Implement the function `ioremap_attr` for MPU systems.

Signed-off-by: Harry Ramsey <harry.ramsey@arm.com>
---
 xen/arch/arm/mpu/mm.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/mpu/mm.c b/xen/arch/arm/mpu/mm.c
index c5128244b7..3570ce6b27 100644
--- a/xen/arch/arm/mpu/mm.c
+++ b/xen/arch/arm/mpu/mm.c
@@ -475,8 +475,13 @@ void free_init_memory(void)
 
 void __iomem *ioremap_attr(paddr_t start, size_t len, unsigned int flags)
 {
-    BUG_ON("unimplemented");
-    return NULL;
+    paddr_t start_pg = round_pgdown(start);
+    paddr_t end_pg = round_pgup(start_pg + len);
+    if ( xen_mpumap_update(start_pg, end_pg, flags) )
+        return NULL;
+
+    /* Mapped or already mapped */
+    return maddr_to_virt(start_pg);
 }
 
 /*
-- 
2.43.0