Pierre Morel
2020-Jul-15 08:31 UTC
[PATCH v7 0/2] s390: virtio: let arch validate VIRTIO features
Hi all, The goal of the series is to give a chance to the architecture to validate VIRTIO device features. in this respin: 1) I kept removed the ack from Jason as I reworked the patch @Jason, the nature and goal of the patch did not really changed please can I get back your acked-by with these changes? 2) Rewording for warning messages Regards, Pierre Pierre Morel (2): virtio: let arch validate VIRTIO features s390: virtio: PV needs VIRTIO I/O device protection arch/s390/mm/init.c | 28 ++++++++++++++++++++++++++++ drivers/virtio/virtio.c | 19 +++++++++++++++++++ include/linux/virtio_config.h | 1 + 3 files changed, 48 insertions(+) -- 2.25.1 Changelog to v7: - typo in warning message (Connie) to v6: - rewording warning messages (Connie, Halil) to v5: - return directly from S390 arch_validate_virtio_features() when the guest is not protected. (Connie) - Somme rewording (Connie, Michael) - moved back code from arch/s390/ ...kernel/uv.c to ...mm/init.c (Christian) to v4: - separate virtio and arch code (Pierre) - moved code from arch/s390/mm/init.c to arch/s390/kernel/uv.c (as interpreted from Heiko's comment) - moved validation inside the arch code (Connie) - moved the call to arch validation before VIRTIO_F_1 test (Michael) to v3: - add warning (Connie, Christian) - add comment (Connie) - change hook name (Halil, Connie) to v2: - put the test in virtio_finalize_features() (Connie) - put the test inside VIRTIO core (Jason) - pass a virtio device as parameter (Halil)
Pierre Morel
2020-Jul-15 08:31 UTC
[PATCH v7 1/2] virtio: let arch validate VIRTIO features
An architecture may need to validate the VIRTIO devices features based on architecture specifics. Signed-off-by: Pierre Morel <pmorel at linux.ibm.com> Reviewed-by: Cornelia Huck <cohuck at redhat.com> Acked-by: Christian Borntraeger <borntraeger at de.ibm.com> Acked-by: Halil Pasic <pasic at linux.ibm.com> --- drivers/virtio/virtio.c | 19 +++++++++++++++++++ include/linux/virtio_config.h | 1 + 2 files changed, 20 insertions(+) diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index a977e32a88f2..c4e14d46a5b6 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_validate_virtio_features - provide arch specific hook when finalizing + * features for VIRTIO device dev + * @dev: the VIRTIO device being added + * + * Permits the platform to handle architecture-specific requirements when + * device features are finalized. This is the default implementation. + * Architecture implementations can override this. + */ + +int __weak arch_validate_virtio_features(struct virtio_device *dev) +{ + return 0; +} + int virtio_finalize_features(struct virtio_device *dev) { int ret = dev->config->finalize_features(dev); @@ -176,6 +191,10 @@ int virtio_finalize_features(struct virtio_device *dev) if (ret) return ret; + ret = arch_validate_virtio_features(dev); + if (ret) + return ret; + if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) return 0; diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index bb4cc4910750..3f4117adf311 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -459,4 +459,5 @@ static inline void virtio_cwrite64(struct virtio_device *vdev, _r; \ }) +int arch_validate_virtio_features(struct virtio_device *dev); #endif /* _LINUX_VIRTIO_CONFIG_H */ -- 2.25.1
Pierre Morel
2020-Jul-15 08:31 UTC
[PATCH v7 2/2] s390: virtio: PV needs VIRTIO I/O device protection
If protected virtualization is active on s390, the virtio queues are not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been negotiated. Use the new arch_validate_virtio_features() interface to fail probe if that's not the case, preventing a host error on access attempt. Signed-off-by: Pierre Morel <pmorel at linux.ibm.com> Reviewed-by: Cornelia Huck <cohuck at redhat.com> Acked-by: Halil Pasic <pasic at linux.ibm.com> Acked-by: Christian Borntraeger <borntraeger at de.ibm.com> --- arch/s390/mm/init.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c index 6dc7c3b60ef6..d39af6554d4f 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_config.h> pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir); @@ -161,6 +162,33 @@ bool force_dma_unencrypted(struct device *dev) return is_prot_virt_guest(); } +/* + * arch_validate_virtio_features + * @dev: the VIRTIO device being added + * + * Return an error if required features are missing on a guest running + * with protected virtualization. + */ +int arch_validate_virtio_features(struct virtio_device *dev) +{ + if (!is_prot_virt_guest()) + return 0; + + if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) { + dev_warn(&dev->dev, + "legacy virtio not supported with protected virtualization\n"); + return -ENODEV; + } + + if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) { + dev_warn(&dev->dev, + "support for limited memory access required for protected virtualization\n"); + return -ENODEV; + } + + return 0; +} + /* protected virtualization */ static void pv_init(void) { -- 2.25.1
