• Martin Schwidefsky's avatar
    s390/mm: simplify the TLB flushing code · 64f31d58
    Martin Schwidefsky authored
    ptep_flush_lazy and pmdp_flush_lazy use mm->context.attach_count to
    decide between a lazy TLB flush vs an immediate TLB flush. The field
    contains two 16-bit counters, the number of CPUs that have the mm
    attached and can create TLB entries for it and the number of CPUs in
    the middle of a page table update.
    
    The __tlb_flush_asce, ptep_flush_direct and pmdp_flush_direct functions
    use the attach counter and a mask check with mm_cpumask(mm) to decide
    between a local flush local of the current CPU and a global flush.
    
    For all these functions the decision between lazy vs immediate and
    local vs global TLB flush can be based on CPU masks. There are two
    masks:  the mm->context.cpu_attach_mask with the CPUs that are actively
    using the mm, and the mm_cpumask(mm) with the CPUs that have used the
    mm since the last full flush. The decision between lazy vs immediate
    flush is based on the mm->context.cpu_attach_mask, to decide between
    local vs global flush the mm_cpumask(mm) is used.
    
    With this patch all checks will use the CPU masks, the old counter
    mm->context.attach_count with its two 16-bit values is turned into a
    single counter mm->context.flush_count that keeps track of the number
    of CPUs with incomplete page table updates. The sole user of this
    counter is finish_arch_post_lock_switch() which waits for the end of
    all page table updates.
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    64f31d58
tlbflush.h 4.52 KB