[PATCH 5/5] xen/arm: map static memory on demand

[Hari Limaye <hari.limaye@xxxxxxx>]

From: Penny Zheng <Penny.Zheng@xxxxxxx>

In the function `init_staticmem_pages` we need to have mapped static
memory banks for initialization. Unlike on an MMU system, we cannot map
the entire RAM on an MPU system as we have a limited number of MPU
memory regions. To solve this, transiently map the static memory banks
for initialization.

Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>
Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
Signed-off-by: Hari Limaye <hari.limaye@xxxxxxx>
---
 xen/arch/arm/include/asm/mmu/mm.h |  3 +++
 xen/arch/arm/include/asm/mpu/mm.h |  4 ++++
 xen/arch/arm/mpu/setup.c          | 11 +++++++++++
 xen/include/xen/static-memory.h   |  8 ++++++++
 4 files changed, 26 insertions(+)

diff --git a/xen/arch/arm/include/asm/mmu/mm.h 
b/xen/arch/arm/include/asm/mmu/mm.h
index 7f4d59137d..645a0ea3cb 100644
--- a/xen/arch/arm/include/asm/mmu/mm.h
+++ b/xen/arch/arm/include/asm/mmu/mm.h
@@ -110,6 +110,9 @@ void dump_pt_walk(paddr_t ttbr, paddr_t addr,
 extern void switch_ttbr(uint64_t ttbr);
 extern void relocate_and_switch_ttbr(uint64_t ttbr);
 
+static inline void map_staticmem_pages_to_xen(paddr_t start, paddr_t end) {}
+static inline void unmap_staticmem_pages_to_xen(paddr_t start, paddr_t end) {}
+
 #endif /* __ARM_MMU_MM_H__ */
 
 /*
diff --git a/xen/arch/arm/include/asm/mpu/mm.h 
b/xen/arch/arm/include/asm/mpu/mm.h
index 177550f5bd..118034bbdc 100644
--- a/xen/arch/arm/include/asm/mpu/mm.h
+++ b/xen/arch/arm/include/asm/mpu/mm.h
@@ -128,6 +128,10 @@ void *map_mm_range(paddr_t start, paddr_t end, unsigned 
int flags);
  */
 void unmap_mm_range(paddr_t start);
 
+/* {un}map_staticmem_pages_to_xen used while initializing static memory banks 
*/
+void map_staticmem_pages_to_xen(paddr_t start, paddr_t end);
+void unmap_staticmem_pages_to_xen(paddr_t start, paddr_t end);
+
 /*
  * Checks whether a given memory range is present in the provided table of
  * MPU protection regions.
diff --git a/xen/arch/arm/mpu/setup.c b/xen/arch/arm/mpu/setup.c
index 163573b932..dbc3107333 100644
--- a/xen/arch/arm/mpu/setup.c
+++ b/xen/arch/arm/mpu/setup.c
@@ -83,6 +83,17 @@ void * __init early_fdt_map(paddr_t fdt_paddr)
     return fdt_virt;
 }
 
+void __init map_staticmem_pages_to_xen(paddr_t start, paddr_t end)
+{
+    if ( !map_mm_range(start, end, PAGE_HYPERVISOR) )
+        panic("Unable to map staticmem pages to Xen!");
+}
+
+void __init unmap_staticmem_pages_to_xen(paddr_t start, paddr_t end)
+{
+    unmap_mm_range(start);
+}
+
 /*
  * copy_from_paddr - copy data from a physical address
  * @dst: destination virtual address
diff --git a/xen/include/xen/static-memory.h b/xen/include/xen/static-memory.h
index e445aa8057..d99abac113 100644
--- a/xen/include/xen/static-memory.h
+++ b/xen/include/xen/static-memory.h
@@ -18,7 +18,15 @@ static inline void init_staticmem_bank(const struct membank 
*bank)
     if ( mfn_x(bank_end) <= mfn_x(bank_start) )
         return;
 
+    /* Map temporarily before initialization */
+    map_staticmem_pages_to_xen(mfn_to_maddr(bank_start),
+                               mfn_to_maddr(bank_end));
+
     unprepare_staticmem_pages(mfn_to_page(bank_start), bank_pages, false);
+
+    /* Unmap immediately after initialization */
+    unmap_staticmem_pages_to_xen(mfn_to_maddr(bank_start),
+                                 mfn_to_maddr(bank_end));
 }
 
 void allocate_static_memory(struct domain *d, struct kernel_info *kinfo,
-- 
2.34.1