From 2f6b8826a542a5a2e8eb3fbf097ea6982ba5bf31 Mon Sep 17 00:00:00 2001 From: Fabiano Rosas Date: Thu, 29 Feb 2024 12:30:04 -0300 Subject: [PATCH] migration/ram: Add incoming 'mapped-ram' migration Add the necessary code to parse the format changes for the 'mapped-ram' capability. One of the more notable changes in behavior is that in the 'mapped-ram' case ram pages are restored in one go rather than constantly looping through the migration stream. Signed-off-by: Nikolay Borisov Reviewed-by: Peter Xu Signed-off-by: Fabiano Rosas Link: https://lore.kernel.org/r/20240229153017.2221-11-farosas@suse.de Signed-off-by: Peter Xu --- migration/ram.c | 143 +++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 141 insertions(+), 2 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index f807824d49..18620784c6 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -106,6 +106,12 @@ */ #define MAPPED_RAM_FILE_OFFSET_ALIGNMENT 0x100000 +/* + * When doing mapped-ram migration, this is the amount we read from + * the pages region in the migration file at a time. + */ +#define MAPPED_RAM_LOAD_BUF_SIZE 0x100000 + XBZRLECacheStats xbzrle_counters; /* used by the search for pages to send */ @@ -2998,6 +3004,35 @@ static void mapped_ram_setup_ramblock(QEMUFile *file, RAMBlock *block) qemu_set_offset(file, block->pages_offset + block->used_length, SEEK_SET); } +static bool mapped_ram_read_header(QEMUFile *file, MappedRamHeader *header, + Error **errp) +{ + size_t ret, header_size = sizeof(MappedRamHeader); + + ret = qemu_get_buffer(file, (uint8_t *)header, header_size); + if (ret != header_size) { + error_setg(errp, "Could not read whole mapped-ram migration header " + "(expected %zd, got %zd bytes)", header_size, ret); + return false; + } + + /* migration stream is big-endian */ + header->version = be32_to_cpu(header->version); + + if (header->version > MAPPED_RAM_HDR_VERSION) { + error_setg(errp, "Migration mapped-ram capability version not " + "supported (expected <= %d, got %d)", MAPPED_RAM_HDR_VERSION, + header->version); + return false; + } + + header->page_size = be64_to_cpu(header->page_size); + header->bitmap_offset = be64_to_cpu(header->bitmap_offset); + header->pages_offset = be64_to_cpu(header->pages_offset); + + return true; +} + /* * Each of ram_save_setup, ram_save_iterate and ram_save_complete has * long-running RCU critical section. When rcu-reclaims in the code @@ -3899,22 +3934,126 @@ void colo_flush_ram_cache(void) trace_colo_flush_ram_cache_end(); } +static bool read_ramblock_mapped_ram(QEMUFile *f, RAMBlock *block, + long num_pages, unsigned long *bitmap, + Error **errp) +{ + ERRP_GUARD(); + unsigned long set_bit_idx, clear_bit_idx; + ram_addr_t offset; + void *host; + size_t read, unread, size; + + for (set_bit_idx = find_first_bit(bitmap, num_pages); + set_bit_idx < num_pages; + set_bit_idx = find_next_bit(bitmap, num_pages, clear_bit_idx + 1)) { + + clear_bit_idx = find_next_zero_bit(bitmap, num_pages, set_bit_idx + 1); + + unread = TARGET_PAGE_SIZE * (clear_bit_idx - set_bit_idx); + offset = set_bit_idx << TARGET_PAGE_BITS; + + while (unread > 0) { + host = host_from_ram_block_offset(block, offset); + if (!host) { + error_setg(errp, "page outside of ramblock %s range", + block->idstr); + return false; + } + + size = MIN(unread, MAPPED_RAM_LOAD_BUF_SIZE); + + read = qemu_get_buffer_at(f, host, size, + block->pages_offset + offset); + if (!read) { + goto err; + } + offset += read; + unread -= read; + } + } + + return true; + +err: + qemu_file_get_error_obj(f, errp); + error_prepend(errp, "(%s) failed to read page " RAM_ADDR_FMT + "from file offset %" PRIx64 ": ", block->idstr, offset, + block->pages_offset + offset); + return false; +} + +static void parse_ramblock_mapped_ram(QEMUFile *f, RAMBlock *block, + ram_addr_t length, Error **errp) +{ + g_autofree unsigned long *bitmap = NULL; + MappedRamHeader header; + size_t bitmap_size; + long num_pages; + + if (!mapped_ram_read_header(f, &header, errp)) { + return; + } + + block->pages_offset = header.pages_offset; + + /* + * Check the alignment of the file region that contains pages. We + * don't enforce MAPPED_RAM_FILE_OFFSET_ALIGNMENT to allow that + * value to change in the future. Do only a sanity check with page + * size alignment. + */ + if (!QEMU_IS_ALIGNED(block->pages_offset, TARGET_PAGE_SIZE)) { + error_setg(errp, + "Error reading ramblock %s pages, region has bad alignment", + block->idstr); + return; + } + + num_pages = length / header.page_size; + bitmap_size = BITS_TO_LONGS(num_pages) * sizeof(unsigned long); + + bitmap = g_malloc0(bitmap_size); + if (qemu_get_buffer_at(f, (uint8_t *)bitmap, bitmap_size, + header.bitmap_offset) != bitmap_size) { + error_setg(errp, "Error reading dirty bitmap"); + return; + } + + if (!read_ramblock_mapped_ram(f, block, num_pages, bitmap, errp)) { + return; + } + + /* Skip pages array */ + qemu_set_offset(f, block->pages_offset + length, SEEK_SET); + + return; +} + static int parse_ramblock(QEMUFile *f, RAMBlock *block, ram_addr_t length) { int ret = 0; /* ADVISE is earlier, it shows the source has the postcopy capability on */ bool postcopy_advised = migration_incoming_postcopy_advised(); + Error *local_err = NULL; assert(block); + if (migrate_mapped_ram()) { + parse_ramblock_mapped_ram(f, block, length, &local_err); + if (local_err) { + error_report_err(local_err); + return -EINVAL; + } + return 0; + } + if (!qemu_ram_is_migratable(block)) { error_report("block %s should not be migrated !", block->idstr); return -EINVAL; } if (length != block->used_length) { - Error *local_err = NULL; - ret = qemu_ram_resize(block, length, &local_err); if (local_err) { error_report_err(local_err);