Re: [PATCH v9 00/21] KVM: s390: enable zPCI for interpretive execution

[Matthew Rosato <mjrosato@linux.ibm.com>]

On 6/6/22 4:33 PM, Matthew Rosato wrote:
> 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 the most recent QEMU series.
> 

Latest QEMU series:

https://lore.kernel.org/kvm/20220606203614.110928-1-mjrosato@linux.ibm.com/