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Re: [qemu-s390x] [Qemu-devel] [PATCH v3] s390x/cpumodel: Set up CPU mode
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From: |
Christian Borntraeger |
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Subject: |
Re: [qemu-s390x] [Qemu-devel] [PATCH v3] s390x/cpumodel: Set up CPU model for AQIC interception |
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Date: |
Fri, 15 Feb 2019 10:58:44 +0100 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 15.02.2019 10:53, Pierre Morel wrote:
> On 14/02/2019 13:14, Pierre Morel wrote:
>> A new CPU model facilities is introduced to support AP devices
>> interruption interception for a KVM guest.
>>
>> "APQI" for "AP-Queue Interruption" facility
>>
>> The S390_FEAT_AP_QUEUE_INTERRUPT_CONTROL, CPU facility indicates
>> whether the PQAP instruction with the AQIC command is available
>> to the guest.
>> This feature will be enabled only if the AP instructions are
>> available on the linux host and AQIC facility is installed on
>> the host.
>>
>> This feature must be turned on from userspace to intercept AP
>> instructions on the KVM guest. The QEMU command line to turn
>> this feature on looks something like this:
>>
>> qemu-system-s390x ... -cpu xxx,apqi=on ...
>
>
>
> Hi,
>
> I suddenly have a very big doubt on this QEMU patch.
>
> Older Linux advertise PQAP/AQIC feature (65)
Which Linuxes advertise PQAP/AQIC (stfle.65)?
This was never advertised by any previous Linux as far as I can tell.