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=-10.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 8578CC433E0 for ; Mon, 15 Feb 2021 14:06:02 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 0213B64DCF for ; Mon, 15 Feb 2021 14:06:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0213B64DCF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47786 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lBeVk-0008TR-UZ for qemu-devel@archiver.kernel.org; Mon, 15 Feb 2021 09:06:00 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:42002) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lBeU2-0006sU-Hz for qemu-devel@nongnu.org; Mon, 15 Feb 2021 09:04:21 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:41183) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lBeTy-0000DH-4R for qemu-devel@nongnu.org; Mon, 15 Feb 2021 09:04:14 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613397845; 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=aSYVgQC5K2BEBdHvQ5odX1akuFfq1PXvblf/csbeS1s=; b=F8oV1DaIMJIUxrpaohnNRzeZD1DnBhJMvYJwyHTje04P/1yZCEKXMouoZM2AwI9Ab1zqyP u8z5ppbrl3gIGi1QVMy6lowN8VXqaONltea6Y1Qf5ZfhPerOr353e+/gNFNy4K8Xx6tdaI TSUj76OF5msoWXRGKqkAxuXvKyq13F0= 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-477-_pEY-ZKKMhqhh9h9yQHrZw-1; Mon, 15 Feb 2021 09:04:02 -0500 X-MC-Unique: _pEY-ZKKMhqhh9h9yQHrZw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B1C061020C21; Mon, 15 Feb 2021 14:03:59 +0000 (UTC) Received: from [10.36.114.89] (ovpn-114-89.ams2.redhat.com [10.36.114.89]) by smtp.corp.redhat.com (Postfix) with ESMTP id 41ABF104FB; Mon, 15 Feb 2021 14:03:43 +0000 (UTC) Subject: Re: [PATCH v5 00/11] virtio-mem: vfio support From: David Hildenbrand To: "Michael S. Tsirkin" , Alex Williamson References: <20210121110540.33704-1-david@redhat.com> <20210127074407-mutt-send-email-mst@kernel.org> <0c34a461-bdfe-3512-b9f6-69bdb2b34f19@redhat.com> Organization: Red Hat GmbH Message-ID: Date: Mon, 15 Feb 2021 15:03:43 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <0c34a461-bdfe-3512-b9f6-69bdb2b34f19@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=david@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=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Pankaj Gupta , Wei Yang , qemu-devel@nongnu.org, Peter Xu , "Dr. David Alan Gilbert" , Auger Eric , Pankaj Gupta , Paolo Bonzini , teawater , Jonathan Cameron , Igor Mammedov , Marek Kedzierski Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 08.02.21 09:28, David Hildenbrand wrote: > On 27.01.21 13:45, Michael S. Tsirkin wrote: >> On Thu, Jan 21, 2021 at 12:05:29PM +0100, David Hildenbrand wrote: >>> A virtio-mem device manages a memory region in guest physical address >>> space, represented as a single (currently large) memory region in QEMU, >>> mapped into system memory address space. Before the guest is allowed to use >>> memory blocks, it must coordinate with the hypervisor (plug blocks). After >>> a reboot, all memory is usually unplugged - when the guest comes up, it >>> detects the virtio-mem device and selects memory blocks to plug (based on >>> resize requests from the hypervisor). >>> >>> Memory hot(un)plug consists of (un)plugging memory blocks via a virtio-mem >>> device (triggered by the guest). When unplugging blocks, we discard the >>> memory - similar to memory balloon inflation. In contrast to memory >>> ballooning, we always know which memory blocks a guest may actually use - >>> especially during a reboot, after a crash, or after kexec (and during >>> hibernation as well). Guests agreed to not access unplugged memory again, >>> especially not via DMA. >>> >>> The issue with vfio is, that it cannot deal with random discards - for this >>> reason, virtio-mem and vfio can currently only run mutually exclusive. >>> Especially, vfio would currently map the whole memory region (with possible >>> only little/no plugged blocks), resulting in all pages getting pinned and >>> therefore resulting in a higher memory consumption than expected (turning >>> virtio-mem basically useless in these environments). >>> >>> To make vfio work nicely with virtio-mem, we have to map only the plugged >>> blocks, and map/unmap properly when plugging/unplugging blocks (including >>> discarding of RAM when unplugging). We achieve that by using a new notifier >>> mechanism that communicates changes. >> >> series >> >> Acked-by: Michael S. Tsirkin >> >> virtio bits >> >> Reviewed-by: Michael S. Tsirkin >> >> This needs to go through vfio tree I assume. > > Thanks Michael. > > @Alex, what are your suggestions? Gentle ping. -- Thanks, David / dhildenb