• Alexey Kardashevskiy's avatar
    powerpc/powernv: Add indirect levels to it_userspace · 090bad39
    Alexey Kardashevskiy authored
    We want to support sparse memory and therefore huge chunks of DMA windows
    do not need to be mapped. If a DMA window big enough to require 2 or more
    indirect levels, and a DMA window is used to map all RAM (which is
    a default case for 64bit window), we can actually save some memory by
    not allocation TCE for regions which we are not going to map anyway.
    
    The hardware tables alreary support indirect levels but we also keep
    host-physical-to-userspace translation array which is allocated by
    vmalloc() and is a flat array which might use quite some memory.
    
    This converts it_userspace from vmalloc'ed array to a multi level table.
    
    As the format becomes platform dependend, this replaces the direct access
    to it_usespace with a iommu_table_ops::useraddrptr hook which returns
    a pointer to the userspace copy of a TCE; future extension will return
    NULL if the level was not allocated.
    
    This should not change non-KVM handling of TCE tables and it_userspace
    will not be allocated for non-KVM tables.
    Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
    Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    090bad39
pci-ioda-tce.c 8.75 KB