Re: [PATCH v2 00/30] KVM: s390: enable zPCI for interpretive execution

From: Matthew Rosato
Date: Fri Jan 14 2022 - 15:50:00 EST


On 1/14/22 3:31 PM, Matthew Rosato wrote:
Enable interpretive execution of zPCI instructions + adapter interruption
forwarding for s390x KVM vfio-pci. This is done by introducing a series
of new vfio-pci feature ioctls that are unique vfio-pci-zdev (s390x) and
are used to negotiate the various aspects of zPCI interpretation setup.
By allowing intepretation of zPCI instructions and firmware delivery of
interrupts to guests, we can significantly reduce the frequency of guest
SIE exits for zPCI. We then see additional gains by handling a hot-path
instruction that can still intercept to the hypervisor (RPCIT) directly
in kvm.

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 reply with a link to the associated QEMU series.

https://lore.kernel.org/qemu-devel/20220114203849.243657-1-mjrosato@xxxxxxxxxxxxx/