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

Cornelia Huck
2018-07-02T15:41:03Z

On Mon, 2 Jul 2018 11:37:11 -0400
Tony Krowiak <akrowiak@linux.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@de.ibm.com>
> >> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> >> Signed-off-by: Tony Krowiak <akrowiak@linux.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?