From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9EDB3C56202 for ; Wed, 18 Nov 2020 11:30:49 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EC8622463B for ; Wed, 18 Nov 2020 11:30:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EC8622463B Authentication-Results: mail.kernel.org; dmarc=pass (p=none dis=none) header.from=nongnu.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38242 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kfLfj-0005NF-SL for qemu-devel@archiver.kernel.org; Wed, 18 Nov 2020 06:30:47 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:36680) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kfLY5-000595-Fq for qemu-devel@nongnu.org; Wed, 18 Nov 2020 06:22:53 -0500 Received: from relay.sw.ru ([185.231.240.75]:41862 helo=relay3.sw.ru) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kfLXr-0003Ol-5l for qemu-devel@nongnu.org; Wed, 18 Nov 2020 06:22:53 -0500 Received: from [192.168.15.76] (helo=andrey-MS-7B54.sw.ru) by relay3.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1kfLXb-009A89-AU; Wed, 18 Nov 2020 14:22:23 +0300 To: qemu-devel@nongnu.org Cc: Den Lunev , Eric Blake , Paolo Bonzini , Juan Quintela , "Dr . David Alan Gilbert" , Markus Armbruster , Andrey Gruzdev Subject: [PATCH 5/7] Implementation of vm_start() BH. Date: Wed, 18 Nov 2020 14:22:31 +0300 Message-Id: <20201118112233.264530-6-andrey.gruzdev@virtuozzo.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201118112233.264530-1-andrey.gruzdev@virtuozzo.com> References: <20201118112233.264530-1-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=185.231.240.75; envelope-from=andrey.gruzdev@virtuozzo.com; helo=relay3.sw.ru X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/18 06:22:34 X-ACL-Warn: Detected OS = Linux 3.11 and newer [fuzzy] X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Reply-to: Andrey Gruzdev From: Andrey Gruzdev via To avoid saving updated versions of memory pages we need to start tracking RAM writes before we resume operation of vCPUs. This sequence is especially critical for virtio device backends whos VQs are mapped to main memory and accessed directly not using MMIO callbacks. One problem is that vm_start() routine makes calls state change notifier callbacks directly from itself. Virtio drivers do some stuff with syncing/flusing VQs in its notifier routines. Since we poll UFFD and process faults on the same thread, that leads to the situation when the thread locks in vm_start() if we try to call it from the migration thread. The solution is to call ram_write_tracking_start() directly from migration thread and then schedule BH for vm_start. Signed-off-by: Andrey Gruzdev --- migration/migration.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/migration/migration.c b/migration/migration.c index 1ffbb4ce4a..381da4a4d3 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3716,7 +3716,13 @@ static void *migration_thread(void *opaque) static void wt_migration_vm_start_bh(void *opaque) { - /* TODO: implement */ + MigrationState *s = opaque; + + qemu_bh_delete(s->wt_vm_start_bh); + s->wt_vm_start_bh = NULL; + + vm_start(); + s->downtime = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - s->downtime_start; } /* -- 2.25.1