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=-2.3 required=3.0 tests=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 4D109C35646 for ; Fri, 21 Feb 2020 16:41:59 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 2015024653 for ; Fri, 21 Feb 2020 16:41:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2015024653 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id E34648645E; Fri, 21 Feb 2020 16:41:58 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id KJ22Z5UTIJg1; Fri, 21 Feb 2020 16:41:58 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 88E2F86463; Fri, 21 Feb 2020 16:41:58 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 70890C1D8E; Fri, 21 Feb 2020 16:41:58 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 4793DC013E; Fri, 21 Feb 2020 16:41:56 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 31145875B1; Fri, 21 Feb 2020 16:41:56 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id M+5UhNs40P+8; Fri, 21 Feb 2020 16:41:55 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by whitealder.osuosl.org (Postfix) with ESMTPS id 8B8BD87476; Fri, 21 Feb 2020 16:41:55 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 8193268BFE; Fri, 21 Feb 2020 17:41:51 +0100 (CET) Date: Fri, 21 Feb 2020 17:41:51 +0100 From: Christoph Hellwig To: "Michael S. Tsirkin" Subject: Re: [PATCH 0/2] virtio: decouple protected guest RAM form VIRTIO_F_IOMMU_PLATFORM Message-ID: <20200221164151.GD10054@lst.de> References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220163055-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200220163055-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: linux-s390@vger.kernel.org, Janosch Frank , "Lendacky, Thomas" , Jason Wang , Cornelia Huck , Ram Pai , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Halil Pasic , Christian Borntraeger , iommu@lists.linux-foundation.org, David Gibson , Michael Mueller , Viktor Mihajlovski , Robin Murphy , Christoph Hellwig X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Thu, Feb 20, 2020 at 04:33:35PM -0500, Michael S. Tsirkin wrote: > So it sounds like a host issue: the emulation of s390 unnecessarily complicated. > Working around it by the guest looks wrong ... Yes. If your host (and I don't care if you split hypervisor, ultravisor and megavisor out in your implementation) wants to support a VM architecture where the host can't access all guest memory you need to ensure the DMA API is used. Extra points for simply always setting the flag and thus future proofing the scheme. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu