It think I found various BUGs in the recently added Multiple-epoch facility support in KVM. Along with it, two cleanups. 1. The clock-comparator sign control is not considered. I sent a patch with this previously. This now contains fixes and simplifications. 2. SET CLOCK from the guest does not work reliably if the facility is enabled (epoch index not set). 3. Hotplugged CPUs don't inherit the epoch index. 4. TOD clock syncs don't take care of overflows/underflows in the epoch value and miss to update the epoch index. This is RFC as I have basically no machine to test. Hopefully somebody can jump in and verify that we now handle the epoch index in all scenarios correctly. Most importantly, with Multiple-epoch facility, the condition Guest TOD = Host TOD - 1 Is represented by both, epoch and epoch_idx containing 0xff. So it is treated as a 64+8bit signed number - we have to properly take care of over/underflows when modifying the epoch. David Hildenbrand (6): KVM: s390: take care of clock-comparator sign control KVM: s390: provide only a single function for setting the tod KVM: s390: consider epoch index on hotplugged CPUs KVM: s390: consider epoch index on TOD clock syncs KVM: s390: no need to inititalize kvm->arch members to 0 KVM: s390: generalize kvm_s390_get_tod_clock_ext() arch/s390/kvm/interrupt.c | 25 ++++++++--- arch/s390/kvm/kvm-s390.c | 109 +++++++++++++++++++++++----------------------- arch/s390/kvm/kvm-s390.h | 5 +-- arch/s390/kvm/priv.c | 9 ++-- 4 files changed, 80 insertions(+), 68 deletions(-) -- 2.14.3
