Il 15/07/2014 15:27, Christian Borntraeger ha scritto: > Paolo, > > The following changes since commit 9f6226a762c7ae02f6a23a3d4fc552dafa57ea23: > > arch: x86: kvm: x86.c: Cleaning up variable is set more than once (2014-06-30 16:52:04 +0200) > > are available in the git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git tags/kvm-s390-20140715 > > for you to fetch changes up to 6352e4d2dd9a349024a41356148eced553e1dce4: > > KVM: s390: implement KVM_(S|G)ET_MP_STATE for user space state control (2014-07-10 14:11:17 +0200) > > ---------------------------------------------------------------- > This series enables the "KVM_(S|G)ET_MP_STATE" ioctls on s390 to make > the cpu state settable by user space. > > This is necessary to avoid races in s390 SIGP/reset handling which > happen because some SIGPs are handled in QEMU, while others are > handled in the kernel. Together with the busy conditions as return > value of SIGP races happen especially in areas like starting and > stopping of CPUs. (For example, there is a program 'cpuplugd', that > runs on several s390 distros which does automatic onlining and > offlining on cpus.) > > As soon as the MPSTATE interface is used, user space takes complete > control of the cpu states. Otherwise the kernel will use the old way. > > Therefore, the new kernel continues to work fine with old QEMUs. > > ---------------------------------------------------------------- > David Hildenbrand (5): > KVM: s390: allow only one SIGP STOP (AND STORE STATUS) at a time > KVM: s390: move finalization of SIGP STOP orders to kvm_s390_vcpu_stop > KVM: s390: remove __cpu_is_stopped and expose is_vcpu_stopped > KVM: prepare for KVM_(S|G)ET_MP_STATE on other architectures > KVM: s390: implement KVM_(S|G)ET_MP_STATE for user space state control > > Documentation/virtual/kvm/api.txt | 31 ++++++++++++++--------- > arch/s390/include/asm/kvm_host.h | 1 + > arch/s390/kvm/diag.c | 3 ++- > arch/s390/kvm/intercept.c | 32 ++++++++++-------------- > arch/s390/kvm/kvm-s390.c | 52 +++++++++++++++++++++++++++++++-------- > arch/s390/kvm/kvm-s390.h | 10 ++++++-- > arch/s390/kvm/sigp.c | 7 +++++- > include/uapi/linux/kvm.h | 7 +++++- > 8 files changed, 98 insertions(+), 45 deletions(-) > Alex, wdyt about this patch series? Does it make sense to use KVM_GET/SET_MP_STATE or should the one-reg interface be a better match? It's a bit weird that running and halted map to the same mp_state on s390. I would be more confident that KVM_GET/SET_MP_STATE is the right choice if it had at least the KVM_MP_STATE_RUNNABLE and KVM_MP_STATE_HALTED. Christian, where is the halted state stored, is it in the PSW? Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
