On 19.12.2011, at 14:59, Avi Kivity wrote: > On 12/19/2011 03:54 PM, Alexander Graf wrote: >> On 04.12.2011, at 19:26, Raghavendra K T wrote: >> >>> Extend the KVM Hypervisor to enable KICK_VCPU feature that allows >>> a vcpu to kick the halted vcpu to continue with execution in PV ticket >>> spinlock. >>> >>> Signed-off-by: Srivatsa Vaddagiri <va...@linux.vnet.ibm.com> >>> Signed-off-by: Raghavendra K T <raghavendra...@linux.vnet.ibm.com> >>> --- >>> diff --git a/target-i386/kvm.c b/target-i386/kvm.c >>> index 5bfc21f..69bce21 100644 >>> --- a/target-i386/kvm.c >>> +++ b/target-i386/kvm.c >>> @@ -97,6 +97,7 @@ struct kvm_para_features { >>> { KVM_CAP_NOP_IO_DELAY, KVM_FEATURE_NOP_IO_DELAY }, >>> { KVM_CAP_PV_MMU, KVM_FEATURE_MMU_OP }, >>> { KVM_CAP_ASYNC_PF, KVM_FEATURE_ASYNC_PF }, >>> + { KVM_CAP_KICK_VCPU, KVM_FEATURE_KICK_VCPU }, >> >> So this is handled in the kernel? Who enables the feature? Is it always on? >> Why bother with it in user space at all then? > > Backwards compatibility
If we want backwards compatibility, we need more than just a simple feature check, no? Oh, you feed that into CPUID? That's nifty. Ok, so you behave like VMX/SVM do on real hardware - you always expose the functionality but don't list it in CPUID for older user space. Makes sense. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html