• Alexey Kardashevskiy's avatar
    vfio: powerpc/spapr: Support Dynamic DMA windows · e633bc86
    Alexey Kardashevskiy authored
    This adds create/remove window ioctls to create and remove DMA windows.
    sPAPR defines a Dynamic DMA windows capability which allows
    para-virtualized guests to create additional DMA windows on a PCI bus.
    The existing linux kernels use this new window to map the entire guest
    memory and switch to the direct DMA operations saving time on map/unmap
    requests which would normally happen in a big amounts.
    This adds 2 ioctl handlers - VFIO_IOMMU_SPAPR_TCE_CREATE and
    VFIO_IOMMU_SPAPR_TCE_REMOVE - to create and remove windows.
    Up to 2 windows are supported now by the hardware and by this driver.
    This changes VFIO_IOMMU_SPAPR_TCE_GET_INFO handler to return additional
    information such as a number of supported windows and maximum number
    levels of TCE tables.
    DDW is added as a capability, not as a SPAPR TCE IOMMU v2 unique feature
    as we still want to support v2 on platforms which cannot do DDW for
    the sake of TCE acceleration in KVM (coming soon).
    Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
    [aw: for the vfio related changes]
    Acked-by: default avatarAlex Williamson <alex.williamson@redhat.com>
    Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
vfio.txt 21.3 KB