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authorAlex Williamson <alex.williamson@redhat.com>2015-10-15 15:08:48 -0600
committerAlex Williamson <alex.williamson@redhat.com>2015-11-04 09:56:16 -0700
commit033291eccbdb1b70ffc02641edae19ac825dc75d (patch)
tree9aa8159b1f29b389102c29f9e1ca265712d32f89 /include/uapi
parente324fc82ea453fcbd3898ec7afb792f750c68979 (diff)
downloadop-kernel-dev-033291eccbdb1b70ffc02641edae19ac825dc75d.zip
op-kernel-dev-033291eccbdb1b70ffc02641edae19ac825dc75d.tar.gz
vfio: Include No-IOMMU mode
There is really no way to safely give a user full access to a DMA capable device without an IOMMU to protect the host system. There is also no way to provide DMA translation, for use cases such as device assignment to virtual machines. However, there are still those users that want userspace drivers even under those conditions. The UIO driver exists for this use case, but does not provide the degree of device access and programming that VFIO has. In an effort to avoid code duplication, this introduces a No-IOMMU mode for VFIO. This mode requires building VFIO with CONFIG_VFIO_NOIOMMU and enabling the "enable_unsafe_noiommu_mode" option on the vfio driver. This should make it very clear that this mode is not safe. Additionally, CAP_SYS_RAWIO privileges are necessary to work with groups and containers using this mode. Groups making use of this support are named /dev/vfio/noiommu-$GROUP and can only make use of the special VFIO_NOIOMMU_IOMMU for the container. Use of this mode, specifically binding a device without a native IOMMU group to a VFIO bus driver will taint the kernel and should therefore not be considered supported. This patch includes no-iommu support for the vfio-pci bus driver only. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'include/uapi')
-rw-r--r--include/uapi/linux/vfio.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 9fd7b5d..751b69f 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -39,6 +39,13 @@
#define VFIO_SPAPR_TCE_v2_IOMMU 7
/*
+ * The No-IOMMU IOMMU offers no translation or isolation for devices and
+ * supports no ioctls outside of VFIO_CHECK_EXTENSION. Use of VFIO's No-IOMMU
+ * code will taint the host kernel and should be used with extreme caution.
+ */
+#define VFIO_NOIOMMU_IOMMU 8
+
+/*
* The IOCTL interface is designed for extensibility by embedding the
* structure length (argsz) and flags into structures passed between
* kernel and userspace. We therefore use the _IO() macro for these
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