This patch will forward the yieldto hypercall (diag9c) if in the host the target CPU is also not running. As we do not yet have performance data (and recommendations) the default is turned off, but this can be changed during runtime. Pierre Morel (1): s390:kvm: diag9c forwarding Documentation/virt/kvm/s390-diag.rst | 33 ++++++++++++++++++++++++++++ arch/s390/include/asm/kvm_host.h | 1 + arch/s390/include/asm/smp.h | 1 + arch/s390/kernel/smp.c | 1 + arch/s390/kvm/diag.c | 31 +++++++++++++++++++++++--- arch/s390/kvm/kvm-s390.c | 6 +++++ arch/s390/kvm/kvm-s390.h | 8 +++++++ 7 files changed, 78 insertions(+), 3 deletions(-) -- 2.17.1 Changelog: >From v2: - update overrun comparison, avoid comparison on unsigned (Pierre) >From v1: - more precise comments (Connie) - Documentation (Janosch)