• Will Deacon's avatar
    iommu: Allow default domain type to be set on the kernel command line · fccb4e3b
    Will Deacon authored
    The IOMMU core currently initialises the default domain for each group
    to IOMMU_DOMAIN_DMA, under the assumption that devices will use
    IOMMU-backed DMA ops by default. However, in some cases it is desirable
    for the DMA ops to bypass the IOMMU for performance reasons, reserving
    use of translation for subsystems such as VFIO that require it for
    enforcing device isolation.
    Rather than modify each IOMMU driver to provide different semantics for
    DMA domains, instead we introduce a command line parameter that can be
    used to change the type of the default domain. Passthrough can then be
    specified using "iommu.passthrough=1" on the kernel command line.
    Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>