Add qemu_ram_alloc_from_ptr function

Provide a function to add an allocated region of memory to the qemu RAM.

This patch is copied from Marcelo's qemu_ram_map() in qemu-kvm and given the
clearer name qemu_ram_alloc_from_ptr().

Signed-off-by: Cam Macdonell <cam@cs.ualberta.ca>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

cpu-common.h

@@ -40,6 +40,8 @@ static inline void cpu_register_physical_memory(target_phys_addr_t start_addr,
 }
 
 ram_addr_t cpu_get_physical_page_desc(target_phys_addr_t addr);
+ram_addr_t qemu_ram_alloc_from_ptr(DeviceState *dev, const char *name,
+                        ram_addr_t size, void *host);
 ram_addr_t qemu_ram_alloc(DeviceState *dev, const char *name, ram_addr_t size);
 void qemu_ram_free(ram_addr_t addr);
 /* This should only be used for ram local to a device.  */

exec.c

@@ -2808,6 +2808,49 @@ static ram_addr_t last_ram_offset(void)
     return last;
 }
 
+ram_addr_t qemu_ram_alloc_from_ptr(DeviceState *dev, const char *name,
+                        ram_addr_t size, void *host)
+{
+    RAMBlock *new_block, *block;
+
+    size = TARGET_PAGE_ALIGN(size);
+    new_block = qemu_mallocz(sizeof(*new_block));
+
+    if (dev && dev->parent_bus && dev->parent_bus->info->get_dev_path) {
+        char *id = dev->parent_bus->info->get_dev_path(dev);
+        if (id) {
+            snprintf(new_block->idstr, sizeof(new_block->idstr), "%s/", id);
+            qemu_free(id);
+        }
+    }
+    pstrcat(new_block->idstr, sizeof(new_block->idstr), name);
+
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
+        if (!strcmp(block->idstr, new_block->idstr)) {
+            fprintf(stderr, "RAMBlock \"%s\" already registered, abort!\n",
+                    new_block->idstr);
+            abort();
+        }
+    }
+
+    new_block->host = host;
+
+    new_block->offset = find_ram_offset(size);
+    new_block->length = size;
+
+    QLIST_INSERT_HEAD(&ram_list.blocks, new_block, next);
+
+    ram_list.phys_dirty = qemu_realloc(ram_list.phys_dirty,
+                                       last_ram_offset() >> TARGET_PAGE_BITS);
+    memset(ram_list.phys_dirty + (new_block->offset >> TARGET_PAGE_BITS),
+           0xff, size >> TARGET_PAGE_BITS);
+
+    if (kvm_enabled())
+        kvm_setup_guest_memory(new_block->host, size);
+
+    return new_block->offset;
+}
+
 ram_addr_t qemu_ram_alloc(DeviceState *dev, const char *name, ram_addr_t size)
 {
     RAMBlock *new_block, *block;