Re: [PATCH v8 1/2] virtio: let arch validate VIRTIO features
flat view
From: Cornelia Huck <cohuck@redhat.com>
Date: 2020-08-18 17:21:22
Also in:
kvm, linux-s390, lkml
On Tue, 18 Aug 2020 16:58:30 +0200 Pierre Morel [off-list ref] wrote:
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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 <redacted> --- 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?
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+ menuconfig VIRTIO_MENU bool "Virtio drivers" default ydiff --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?]
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+ 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 */
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