qemu-s390x
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [qemu-s390x] [RFC 19/19] s390/facilities: enable AP facilities neede


From: Christian Borntraeger
Subject: Re: [qemu-s390x] [RFC 19/19] s390/facilities: enable AP facilities needed by guest
Date: Thu, 2 Nov 2017 16:53:16 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0


On 11/02/2017 04:36 PM, Tony Krowiak wrote:
> On 11/02/2017 08:08 AM, Christian Borntraeger wrote:
>>
>> On 10/16/2017 11:25 AM, Martin Schwidefsky wrote:
>>> On Fri, 13 Oct 2017 13:39:04 -0400
>>> Tony Krowiak <address@hidden> 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 <address@hidden>
>>>> ---
>>>>  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 don't believe these facilities control whether or not AP instructions will 
> be available
> 
> to the guest.

This is actually handled by your patch2 enabling the ECA bit.
I think we must decide if we want to be able to disable these instructions
via the cpu model. If yes we must then couple the facilities with the 
enablement.




reply via email to

[Prev in Thread] Current Thread [Next in Thread]