linux-kernel - Re: [PATCH v6 05/21] KVM: s390: CPU model support for AP virtualization

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Date:   Mon, 2 Jul 2018 11:54:28 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     Cornelia Huck <cohuck@...hat.com>
Cc:     Christian Borntraeger <borntraeger@...ibm.com>,
        Tony Krowiak <akrowiak@...ux.vnet.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, kwankhede@...dia.com,
        bjsdjshi@...ux.vnet.ibm.com, pbonzini@...hat.com,
        alex.williamson@...hat.com, pmorel@...ux.vnet.ibm.com,
        alifm@...ux.vnet.ibm.com, mjrosato@...ux.vnet.ibm.com,
        jjherne@...ux.vnet.ibm.com, thuth@...hat.com,
        pasic@...ux.vnet.ibm.com, berrange@...hat.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com
Subject: Re: [PATCH v6 05/21] KVM: s390: CPU model support for AP
 virtualization

On 07/02/2018 11:41 AM, Cornelia Huck wrote:
> On Mon, 2 Jul 2018 11:37:11 -0400
> Tony Krowiak <akrowiak@...ux.ibm.com> wrote:
>
>> On 07/02/2018 10:38 AM, Christian Borntraeger wrote:
>>> On 06/29/2018 11:11 PM, Tony Krowiak wrote:
>>>> Introduces a new CPU model feature and two CPU model
>>>> facilities to support AP virtualization for KVM guests.
>>>>
>>>> CPU model feature:
>>>>
>>>> The KVM_S390_VM_CPU_FEAT_AP feature indicates that
>>>> AP instructions are available on the guest. This
>>>> feature will be enabled by the kernel only if the AP
>>>> instructions are installed on the linux host. This feature
>>>> must be specifically turned on for the KVM guest from
>>>> userspace to use the VFIO AP device driver for guest
>>>> access to AP devices.
>>>>
>>>> CPU model facilities:
>>>>
>>>> 1. AP Query Configuration Information (QCI) facility is installed.
>>>>
>>>>      This is indicated by setting facilities bit 12 for
>>>>      the guest. The kernel will not enable this facility
>>>>      for the guest if it is not set on the host. This facility
>>>>      must not be set by userspace if the KVM_S390_VM_CPU_FEAT_AP
>>>>      feature is not installed.
>>>>
>>>>      If this facility is not set for the KVM guest, then only
>>>>      APQNs with an APQI less than 16 will be available to the
>>>>      guest regardless of the guest's matrix configuration. This
>>>>      is a limitation of the AP bus running on the guest.
>>>>
>>>> 2. AP Facilities Test facility (APFT) is installed.
>>>>
>>>>      This is indicated by setting facilities bit 15 for
>>>>      the guest. The kernel will not enable this facility for
>>>>      the guest if it is not set on the host. This facility
>>>>      must not be set by userspace if the KVM_S390_VM_CPU_FEAT_AP
>>>>      feature is not installed.
>>>>
>>>>      If this facility is not set for the KVM guest, then no
>>>>      AP devices will be available to the guest regardless of
>>>>      the guest's matrix configuration. This is a limitation
>>>>      of the AP bus running under the guest.
>>>>
>>>> Reviewed-by: Christian Borntraeger <borntraeger@...ibm.com>
>>>> Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>
>>>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>>> I think it probably should be at the end of the series, other than that its good.
>> If I move this to the end of the series, the very next patch checks the
>>
>> KVM_S390_VM_CPU_FEAT_AP feature?
> Introduce it here, offer it only with the last patch?

I apologize, but I don't know what you mean by this. Are you suggesting 
this patch
should only include the #define for KVM_S390_VM_CPU_FEAT_AP?

>