linux-kernel - Re: [PATCH v3 1/1] s390: virtio: let arch accept devices without IOMMU feature

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 29 Jun 2020 11:57:14 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Pierre Morel <pmorel@...ux.ibm.com>
Cc:     linux-kernel@...r.kernel.org, pasic@...ux.ibm.com,
        borntraeger@...ibm.com, frankja@...ux.ibm.com, jasowang@...hat.com,
        cohuck@...hat.com, kvm@...r.kernel.org, linux-s390@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, thomas.lendacky@....com,
        david@...son.dropbear.id.au, linuxram@...ibm.com,
        heiko.carstens@...ibm.com, gor@...ux.ibm.com
Subject: Re: [PATCH v3 1/1] s390: virtio: let arch accept devices without
 IOMMU feature

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 <pmorel@...ux.ibm.com>
> Acked-by: Jason Wang <jasowang@...hat.com>
> Acked-by: Christian Borntraeger <borntraeger@...ibm.com>
> ---
>  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 <asm/kasan.h>
>  #include <asm/dma-mapping.h>
>  #include <asm/uv.h>
> +#include <linux/virtio.h>
>  
>  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