Add helper to retrieve page size of RAM backing, when hugetlbfs 
is used.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: git/qemu/exec.c
===================================================================
--- qemu.orig/exec.c
+++ qemu/exec.c
@@ -961,8 +961,27 @@ static void *file_ram_alloc(RAMBlock *bl
         return (NULL);
     }
     block->fd = fd;
+    block->hpagesize = hpagesize;
     return area;
 }
+
+uint32_t qemu_get_ram_hpagesize(ram_addr_t addr)
+{
+    RAMBlock *block;
+
+    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+        if (addr - block->offset < block->length) {
+            return block->hpagesize;
+        }
+    }
+
+    fprintf(stderr, "%s: Bad ram offset %" PRIx64 "\n", __func__,
+                    (uint64_t)addr);
+    abort();
+
+    return 0;
+}
+
 #else
 static void *file_ram_alloc(RAMBlock *block,
                             ram_addr_t memory,
Index: qemu/include/exec/cpu-all.h
===================================================================
--- qemu.orig/include/exec/cpu-all.h
+++ qemu/include/exec/cpu-all.h
@@ -448,6 +448,7 @@ typedef struct RAMBlock {
     ram_addr_t offset;
     ram_addr_t length;
     uint32_t flags;
+    uint32_t hpagesize;
     char idstr[256];
     /* Reads can take either the iothread or the ramlist lock.
      * Writes must take both locks.
Index: git/qemu/include/exec/cpu-common.h
===================================================================
--- qemu.orig/include/exec/cpu-common.h
+++ qemu/include/exec/cpu-common.h
@@ -54,6 +54,9 @@ void qemu_ram_remap(ram_addr_t addr, ram
 /* This should not be used by devices.  */
 MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr);
 void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev);
+#ifdef __linux__
+uint32_t qemu_get_ram_hpagesize(ram_addr_t addr);
+#endif
 
 void cpu_physical_memory_rw(hwaddr addr, uint8_t *buf,
                             int len, int is_write);