diff options
| -rw-r--r-- | migration/ram.c | 130 | ||||
| -rw-r--r-- | trace-events | 1 |
2 files changed, 130 insertions, 1 deletions
diff --git a/migration/ram.c b/migration/ram.c index d09d5ab633..af5f3692fb 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1932,6 +1932,14 @@ static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host) /* Must be called from within a rcu critical section. * Returns a pointer from within the RCU-protected ram_list. */ +/* + * Read a RAMBlock ID from the stream f, find the host address of the + * start of that block and add on 'offset' + * + * f: Stream to read from + * offset: Offset within the block + * flags: Page flags (mostly to see if it's a continuation of previous block) + */ static inline void *host_from_stream_offset(QEMUFile *f, ram_addr_t offset, int flags) @@ -2077,11 +2085,126 @@ int ram_postcopy_incoming_init(MigrationIncomingState *mis) return postcopy_ram_incoming_init(mis, ram_pages); } +/* + * Called in postcopy mode by ram_load(). + * rcu_read_lock is taken prior to this being called. + */ +static int ram_load_postcopy(QEMUFile *f) +{ + int flags = 0, ret = 0; + bool place_needed = false; + bool matching_page_sizes = qemu_host_page_size == TARGET_PAGE_SIZE; + MigrationIncomingState *mis = migration_incoming_get_current(); + /* Temporary page that is later 'placed' */ + void *postcopy_host_page = postcopy_get_tmp_page(mis); + + while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) { + ram_addr_t addr; + void *host = NULL; + void *page_buffer = NULL; + void *place_source = NULL; + uint8_t ch; + bool all_zero = false; + + addr = qemu_get_be64(f); + flags = addr & ~TARGET_PAGE_MASK; + addr &= TARGET_PAGE_MASK; + + trace_ram_load_postcopy_loop((uint64_t)addr, flags); + place_needed = false; + if (flags & (RAM_SAVE_FLAG_COMPRESS | RAM_SAVE_FLAG_PAGE)) { + host = host_from_stream_offset(f, addr, flags); + if (!host) { + error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); + ret = -EINVAL; + break; + } + page_buffer = host; + /* + * Postcopy requires that we place whole host pages atomically. + * To make it atomic, the data is read into a temporary page + * that's moved into place later. + * The migration protocol uses, possibly smaller, target-pages + * however the source ensures it always sends all the components + * of a host page in order. + */ + page_buffer = postcopy_host_page + + ((uintptr_t)host & ~qemu_host_page_mask); + /* If all TP are zero then we can optimise the place */ + if (!((uintptr_t)host & ~qemu_host_page_mask)) { + all_zero = true; + } + + /* + * If it's the last part of a host page then we place the host + * page + */ + place_needed = (((uintptr_t)host + TARGET_PAGE_SIZE) & + ~qemu_host_page_mask) == 0; + place_source = postcopy_host_page; + } + + switch (flags & ~RAM_SAVE_FLAG_CONTINUE) { + case RAM_SAVE_FLAG_COMPRESS: + ch = qemu_get_byte(f); + memset(page_buffer, ch, TARGET_PAGE_SIZE); + if (ch) { + all_zero = false; + } + break; + + case RAM_SAVE_FLAG_PAGE: + all_zero = false; + if (!place_needed || !matching_page_sizes) { + qemu_get_buffer(f, page_buffer, TARGET_PAGE_SIZE); + } else { + /* Avoids the qemu_file copy during postcopy, which is + * going to do a copy later; can only do it when we + * do this read in one go (matching page sizes) + */ + qemu_get_buffer_in_place(f, (uint8_t **)&place_source, + TARGET_PAGE_SIZE); + } + break; + case RAM_SAVE_FLAG_EOS: + /* normal exit */ + break; + default: + error_report("Unknown combination of migration flags: %#x" + " (postcopy mode)", flags); + ret = -EINVAL; + } + + if (place_needed) { + /* This gets called at the last target page in the host page */ + if (all_zero) { + ret = postcopy_place_page_zero(mis, + host + TARGET_PAGE_SIZE - + qemu_host_page_size); + } else { + ret = postcopy_place_page(mis, host + TARGET_PAGE_SIZE - + qemu_host_page_size, + place_source); + } + } + if (!ret) { + ret = qemu_file_get_error(f); + } + } + + return ret; +} + static int ram_load(QEMUFile *f, void *opaque, int version_id) { int flags = 0, ret = 0; static uint64_t seq_iter; int len = 0; + /* + * If system is running in postcopy mode, page inserts to host memory must + * be atomic + */ + bool postcopy_running = postcopy_state_get() >= POSTCOPY_INCOMING_LISTENING; seq_iter++; @@ -2095,7 +2218,12 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) * critical section. */ rcu_read_lock(); - while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) { + + if (postcopy_running) { + ret = ram_load_postcopy(f); + } + + while (!postcopy_running && !ret && !(flags & RAM_SAVE_FLAG_EOS)) { ram_addr_t addr, total_ram_bytes; void *host = NULL; uint8_t ch; diff --git a/trace-events b/trace-events index c493f5dc10..ad7afcb165 100644 --- a/trace-events +++ b/trace-events @@ -1257,6 +1257,7 @@ get_queued_page_not_dirty(const char *block_name, uint64_t tmp_offset, uint64_t migration_bitmap_sync_start(void) "" migration_bitmap_sync_end(uint64_t dirty_pages) "dirty_pages %" PRIu64"" migration_throttle(void) "" +ram_load_postcopy_loop(uint64_t addr, int flags) "@%" PRIx64 " %x" ram_postcopy_send_discard_bitmap(void) "" ram_save_queue_pages(const char *rbname, size_t start, size_t len) "%s: start: %zx len: %zx" |