diff options
Diffstat (limited to 'arch_init.c')
| -rw-r--r-- | arch_init.c | 73 |
1 files changed, 51 insertions, 22 deletions
diff --git a/arch_init.c b/arch_init.c index 8414726e30..691b5e2e91 100644 --- a/arch_init.c +++ b/arch_init.c @@ -52,6 +52,7 @@ #include "exec/ram_addr.h" #include "hw/acpi/acpi.h" #include "qemu/host-utils.h" +#include "qemu/rcu_queue.h" #ifdef DEBUG_ARCH_INIT #define DPRINTF(fmt, ...) \ @@ -487,7 +488,6 @@ static void migration_bitmap_sync_range(ram_addr_t start, ram_addr_t length) } -/* Needs iothread lock! */ /* Fix me: there are too many global variables used in migration process. */ static int64_t start_time; static int64_t bytes_xfer_prev; @@ -500,6 +500,7 @@ static void migration_bitmap_sync_init(void) num_dirty_pages_period = 0; } +/* Called with iothread lock held, to protect ram_list.dirty_memory[] */ static void migration_bitmap_sync(void) { RAMBlock *block; @@ -523,9 +524,12 @@ static void migration_bitmap_sync(void) trace_migration_bitmap_sync_start(); address_space_sync_dirty_bitmap(&address_space_memory); - QTAILQ_FOREACH(block, &ram_list.blocks, next) { + rcu_read_lock(); + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { migration_bitmap_sync_range(block->mr->ram_addr, block->used_length); } + rcu_read_unlock(); + trace_migration_bitmap_sync_end(migration_dirty_pages - num_dirty_pages_init); num_dirty_pages_period += migration_dirty_pages - num_dirty_pages_init; @@ -648,6 +652,8 @@ static int ram_save_page(QEMUFile *f, RAMBlock* block, ram_addr_t offset, /* * ram_find_and_save_block: Finds a page to send and sends it to f * + * Called within an RCU critical section. + * * Returns: The number of bytes written. * 0 means no dirty pages */ @@ -661,7 +667,7 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage) MemoryRegion *mr; if (!block) - block = QTAILQ_FIRST(&ram_list.blocks); + block = QLIST_FIRST_RCU(&ram_list.blocks); while (true) { mr = block->mr; @@ -672,9 +678,9 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage) } if (offset >= block->used_length) { offset = 0; - block = QTAILQ_NEXT(block, next); + block = QLIST_NEXT_RCU(block, next); if (!block) { - block = QTAILQ_FIRST(&ram_list.blocks); + block = QLIST_FIRST_RCU(&ram_list.blocks); complete_round = true; ram_bulk_stage = false; } @@ -688,9 +694,9 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage) } } } + last_seen_block = block; last_offset = offset; - return bytes_sent; } @@ -728,9 +734,10 @@ uint64_t ram_bytes_total(void) RAMBlock *block; uint64_t total = 0; - QTAILQ_FOREACH(block, &ram_list.blocks, next) + rcu_read_lock(); + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) total += block->used_length; - + rcu_read_unlock(); return total; } @@ -776,6 +783,13 @@ static void reset_ram_globals(void) #define MAX_WAIT 50 /* ms, half buffered_file limit */ + +/* Each of ram_save_setup, ram_save_iterate and ram_save_complete has + * long-running RCU critical section. When rcu-reclaims in the code + * start to become numerous it will be necessary to reduce the + * granularity of these critical sections. + */ + static int ram_save_setup(QEMUFile *f, void *opaque) { RAMBlock *block; @@ -816,8 +830,10 @@ static int ram_save_setup(QEMUFile *f, void *opaque) acct_clear(); } + /* iothread lock needed for ram_list.dirty_memory[] */ qemu_mutex_lock_iothread(); qemu_mutex_lock_ramlist(); + rcu_read_lock(); bytes_transferred = 0; reset_ram_globals(); @@ -830,7 +846,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque) * gaps due to alignment or unplugs. */ migration_dirty_pages = 0; - QTAILQ_FOREACH(block, &ram_list.blocks, next) { + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { uint64_t block_pages; block_pages = block->used_length >> TARGET_PAGE_BITS; @@ -839,17 +855,18 @@ static int ram_save_setup(QEMUFile *f, void *opaque) memory_global_dirty_log_start(); migration_bitmap_sync(); + qemu_mutex_unlock_ramlist(); qemu_mutex_unlock_iothread(); qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE); - QTAILQ_FOREACH(block, &ram_list.blocks, next) { + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { