From patchwork Fri Apr 11 11:45:31 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Prasad Pandit X-Patchwork-Id: 14048270 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 7A226C369A8 for ; Fri, 11 Apr 2025 11:47:58 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1u3Cpr-0007EC-Cb; Fri, 11 Apr 2025 07:46:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1u3Cpk-0007D0-ID for qemu-devel@nongnu.org; Fri, 11 Apr 2025 07:46:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1u3Cpi-0001UC-WA for qemu-devel@nongnu.org; Fri, 11 Apr 2025 07:46:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744371966; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=12zeTQzrHuHdLsq7BhjW1/VWooFa0qfz0ggP5mTDgSo=; b=DYUL3BhcnsjMkAlgp9TTe0bARW9r2DkzKGg7VhWRm94uxQg8uMoFFabbTy07Lsd95KuhXN bvPwe63ILbbFNbRVw+xdZYRzGZjxb1RUU/mHgal24MEgku+hZJ2Xwzg4r3qxnGQTg6VGAz zQGL59B10furEuu1K5DsGsO19fc2Tn0= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-643-h_Rc4vUGOzq0V6iRBZPIxQ-1; Fri, 11 Apr 2025 07:46:03 -0400 X-MC-Unique: h_Rc4vUGOzq0V6iRBZPIxQ-1 X-Mimecast-MFC-AGG-ID: h_Rc4vUGOzq0V6iRBZPIxQ_1744371962 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4B2461801A12; Fri, 11 Apr 2025 11:46:02 +0000 (UTC) Received: from kaapi.redhat.com (unknown [10.74.16.160]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DFE4F180175B; Fri, 11 Apr 2025 11:45:58 +0000 (UTC) From: Prasad Pandit To: qemu-devel@nongnu.org Cc: farosas@suse.de, peterx@redhat.com, berrange@redhat.com Subject: [PATCH v9 4/7] migration/ram: Implement save_postcopy_prepare() Date: Fri, 11 Apr 2025 17:15:31 +0530 Message-ID: <20250411114534.3370816-5-ppandit@redhat.com> In-Reply-To: <20250411114534.3370816-1-ppandit@redhat.com> References: <20250411114534.3370816-1-ppandit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.129.124; envelope-from=ppandit@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.681, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, 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: 2.1.29 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Peter Xu Implement save_postcopy_prepare(), preparing for the enablement of both multifd and postcopy. Signed-off-by: Peter Xu Signed-off-by: Prasad Pandit --- migration/ram.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) v8: reorder patch and some typographical corrections. - https://lore.kernel.org/qemu-devel/20250318123846.1370312-1-ppandit@redhat.com/T/#t diff --git a/migration/ram.c b/migration/ram.c index 424df6d9f1..753042456e 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -4420,6 +4420,42 @@ static int ram_resume_prepare(MigrationState *s, void *opaque) return 0; } +static bool ram_save_postcopy_prepare(QEMUFile *f, void *opaque, Error **errp) +{ + int ret; + + if (migrate_multifd()) { + /* + * When multifd is enabled, source QEMU needs to make sure all the + * pages queued before postcopy starts have been flushed. + * + * The load of these pages must happen before switching to postcopy. + * It's because loading of guest pages (so far) in multifd recv + * threads is still non-atomic, so the load cannot happen with vCPUs + * running on the destination side. + * + * This flush and sync will guarantee that those pages are loaded + * _before_ postcopy starts on the destination. The rationale is, + * this happens before VM stops (and before source QEMU sends all + * the rest of the postcopy messages). So when the destination QEMU + * receives the postcopy messages, it must have received the sync + * message on the main channel (either RAM_SAVE_FLAG_MULTIFD_FLUSH, + * or RAM_SAVE_FLAG_EOS), and such message would guarantee that + * all previous guest pages queued in the multifd channels are + * completely loaded. + */ + ret = multifd_ram_flush_and_sync(f); + if (ret < 0) { + error_setg(errp, "%s: multifd flush and sync failed", __func__); + return false; + } + } + + qemu_put_be64(f, RAM_SAVE_FLAG_EOS); + + return true; +} + void postcopy_preempt_shutdown_file(MigrationState *s) { qemu_put_be64(s->postcopy_qemufile_src, RAM_SAVE_FLAG_EOS); @@ -4439,6 +4475,7 @@ static SaveVMHandlers savevm_ram_handlers = { .load_setup = ram_load_setup, .load_cleanup = ram_load_cleanup, .resume_prepare = ram_resume_prepare, + .save_postcopy_prepare = ram_save_postcopy_prepare, }; static void ram_mig_ram_block_resized(RAMBlockNotifier *n, void *host,