diff options
| -rw-r--r-- | exec.c | 31 | ||||
| -rw-r--r-- | include/exec/memory.h | 12 | ||||
| -rw-r--r-- | memory.c | 10 | ||||
| -rw-r--r-- | migration/ram.c | 1 |
4 files changed, 53 insertions, 1 deletions
@@ -197,6 +197,7 @@ typedef struct subpage_t { static void io_mem_init(void); static void memory_map_init(void); +static void tcg_log_global_after_sync(MemoryListener *listener); static void tcg_commit(MemoryListener *listener); static MemoryRegion io_mem_watch; @@ -905,6 +906,7 @@ void cpu_address_space_init(CPUState *cpu, int asidx, newas->cpu = cpu; newas->as = as; if (tcg_enabled()) { + newas->tcg_as_listener.log_global_after_sync = tcg_log_global_after_sync; newas->tcg_as_listener.commit = tcg_commit; memory_listener_register(&newas->tcg_as_listener, as); } @@ -3142,6 +3144,35 @@ void address_space_dispatch_free(AddressSpaceDispatch *d) g_free(d); } +static void do_nothing(CPUState *cpu, run_on_cpu_data d) +{ +} + +static void tcg_log_global_after_sync(MemoryListener *listener) +{ + CPUAddressSpace *cpuas; + + /* Wait for the CPU to end the current TB. This avoids the following + * incorrect race: + * + * vCPU migration + * ---------------------- ------------------------- + * TLB check -> slow path + * notdirty_mem_write + * write to RAM + * mark dirty + * clear dirty flag + * TLB check -> fast path + * read memory + * write to RAM + * + * by pushing the migration thread's memory read after the vCPU thread has + * written the memory. + */ + cpuas = container_of(listener, CPUAddressSpace, tcg_as_listener); + run_on_cpu(cpuas->cpu, do_nothing, RUN_ON_CPU_NULL); +} + static void tcg_commit(MemoryListener *listener) { CPUAddressSpace *cpuas; diff --git a/include/exec/memory.h b/include/exec/memory.h index d99eb25d2e..fddc2ff48a 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -425,6 +425,7 @@ struct MemoryListener { void (*log_clear)(MemoryListener *listener, MemoryRegionSection *section); void (*log_global_start)(MemoryListener *listener); void (*log_global_stop)(MemoryListener *listener); + void (*log_global_after_sync)(MemoryListener *listener); void (*eventfd_add)(MemoryListener *listener, MemoryRegionSection *section, bool match_data, uint64_t data, EventNotifier *e); void (*eventfd_del)(MemoryListener *listener, MemoryRegionSection *section, @@ -1688,6 +1689,17 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr, void memory_global_dirty_log_sync(void); /** + * memory_global_dirty_log_sync: synchronize the dirty log for all memory + * + * Synchronizes the vCPUs with a thread that is reading the dirty bitmap. + * This function must be called after the dirty log bitmap is cleared, and + * before dirty guest memory pages are read. If you are using + * #DirtyBitmapSnapshot, memory_region_snapshot_and_clear_dirty() takes + * care of doing this. + */ +void memory_global_after_dirty_log_sync(void); + +/** * memory_region_transaction_begin: Start a transaction. * * During a transaction, changes will be accumulated and made visible @@ -2127,9 +2127,12 @@ DirtyBitmapSnapshot *memory_region_snapshot_and_clear_dirty(MemoryRegion *mr, hwaddr size, unsigned client) { + DirtyBitmapSnapshot *snapshot; assert(mr->ram_block); memory_region_sync_dirty_bitmap(mr); - return cpu_physical_memory_snapshot_and_clear_dirty(mr, addr, size, client); + snapshot = cpu_physical_memory_snapshot_and_clear_dirty(mr, addr, size, client); + memory_global_after_dirty_log_sync(); + return snapshot; } bool memory_region_snapshot_get_dirty(MemoryRegion *mr, DirtyBitmapSnapshot *snap, @@ -2620,6 +2623,11 @@ void memory_global_dirty_log_sync(void) memory_region_sync_dirty_bitmap(NULL); } +void memory_global_after_dirty_log_sync(void) +{ + MEMORY_LISTENER_CALL_GLOBAL(log_global_after_sync, Forward); +} + static VMChangeStateEntry *vmstate_change; void memory_global_dirty_log_start(void) diff --git a/migration/ram.c b/migration/ram.c index 35552c090b..b01a37e7ca 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1857,6 +1857,7 @@ static void migration_bitmap_sync(RAMState *rs) rcu_read_unlock(); qemu_mutex_unlock(&rs->bitmap_mutex); + memory_global_after_dirty_log_sync(); trace_migration_bitmap_sync_end(rs->num_dirty_pages_period); end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); |