linux/virt
Marcelo Tosatti 63b5cf04f4 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
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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: Marcelo Tosatti <mtosatti@redhat.com>

Conflicts:
	include/uapi/linux/kvm.h
2014-04-22 10:51:06 -03:00
..
kvm Lazy storage key handling 2014-04-22 10:51:06 -03:00