Implement counters for nested guest shadow events
JIRA: https://issues.redhat.com/browse/RHEL-11438
These patches add KVM performance counters for the shadow/unshadow events can help to diagnose performance issues. Tested by running a nested guest on a s390x host and checking that some of the counters in /sys/kernel/debug/kvm/gmap* increase during the runtime.
Signed-off-by: Thomas Huth thuth@redhat.com