• Marcelo Tosatti's avatar
    Merge tag 'kvm-s390-20140422' of... · 63b5cf04
    Marcelo Tosatti authored
    Merge tag 'kvm-s390-20140422' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into queue
    
    Lazy storage key handling
    -------------------------
    Linux does not use the ACC and F bits of the storage key. Newer Linux
    versions also do not use the storage keys for dirty and reference
    tracking. We can optimize the guest handling for those guests for faults
    as well as page-in and page-out by simply not caring about the guest
    visible storage key. We trap guest storage key instruction to enable
    those keys only on demand.
    
    Migration bitmap
    
    Until now s390 never provided a proper dirty bitmap.  Let's provide a
    proper migration bitmap for s390. We also change the user dirty tracking
    to a fault based mechanism. This makes the host completely independent
    from the storage keys. Long term this will allow us to back guest memory
    with large pages.
    
    per-VM device attributes
    ------------------------
    To avoid the introduction of new ioctls, let's provide the
    attribute semanantic also on the VM-"device".
    
    Userspace controlled CMMA
    -------------------------
    The CMMA assist is changed from "always on" to "on if requested" via
    per-VM device attributes. In addition a callback to reset all usage
    states is provided.
    
    Proper guest DAT handling for intercepts
    ----------------------------------------
    While instructions handled by SIE take care of all addressing aspects,
    KVM/s390 currently does not care about guest address translation of
    intercepts. This worked out fine, because
    - the s390 Linux kernel has a 1:1 mapping between kernel virtual<->real
     for all pages up to memory size
    - intercepts happen only for a small amount of cases
    - all of these intercepts happen to be in the kernel text for current
      distros
    
    Of course we need to be better for other intercepts, kernel modules etc.
    We provide the infrastructure and rework all in-kernel intercepts to work
    on logical addresses (paging etc) instead of real ones. The code has
    been running internally for several months now, so it is time for going
    public.
    
    GDB support
    -----------
    We provide breakpoints, single stepping and watchpoints.
    
    Fixes/Cleanups
    --------------
    - Improve program check delivery
    - Factor out the handling of transactional memory  on program checks
    - Use the existing define __LC_PGM_TDB
    - Several cleanups in the lowcore structure
    - Documentation
    
    NOTES
    -----
    - All patches touching base s390 are either ACKed or written by the s390
      maintainers
    - One base KVM patch "KVM: add kvm_is_error_gpa() helper"
    - One patch introduces the notion of VM device attributes
    Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
    
    Conflicts:
    	include/uapi/linux/kvm.h
    63b5cf04
kvm_host.h 29.9 KB