From patchwork Wed Nov 18 13:20:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Gruzdev X-Patchwork-Id: 11915093 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 31ED5138B for ; Wed, 18 Nov 2020 13:26:17 +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 E31452168B for ; Wed, 18 Nov 2020 13:26:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E31452168B 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+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:60042 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kfNTT-0004z8-QD for patchwork-qemu-devel@patchwork.kernel.org; Wed, 18 Nov 2020 08:26:15 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:33974) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kfNOP-0007yy-Hi for qemu-devel@nongnu.org; Wed, 18 Nov 2020 08:21:02 -0500 Received: from relay.sw.ru ([185.231.240.75]:48182 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 1kfNOG-00023p-NN for qemu-devel@nongnu.org; Wed, 18 Nov 2020 08:21:01 -0500 Received: from [192.168.15.37] (helo=andrey-MS-7B54.sw.ru) by relay3.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1kfNO2-009Ap3-8x; Wed, 18 Nov 2020 16:20:38 +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 v2 5/7] Implementation of vm_start() BH. Date: Wed, 18 Nov 2020 16:20:46 +0300 Message-Id: <20201118132048.429092-6-andrey.gruzdev@virtuozzo.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201118132048.429092-1-andrey.gruzdev@virtuozzo.com> References: <20201118132048.429092-1-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 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+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" Reply-to: Andrey Gruzdev X-Patchwork-Original-From: Andrey Gruzdev via From: Andrey Gruzdev 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 158e5441ec..dba388f8bd 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; } /*