Hi all,
The goal of the series is to give a chance to the architecture
to validate VIRTIO device features.
in this respin:
I use the original idea from Connie for an optional
arch_has_restricted_memory_access.
I renamed the callback accordingly, added the definition of
ARCH_HAS_RESTRICTED_MEMORY_ACCESS inside the VIRTIO Kconfig
and the selection in the PROTECTED_VIRTUALIZATION_GUEST
config entry.
Regards,
Pierre
Pierre Morel (2):
virtio: let arch validate VIRTIO features
s390: virtio: PV needs VIRTIO I/O device protection
arch/s390/Kconfig | 1 +
arch/s390/mm/init.c | 30 ++++++++++++++++++++++++++++++
drivers/virtio/Kconfig | 6 ++++++
drivers/virtio/virtio.c | 4 ++++
include/linux/virtio_config.h | 9 +++++++++
5 files changed, 50 insertions(+)
--
2.25.1
Changelog
to v8:
- refactoring by using an optional callback
(Connie)
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)
An architecture may need to validate the VIRTIO devices features
based on architecture specifics.
Provide a new Kconfig entry, CONFIG_ARCH_HAS_RESTRICTED_MEMORY_ACCESS,
the architecture can select when it provides a callback named
arch_has_restricted_memory_access to validate the virtio device
features.
Signed-off-by: Pierre Morel <[email protected]>
---
drivers/virtio/Kconfig | 6 ++++++
drivers/virtio/virtio.c | 4 ++++
include/linux/virtio_config.h | 9 +++++++++
3 files changed, 19 insertions(+)
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 5809e5f5b157..eef09e3c92f9 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -6,6 +6,12 @@ config VIRTIO
bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
or CONFIG_S390_GUEST.
+config ARCH_HAS_RESTRICTED_MEMORY_ACCESS
+ bool
+ help
+ This option is selected by any architecture enforcing
+ VIRTIO_F_IOMMU_PLATFORM
+
menuconfig VIRTIO_MENU
bool "Virtio drivers"
default y
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index a977e32a88f2..1471db7d6510 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -176,6 +176,10 @@ int virtio_finalize_features(struct virtio_device *dev)
if (ret)
return ret;
+ ret = arch_has_restricted_memory_access(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..f6b82541c497 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -459,4 +459,13 @@ static inline void virtio_cwrite64(struct virtio_device *vdev,
_r; \
})
+#ifdef CONFIG_ARCH_HAS_RESTRICTED_MEMORY_ACCESS
+int arch_has_restricted_memory_access(struct virtio_device *dev);
+#else
+static inline int arch_has_restricted_memory_access(struct virtio_device *dev)
+{
+ return 0;
+}
+#endif /* CONFIG_ARCH_HAS_RESTRICTED_MEMORY_ACCESS */
+
#endif /* _LINUX_VIRTIO_CONFIG_H */
--
2.25.1
On Tue, 18 Aug 2020 16:58:30 +0200
Pierre Morel <[email protected]> wrote:
> An architecture may need to validate the VIRTIO devices features
> based on architecture specifics.
>
> Provide a new Kconfig entry, CONFIG_ARCH_HAS_RESTRICTED_MEMORY_ACCESS,
> the architecture can select when it provides a callback named
> arch_has_restricted_memory_access to validate the virtio device
> features.
>
> Signed-off-by: Pierre Morel <[email protected]>
> ---
> drivers/virtio/Kconfig | 6 ++++++
> drivers/virtio/virtio.c | 4 ++++
> include/linux/virtio_config.h | 9 +++++++++
> 3 files changed, 19 insertions(+)
>
> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> index 5809e5f5b157..eef09e3c92f9 100644
> --- a/drivers/virtio/Kconfig
> +++ b/drivers/virtio/Kconfig
> @@ -6,6 +6,12 @@ config VIRTIO
> bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
> or CONFIG_S390_GUEST.
>
> +config ARCH_HAS_RESTRICTED_MEMORY_ACCESS
> + bool
> + help
> + This option is selected by any architecture enforcing
> + VIRTIO_F_IOMMU_PLATFORM
This option is only for a very specific case of "restricted memory
access", namely the kind that requires IOMMU_PLATFORM for virtio
devices. ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS? Or is this intended
to cover cases outside of virtio as well?
> +
> menuconfig VIRTIO_MENU
> bool "Virtio drivers"
> default y
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index a977e32a88f2..1471db7d6510 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -176,6 +176,10 @@ int virtio_finalize_features(struct virtio_device *dev)
> if (ret)
> return ret;
>
> + ret = arch_has_restricted_memory_access(dev);
> + if (ret)
> + return ret;
Hm, I'd rather have expected something like
if (arch_has_restricted_memory_access(dev)) {
// enforce VERSION_1 and IOMMU_PLATFORM
}
Otherwise, you're duplicating the checks in the individual architecture
callbacks again.
[Not sure whether the device argument would be needed here; are there
architectures where we'd only require IOMMU_PLATFORM for a subset of
virtio devices?]
