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 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 8C64FC61DA4 for ; Thu, 2 Feb 2023 11:11:53 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pNXV6-0004Yb-3z; Thu, 02 Feb 2023 06:11:32 -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 1pNXV0-0004RR-4r for qemu-devel@nongnu.org; Thu, 02 Feb 2023 06:11:28 -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 1pNXUu-00022A-OK for qemu-devel@nongnu.org; Thu, 02 Feb 2023 06:11:24 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675336279; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=jgXOPo4A9Htaj/+foy0ZD+KO6C8dRYaIw4VwkQT2EWA=; b=VXRtATTSomCpbArAUbvRWvfDWjAJ03MbHss5xXZScDEaXy4Ouzfo7ea4Rd21UF6APXnekn s+m8Swefkd4MA4Oi/NfpwkZwyizdk+QhzyI3E3/zfa6SLE+N6Yt1ZaeXySLHxoYV9UqPMV hYeMSUaE5s1PBDh2O1tyKHzXIqHH6KU= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-478-FwUkpZqcP3KiN_6OKMhuAA-1; Thu, 02 Feb 2023 06:11:17 -0500 X-MC-Unique: FwUkpZqcP3KiN_6OKMhuAA-1 Received: by mail-wm1-f70.google.com with SMTP id o31-20020a05600c511f00b003dc53da325dso2641454wms.8 for ; Thu, 02 Feb 2023 03:11:17 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=jgXOPo4A9Htaj/+foy0ZD+KO6C8dRYaIw4VwkQT2EWA=; b=fOzEc+s3+dxKNuO2XMoJJJb1tyubu1F2FqTNpg9t+UopzPs4mb630raZmcWLVXb+/m AgZstv8qSNahnIQxTWhAySYeE6X6/dSascaPZKmVybZk6TLu2FDNwvxtEQmM5QXmzhaq jJamJeBBj8qaWl3D/5d7pm9Lt/SQbFcWPNm7xvznM0jXgnDOcDUgD6YL/CnXGAJXU6nO 0yXFvhxrekNmeyQB6RkBzRJ14RjRraRZnAOt13CmIdQdjNHOzDZqR1XYoucSd8cglOvJ J4gkpRGHpJaGb4ioMEnNc199LVrOVs+tSz1zmDrFHjv4tf3vfqZ8vRHcc6XM4EgTk3wp hQfg== X-Gm-Message-State: AO0yUKUIX7d7hjcKKJVu3MPxF86EzB0oAi29tdQqcYBC8LvFoYUz5Ugt ChETH9QfuXu4KueM/SGBswJVJ6qV4HX2jsEf1VxcpTYpQE7OKcbf7Wsr0DFyiX6IiIPh8mgY/vR yzv4G4HCGqQD0uXg= X-Received: by 2002:a05:600c:600c:b0:3db:1afd:ac36 with SMTP id az12-20020a05600c600c00b003db1afdac36mr5909929wmb.32.1675336276682; Thu, 02 Feb 2023 03:11:16 -0800 (PST) X-Google-Smtp-Source: AK7set+pKVCF/PNM3eaK1SxkiNKutvOd4oL9LaqSLHrRLyGnx651t8oDLGI4h4NU+9barDa2sVSYZw== X-Received: by 2002:a05:600c:600c:b0:3db:1afd:ac36 with SMTP id az12-20020a05600c600c00b003db1afdac36mr5909910wmb.32.1675336276471; Thu, 02 Feb 2023 03:11:16 -0800 (PST) Received: from redhat.com ([2a02:14f:1fc:826d:55d8:70a4:3d30:fc2f]) by smtp.gmail.com with ESMTPSA id r9-20020a05600c158900b003dc4ecfc4d7sm4181629wmf.29.2023.02.02.03.11.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Feb 2023 03:11:15 -0800 (PST) Date: Thu, 2 Feb 2023 06:11:11 -0500 From: "Michael S. Tsirkin" To: David Hildenbrand Cc: qemu-devel@nongnu.org, "Dr . David Alan Gilbert" , Juan Quintela , Peter Xu , Michal Privoznik Subject: Re: [PATCH v5 0/8] virtio-mem: Handle preallocation with migration Message-ID: <20230202061102-mutt-send-email-mst@kernel.org> References: <20230117112249.244096-1-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230117112249.244096-1-david@redhat.com> Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@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 On Tue, Jan 17, 2023 at 12:22:41PM +0100, David Hildenbrand wrote: > 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 Reviewed-by: Michael S. Tsirkin > v4 -> v5: > - "migration/savevm: Move more savevm handling into vmstate_save()" > -- Extended patch description regarding tracing > - "migration/savevm: Prepare vmdesc json writer in > qemu_savevm_state_setup()" > -- Move freeing to migrate_fd_cleanup() > - "migration/savevm: Allow immutable device state to be migrated early (i.e., > before RAM)" > -- "immutable" -> "early_setup" > -- Extend comment > - Added some RBs (thanks!) > > v3 -> v4: > - First 3 patches: > -- Minimze code changes and simplify > -- Save immutable device state during qemu_savevm_state_setup() > -- Don't use vmsd priorities, use a new flag > -- Split it logically up > - "migration/ram: Factor out check for advised postcopy" > -- Don't factor out postcopy_is_running() > - "virtio-mem: Migrate immutable properties early" > -- Adjust to changed vmsd interface > - "virtio-mem: Proper support for preallocation with migration" > -- Drop sanity check in virtio_mem_post_load_early() > > 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 (8): > migration/savevm: Move more savevm handling into vmstate_save() > migration/savevm: Prepare vmdesc json writer in > qemu_savevm_state_setup() > migration/savevm: Allow immutable device state to be migrated early > (i.e., before RAM) > migration/vmstate: Introduce VMSTATE_WITH_TMP_TEST() and > VMSTATE_BITMAP_TEST() > migration/ram: Factor out check for advised postcopy > virtio-mem: Fail if a memory backend with "prealloc=on" is specified > virtio-mem: Migrate immutable properties early > virtio-mem: Proper support for preallocation with migration > > hw/core/machine.c | 4 +- > hw/virtio/virtio-mem.c | 144 ++++++++++++++++++++++++++++++++- > include/hw/virtio/virtio-mem.h | 8 ++ > include/migration/misc.h | 4 +- > include/migration/vmstate.h | 28 ++++++- > migration/migration.c | 9 +++ > migration/migration.h | 4 + > migration/ram.c | 8 +- > migration/savevm.c | 105 +++++++++++++----------- > 9 files changed, 255 insertions(+), 59 deletions(-) > > -- > 2.39.0