• Carsten Otte's avatar
    s390: KVM preparation: provide hook to enable pgstes in user pagetable · 402b0862
    Carsten Otte authored
    
    
    The SIE instruction on s390 uses the 2nd half of the page table page to
    virtualize the storage keys of a guest. This patch offers the s390_enable_sie
    function, which reorganizes the page tables of a single-threaded process to
    reserve space in the page table:
    s390_enable_sie makes sure that the process is single threaded and then uses
    dup_mm to create a new mm with reorganized page tables. The old mm is freed
    and the process has now a page status extended field after every page table.
    
    Code that wants to exploit pgstes should SELECT CONFIG_PGSTE.
    
    This patch has a small common code hit, namely making dup_mm non-static.
    
    Edit (Carsten): I've modified Martin's patch, following Jeremy Fitzhardinge's
    review feedback. Now we do have the prototype for dup_mm in
    include/linux/sched.h. Following Martin's suggestion, s390_enable_sie() does now
    call task_lock() to prevent race against ptrace modification of mm_users.
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    Signed-off-by: default avatarCarsten Otte <cotte@de.ibm.com>
    Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
    402b0862
setup.c 24.3 KB