> +
> 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..f6b82541c497 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -459,4 +459,13 @@ static inline void virtio_cwrite64(struct virtio_device *vdev,
> _r; \
> })
>
> +#ifdef CONFIG_ARCH_HAS_RESTRICTED_MEMORY_ACCESS
> +int arch_has_restricted_memory_access(struct virtio_device *dev);
> +#else
> +static inline int arch_has_restricted_memory_access(struct virtio_device *dev)
> +{
> + return 0;
> +}
> +#endif /* CONFIG_ARCH_HAS_RESTRICTED_MEMORY_ACCESS */
> +
> #endif /* _LINUX_VIRTIO_CONFIG_H */
On 2020-08-18 19:19, Cornelia Huck wrote:
> On Tue, 18 Aug 2020 16:58:30 +0200
> Pierre Morel <[email protected]> wrote:
>
...
>> +config ARCH_HAS_RESTRICTED_MEMORY_ACCESS
>> + bool
>> + help
>> + This option is selected by any architecture enforcing
>> + VIRTIO_F_IOMMU_PLATFORM
>
> This option is only for a very specific case of "restricted memory
> access", namely the kind that requires IOMMU_PLATFORM for virtio
> devices. ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS? Or is this intended
> to cover cases outside of virtio as well?
AFAIK we did not identify other restrictions so adding VIRTIO in the
name should be the best thing to do.
If new restrictions appear they also may be orthogonal.
I will change to ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS if no one
complains.
>
>> +
>> menuconfig VIRTIO_MENU
>> bool "Virtio drivers"
>> default y
>> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
>> index a977e32a88f2..1471db7d6510 100644
>> --- a/drivers/virtio/virtio.c
>> +++ b/drivers/virtio/virtio.c
>> @@ -176,6 +176,10 @@ int virtio_finalize_features(struct virtio_device *dev)
>> if (ret)
>> return ret;
>>
>> + ret = arch_has_restricted_memory_access(dev);
>> + if (ret)
>> + return ret;
>
> Hm, I'd rather have expected something like
>
> if (arch_has_restricted_memory_access(dev)) {
may be also change the callback name to
arch_has_restricted_virtio_memory_access() ?
> // enforce VERSION_1 and IOMMU_PLATFORM
> }
>
> Otherwise, you're duplicating the checks in the individual architecture
> callbacks again.
Yes, I agree and go back this way.
>
> [Not sure whether the device argument would be needed here; are there
> architectures where we'd only require IOMMU_PLATFORM for a subset of
> virtio devices?]
I don't think so and since we do the checks locally, we do not need the
device argument anymore.
Thanks,
Pierre
--
Pierre Morel
IBM Lab Boeblingen
On Wed, 19 Aug 2020 10:50:18 +0200
Pierre Morel <[email protected]> wrote:
> On 2020-08-18 19:19, Cornelia Huck wrote:
> > On Tue, 18 Aug 2020 16:58:30 +0200
> > Pierre Morel <[email protected]> wrote:
> >
> ...
> >> +config ARCH_HAS_RESTRICTED_MEMORY_ACCESS
> >> + bool
> >> + help
> >> + This option is selected by any architecture enforcing
> >> + VIRTIO_F_IOMMU_PLATFORM
> >
> > This option is only for a very specific case of "restricted memory
> > access", namely the kind that requires IOMMU_PLATFORM for virtio
> > devices. ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS? Or is this intended
> > to cover cases outside of virtio as well?
>
> AFAIK we did not identify other restrictions so adding VIRTIO in the
> name should be the best thing to do.
>
> If new restrictions appear they also may be orthogonal.
>
> I will change to ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS if no one
> complains.
>
> >
> >> +
> >> menuconfig VIRTIO_MENU
> >> bool "Virtio drivers"
> >> default y
> >> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> >> index a977e32a88f2..1471db7d6510 100644
> >> --- a/drivers/virtio/virtio.c
> >> +++ b/drivers/virtio/virtio.c
> >> @@ -176,6 +176,10 @@ int virtio_finalize_features(struct virtio_device *dev)
> >> if (ret)
> >> return ret;
> >>
> >> + ret = arch_has_restricted_memory_access(dev);
> >> + if (ret)
> >> + return ret;
> >
> > Hm, I'd rather have expected something like
> >
> > if (arch_has_restricted_memory_access(dev)) {
>
> may be also change the callback name to
> arch_has_restricted_virtio_memory_access() ?
Yes, why not.
>
> > // enforce VERSION_1 and IOMMU_PLATFORM
> > }
> >
> > Otherwise, you're duplicating the checks in the individual architecture
> > callbacks again.
>
> Yes, I agree and go back this way.
>
> >
> > [Not sure whether the device argument would be needed here; are there
> > architectures where we'd only require IOMMU_PLATFORM for a subset of
> > virtio devices?]
>
> I don't think so and since we do the checks locally, we do not need the
> device argument anymore.
Yes, that would also remove some layering entanglement.