From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH v3 1/1] s390: virtio: let arch accept devices without IOMMU feature Date: Mon, 29 Jun 2020 18:09:53 +0200 Message-ID: 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"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20200629115651-mutt-send-email-mst@kernel.org> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" To: "Michael S. Tsirkin" Cc: gor@linux.ibm.com, linux-s390@vger.kernel.org, frankja@linux.ibm.com, kvm@vger.kernel.org, thomas.lendacky@amd.com, heiko.carstens@de.ibm.com, cohuck@redhat.com, linuxram@us.ibm.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, david@gibson.dropbear.id.au List-Id: virtualization@lists.linuxfoundation.org On 2020-06-29 17:57, 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(+) >> >> 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? Yes, you are right, Thanks, Pierre -- Pierre Morel IBM Lab Boeblingen