Re: [PATCH v8 00/22] KVM: s390: enable zPCI for interpretive execution

[Matthew Rosato]

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@xxxxxxxxxxxxx/
>
> ---
>
> 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@xxxxxxxxxxxxx/