• Nicholas Piggin's avatar
    powerpc/64s/radix: introduce options to disable use of the tlbie instruction · 2275d7b5
    Nicholas Piggin authored
    Introduce two options to control the use of the tlbie instruction. A
    boot time option which completely disables the kernel using the
    instruction, this is currently incompatible with HASH MMU, KVM, and
    coherent accelerators.
    
    And a debugfs option can be switched at runtime and avoids using tlbie
    for invalidating CPU TLBs for normal process and kernel address
    mappings. Coherent accelerators are still managed with tlbie, as will
    KVM partition scope translations.
    
    Cross-CPU TLB flushing is implemented with IPIs and tlbiel. This is a
    basic implementation which does not attempt to make any optimisation
    beyond the tlbie implementation.
    
    This is useful for performance testing among other things. For example
    in certain situations on large systems, using IPIs may be faster than
    tlbie as they can be directed rather than broadcast. Later we may also
    take advantage of the IPIs to do more interesting things such as trim
    the mm cpumask more aggressively.
    Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/20190902152931.17840-7-npiggin@gmail.com
    2275d7b5
main.c 8.75 KB