On 3/14/22 3:44 PM, Matthew Rosato wrote:
Note: A few patches in this series are dependent on Baolu's IOMMU domain ops
split, which is currently in the next branch of linux-iommu. This series
applies on top:
https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git
Enable interpretive execution of zPCI instructions + adapter interruption
forwarding for s390x KVM vfio-pci. This is done by introducing a new IOMMU
domain for s390x (KVM-managed), indicating via vfio that this IOMMU domain
should be used instead of the default, with subsequent management of the
hardware assists being handled via a new KVM ioctl for zPCI management.
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 via the new IOMMU domain, whose map operations update the host
DMA table with pinned guest entries over the specified range.
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.
QEMU series:
https://lore.kernel.org/kvm/20220314194920.58888-1-mjros...@linux.ibm.com/
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