From ee64722514fabcad2430982ade86180208f5be4f Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Mon, 27 Jul 2020 22:42:32 +0300 Subject: [PATCH] migration/savevm: don't worry if bitmap migration postcopy failed First, if only bitmaps postcopy is enabled (and not ram postcopy) postcopy_pause_incoming crashes on an assertion assert(mis->to_src_file). And anyway, bitmaps postcopy is not prepared to be somehow recovered. The original idea instead is that if bitmaps postcopy failed, we just lose some bitmaps, which is not critical. So, on failure we just need to remove unfinished bitmaps and guest should continue execution on destination. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Andrey Shinkevich Reviewed-by: Eric Blake Message-Id: <20200727194236.19551-18-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake --- migration/savevm.c | 37 ++++++++++++++++++++++++++++++++----- 1 file changed, 32 insertions(+), 5 deletions(-) diff --git a/migration/savevm.c b/migration/savevm.c index 45c9dd9d8a..a843d202b5 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1813,6 +1813,9 @@ static void *postcopy_ram_listen_thread(void *opaque) MigrationIncomingState *mis = migration_incoming_get_current(); QEMUFile *f = mis->from_src_file; int load_res; + MigrationState *migr = migrate_get_current(); + + object_ref(OBJECT(migr)); migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_POSTCOPY_ACTIVE); @@ -1839,11 +1842,24 @@ static void *postcopy_ram_listen_thread(void *opaque) trace_postcopy_ram_listen_thread_exit(); if (load_res < 0) { - error_report("%s: loadvm failed: %d", __func__, load_res); qemu_file_set_error(f, load_res); - migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_ACTIVE, - MIGRATION_STATUS_FAILED); - } else { + dirty_bitmap_mig_cancel_incoming(); + if (postcopy_state_get() == POSTCOPY_INCOMING_RUNNING && + !migrate_postcopy_ram() && migrate_dirty_bitmaps()) + { + error_report("%s: loadvm failed during postcopy: %d. All states " + "are migrated except dirty bitmaps. Some dirty " + "bitmaps may be lost, and present migrated dirty " + "bitmaps are correctly migrated and valid.", + __func__, load_res); + load_res = 0; /* prevent further exit() */ + } else { + error_report("%s: loadvm failed: %d", __func__, load_res); + migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_ACTIVE, + MIGRATION_STATUS_FAILED); + } + } + if (load_res >= 0) { /* * This looks good, but it's possible that the device loading in the * main thread hasn't finished yet, and so we might not be in 'RUN' @@ -1879,6 +1895,8 @@ static void *postcopy_ram_listen_thread(void *opaque) mis->have_listen_thread = false; postcopy_state_set(POSTCOPY_INCOMING_END); + object_unref(OBJECT(migr)); + return NULL; } @@ -2437,6 +2455,8 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis) { trace_postcopy_pause_incoming(); + assert(migrate_postcopy_ram()); + /* Clear the triggered bit to allow one recovery */ mis->postcopy_recover_triggered = false; @@ -2521,15 +2541,22 @@ out: if (ret < 0) { qemu_file_set_error(f, ret); + /* Cancel bitmaps incoming regardless of recovery */ + dirty_bitmap_mig_cancel_incoming(); + /* * If we are during an active postcopy, then we pause instead * of bail out to at least keep the VM's dirty data. Note * that POSTCOPY_INCOMING_LISTENING stage is still not enough, * during which we're still receiving device states and we * still haven't yet started the VM on destination. + * + * Only RAM postcopy supports recovery. Still, if RAM postcopy is + * enabled, canceled bitmaps postcopy will not affect RAM postcopy + * recovering. */ if (postcopy_state_get() == POSTCOPY_INCOMING_RUNNING && - postcopy_pause_incoming(mis)) { + migrate_postcopy_ram() && postcopy_pause_incoming(mis)) { /* Reset f to point to the newly created channel */ f = mis->from_src_file; goto retry; -- 2.11.4.GIT