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Re: [Qemu-devel] [PATCH v3] s390x/cpumodel: Set up CPU model for AQIC in

From: Pierre Morel
Subject: Re: [Qemu-devel] [PATCH v3] s390x/cpumodel: Set up CPU model for AQIC interception
Date: Fri, 15 Feb 2019 12:00:00 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0

On 15/02/2019 10:58, Christian Borntraeger wrote:

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 ...


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.

OK, very sorry, you are right, I checked on a different machine and it is not.
I must have left something in my system.

Sorry for the panic.
I will look at what made me experience this.


Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany

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