.h>
allows to avoid generation of empty <asm/mem_access.h> header
for the case when !CONFIG_MEM_ACCESS.

For Arm it was explicitly added inclusion of <asm/mem_access.h> for p2m.c
and traps.c because they require some functions from <asm/mem_access.h> which
aren't available in case of !CONFIG_MEM_ACCESS.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
---
Changes in V3:
 - Remove unnecessary comment.
---
 xen/arch/arm/p2m.c                    | 1 +
 xen/arch/arm/traps.c                  | 1 +
 xen/arch/ppc/include/asm/mem_access.h | 5 -----
 xen/include/xen/mem_access.h          | 2 ++
 4 files changed, 4 insertions(+), 5 deletions(-)
 delete mode 100644 xen/arch/ppc/include/asm/mem_access.h

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index de32a2d638..b6ea4480a0 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -11,6 +11,7 @@
 #include <asm/event.h>
 #include <asm/flushtlb.h>
 #include <asm/guest_walk.h>
+#include <asm/mem_access.h>
 #include <asm/page.h>
 #include <asm/traps.h>
 
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index ce89f16404..b720b49dd2 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -35,6 +35,7 @@
 #include <asm/cpufeature.h>
 #include <asm/event.h>
 #include <asm/hsr.h>
+#include <asm/mem_access.h>
 #include <asm/mmio.h>
 #include <asm/regs.h>
 #include <asm/smccc.h>
diff --git a/xen/arch/ppc/include/asm/mem_access.h b/xen/arch/ppc/include/asm/mem_access.h
deleted file mode 100644
index e7986dfdbd..0000000000
--- a/xen/arch/ppc/include/asm/mem_access.h
+++ /dev/null
@@ -1,5 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-#ifndef __ASM_PPC_MEM_ACCESS_H__
-#define __ASM_PPC_MEM_ACCESS_H__
-
-#endif /* __ASM_PPC_MEM_ACCESS_H__ */
diff --git a/xen/include/xen/mem_access.h b/xen/include/xen/mem_access.h
index 4e4811680d..87d93b31f6 100644
--- a/xen/include/xen/mem_access.h
+++ b/xen/include/xen/mem_access.h
@@ -33,7 +33,9 @@
  */
 struct vm_event_st;
 
+#ifdef CONFIG_MEM_ACCESS
 #include <asm/mem_access.h>
+#endif
 
 /*
  * Additional access types, which are used to further restrict
-- 
2.41.0