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=-10.3 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 14D4AC433DB for ; Mon, 8 Feb 2021 15:08:16 +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 4067E64EC6 for ; Mon, 8 Feb 2021 15:08:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4067E64EC6 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]:48984 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l9896-0002KN-OZ for qemu-devel@archiver.kernel.org; Mon, 08 Feb 2021 10:08:12 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:33472) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l91v7-0001MT-Sr for qemu-devel@nongnu.org; Mon, 08 Feb 2021 03:29:25 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:49335) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l91v2-00021x-SJ for qemu-devel@nongnu.org; Mon, 08 Feb 2021 03:29:21 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612772952; 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=OVERSDC538IuUFJYx6E2l9QMHJBDLzPsyZ5cuiZf7Pg=; b=A63KtudeFRGVGnTDlDS6bQ2z63FbN4WvezUvTZHB8G6cszRgmxr0NnDoC2VhHsgy5Q7Ecc VUtd8GxW4nsZhFmOPKot/aV50zd70FESRu31lxoS8lTp+6NZKrv60J+bUJXvdaI3gAJdVi FhTPtTdmz7V1fm1iuhvJPI7TdmHIwhM= 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-174-bgvYYUnBOxK1rzkEFGOSVg-1; Mon, 08 Feb 2021 03:29:10 -0500 X-MC-Unique: bgvYYUnBOxK1rzkEFGOSVg-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 72C14107ACC7; Mon, 8 Feb 2021 08:29:09 +0000 (UTC) Received: from [10.36.113.240] (ovpn-113-240.ams2.redhat.com [10.36.113.240]) by smtp.corp.redhat.com (Postfix) with ESMTP id 24CB362467; Mon, 8 Feb 2021 08:28:54 +0000 (UTC) Subject: Re: [PATCH v5 00/11] virtio-mem: vfio support To: "Michael S. Tsirkin" , Alex Williamson References: <20210121110540.33704-1-david@redhat.com> <20210127074407-mutt-send-email-mst@kernel.org> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <0c34a461-bdfe-3512-b9f6-69bdb2b34f19@redhat.com> Date: Mon, 8 Feb 2021 09:28:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20210127074407-mutt-send-email-mst@kernel.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 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=63.128.21.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -33 X-Spam_score: -3.4 X-Spam_bar: --- X-Spam_report: (-3.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.569, 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_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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 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? -- Thanks, David / dhildenb