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ramblock-notifier: new

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This adds a notify interface of ram block additions and removals.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-12-21 00:31:36 +08:00
parent fb5e19d2e1
commit 0987d735a3
6 changed files with 112 additions and 49 deletions
Download patch file Download diff file Expand all files Collapse all files

6
include/exec/memory.h
View file

@ -16,16 +16,12 @@
#ifndef CONFIG_USER_ONLY
#define DIRTY_MEMORY_VGA 0
#define DIRTY_MEMORY_CODE 1
#define DIRTY_MEMORY_MIGRATION 2
#define DIRTY_MEMORY_NUM 3 /* num of dirty bits */
#include "exec/cpu-common.h"
#ifndef CONFIG_USER_ONLY
#include "exec/hwaddr.h"
#endif
#include "exec/memattrs.h"
#include "exec/ramlist.h"
#include "qemu/queue.h"
#include "qemu/int128.h"
#include "qemu/notify.h"

46
include/exec/ram_addr.h
View file

@ -21,6 +21,7 @@
#ifndef CONFIG_USER_ONLY
#include "hw/xen/xen.h"
#include "exec/ramlist.h"
struct RAMBlock {
struct rcu_head rcu;
@ -35,6 +36,7 @@ struct RAMBlock {
char idstr[256];
/* RCU-enabled, writes protected by the ramlist lock */
QLIST_ENTRY(RAMBlock) next;
QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
int fd;
size_t page_size;
};
@ -50,51 +52,7 @@ static inline void *ramblock_ptr(RAMBlock *block, ram_addr_t 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);

72
include/exec/ramlist.h Normal file
View file

@ -0,0 +1,72 @@
#ifndef RAMLIST_H
#define RAMLIST_H
#include "qemu/queue.h"
#include "qemu/thread.h"
#include "qemu/rcu.h"
typedef struct RAMBlockNotifier RAMBlockNotifier;
#define DIRTY_MEMORY_VGA 0
#define DIRTY_MEMORY_CODE 1
#define DIRTY_MEMORY_MIGRATION 2
#define DIRTY_MEMORY_NUM 3 /* num of dirty bits */
/* 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;
QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
} RAMList;
extern RAMList ram_list;
void qemu_mutex_lock_ramlist(void);
void qemu_mutex_unlock_ramlist(void);
struct RAMBlockNotifier {
void (*ram_block_added)(RAMBlockNotifier *n, void *host, size_t size);
void (*ram_block_removed)(RAMBlockNotifier *n, void *host, size_t size);
QLIST_ENTRY(RAMBlockNotifier) next;
};
void ram_block_notifier_add(RAMBlockNotifier *n);
void ram_block_notifier_remove(RAMBlockNotifier *n);
void ram_block_notify_add(void *host, size_t size);
void ram_block_notify_remove(void *host, size_t size);
#endif /* RAMLIST_H */