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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 78325C433E1 for ; Wed, 10 Jun 2020 10:17:37 +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 476592064C for ; Wed, 10 Jun 2020 10:17:37 +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="nmVwxz2b" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 476592064C 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]:47828 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jixnY-0002nn-PC for qemu-devel@archiver.kernel.org; Wed, 10 Jun 2020 06:17:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:55828) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jixm2-0001fj-U1; Wed, 10 Jun 2020 06:15:59 -0400 Received: from ozlabs.org ([203.11.71.1]:34081) by eggs.gnu.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jixm0-00083V-1S; Wed, 10 Jun 2020 06:15:58 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 49hjYT3Ldmz9sQx; Wed, 10 Jun 2020 20:15:41 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1591784141; bh=kbYY1DGFXehDXUZKCqytgYqkpJwAwWtz1LoghtEPn20=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nmVwxz2beFE9nHWWdu1wACSCiyeApQbnTUnyl9nLUCCny+BnpOYRxQER9XosyJQ1w /UK8N5Q0bPwh+o9JMEcookzRDR9Tdn+Bh6MPzr1laSifySBAvVgaUQoVaWCOu5XadR Y46aypcTaM6+MgPYMZXPUKLjy6Pcf662XOjyOwR4= Date: Wed, 10 Jun 2020 20:07:56 +1000 From: David Gibson To: David Hildenbrand Subject: Re: [PATCH v2 1/1] virtio-ccw: auto-manage VIRTIO_F_IOMMU_PLATFORM if PV Message-ID: <20200610100756.GO494336@umbus.fritz.box> References: <20200606013217.2cffa3ed.pasic@linux.ibm.com> <20200608181428.3c6f127c.cohuck@redhat.com> <20200608190045.319dd68b.pasic@linux.ibm.com> <20200609084402.35d317ec.cohuck@redhat.com> <20200609114130.0ca9190b.pasic@linux.ibm.com> <20200609174747.4e300818@ibm-vm> <20200609182839.7ac80938.pasic@linux.ibm.com> <20200609124155-mutt-send-email-mst@kernel.org> <20200610043118.GF494336@umbus.fritz.box> <4e5d62d8-9bfb-67d5-7398-2079729fd85e@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="jozmn01XJZjDjM3N" Content-Disposition: inline In-Reply-To: <4e5d62d8-9bfb-67d5-7398-2079729fd85e@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 06:15:42 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: Viktor Mihajlovski , Thomas Huth , Boris Fiuczynski , Janosch Frank , Pierre Morel , "Michael S. Tsirkin" , Cornelia Huck , qemu-devel@nongnu.org, Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Claudio Imbrenda , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --jozmn01XJZjDjM3N Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jun 10, 2020 at 09:22:45AM +0200, David Hildenbrand wrote: > On 10.06.20 06:31, David Gibson wrote: > > On Tue, Jun 09, 2020 at 12:44:39PM -0400, Michael S. Tsirkin wrote: > >> On Tue, Jun 09, 2020 at 06:28:39PM +0200, Halil Pasic wrote: > >>> On Tue, 9 Jun 2020 17:47:47 +0200 > >>> Claudio Imbrenda wrote: > >>> > >>>> On Tue, 9 Jun 2020 11:41:30 +0200 > >>>> Halil Pasic wrote: > >>>> > >>>> [...] > >>>> > >>>>> I don't know. Janosch could answer that, but he is on vacation. Add= ing > >>>>> Claudio maybe he can answer. My understanding is, that while it mig= ht > >>>>> be possible, it is ugly at best. The ability to do a transition is > >>>>> indicated by a CPU model feature. Indicating the feature to the gue= st > >>>>> and then failing the transition sounds wrong to me. > >>>> > >>>> I agree. If the feature is advertised, then it has to work. I don't > >>>> think we even have an architected way to fail the transition for that > >>>> reason. > >>>> > >>>> What __could__ be done is to prevent qemu from even starting if an > >>>> incompatible device is specified together with PV. > >>> > >>> AFAIU, the "specified together with PV" is the problem here. Currently > >>> we don't "specify PV" but PV is just a capability that is managed by = the > >>> CPU model (like so many other). > >> > >> So if we want to keep it user friendly, there could be > >> protection property with values on/off/auto, and auto > >> would poke at host capability to figure out whether > >> it's supported. > >> > >> Both virtio and CPU would inherit from that. > >=20 > > Right, that's what I have in mind for my 'host-trust-limitation' > > property (a generalized version of the existing 'memory-encryption' > > machine option). My draft patches already set virtio properties > > accordingly, it should be possible to set (default) cpu properties as > > well. >=20 > No crazy CPU model hacks please (at least speaking for the s390x). Uh... I'm not really sure what you have in mind here. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --jozmn01XJZjDjM3N Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAl7gsPwACgkQbDjKyiDZ s5L0sBAAx3ZTgpDbASeYbEurpTjq1D3wxIKbpNP9U5tWo2p+Pib5iDMCJ679kpoX Sc4IRQD2a1Wc4yFg2DKdtoC9fmEHpR/SqdtohEG24vs+EXLKUhwAzg5Gx+I/prWk EvDIqMJYip0WH5uvgv2MMz0NLLoXXeqUNenMci93QrwjpoPDP0/jh9A6dsZ3X9S5 6EB8morrgCyQyX6GxRKm+zuM6YTEjz4MB4yWattbIihh4HHgIsDbSw37oYvVSPSo VrdPVGgcNCfF6vi0bu+QZDQEhwHOlcynMQNTMHn1aCFfgGcGh0qyRP+bPkPyMzIh 1woOr+o0hlZDjZfb2sF7P+k1W1YQ1T7YdNAgX1hApdE/v+RY36b3tjappZs3nJi7 ItaFU1Xg8lh5BQL5cbrTdAMYk7FJa2m7Et6u4N/eXUHq8lOScHVyTrircDFFlN/G 7ZyBJueIZ6Lj7um2DZKOyi4UHiBf/u1FUgUFbOGAkyaBajXzQOBvoSrm9y+ktEYQ 2/jqha4XwnLX08Ht3EkuRTFFFXPMRaPYPqYf88FiHfmjNq1+LqdX7hey5S9Dn69M ajHke3Dw17RhhpTqQvCcCP6M+jh4UCjqxXvR0q19EjMoS14jLqiK7BSpseVmScqp rsG8nRyIT6sLseThoRX9utyiSfAZ+KK4Wpf4ssGcc7HHE3plJkQ= =uDZn -----END PGP SIGNATURE----- --jozmn01XJZjDjM3N--