-ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
- bool share, const char *mem_path,
- Error **errp);
-ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
- MemoryRegion *mr, Error **errp);
-ram_addr_t qemu_ram_alloc(ram_addr_t size, MemoryRegion *mr, Error **errp);
-ram_addr_t qemu_ram_alloc_resizeable(ram_addr_t size, ram_addr_t max_size,
- void (*resized)(const char*,
- uint64_t length,
- void *host),
- MemoryRegion *mr, Error **errp);
+struct RAMBlock {
+ struct rcu_head rcu;
+ struct MemoryRegion *mr;
+ uint8_t *host;
+ ram_addr_t offset;
+ ram_addr_t used_length;
+ ram_addr_t max_length;
+ void (*resized)(const char*, uint64_t length, void *host);
+ uint32_t flags;
+ /* Protected by iothread lock. */
+ char idstr[256];
+ /* RCU-enabled, writes protected by the ramlist lock */
+ QLIST_ENTRY(RAMBlock) next;
+ int fd;
+};
+
+static inline bool offset_in_ramblock(RAMBlock *b, ram_addr_t offset)
+{
+ return (b && b->host && offset < b->used_length) ? true : false;
+}
+
+static inline void *ramblock_ptr(RAMBlock *block, ram_addr_t offset)
+{
+ assert(offset_in_ramblock(block, offset));
+ return (char *)block->host + offset;
+}
+
+/* The dirty memory bitmap is split into fixed-size blocks to allow growth
+ * under RCU. The bitmap for a block can be accessed as follows:
+ *
+ * rcu_read_lock();
+ *
+ * DirtyMemoryBlocks *blocks =
+ * atomic_rcu_read(&ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION]);
+ *
+ * ram_addr_t idx = (addr >> TARGET_PAGE_BITS) / DIRTY_MEMORY_BLOCK_SIZE;
+ * unsigned long *block = blocks.blocks[idx];
+ * ...access block bitmap...
+ *
+ * rcu_read_unlock();
+ *
+ * Remember to check for the end of the block when accessing a range of
+ * addresses. Move on to the next block if you reach the end.
+ *
+ * Organization into blocks allows dirty memory to grow (but not shrink) under
+ * RCU. When adding new RAMBlocks requires the dirty memory to grow, a new
+ * DirtyMemoryBlocks array is allocated with pointers to existing blocks kept
+ * the same. Other threads can safely access existing blocks while dirty
+ * memory is being grown. When no threads are using the old DirtyMemoryBlocks
+ * anymore it is freed by RCU (but the underlying blocks stay because they are
+ * pointed to from the new DirtyMemoryBlocks).
+ */
+#define DIRTY_MEMORY_BLOCK_SIZE ((ram_addr_t)256 * 1024 * 8)
+typedef struct {
+ struct rcu_head rcu;
+ unsigned long *blocks[];
+} DirtyMemoryBlocks;
+
+typedef struct RAMList {
+ QemuMutex mutex;
+ RAMBlock *mru_block;
+ /* RCU-enabled, writes protected by the ramlist lock. */
+ QLIST_HEAD(, RAMBlock) blocks;
+ DirtyMemoryBlocks *dirty_memory[DIRTY_MEMORY_NUM];
+ uint32_t version;
+} RAMList;
+extern RAMList ram_list;
+
+ram_addr_t last_ram_offset(void);
+void qemu_mutex_lock_ramlist(void);
+void qemu_mutex_unlock_ramlist(void);
+
+RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
+ bool share, const char *mem_path,
+ Error **errp);
+RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
+ MemoryRegion *mr, Error **errp);
+RAMBlock *qemu_ram_alloc(ram_addr_t size, MemoryRegion *mr, Error **errp);
+RAMBlock *qemu_ram_alloc_resizeable(ram_addr_t size, ram_addr_t max_size,
+ void (*resized)(const char*,
+ uint64_t length,
+ void *host),
+ MemoryRegion *mr, Error **errp);