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 X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D548C28CBC for ; Wed, 6 May 2020 16:12:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 06A73208CA for ; Wed, 6 May 2020 16:12:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="SkNYtRrZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729817AbgEFQMz (ORCPT ); Wed, 6 May 2020 12:12:55 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:32466 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729610AbgEFQMy (ORCPT ); Wed, 6 May 2020 12:12:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588781573; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HZRDjL7nazpxt3wSuOJ5/WwzUELoarexy41YvOu/dZk=; b=SkNYtRrZRdBg7a5ZvQQo9V5c0Gxha1HH5bf28A6gqxdLCtBXFLqExjwtMvXG5NITAfrmGk vLl+dZ84jrhAYsXrl8xRHjyPSnzgQMZkmpzAmXJQIUX9it/vGkfwZUJ9Y9vg3F7clDdORp sjpEXNyKGBsAIEofTeNVF9yMm4nbaLQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-488-l-m5nLYwP7axoWQd8MLKoA-1; Wed, 06 May 2020 12:12:37 -0400 X-MC-Unique: l-m5nLYwP7axoWQd8MLKoA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E01D41005510; Wed, 6 May 2020 16:12:35 +0000 (UTC) Received: from [10.3.114.73] (ovpn-114-73.phx2.redhat.com [10.3.114.73]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5F6CA6299C; Wed, 6 May 2020 16:12:29 +0000 (UTC) Subject: Re: [PATCH v1 10/17] virtio-mem: Paravirtualized memory hot(un)plug To: David Hildenbrand , qemu-devel@nongnu.org Cc: kvm@vger.kernel.org, qemu-s390x@nongnu.org, Richard Henderson , Paolo Bonzini , "Dr . David Alan Gilbert" , Eduardo Habkost , "Michael S . Tsirkin" , Markus Armbruster , Igor Mammedov References: <20200506094948.76388-1-david@redhat.com> <20200506094948.76388-11-david@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: <051610a8-4773-2de5-0d4c-48e39791f05e@redhat.com> Date: Wed, 6 May 2020 11:12:23 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200506094948.76388-11-david@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 5/6/20 4:49 AM, David Hildenbrand wrote: > This is the very basic/initial version of virtio-mem. An introduction to > virtio-mem can be found in the Linux kernel driver [1]. While it can be > used in the current state for hotplug of a smaller amount of memory, it > will heavily benefit from resizeable memory regions in the future. > > Each virtio-mem device manages a memory region (provided via a memory > backend). After requested by the hypervisor ("requested-size"), the > guest can try to plug/unplug blocks of memory within that region, in order > to reach the requested size. Initially, and after a reboot, all memory is > unplugged (except in special cases - reboot during postcopy). > > The guest may only try to plug/unplug blocks of memory within the usable > region size. The usable region size is a little bigger than the > requested size, to give the device driver some flexibility. The usable > region size will only grow, except on reboots or when all memory is > requested to get unplugged. The guest can never plug more memory than > requested. Unplugged memory will get zapped/discarded, similar to in a > balloon device. > > The block size is variable, however, it is always chosen in a way such that > THP splits are avoided (e.g., 2MB). The state of each block > (plugged/unplugged) is tracked in a bitmap. > > As virtio-mem devices (e.g., virtio-mem-pci) will be memory devices, we now > expose "VirtioMEMDeviceInfo" via "query-memory-devices". > > +++ b/qapi/misc.json > @@ -1354,19 +1354,56 @@ > } > } > > +## > +# @VirtioMEMDeviceInfo: > +# > +# @memdev: memory backend linked with the region > +# > +# Since: 5.1 Here you claim 5.1, > +## > +{ 'struct': 'VirtioMEMDeviceInfo', > + 'data': { '*id': 'str', > + 'memaddr': 'size', > + 'requested-size': 'size', > + 'size': 'size', > + 'max-size': 'size', > + 'block-size': 'size', > + 'node': 'int', > + 'memdev': 'str' > + } > +} > + > ## > # @MemoryDeviceInfo: > # > # Union containing information about a memory device > # > # nvdimm is included since 2.12. virtio-pmem is included since 4.1. > +# virtio-mem is included since 5.2. but here 5.2. They should probably be the same :) -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org