From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-1.mimecast.com ([207.211.31.81]:49991 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730188AbgF2TGV (ORCPT ); Mon, 29 Jun 2020 15:06:21 -0400 Date: Mon, 29 Jun 2020 18:05:26 +0200 From: Cornelia Huck Subject: Re: [PATCH v3 1/1] s390: virtio: let arch accept devices without IOMMU feature Message-ID: <20200629180526.41d0732b.cohuck@redhat.com> In-Reply-To: <20200629115651-mutt-send-email-mst@kernel.org> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: "Michael S. Tsirkin" Cc: Pierre Morel , 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 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.