include/exec/ramlist.h

   1 #ifndef RAMLIST_H
   2 #define RAMLIST_H
   3
   4 #include "qemu/queue.h"
   5 #include "qemu/thread.h"
   6 #include "qemu/rcu.h"
   7 #include "qemu/rcu_queue.h"
   8
   9 typedef struct RAMBlockNotifier RAMBlockNotifier;
  10
  11 #define DIRTY_MEMORY_VGA       0
  12 #define DIRTY_MEMORY_CODE      1
  13 #define DIRTY_MEMORY_MIGRATION 2
  14 #define DIRTY_MEMORY_NUM       3        /* num of dirty bits */
  15
  16 /* The dirty memory bitmap is split into fixed-size blocks to allow growth
  17  * under RCU.  The bitmap for a block can be accessed as follows:
  18  *
  19  *   rcu_read_lock();
  20  *
  21  *   DirtyMemoryBlocks *blocks =
  22  *       qatomic_rcu_read(&ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION]);
  23  *
  24  *   ram_addr_t idx = (addr >> TARGET_PAGE_BITS) / DIRTY_MEMORY_BLOCK_SIZE;
  25  *   unsigned long *block = blocks.blocks[idx];
  26  *   ...access block bitmap...
  27  *
  28  *   rcu_read_unlock();
  29  *
  30  * Remember to check for the end of the block when accessing a range of
  31  * addresses.  Move on to the next block if you reach the end.
  32  *
  33  * Organization into blocks allows dirty memory to grow (but not shrink) under
  34  * RCU.  When adding new RAMBlocks requires the dirty memory to grow, a new
  35  * DirtyMemoryBlocks array is allocated with pointers to existing blocks kept
  36  * the same.  Other threads can safely access existing blocks while dirty
  37  * memory is being grown.  When no threads are using the old DirtyMemoryBlocks
  38  * anymore it is freed by RCU (but the underlying blocks stay because they are
  39  * pointed to from the new DirtyMemoryBlocks).
  40  */
  41 #define DIRTY_MEMORY_BLOCK_SIZE ((ram_addr_t)256 * 1024 * 8)
  42 typedef struct {
  43     struct rcu_head rcu;
  44     unsigned long *blocks[];
  45 } DirtyMemoryBlocks;
  46
  47 typedef struct RAMList {
  48     QemuMutex mutex;
  49     RAMBlock *mru_block;
  50     /* RCU-enabled, writes protected by the ramlist lock. */
  51     QLIST_HEAD(, RAMBlock) blocks;
  52     DirtyMemoryBlocks *dirty_memory[DIRTY_MEMORY_NUM];
  53     uint32_t version;
  54     QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
  55 } RAMList;
  56 extern RAMList ram_list;
  57
  58 /* Should be holding either ram_list.mutex, or the RCU lock. */
  59 #define  INTERNAL_RAMBLOCK_FOREACH(block)  \
  60     QLIST_FOREACH_RCU(block, &ram_list.blocks, next)
  61 /* Never use the INTERNAL_ version except for defining other macros */
  62 #define RAMBLOCK_FOREACH(block) INTERNAL_RAMBLOCK_FOREACH(block)
  63
  64 void qemu_mutex_lock_ramlist(void);
  65 void qemu_mutex_unlock_ramlist(void);
  66
  67 struct RAMBlockNotifier {
  68     void (*ram_block_added)(RAMBlockNotifier *n, void *host, size_t size,
  69                             size_t max_size);
  70     void (*ram_block_removed)(RAMBlockNotifier *n, void *host, size_t size,
  71                               size_t max_size);
  72     void (*ram_block_resized)(RAMBlockNotifier *n, void *host, size_t old_size,
  73                               size_t new_size);
  74     QLIST_ENTRY(RAMBlockNotifier) next;
  75 };
  76
  77 void ram_block_notifier_add(RAMBlockNotifier *n);
  78 void ram_block_notifier_remove(RAMBlockNotifier *n);
  79 void ram_block_notify_add(void *host, size_t size, size_t max_size);
  80 void ram_block_notify_remove(void *host, size_t size, size_t max_size);
  81 void ram_block_notify_resize(void *host, size_t old_size, size_t new_size);
  82
  83 GString *ram_block_format(void);
  84
  85 #endif /* RAMLIST_H */