diff options
| -rw-r--r-- | migration/postcopy-ram.c | 31 | ||||
| -rw-r--r-- | migration/ram.c | 21 | ||||
| -rw-r--r-- | migration/ram.h | 1 |
3 files changed, 49 insertions, 4 deletions
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index 2e9697bdd2..3609ce7e52 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -671,6 +671,29 @@ int postcopy_wake_shared(struct PostCopyFD *pcfd, return ret; } +static int postcopy_request_page(MigrationIncomingState *mis, RAMBlock *rb, + ram_addr_t start, uint64_t haddr) +{ + void *aligned = (void *)(uintptr_t)ROUND_DOWN(haddr, qemu_ram_pagesize(rb)); + + /* + * Discarded pages (via RamDiscardManager) are never migrated. On unlikely + * access, place a zeropage, which will also set the relevant bits in the + * recv_bitmap accordingly, so we won't try placing a zeropage twice. + * + * Checking a single bit is sufficient to handle pagesize > TPS as either + * all relevant bits are set or not. + */ + assert(QEMU_IS_ALIGNED(start, qemu_ram_pagesize(rb))); + if (ramblock_page_is_discarded(rb, start)) { + bool received = ramblock_recv_bitmap_test_byte_offset(rb, start); + + return received ? 0 : postcopy_place_page_zero(mis, aligned, rb); + } + + return migrate_send_rp_req_pages(mis, rb, start, haddr); +} + /* * Callback from shared fault handlers to ask for a page, * the page must be specified by a RAMBlock and an offset in that rb @@ -690,7 +713,7 @@ int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb, qemu_ram_get_idstr(rb), rb_offset); return postcopy_wake_shared(pcfd, client_addr, rb); } - migrate_send_rp_req_pages(mis, rb, aligned_rbo, client_addr); + postcopy_request_page(mis, rb, aligned_rbo, client_addr); return 0; } @@ -984,8 +1007,8 @@ retry: * Send the request to the source - we want to request one * of our host page sizes (which is >= TPS) */ - ret = migrate_send_rp_req_pages(mis, rb, rb_offset, - msg.arg.pagefault.address); + ret = postcopy_request_page(mis, rb, rb_offset, + msg.arg.pagefault.address); if (ret) { /* May be network failure, try to wait for recovery */ if (ret == -EIO && postcopy_pause_fault_thread(mis)) { @@ -993,7 +1016,7 @@ retry: goto retry; } else { /* This is a unavoidable fault */ - error_report("%s: migrate_send_rp_req_pages() get %d", + error_report("%s: postcopy_request_page() get %d", __func__, ret); break; } diff --git a/migration/ram.c b/migration/ram.c index e8c06f207c..4f629de7d0 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -912,6 +912,27 @@ static uint64_t ramblock_dirty_bitmap_clear_discarded_pages(RAMBlock *rb) return cleared_bits; } +/* + * Check if a host-page aligned page falls into a discarded range as managed by + * a RamDiscardManager responsible for the mapped memory region of the RAMBlock. + * + * Note: The result is only stable while migrating (precopy/postcopy). + */ +bool ramblock_page_is_discarded(RAMBlock *rb, ram_addr_t start) +{ + if (rb->mr && memory_region_has_ram_discard_manager(rb->mr)) { + RamDiscardManager *rdm = memory_region_get_ram_discard_manager(rb->mr); + MemoryRegionSection section = { + .mr = rb->mr, + .offset_within_region = start, + .size = int128_make64(qemu_ram_pagesize(rb)), + }; + + return !ram_discard_manager_is_populated(rdm, §ion); + } + return false; +} + /* Called with RCU critical section */ static void ramblock_sync_dirty_bitmap(RAMState *rs, RAMBlock *rb) { diff --git a/migration/ram.h b/migration/ram.h index 4833e9fd5b..dda1988f3d 100644 --- a/migration/ram.h +++ b/migration/ram.h @@ -72,6 +72,7 @@ void ramblock_recv_bitmap_set_range(RAMBlock *rb, void *host_addr, size_t nr); int64_t ramblock_recv_bitmap_send(QEMUFile *file, const char *block_name); int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb); +bool ramblock_page_is_discarded(RAMBlock *rb, ram_addr_t start); /* ram cache */ int colo_init_ram_cache(void); |