[PATCH v10 1/2] virtio: let arch advertise guest's memory access restrictions
From: Pierre Morel <hidden>
Date: 2020-08-31 09:10:58
Also in:
kvm, linux-s390, lkml
Subsystem:
the rest, virtio core · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang
An architecture may restrict host access to guest memory, e.g. IBM s390 Secure Execution or AMD SEV. Provide a new Kconfig entry the architecture can select, CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS, when it provides the arch_has_restricted_virtio_memory_access callback to advertise to VIRTIO common code when the architecture restricts memory access from the host. The common code can then fail the probe for any device where VIRTIO_F_IOMMU_PLATFORM is required, but not set. Signed-off-by: Pierre Morel <redacted> Reviewed-by: Cornelia Huck <cohuck@redhat.com> --- drivers/virtio/Kconfig | 6 ++++++ drivers/virtio/virtio.c | 15 +++++++++++++++ include/linux/virtio_config.h | 9 +++++++++ 3 files changed, 30 insertions(+)
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 5809e5f5b157..9cd1c267c143 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_VIRTIO_MEMORY_ACCESS + bool + help + This option is selected if the architecture may need to enforce + 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..57ca41d77b09 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c@@ -176,6 +176,21 @@ int virtio_finalize_features(struct virtio_device *dev) if (ret) return ret; + ret = arch_has_restricted_virtio_memory_access(); + if (ret) { + if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) { + dev_warn(&dev->dev, + "device must provide VIRTIO_F_VERSION_1\n"); + return -ENODEV; + } + + if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) { + dev_warn(&dev->dev, + "device must provide VIRTIO_F_IOMMU_PLATFORM\n"); + return -ENODEV; + } + } + 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..e380664642b4 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_VIRTIO_MEMORY_ACCESS +int arch_has_restricted_virtio_memory_access(void); +#else +static inline int arch_has_restricted_virtio_memory_access(void) +{ + return 0; +} +#endif /* CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS */ + #endif /* _LINUX_VIRTIO_CONFIG_H */
--
2.25.1
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