qemu_put_byte(f, strlen(block->idstr)); qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr)); qemu_put_be64(f, block->used_length); } - qemu_mutex_unlock_ramlist(); + rcu_read_unlock(); ram_control_before_iterate(f, RAM_CONTROL_SETUP); ram_control_after_iterate(f, RAM_CONTROL_SETUP); @@ -866,12 +883,14 @@ static int ram_save_iterate(QEMUFile *f, void *opaque) int64_t t0; int total_sent = 0; - qemu_mutex_lock_ramlist(); - + rcu_read_lock(); if (ram_list.version != last_version) { reset_ram_globals(); } + /* Read version before ram_list.blocks */ + smp_rmb(); + ram_control_before_iterate(f, RAM_CONTROL_ROUND); t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); @@ -902,8 +921,7 @@ static int ram_save_iterate(QEMUFile *f, void *opaque) } i++; } - - qemu_mutex_unlock_ramlist(); + rcu_read_unlock(); /* * Must occur before EOS (or any QEMUFile operation) @@ -928,9 +946,11 @@ static int ram_save_iterate(QEMUFile *f, void *opaque) return total_sent; } +/* Called with iothread lock */ static int ram_save_complete(QEMUFile *f, void *opaque) { - qemu_mutex_lock_ramlist(); + rcu_read_lock(); + migration_bitmap_sync(); ram_control_before_iterate(f, RAM_CONTROL_FINISH); @@ -952,7 +972,7 @@ static int ram_save_complete(QEMUFile *f, void *opaque) ram_control_after_iterate(f, RAM_CONTROL_FINISH); migration_end(); - qemu_mutex_unlock_ramlist(); + rcu_read_unlock(); qemu_put_be64(f, RAM_SAVE_FLAG_EOS); return 0; @@ -966,7 +986,9 @@ static uint64_t ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size) if (remaining_size < max_size) { qemu_mutex_lock_iothread(); + rcu_read_lock(); migration_bitmap_sync(); + rcu_read_unlock(); qemu_mutex_unlock_iothread(); remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE; } @@ -1008,6 +1030,9 @@ static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host) return 0; } +/* Must be called from within a rcu critical section. + * Returns a pointer from within the RCU-protected ram_list. + */ static inline void *host_from_stream_offset(QEMUFile *f, ram_addr_t offset, int flags) @@ -1029,7 +1054,7 @@ static inline void *host_from_stream_offset(QEMUFile *f, qemu_get_buffer(f, (uint8_t *)id, len); id[len] = 0; - QTAILQ_FOREACH(block, &ram_list.blocks, next) { + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { if (!strncmp(id, block->idstr, sizeof(id)) && block->max_length > offset) { return memory_region_get_ram_ptr(block->mr) + offset; @@ -1062,6 +1087,12 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) ret = -EINVAL; } + /* This RCU critical section can be very long running. + * When RCU reclaims in the code start to become numerous, + * it will be necessary to reduce the granularity of this + * critical section. + */ + rcu_read_lock(); while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) { ram_addr_t addr, total_ram_bytes; void *host; @@ -1086,7 +1117,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) id[len] = 0; length = qemu_get_be64(f); - QTAILQ_FOREACH(block, &ram_list.blocks, next) { + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { if (!strncmp(id, block->idstr, sizeof(id))) { if (length != block->used_length) { Error *local_err = NULL; @@ -1116,7 +1147,6 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) ret = -EINVAL; break; } - ch = qemu_get_byte(f); ram_handle_compressed(host, ch, TARGET_PAGE_SIZE); break; @@ -1127,7 +1157,6 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) ret = -EINVAL; break; } - qemu_get_buffer(f, host, TARGET_PAGE_SIZE); break; case RAM_SAVE_FLAG_XBZRLE: @@ -1137,7 +1166,6 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) ret = -EINVAL; break; } - if (load_xbzrle(f, addr, host) < 0) { error_report("Failed to decompress XBZRLE page at " RAM_ADDR_FMT, addr); @@ -1162,6 +1190,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) } } + rcu_read_unlock(); DPRINTF("Completed load of VM with exit code %d seq iteration " "%" PRIu64 "\n", ret, seq_iter); return ret; |