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Message-ID: <59746b70-de0e-35ba-98e7-b30aed2c959f@linux.ibm.com>
Date:   Tue, 24 May 2022 15:06:50 -0400
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Subject: Re: [PATCH v8 00/22] KVM: s390: enable zPCI for interpretive
 execution
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From:   Matthew Rosato <mjrosato@linux.ibm.com>
To:     linux-s390@vger.kernel.org
Cc:     alex.williamson@redhat.com, cohuck@redhat.com,
        schnelle@linux.ibm.com, farman@linux.ibm.com, pmorel@linux.ibm.com,
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        svens@linux.ibm.com, frankja@linux.ibm.com, david@redhat.com,
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        jgg@nvidia.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org
References: <20220524185907.140285-1-mjrosato@linux.ibm.com>
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On 5/24/22 2:58 PM, Matthew Rosato wrote:
> Note: this version of the series is built on top of vfio -next:
> https://github.com/awilliam/linux-vfio/tree/next
> As it now depends on 'vfio: remove VFIO_GROUP_NOTIFY_SET_KVM' and its
> prereqs.
> Additionally, if you care to try testing this series on top of vfio -next
> you'll also want to pick up this fix:
> https://lore.kernel.org/kvm/20220519182929.581898-1-mjrosato@linux.ibm.com/
> 
> ---
> 
> Enable interpretive execution of zPCI instructions + adapter interruption
> forwarding for s390x KVM vfio-pci.  This is done by triggering a routine
> when the VFIO group is associated with the KVM guest, transmitting to
> firmware a special token (GISA designation) to enable that specific guest
> for interpretive execution on that zPCI device.  Load/store interpreation
> enablement is then controlled by userspace (based upon whether or not a
> SHM bit is placed in the virtual function handle).  Adapter Event
> Notification interpretation is controlled from userspace via a new KVM
> ioctl.
> 
> By allowing intepretation of zPCI instructions and firmware delivery of
> interrupts to guests, we can reduce the frequency of guest SIE exits for
> zPCI.
> 
>  From the perspective of guest configuration, you passthrough zPCI devices
> in the same manner as before, with intepretation support being used by
> default if available in kernel+qemu.
> 
> Will follow up with a link an updated QEMU series.
> 

QEMU v6 series:
https://lore.kernel.org/kvm/20220524190305.140717-1-mjrosato@linux.ibm.com/