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=-0.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 E1429C433E0 for ; Wed, 10 Jun 2020 05:02:26 +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 A6143207ED for ; Wed, 10 Jun 2020 05:02:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="krvd+2BQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A6143207ED Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:41530 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jissb-0008Th-RO for qemu-devel@archiver.kernel.org; Wed, 10 Jun 2020 01:02:25 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37036) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jisjJ-0002ZT-TD; Wed, 10 Jun 2020 00:52:49 -0400 Received: from ozlabs.org ([203.11.71.1]:32969) by eggs.gnu.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jisjI-0004ec-3H; Wed, 10 Jun 2020 00:52:49 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 49hZFC1mt1z9sSF; Wed, 10 Jun 2020 14:46:07 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1591764367; bh=GcrZ2bo9JXzoBwffO7M8WF0qoOU1c9mkyt0UHk5oGSU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=krvd+2BQXK5AnDK0PSKE7jD7mtk1nz7TIT0g/Od0Xrn0V5njP2aH/cUMTmnkosmIF NG6HKKqN5XhHDie3fVJ16DTlwO/vPsOi2b2MLTBBpq0RIQXBvXl+PZ+9ZPjFU6iqPe QKhn3JynjyyptLOXjKxZQP8FEmLmaSFML307Ado4= Date: Wed, 10 Jun 2020 14:25:54 +1000 From: David Gibson To: Cornelia Huck Subject: Re: [PATCH v2 1/1] virtio-ccw: auto-manage VIRTIO_F_IOMMU_PLATFORM if PV Message-ID: <20200610042554.GD494336@umbus.fritz.box> References: <20200514221155.32079-1-pasic@linux.ibm.com> <20200520121507-mutt-send-email-mst@kernel.org> <20200606013217.2cffa3ed.pasic@linux.ibm.com> <20200608181428.3c6f127c.cohuck@redhat.com> <20200608190045.319dd68b.pasic@linux.ibm.com> <20200609084402.35d317ec.cohuck@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="/3yNEOqWowh/8j+e" Content-Disposition: inline In-Reply-To: <20200609084402.35d317ec.cohuck@redhat.com> Received-SPF: pass client-ip=203.11.71.1; envelope-from=dgibson@ozlabs.org; helo=ozlabs.org X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/10 00:46:07 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Spam_score_int: -9 X-Spam_score: -1.0 X-Spam_bar: - X-Spam_report: (-1.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=1, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: Thomas Huth , Boris Fiuczynski , Janosch Frank , Pierre Morel , "Michael S. Tsirkin" , David Hildenbrand , qemu-devel@nongnu.org, Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Viktor Mihajlovski , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --/3yNEOqWowh/8j+e Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jun 09, 2020 at 08:44:02AM +0200, Cornelia Huck wrote: > On Mon, 8 Jun 2020 19:00:45 +0200 > Halil Pasic wrote: >=20 >=20 > > > I'm also not 100% sure about migration... would it make sense to > > > discuss all of this in the context of the cross-arch patchset? It see= ms > > > power has similar issues. > > > =20 > >=20 > > I'm going to definitely have a good look at that. What I think special > > about s390 is that F_ACCESS_PLATFORM is hurting us because all IO needs > > to go through ZONE_DMA (this is a problem of the implementation that > > stemming form a limitation of the DMA API, upstream didn't let me > > fix it).=20 >=20 > My understanding is that power runs into similar issues, but I don't > know much about power, so I might be entirely wrong :) Sort of, but not to the same extent, I think. [snip] > > > (Can we disallow transition to pv if it is off? Maybe with the machine > > > property approach from the cross-arch patchset?) =20 > >=20 > > No we can't disallow transition because for hotplug that already > > happened. >=20 > I mean, can a virtio devices without IOMMU_PLATFORM act as a transition > blocker (i.e. an attempt by a guest to move to pv would fail?) This might be possible, but I suspect having to explicitly say you want pv support, then having it validate virtio (and anything else it needs) will give a better UX. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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