diff options
Diffstat (limited to 'include/exec/ram_addr.h')
| -rw-r--r-- | include/exec/ram_addr.h | 189 |
1 files changed, 165 insertions, 24 deletions
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index f2e872d87a..b1413a1286 100644 --- a/include/exec/ram_addr.h +++ b/include/exec/ram_addr.h @@ -49,13 +49,43 @@ 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; - /* Protected by the iothread lock. */ - unsigned long *dirty_memory[DIRTY_MEMORY_NUM]; 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; @@ -89,30 +119,70 @@ static inline bool cpu_physical_memory_get_dirty(ram_addr_t start, ram_addr_t length, unsigned client) { - unsigned long end, page, next; + DirtyMemoryBlocks *blocks; + unsigned long end, page; + bool dirty = false; assert(client < DIRTY_MEMORY_NUM); end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS; page = start >> TARGET_PAGE_BITS; - next = find_next_bit(ram_list.dirty_memory[client], end, page); - return next < end; + rcu_read_lock(); + + blocks = atomic_rcu_read(&ram_list.dirty_memory[client]); + + while (page < end) { + unsigned long idx = page / DIRTY_MEMORY_BLOCK_SIZE; + unsigned long offset = page % DIRTY_MEMORY_BLOCK_SIZE; + unsigned long num = MIN(end - page, DIRTY_MEMORY_BLOCK_SIZE - offset); + + if (find_next_bit(blocks->blocks[idx], offset, num) < num) { + dirty = true; + break; + } + + page += num; + } + + rcu_read_unlock(); + + return dirty; } static inline bool cpu_physical_memory_all_dirty(ram_addr_t start, ram_addr_t length, unsigned client) { - unsigned long end, page, next; + DirtyMemoryBlocks *blocks; + unsigned long end, page; + bool dirty = true; assert(client < DIRTY_MEMORY_NUM); end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS; page = start >> TARGET_PAGE_BITS; - next = find_next_zero_bit(ram_list.dirty_memory[client], end, page); - return next >= end; + rcu_read_lock(); + + blocks = atomic_rcu_read(&ram_list.dirty_memory[client]); + + while (page < end) { + unsigned long idx = page / DIRTY_MEMORY_BLOCK_SIZE; + unsigned long offset = page % DIRTY_MEMORY_BLOCK_SIZE; + unsigned long num = MIN(end - page, DIRTY_MEMORY_BLOCK_SIZE - offset); + + if (find_next_zero_bit(blocks->blocks[idx], offset, num) < num) { + dirty = false; + break; + } + + page += num; + } + + rcu_read_unlock(); + + return dirty; } static inline bool cpu_physical_memory_get_dirty_flag(ram_addr_t addr, @@ -154,16 +224,31 @@ static inline uint8_t cpu_physical_memory_range_includes_clean(ram_addr_t start, static inline void cpu_physical_memory_set_dirty_flag(ram_addr_t addr, unsigned client) { + unsigned long page, idx, offset; + DirtyMemoryBlocks *blocks; + assert(client < DIRTY_MEMORY_NUM); - set_bit_atomic(addr >> TARGET_PAGE_BITS, ram_list.dirty_memory[client]); + + page = addr >> TARGET_PAGE_BITS; + idx = page / DIRTY_MEMORY_BLOCK_SIZE; + offset = page % DIRTY_MEMORY_BLOCK_SIZE; + + rcu_read_lock(); + + blocks = atomic_rcu_read(&ram_list.dirty_memory[client]); + + set_bit_atomic(offset, blocks->blocks[idx]); + + rcu_read_unlock(); } static inline void cpu_physical_memory_set_dirty_range(ram_addr_t start, ram_addr_t length, uint8_t mask) { + DirtyMemoryBlocks *blocks[DIRTY_MEMORY_NUM]; unsigned long end, page; - unsigned long **d = ram_list.dirty_memory; + int i; if (!mask && !xen_enabled()) { return; @@ -171,15 +256,36 @@ static inline void cpu_physical_memory_set_dirty_range(ram_addr_t start, end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS; page = start >> TARGET_PAGE_BITS; - if (likely(mask & (1 << DIRTY_MEMORY_MIGRATION))) { - bitmap_set_atomic(d[DIRTY_MEMORY_MIGRATION], page, end - page); - } - if (unlikely(mask & (1 << DIRTY_MEMORY_VGA))) { - bitmap_set_atomic(d[DIRTY_MEMORY_VGA], page, end - page); + + rcu_read_lock(); + + for (i = 0; i < DIRTY_MEMORY_NUM; i++) { + blocks[i] = atomic_rcu_read(&ram_list.dirty_memory[i]); } - if (unlikely(mask & (1 << DIRTY_MEMORY_CODE))) { - bitmap_set_atomic(d[DIRTY_MEMORY_CODE], page, end - page); + + while (page < end) { + unsigned long idx = page / DIRTY_MEMORY_BLOCK_SIZE; + unsigned long offset = page % DIRTY_MEMORY_BLOCK_SIZE; + unsigned long num = MIN(end - page, DIRTY_MEMORY_BLOCK_SIZE - offset); + + if (likely(mask & (1 << DIRTY_MEMORY_MIGRATION))) { + bitmap_set_atomic(blocks[DIRTY_MEMORY_MIGRATION]->blocks[idx], + offset, num); + } + if (unlikely(mask & (1 << DIRTY_MEMORY_VGA))) { + bitmap_set_atomic(blocks[DIRTY_MEMORY_VGA]->blocks[idx], + offset, num); + } + if (unlikely(mask & (1 << DIRTY_MEMORY_CODE))) { + bitmap_set_atomic(blocks[DIRTY_MEMORY_CODE]->blocks[idx], + offset, num); + } + + page += num; } + + rcu_read_unlock(); + xen_modified_memory(start, length); } @@ -199,21 +305,41 @@ static inline void cpu_physical_memory_set_dirty_lebitmap(unsigned long *bitmap, /* start address is aligned at the start of a word? */ if ((((page * BITS_PER_LONG) << TARGET_PAGE_BITS) == start) && (hpratio == 1)) { + unsigned long **blocks[DIRTY_MEMORY_NUM]; + unsigned long idx; + unsigned long offset; long k; long nr = BITS_TO_LONGS(pages); + idx = (start >> TARGET_PAGE_BITS) / DIRTY_MEMORY_BLOCK_SIZE; + offset = BIT_WORD((start >> TARGET_PAGE_BITS) % + DIRTY_MEMORY_BLOCK_SIZE); + + rcu_read_lock(); + + for (i = 0; i < DIRTY_MEMORY_NUM; i++) { + blocks[i] = atomic_rcu_read(&ram_list.dirty_memory[i])->blocks; + } + for (k = 0; k < nr; k++) { if (bitmap[k]) { unsigned long temp = leul_to_cpu(bitmap[k]); - unsigned long **d = ram_list.dirty_memory; - atomic_or(&d[DIRTY_MEMORY_MIGRATION][page + k], temp); - atomic_or(&d[DIRTY_MEMORY_VGA][page + k], temp); + atomic_or(&blocks[DIRTY_MEMORY_MIGRATION][idx][offset], temp); + atomic_or(&blocks[DIRTY_MEMORY_VGA][idx][offset], temp); if (tcg_enabled()) { - atomic_or(&d[DIRTY_MEMORY_CODE][page + k], temp); + atomic_or(&blocks[DIRTY_MEMORY_CODE][idx][offset], temp); } } + + if (++offset >= BITS_TO_LONGS(DIRTY_MEMORY_BLOCK_SIZE)) { + offset = 0; + idx++; + } } + + rcu_read_unlock(); + xen_modified_memory(start, pages << TARGET_PAGE_BITS); } else { uint8_t clients = tcg_enabled() ? DIRTY_CLIENTS_ALL : DIRTY_CLIENTS_NOCODE; @@ -265,18 +391,33 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest, if (((page * BITS_PER_LONG) << TARGET_PAGE_BITS) == start) { int k; int nr = BITS_TO_LONGS(length >> TARGET_PAGE_BITS); - unsigned long *src = ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION]; + unsigned long * const *src; + unsigned long idx = (page * BITS_PER_LONG) / DIRTY_MEMORY_BLOCK_SIZE; + unsigned long offset = BIT_WORD((page * BITS_PER_LONG) % + DIRTY_MEMORY_BLOCK_SIZE); + + rcu_read_lock(); + + src = atomic_rcu_read( + &ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION])->blocks; for (k = page; k < page + nr; k++) { - if (src[k]) { - unsigned long bits = atomic_xchg(&src[k], 0); + if (src[idx][offset]) { + unsigned long bits = atomic_xchg(&src[idx][offset], 0); unsigned long new_dirty; new_dirty = ~dest[k]; dest[k] |= bits; new_dirty &= bits; num_dirty += ctpopl(new_dirty); } + + if (++offset >= BITS_TO_LONGS(DIRTY_MEMORY_BLOCK_SIZE)) { + offset = 0; + idx++; + } } + + rcu_read_unlock(); } else { for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) { if (cpu_physical_memory_test_and_clear_dirty( |