Jason Wang
2020-Jul-15 08:36 UTC
[PATCH v7 0/2] s390: virtio: let arch validate VIRTIO features
On 2020/7/15 ??4:31, Pierre Morel wrote:> Hi all, > > The goal of the series is to give a chance to the architecture > to validate VIRTIO device features. > > in this respin: > > 1) I kept removed the ack from Jason as I reworked the patch > @Jason, the nature and goal of the patch did not really changed > please can I get back your acked-by with these changes?Yes. Acked-by: Jason Wang <jasowang at redhat.com> Thanks> > 2) Rewording for warning messages > > Regards, > Pierre > > Pierre Morel (2): > virtio: let arch validate VIRTIO features > s390: virtio: PV needs VIRTIO I/O device protection > > arch/s390/mm/init.c | 28 ++++++++++++++++++++++++++++ > drivers/virtio/virtio.c | 19 +++++++++++++++++++ > include/linux/virtio_config.h | 1 + > 3 files changed, 48 insertions(+) >
Cornelia Huck
2020-Jul-15 09:20 UTC
[PATCH v7 0/2] s390: virtio: let arch validate VIRTIO features
On Wed, 15 Jul 2020 10:31:07 +0200 Pierre Morel <pmorel at linux.ibm.com> wrote:> Hi all, > > The goal of the series is to give a chance to the architecture > to validate VIRTIO device features. > > in this respin: > > 1) I kept removed the ack from Jason as I reworked the patch > @Jason, the nature and goal of the patch did not really changed > please can I get back your acked-by with these changes? > > 2) Rewording for warning messages > > Regards, > Pierre > > Pierre Morel (2): > virtio: let arch validate VIRTIO features > s390: virtio: PV needs VIRTIO I/O device protection > > arch/s390/mm/init.c | 28 ++++++++++++++++++++++++++++ > drivers/virtio/virtio.c | 19 +++++++++++++++++++ > include/linux/virtio_config.h | 1 + > 3 files changed, 48 insertions(+) >LGTM. I assume that this will go either via the virtio tree or via the s390 arch tree, i.e. not through virtio-ccw, right?
Michael S. Tsirkin
2020-Jul-15 09:50 UTC
[PATCH v7 2/2] s390: virtio: PV needs VIRTIO I/O device protection
On Wed, Jul 15, 2020 at 10:31:09AM +0200, Pierre Morel wrote:> If protected virtualization is active on s390, the virtio queues are > not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been > negotiated. Use the new arch_validate_virtio_features() interface to > fail probe if that's not the case, preventing a host error on access > attempt. > > Signed-off-by: Pierre Morel <pmorel at linux.ibm.com> > Reviewed-by: Cornelia Huck <cohuck at redhat.com> > Acked-by: Halil Pasic <pasic at linux.ibm.com> > Acked-by: Christian Borntraeger <borntraeger at de.ibm.com> > --- > arch/s390/mm/init.c | 28 ++++++++++++++++++++++++++++ > 1 file changed, 28 insertions(+) > > diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c > index 6dc7c3b60ef6..d39af6554d4f 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_config.h> > > pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir); > > @@ -161,6 +162,33 @@ bool force_dma_unencrypted(struct device *dev) > return is_prot_virt_guest(); > } > > +/* > + * arch_validate_virtio_features > + * @dev: the VIRTIO device being added > + * > + * Return an error if required features are missing on a guest running > + * with protected virtualization. > + */ > +int arch_validate_virtio_features(struct virtio_device *dev) > +{ > + if (!is_prot_virt_guest()) > + return 0; > + > + if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) { > + dev_warn(&dev->dev, > + "legacy virtio not supported with protected virtualization\n"); > + return -ENODEV; > + } > + > + if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) { > + dev_warn(&dev->dev, > + "support for limited memory access required for protected virtualization\n"); > + return -ENODEV; > + } > + > + return 0; > +} > + > /* protected virtualization */ > static void pv_init(void) > {What bothers me here is that arch code depends on virtio now. It works even with a modular virtio when functions are inline, but it seems fragile: e.g. it breaks virtio as an out of tree module, since layout of struct virtio_device can change. I'm not sure what to do with this yet, will try to think about it over the weekend. Thanks!> -- > 2.25.1
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