On 11/02/2017 01:08 PM, Christian Borntraeger wrote: > > > On 10/16/2017 11:25 AM, Martin Schwidefsky wrote: >> On Fri, 13 Oct 2017 13:39:04 -0400 >> Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx> wrote: >> >>> Sets up the following facilities bits to enable the specified AP >>> facilities for the guest VM: >>> * STFLE.12: Enables the AP Query Configuration Information >>> facility. The AP bus running in the guest uses >>> the information returned from this instruction >>> to configure AP adapters and domains for the >>> guest machine. >>> * STFLE.15: Indicates the AP facilities test is available. >>> The AP bus running in the guest uses the >>> information. >>> >>> Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx> >>> --- >>> arch/s390/tools/gen_facilities.c | 2 ++ >>> 1 files changed, 2 insertions(+), 0 deletions(-) >>> >>> diff --git a/arch/s390/tools/gen_facilities.c b/arch/s390/tools/gen_facilities.c >>> index 70dd8f1..eeaa7db 100644 >>> --- a/arch/s390/tools/gen_facilities.c >>> +++ b/arch/s390/tools/gen_facilities.c >>> @@ -74,8 +74,10 @@ struct facility_def { >>> 8, /* enhanced-DAT 1 */ >>> 9, /* sense-running-status */ >>> 10, /* conditional sske */ >>> + 12, /* AP query configuration */ >>> 13, /* ipte-range */ >>> 14, /* nonquiescing key-setting */ >>> + 15, /* AP special-command facility */ >>> 73, /* transactional execution */ >>> 75, /* access-exception-fetch/store indication */ >>> 76, /* msa extension 3 */ >> >> With this all KVM guests will always have the AP instructions available, no? >> In principles I like this approach, but it differs from the way z/VM does things, >> there the guest will get an exception if it tries to execute an AP instruction >> if there are no AP devices assigned to the guest. I wonder if there is a reason >> why z/VM does it the way it does. > > A good question. For LPAR it seems that you have AP instructions even if you have > no crypto cards. > I've tried to figure these things out last week but I've failed. Right at the beginning of AR-10334-03-POK we have this text: "An adjunct processor (AP) facility consists of the three AP instructions, and one to sixty-four APs.". This reads like if we have AP facility we have to have at least one AP. But when I've tried to get a better understanding how the presence/absence of the AP facility is indicated and what facility bits do we have in this context I got confused. Tony, could you please give us a detailed summary on this (best with references, and focusing on the (guest) program perspective)? Regards, Halil -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html