From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751441AbeFEBwq (ORCPT ); Mon, 4 Jun 2018 21:52:46 -0400 Received: from ozlabs.org ([203.11.71.1]:37907 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751242AbeFEBwp (ORCPT ); Mon, 4 Jun 2018 21:52:45 -0400 Date: Tue, 5 Jun 2018 11:52:36 +1000 From: David Gibson To: Benjamin Herrenschmidt Cc: "Michael S. Tsirkin" , Anshuman Khandual , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, aik@ozlabs.ru, robh@kernel.org, joe@perches.com, elfring@users.sourceforge.net, jasowang@redhat.com, mpe@ellerman.id.au, hch@infradead.org Subject: Re: [RFC V2] virtio: Add platform specific DMA API translation for virito devices Message-ID: <20180605015236.GJ5140@umbus.fritz.box> References: <20180522063317.20956-1-khandual@linux.vnet.ibm.com> <20180523213703-mutt-send-email-mst@kernel.org> <20180604085742.GQ4251@umbus> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="YZVh52eu0Ophig4D" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --YZVh52eu0Ophig4D Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jun 04, 2018 at 07:48:54PM +1000, Benjamin Herrenschmidt wrote: > On Mon, 2018-06-04 at 18:57 +1000, David Gibson wrote: > >=20 > > > - First qemu doesn't know that the guest will switch to "secure mode" > > > in advance. There is no difference between a normal and a secure > > > partition until the partition does the magic UV call to "enter secure > > > mode" and qemu doesn't see any of it. So who can set the flag here ? > >=20 > > This seems weird to me. As a rule HV calls should go through qemu - > > or be allowed to go directly to KVM *by* qemu. >=20 > It's not an HV call, it's a UV call, qemu won't see it, qemu isn't > trusted. Now the UV *will* reflect that to the HV via some synthetized > HV calls, and we *could* have those do a pass by qemu, however, so far, > our entire design doesn't rely on *any* qemu knowledge whatsoever and > it would be sad to add it just for that purpose. >=20 > Additionally, this is rather orthogonal, see my other email, the > problem we are trying to solve is *not* a qemu problem and it doesn't > make sense to leak that into qemu. >=20 > > We generally reserve > > the latter for hot path things. Since this isn't a hot path, having > > the call handled directly by the kernel seems wrong. > > > > Unless a "UV call" is something different I don't know about. >=20 > Yes, a UV call goes to the Ultravisor, not the Hypervisor. The > Hypervisor isn't trusted. Ah, right. Is that implemented in the host kernel, or in something further above? --=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 --YZVh52eu0Ophig4D Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlsV7OIACgkQbDjKyiDZ s5LDZw/+O2nYPWBGyN1jbpBcGO/3bosxPXKBX2ZQFxEyD9OqN+pUnaZf371hjSFR d1XLmUvoZOSp4ErGc+UtEk+OsynoYq7OL2y8q9bAf7ZUiyE7s6Qcnt77F9BASHLV HcYd55P9f9mJl5p8LTD3ZHOee+9aWfY0djF0FTtKgF2uSQsdRhMHF+9YVrh9hq0q b6nsuYEJ97y0/jOdcxRI0n1SPZPzJZHH9zGogRU14iS/D8m8qKRXeJCzHTlGHIuL KPlelYmqj7jc8O6xSkDLPv9p9HsKIxo8Ke2GwNNMuD+osBZb6lLO6fpi65PiL7k8 LcEqe3LfC4gQZtkmWyi/9hfFh68flJbP95+TPlqLLNoN6xog8h6qv+zUotIGPNss 5K9BHZiikGdnK7O5B2HB9aai0Tb6Zg3DkJyg81b8FKv5PmZvGRUyB3qRYEkZ4SxL qAhebhropdXVmx6VYWodQsXumJNgnh6oTlncrZw4bHLXHWUzfDOgLjrVSZbfukUX 23Y+BDrkGFygDCeA+0PA/lYN4nm/LZtqWsqJvlVyiRMwCpmx+Hm/SqzNeXMjg1kB vwwXndA/FfWFMzm0w1+l8JcravBxIcx1iLmanMnEs3d/++hUhKMvnGR0E+35cAw8 daSslcvU9Q45hN0M4tP3bZsYDHxo8bqMwouuFXO+jYrYsEhuF2o= =JaZJ -----END PGP SIGNATURE----- --YZVh52eu0Ophig4D--