linux-kernel - Re: [PATCH v9 21/22] KVM: s390: CPU model support for AP virtualization

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Message-ID: <20180820162653.28e680f3.cohuck@redhat.com>
Date:   Mon, 20 Aug 2018 16:26:53 +0200
From:   Cornelia Huck <cohuck@...hat.com>
To:     Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, borntraeger@...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,
        frankja@...ux.ibm.com, Tony Krowiak <akrowiak@...ux.ibm.com>
Subject: Re: [PATCH v9 21/22] KVM: s390: CPU model support for AP
 virtualization

On Mon, 13 Aug 2018 17:48:18 -0400
Tony Krowiak <akrowiak@...ux.vnet.ibm.com> wrote:

> From: Tony Krowiak <akrowiak@...ux.ibm.com>
> 
> 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.
> 
>    If this facility is not set for the KVM guest, then only
>    APQNs with an APQI less than 16 will be used by a Linux
>    guest regardless of the matrix configuration for the virtual
>    machine. This is a limitation of the Linux AP bus.
> 
> 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.
> 
>    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 for the virtual
>    machine. This is a limitation of the Linux AP bus.
> 
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
> Reviewed-by: Christian Borntraeger <borntraeger@...ibm.com>
> Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>
> Tested-by: Michael Mueller <mimu@...ux.ibm.com>
> Tested-by: Farhan Ali <alifm@...ux.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@...ibm.com>
> ---
>  arch/s390/kvm/kvm-s390.c         |    5 +++++
>  arch/s390/tools/gen_facilities.c |    2 ++
>  2 files changed, 7 insertions(+), 0 deletions(-)

Looks sane to me.