Re: [kvm-unit-tests PATCH v1 2/2] s390x: add migration test for storage keys

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Fri, 13 May 2022 14:46:04 +0200
Janis Schoetterl-Glausch <scgl@linux.ibm.com> wrote:

> On 5/13/22 14:33, Claudio Imbrenda wrote:
> > On Fri, 13 May 2022 13:04:34 +0200
> > Janis Schoetterl-Glausch <scgl@linux.ibm.com> wrote:
> >   
> >> On 5/12/22 16:01, Nico Boehr wrote:  
> >>> Upon migration, we expect storage keys being set by the guest to be preserved,
> >>> so add a test for it.
> >>>
> >>> We keep 128 pages and set predictable storage keys. Then, we migrate and check
> >>> they can be read back and the respective access restrictions are in place when
> >>> the access key in the PSW doesn't match.
> >>>
> >>> TCG currently doesn't implement key-controlled protection, see
> >>> target/s390x/mmu_helper.c, function mmu_handle_skey(), hence add the relevant
> >>> tests as xfails.
> >>>
> >>> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> >>> ---
> >>>  s390x/Makefile         |  1 +
> >>>  s390x/migration-skey.c | 98 ++++++++++++++++++++++++++++++++++++++++++
> >>>  s390x/unittests.cfg    |  4 ++
> >>>  3 files changed, 103 insertions(+)
> >>>  create mode 100644 s390x/migration-skey.c
> >>>  

[...]

> Not at all with regards to skeys. But neither is checking the keys on access.
> And for kvm, both TPROT and checking is handled by SIE.

fair enough

> > 
> > to be fair, this test is only about checking that storage keys are
> > correctly migrated, maybe the check for actual protection is out of
> > scope
> >   
> 
> Having more tests does no harm and might uncover things nobody thought of,
> but I'd also be fine with keeping it short and sweet.
> [...]

I think this migration test should be kept more on focus about migration

we can always have a storage keys "torture test" separately