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diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 5be5cc59869d..3c4551a2f6d0 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -8269,6 +8269,31 @@ The capability has no effect if the nx_huge_pages module parameter is not set. This capability may only be set before any vCPUs are created. +8.39 KVM_CAP_S390_CPU_TOPOLOGY +------------------------------ + +:Capability: KVM_CAP_S390_CPU_TOPOLOGY +:Architectures: s390 +:Type: vm + +This capability indicates that KVM will provide the S390 CPU Topology +facility which consist of the interpretation of the PTF instruction for +the function code 2 along with interception and forwarding of both the +PTF instruction with function codes 0 or 1 and the STSI(15,1,x) +instruction to the userland hypervisor. + +The stfle facility 11, CPU Topology facility, should not be indicated +to the guest without this capability. + +When this capability is present, KVM provides a new attribute group +on vm fd, KVM_S390_VM_CPU_TOPOLOGY. +This new attribute allows to get, set or clear the Modified Change +Topology Report (MTCR) bit of the SCA through the kvm_device_attr +structure. + +When getting the Modified Change Topology Report value, the attr->addr +must point to a byte where the value will be stored or retrieved from. + 9. Known KVM API problems ========================= |