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Re: [qemu-s390x] [PATCH v8 2/6] s390x/cpumodel: Set up CPU model for AP

From: Tony Krowiak
Subject: Re: [qemu-s390x] [PATCH v8 2/6] s390x/cpumodel: Set up CPU model for AP device support
Date: Mon, 17 Sep 2018 14:31:18 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0

On 09/17/2018 04:19 AM, David Hildenbrand wrote:
Am 12.09.18 um 22:08 schrieb Tony Krowiak:
A new CPU model feature and two new CPU model facilities are
introduced to support AP devices for a KVM guest.

CPU model features:

1. The KVM_S390_VM_CPU_FEAT_AP CPU model feature indicates that
    AP facilities are installed. This feature will be enabled by
    the kernel only if the AP facilities are installed on the linux
    host. This feature must be turned on from userspace to access
    AP devices from the KVM guest. The QEMU command line to turn
    this feature looks something like this:

        qemu-system-s390x ... -cpu xxx,ap=on

    This feature will be supported for zEC12 and newer CPU models.
    The feature will not be supported for older models due to
    testability issues.
I think we (me,  Halil and Pierre) agreed that this should not be a
CPU_FEAT but instead some AP_INTERPRETATION toggle, that can be turned
on/off dynamically. (CPU_FEAT cannot be changed after CPUs have been

Can you discuss that with Halil + Pierre?

I will do that.

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