From patchwork Tue Jun 20 13:03:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13285814 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 403BDEB64D7 for ; Tue, 20 Jun 2023 13:05:27 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qBb20-0002i9-8w; Tue, 20 Jun 2023 09:04:24 -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 1qBb1w-0002hc-Hb for qemu-devel@nongnu.org; Tue, 20 Jun 2023 09:04:20 -0400 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 1qBb1u-0006rw-Ry for qemu-devel@nongnu.org; Tue, 20 Jun 2023 09:04:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1687266258; 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=rWUIrI8C9YsuJ+7+y+l3JJ4pfQWH+opp1AGMxC8VxUo=; b=UNcVS+RBv0FYDFuxhiZLlEFXsq46Ap9GkgAzicCCeQdzu+aTsqEks3m/63gZ/hEqK8ww6K ZBz2yN93rydDxvOyECO/smZBxu2LSzAaVHimwM+9FwQX4ETK5GS3lOgux8I5rDJwJl7iyN gxosyIs5lVPlmrP/7+Xnsft8y7rozLc= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-460-I5uONs_aNM2hcBFhnlWvag-1; Tue, 20 Jun 2023 09:04:16 -0400 X-MC-Unique: I5uONs_aNM2hcBFhnlWvag-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id DC8C53810D3B; Tue, 20 Jun 2023 13:04:06 +0000 (UTC) Received: from t480s.fritz.box (unknown [10.39.193.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id CB4CD2166B26; Tue, 20 Jun 2023 13:04:04 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Cc: David Hildenbrand , "Michael S. Tsirkin" , Juan Quintela , Peter Xu , Leonardo Bras , Paolo Bonzini , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Peng Tao Subject: [PATCH v1 4/4] virtio-mem: Support "x-ignore-shared" migration Date: Tue, 20 Jun 2023 15:03:54 +0200 Message-Id: <20230620130354.322180-5-david@redhat.com> In-Reply-To: <20230620130354.322180-1-david@redhat.com> References: <20230620130354.322180-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 To achieve desired "x-ignore-shared" functionality, we should not discard all RAM when realizing the device and not mess with preallocation/postcopy when loading device state. In essence, we should not touch RAM content. As "x-ignore-shared" gets set after realizing the device, we cannot rely on that. Let's simply skip discarding of RAM on incoming migration. Note that virtio_mem_post_load() will call virtio_mem_restore_unplugged() -- unless "x-ignore-shared" is set. So once migration finished we'll have a consistent state. The initial system reset will also not discard any RAM, because virtio_mem_unplug_all() will not call virtio_mem_unplug_all() when no memory is plugged (which is the case before loading the device state). Note that something like VM templating -- see commit b17fbbe55cba ("migration: allow private destination ram with x-ignore-shared") -- is currently incompatible with virtio-mem and ram_block_discard_range() will warn in case a private file mapping is supplied by virtio-mem. For VM templating with virtio-mem, it makes more sense to either (a) Create the template without the virtio-mem device and hotplug a virtio-mem device to the new VM instances using proper own memory backend. (b) Use a virtio-mem device that doesn't provide any memory in the template (requested-size=0) and use private anonymous memory. Signed-off-by: David Hildenbrand --- hw/virtio/virtio-mem.c | 47 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 38 insertions(+), 9 deletions(-) diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c index 9f6169af32..b013dfbaf0 100644 --- a/hw/virtio/virtio-mem.c +++ b/hw/virtio/virtio-mem.c @@ -18,6 +18,7 @@ #include "sysemu/numa.h" #include "sysemu/sysemu.h" #include "sysemu/reset.h" +#include "sysemu/runstate.h" #include "hw/virtio/virtio.h" #include "hw/virtio/virtio-bus.h" #include "hw/virtio/virtio-access.h" @@ -886,11 +887,23 @@ static void virtio_mem_device_realize(DeviceState *dev, Error **errp) return; } - ret = ram_block_discard_range(rb, 0, qemu_ram_get_used_length(rb)); - if (ret) { - error_setg_errno(errp, -ret, "Unexpected error discarding RAM"); - ram_block_coordinated_discard_require(false); - return; + /* + * We don't know at this point whether shared RAM is migrated using + * QEMU or migrated using the file content. "x-ignore-shared" will be + * configurated after realizing the device. So in case we have an + * incoming migration, simply always skip the discard step. + * + * Otherwise, make sure that we start with a clean slate: either the + * memory backend might get reused or the shared file might still have + * memory allocated. + */ + if (!runstate_check(RUN_STATE_INMIGRATE)) { + ret = ram_block_discard_range(rb, 0, qemu_ram_get_used_length(rb)); + if (ret) { + error_setg_errno(errp, -ret, "Unexpected error discarding RAM"); + ram_block_coordinated_discard_require(false); + return; + } } virtio_mem_resize_usable_region(vmem, vmem->requested_size, true); @@ -962,10 +975,6 @@ static int virtio_mem_post_load(void *opaque, int version_id) RamDiscardListener *rdl; int ret; - if (vmem->prealloc && !vmem->early_migration) { - warn_report("Proper preallocation with migration requires a newer QEMU machine"); - } - /* * We started out with all memory discarded and our memory region is mapped * into an address space. Replay, now that we updated the bitmap. @@ -978,6 +987,18 @@ static int virtio_mem_post_load(void *opaque, int version_id) } } + /* + * If shared RAM is migrated using the file content and not using QEMU, + * don't mess with preallocation and postcopy. + */ + if (migrate_ram_is_ignored(vmem->memdev->mr.ram_block)) { + return 0; + } + + if (vmem->prealloc && !vmem->early_migration) { + warn_report("Proper preallocation with migration requires a newer QEMU machine"); + } + if (migration_in_incoming_postcopy()) { return 0; } @@ -1010,6 +1031,14 @@ static int virtio_mem_post_load_early(void *opaque, int version_id) return 0; } + /* + * If shared RAM is migrated using the file content and not using QEMU, + * don't mess with preallocation and postcopy. + */ + if (migrate_ram_is_ignored(rb)) { + return 0; + } + /* * We restored the bitmap and verified that the basic properties * match on source and destination, so we can go ahead and preallocate