From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v3 1/1] s390: virtio: let arch accept devices without IOMMU feature From: Pierre Morel References: <1592390637-17441-1-git-send-email-pmorel@linux.ibm.com> <1592390637-17441-2-git-send-email-pmorel@linux.ibm.com> <20200629115651-mutt-send-email-mst@kernel.org> <20200629180526.41d0732b.cohuck@redhat.com> <26ecd4c6-837b-1ce6-170b-a0155e4dd4d4@linux.ibm.com> Message-ID: Date: Mon, 6 Jul 2020 15:37:37 +0200 MIME-Version: 1.0 In-Reply-To: <26ecd4c6-837b-1ce6-170b-a0155e4dd4d4@linux.ibm.com> Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: To: Cornelia Huck , "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, frankja@linux.ibm.com, jasowang@redhat.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org, thomas.lendacky@amd.com, david@gibson.dropbear.id.au, linuxram@us.ibm.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com On 2020-07-02 15:03, Pierre Morel wrote: > > > On 2020-06-29 18:05, Cornelia Huck wrote: >> On Mon, 29 Jun 2020 11:57:14 -0400 >> "Michael S. Tsirkin" wrote: >> >>> On Wed, Jun 17, 2020 at 12:43:57PM +0200, Pierre Morel wrote: >>>> 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. >>>> >>>> Signed-off-by: Pierre Morel >>>> Acked-by: Jason Wang >>>> Acked-by: Christian Borntraeger >>>> --- >>>>   arch/s390/mm/init.c     |  6 ++++++ >>>>   drivers/virtio/virtio.c | 22 ++++++++++++++++++++++ >>>>   include/linux/virtio.h  |  2 ++ >>>>   3 files changed, 30 insertions(+) >> >>>> @@ -179,6 +194,13 @@ int virtio_finalize_features(struct >>>> virtio_device *dev) >>>>       if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) >>>>           return 0; >>>> +    if (arch_needs_virtio_iommu_platform(dev) && >>>> +        !virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) { >>>> +        dev_warn(&dev->dev, >>>> +             "virtio: device must provide VIRTIO_F_IOMMU_PLATFORM\n"); >>>> +        return -ENODEV; >>>> +    } >>>> + >>>>       virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK); >>>>       status = dev->config->get_status(dev); >>>>       if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) { >>> >>> Well don't you need to check it *before* VIRTIO_F_VERSION_1, not after? >> >> But it's only available with VERSION_1 anyway, isn't it? So it probably >> also needs to fail when this feature is needed if VERSION_1 has not been >> negotiated, I think. would be something like: - if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) - return 0; + if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) { + ret = arch_accept_virtio_features(dev); + if (ret) + dev_warn(&dev->dev, + "virtio: device must provide VIRTIO_F_VERSION_1\n"); + return ret; + } just a thought on the function name: It becomes more general than just IOMMU_PLATFORM related. What do you think of: arch_accept_virtio_features() ? Regards, Pierre -- Pierre Morel IBM Lab Boeblingen