From patchwork Thu Dec 22 11:02:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13079580 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 E1011C4167B for ; Thu, 22 Dec 2022 11:04:28 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p8JLG-0007jB-SY; Thu, 22 Dec 2022 06:02:27 -0500 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 1p8JLD-0007gP-Tu for qemu-devel@nongnu.org; Thu, 22 Dec 2022 06:02:23 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p8JLC-0000Yh-96 for qemu-devel@nongnu.org; Thu, 22 Dec 2022 06:02:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1671706940; 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; bh=GafvN+Y1DbaMYIh3V5J87yVDENzHGmAzmXRp0bWvcaE=; b=AOujQ9OkihYC614lBA/d4tOlw/daW4FtCtNft/uxKJG03X3hOjPiCJ1xkZKAcIq4i5VIxC piJYciiU9v4Ww6rsFDbkgC/hAZxA1ZVW6DK/95speRbkqDPrhUl0iOsA1FzzDIkuvvvKae jOmkszgfRbQ3Y9Ljq2yfe9gSi4laKGs= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-248-VjlhKLOaMWOIGy3TtQlMlg-1; Thu, 22 Dec 2022 06:02:19 -0500 X-MC-Unique: VjlhKLOaMWOIGy3TtQlMlg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E8FD7101A521 for ; Thu, 22 Dec 2022 11:02:18 +0000 (UTC) Received: from t480s.fritz.box (unknown [10.39.193.53]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0B75E140E949; Thu, 22 Dec 2022 11:02:16 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Cc: David Hildenbrand , "Dr . David Alan Gilbert" , Juan Quintela , Peter Xu , "Michael S . Tsirkin" , Michal Privoznik Subject: [PATCH v3 0/6] virtio-mem: Handle preallocation with migration Date: Thu, 22 Dec 2022 12:02:09 +0100 Message-Id: <20221222110215.130392-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Received-SPF: pass client-ip=170.10.133.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_MSPIKE_H2=-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 While playing with migration of virtio-mem with an ordinary file backing, I realized that migration and prealloc doesn't currently work as expected for virtio-mem. Further, Jing Qi reported that setup issues (insufficient huge pages on the destination) result in QEMU getting killed with SIGBUS instead of failing gracefully. In contrast to ordinary memory backend preallocation, virtio-mem preallocates memory before plugging blocks to the guest. Consequently, when migrating we are not actually preallocating on the destination but "only" migrate pages. Fix that be migrating the bitmap early, before any RAM content, and use that information to preallocate memory early, before migrating any RAM. Postcopy needs some extra care, and I realized that prealloc+postcopy is shaky in general. Let's at least try to mimic what ordinary prealloc+postcopy does: temporarily allocate the memory, discard it, and cross fingers that we'll still have sufficient memory when postcopy actually tries placing pages. Cc: Dr. David Alan Gilbert Cc: Juan Quintela Cc: Peter Xu Cc: Michael S. Tsirkin Cc: Michal Privoznik v2 -> v3: - New approach/rewrite, drop RB and TB of last patch v1 -> v2: - Added RBs and Tested-bys - "virtio-mem: Fail if a memory backend with "prealloc=on" is specified" -- Fail instead of warn -- Adjust subject/description David Hildenbrand (6): migration: Allow immutable device state to be migrated early (i.e., before RAM) migration/vmstate: Introduce VMSTATE_WITH_TMP_TEST() and VMSTATE_BITMAP_TEST() migration: Factor out checks for advised and listening incomming postcopy virtio-mem: Fail if a memory backend with "prealloc=on" is specified virtio-mem: Migrate bitmap, size and sanity checks early virtio-mem: Proper support for preallocation with migration hw/core/machine.c | 4 +- hw/virtio/virtio-mem.c | 154 ++++++++++++++++++++++++++++++++- include/hw/virtio/virtio-mem.h | 8 ++ include/migration/misc.h | 6 +- include/migration/vmstate.h | 19 +++- migration/migration.c | 27 ++++++ migration/migration.h | 4 + migration/ram.c | 16 +--- migration/savevm.c | 104 ++++++++++++++++------ migration/savevm.h | 1 + 10 files changed, 298 insertions(+), 45 deletions(-)