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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=unavailable 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 A83FBC433E0 for ; Tue, 16 Jun 2020 09:52:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88D1020767 for ; Tue, 16 Jun 2020 09:52:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728119AbgFPJwU (ORCPT ); Tue, 16 Jun 2020 05:52:20 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:43270 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726467AbgFPJwU (ORCPT ); Tue, 16 Jun 2020 05:52:20 -0400 Received: from pps.filterd (m0187473.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 05G9X2sq115793; Tue, 16 Jun 2020 05:52:14 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 31n45de2f1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Jun 2020 05:52:12 -0400 Received: from m0187473.ppops.net (m0187473.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 05G9XQeg116519; Tue, 16 Jun 2020 05:52:11 -0400 Received: from ppma02fra.de.ibm.com (47.49.7a9f.ip4.static.sl-reverse.com [159.122.73.71]) by mx0a-001b2d01.pphosted.com with ESMTP id 31n45de2e8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Jun 2020 05:52:11 -0400 Received: from pps.filterd (ppma02fra.de.ibm.com [127.0.0.1]) by ppma02fra.de.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 05G9ptwq018283; Tue, 16 Jun 2020 09:52:08 GMT Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by ppma02fra.de.ibm.com with ESMTP id 31mpe8a340-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Jun 2020 09:52:08 +0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 05G9q5OL11338216 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 16 Jun 2020 09:52:05 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B53C811C058; Tue, 16 Jun 2020 09:52:05 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 00A3311C052; Tue, 16 Jun 2020 09:52:05 +0000 (GMT) Received: from oc2783563651 (unknown [9.145.56.227]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 16 Jun 2020 09:52:04 +0000 (GMT) Date: Tue, 16 Jun 2020 11:52:02 +0200 From: Halil Pasic To: Pierre Morel Cc: linux-kernel@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, mst@redhat.com, jasowang@redhat.com, cohuck@redhat.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org, , David Gibson , Ram Pai , Heiko Carstens , Vasily Gorbik Subject: Re: [PATCH v2 1/1] s390: virtio: let arch accept devices without IOMMU feature Message-ID: <20200616115202.0285aa08.pasic@linux.ibm.com> In-Reply-To: <1592224764-1258-2-git-send-email-pmorel@linux.ibm.com> References: <1592224764-1258-1-git-send-email-pmorel@linux.ibm.com> <1592224764-1258-2-git-send-email-pmorel@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-16_03:2020-06-15,2020-06-16 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 suspectscore=0 phishscore=0 adultscore=0 mlxlogscore=999 priorityscore=1501 bulkscore=0 malwarescore=0 spamscore=0 impostorscore=0 clxscore=1011 cotscore=-2147483648 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006160066 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, 15 Jun 2020 14:39:24 +0200 Pierre Morel wrote: I find the subject (commit short) sub optimal. The 'arch' is already accepting devices 'without IOMMU feature'. What you are introducing is the ability to reject. > An architecture protecting the guest memory against unauthorized host > access may want to enforce VIRTIO I/O device protection through the > use of VIRTIO_F_IOMMU_PLATFORM. > > Let's give a chance to the architecture to accept or not devices > without VIRTIO_F_IOMMU_PLATFORM. > I don't particularly like the commit message. In general, I believe using access_platform instead of iommu_platform would really benefit us. > Signed-off-by: Pierre Morel > --- > arch/s390/mm/init.c | 6 ++++++ > drivers/virtio/virtio.c | 9 +++++++++ > include/linux/virtio.h | 2 ++ > 3 files changed, 17 insertions(+) > > diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c > index 87b2d024e75a..3f04ad09650f 100644 > --- a/arch/s390/mm/init.c > +++ b/arch/s390/mm/init.c > @@ -46,6 +46,7 @@ > #include > #include > #include > +#include arch/s390/mm/init.c including virtio.h looks a bit strange to me, but if Heiko and Vasily don't mind, neither do I. > > pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir); > > @@ -162,6 +163,11 @@ bool force_dma_unencrypted(struct device *dev) > return is_prot_virt_guest(); > } > > +int arch_needs_iommu_platform(struct virtio_device *dev) Maybe prefixing the name with virtio_ would help provide the proper context. > +{ > + return is_prot_virt_guest(); > +} > + > /* protected virtualization */ > static void pv_init(void) > { > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > index a977e32a88f2..30091089bee8 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -167,6 +167,11 @@ void virtio_add_status(struct virtio_device *dev, unsigned int status) > } > EXPORT_SYMBOL_GPL(virtio_add_status); > > +int __weak arch_needs_iommu_platform(struct virtio_device *dev) > +{ > + return 0; > +} > + Adding some people that could be interested in overriding this as well to the cc list. > int virtio_finalize_features(struct virtio_device *dev) > { > int ret = dev->config->finalize_features(dev); > @@ -179,6 +184,10 @@ int virtio_finalize_features(struct virtio_device *dev) > if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) > return 0; > > + if (arch_needs_iommu_platform(dev) && > + !virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) > + return -EIO; > + Why EIO? Overall, I think it is a good idea to have something that is going to protect us from this scenario. Regards, Halil > virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK); > status = dev->config->get_status(dev); > if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) { > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index a493eac08393..2c46b310c38c 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -195,4 +195,6 @@ void unregister_virtio_driver(struct virtio_driver *drv); > #define module_virtio_driver(__virtio_driver) \ > module_driver(__virtio_driver, register_virtio_driver, \ > unregister_virtio_driver) > + > +int arch_needs_iommu_platform(struct virtio_device *dev); > #endif /* _LINUX_VIRTIO_H */