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[79.182.31.92]) by smtp.gmail.com with ESMTPSA id d18sm241639wrj.8.2020.06.29.08.57.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jun 2020 08:57:17 -0700 (PDT) Date: Mon, 29 Jun 2020 11:57:14 -0400 From: "Michael S. Tsirkin" To: Pierre Morel Cc: linux-kernel@vger.kernel.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, frankja@linux.ibm.com, jasowang@redhat.com, cohuck@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 Subject: Re: [PATCH v3 1/1] s390: virtio: let arch accept devices without IOMMU feature Message-ID: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1592390637-17441-2-git-send-email-pmorel@linux.ibm.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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(+) > > diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c > index 6dc7c3b60ef6..215070c03226 100644 > --- a/arch/s390/mm/init.c > +++ b/arch/s390/mm/init.c > @@ -45,6 +45,7 @@ > #include > #include > #include > +#include > > pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir); > > @@ -161,6 +162,11 @@ bool force_dma_unencrypted(struct device *dev) > return is_prot_virt_guest(); > } > > +int arch_needs_virtio_iommu_platform(struct virtio_device *dev) > +{ > + 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..aa8e01104f86 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -167,6 +167,21 @@ void virtio_add_status(struct virtio_device *dev, unsigned int status) > } > EXPORT_SYMBOL_GPL(virtio_add_status); > > +/* > + * arch_needs_virtio_iommu_platform - provide arch specific hook when finalizing > + * features for VIRTIO device dev > + * @dev: the VIRTIO device being added > + * > + * Permits the platform to provide architecture specific functionality when > + * devices features are finalized. This is the default implementation. > + * Architecture implementations can override this. > + */ > + > +int __weak arch_needs_virtio_iommu_platform(struct virtio_device *dev) > +{ > + return 0; > +} > + > int virtio_finalize_features(struct virtio_device *dev) > { > int ret = dev->config->finalize_features(dev); > @@ -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? > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index a493eac08393..e8526ae3463e 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_virtio_iommu_platform(struct virtio_device *dev); > #endif /* _LINUX_VIRTIO_H */ > -- > 2.25.1