[PATCH v3 35/52] xen/arm: map static memory on demand

[Penny Zheng <Penny.Zheng@xxxxxxx>]

In function init_staticmem_pages, we need the access to static memory
for proper initialization.
It is not a problem in MMU system, as Xen map the whole RAM in
setup_mm(). However, with limited MPU memory regions, it is too luxury
to map the whole RAM.
As a result, we follow the rule of "map on demand", to map static memory
temporarily before its initialization, and unmap immediately after its
initialization.

Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>
Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
---
v3:
- new commit
---
 xen/arch/arm/include/asm/mm.h |  2 ++
 xen/arch/arm/mmu/mm.c         | 10 ++++++++++
 xen/arch/arm/mpu/mm.c         | 10 ++++++++++
 xen/arch/arm/setup.c          | 21 +++++++++++++++++++++
 4 files changed, 43 insertions(+)

diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
index 66d98b9a29..cffbf8a595 100644
--- a/xen/arch/arm/include/asm/mm.h
+++ b/xen/arch/arm/include/asm/mm.h
@@ -224,6 +224,8 @@ extern void mm_init_secondary_cpu(void);
 extern void setup_frametable_mappings(paddr_t ps, paddr_t pe);
 /* map a physical range in virtual memory */
 void __iomem *ioremap_attr(paddr_t start, size_t len, unsigned int attributes);
+extern int map_staticmem_pages_to_xen(paddr_t start, paddr_t end);
+extern int unmap_staticmem_pages_to_xen(paddr_t start, paddr_t end);
 
 static inline void __iomem *ioremap_nocache(paddr_t start, size_t len)
 {
diff --git a/xen/arch/arm/mmu/mm.c b/xen/arch/arm/mmu/mm.c
index 2f29cb53fe..4196a55c32 100644
--- a/xen/arch/arm/mmu/mm.c
+++ b/xen/arch/arm/mmu/mm.c
@@ -1113,6 +1113,16 @@ int populate_pt_range(unsigned long virt, unsigned long 
nr_mfns)
     return xen_pt_update(virt, INVALID_MFN, nr_mfns, _PAGE_POPULATE);
 }
 
+int __init map_staticmem_pages_to_xen(paddr_t start, paddr_t end)
+{
+    return 0;
+}
+
+int __init unmap_staticmem_pages_to_xen(paddr_t start, paddr_t end)
+{
+    return 0;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/mpu/mm.c b/xen/arch/arm/mpu/mm.c
index a40055ae5e..9d5c1da39c 100644
--- a/xen/arch/arm/mpu/mm.c
+++ b/xen/arch/arm/mpu/mm.c
@@ -614,6 +614,16 @@ void __init setup_frametable_mappings(paddr_t ps, paddr_t 
pe)
            frametable_size - (nr_pdxs * sizeof(struct page_info)));
 }
 
+int __init map_staticmem_pages_to_xen(paddr_t start, paddr_t end)
+{
+    return xen_mpumap_update(start, end, PAGE_HYPERVISOR | _PAGE_TRANSIENT);
+}
+
+int __init unmap_staticmem_pages_to_xen(paddr_t start, paddr_t end)
+{
+    return xen_mpumap_update(start, end, 0);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index f42b53d17b..c21d1db763 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -637,12 +637,33 @@ void __init init_staticmem_pages(void)
             mfn_t bank_start = 
_mfn(PFN_UP(bootinfo.reserved_mem.bank[bank].start));
             unsigned long bank_pages = 
PFN_DOWN(bootinfo.reserved_mem.bank[bank].size);
             mfn_t bank_end = mfn_add(bank_start, bank_pages);
+            int res;
 
             if ( mfn_x(bank_end) <= mfn_x(bank_start) )
                 return;
 
+            /* Map temporarily before initialization */
+            res = map_staticmem_pages_to_xen(mfn_to_maddr(bank_start),
+                                             mfn_to_maddr(bank_end));
+            if ( res )
+            {
+                printk(XENLOG_ERR "Failed to map static memory to Xen: %d\n",
+                       res);
+                return;
+            }
+
             unprepare_staticmem_pages(mfn_to_page(bank_start),
                                       bank_pages, false);
+
+            /* Unmap immediately after initialization */
+            res = unmap_staticmem_pages_to_xen(mfn_to_maddr(bank_start),
+                                               mfn_to_maddr(bank_end));
+            if ( res )
+            {
+                printk(XENLOG_ERR "Failed to unmap static memory to Xen: %d\n",
+                       res);
+                return;
+            }
         }
     }
 #endif
-- 
2.25.1