+2.3. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE_FEAT (r/o)
+
+Allows user space to retrieve available cpu features. A feature is available if
+provided by the hardware and supported by kvm. In theory, cpu features could
+even be completely emulated by kvm.
+
+struct kvm_s390_vm_cpu_feat {
+ __u64 feat[16]; # Bitmap (1 = feature available), MSB 0 bit numbering
+};
+
+Parameters: address of a buffer to load the feature list from.
+Returns: -EFAULT if the given address is not accessible from kernel space.
+ 0 in case of success.
+
+2.4. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR_FEAT (r/w)
+
+Allows user space to retrieve or change enabled cpu features for all VCPUs of a
+VM. Features that are not available cannot be enabled.
+
+See 2.3. for a description of the parameter struct.
+
+Parameters: address of a buffer to store/load the feature list from.
+Returns: -EFAULT if the given address is not accessible from kernel space.
+ -EINVAL if a cpu feature that is not available is to be enabled.
+ -EBUSY if at least one VCPU has already been defined.
+ 0 in case of success.
+
+2.5. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE_SUBFUNC (r/o)
+
+Allows user space to retrieve available cpu subfunctions without any filtering
+done by a set IBC. These subfunctions are indicated to the guest VCPU via
+query or "test bit" subfunctions and used e.g. by cpacf functions, plo and ptff.
+
+A subfunction block is only valid if KVM_S390_VM_CPU_MACHINE contains the
+STFL(E) bit introducing the affected instruction. If the affected instruction
+indicates subfunctions via a "query subfunction", the response block is
+contained in the returned struct. If the affected instruction
+indicates subfunctions via a "test bit" mechanism, the subfunction codes are
+contained in the returned struct in MSB 0 bit numbering.
+
+struct kvm_s390_vm_cpu_subfunc {
+ u8 plo[32]; # always valid (ESA/390 feature)
+ u8 ptff[16]; # valid with TOD-clock steering
+ u8 kmac[16]; # valid with Message-Security-Assist
+ u8 kmc[16]; # valid with Message-Security-Assist
+ u8 km[16]; # valid with Message-Security-Assist
+ u8 kimd[16]; # valid with Message-Security-Assist
+ u8 klmd[16]; # valid with Message-Security-Assist
+ u8 pckmo[16]; # valid with Message-Security-Assist-Extension 3
+ u8 kmctr[16]; # valid with Message-Security-Assist-Extension 4
+ u8 kmf[16]; # valid with Message-Security-Assist-Extension 4
+ u8 kmo[16]; # valid with Message-Security-Assist-Extension 4
+ u8 pcc[16]; # valid with Message-Security-Assist-Extension 4
+ u8 ppno[16]; # valid with Message-Security-Assist-Extension 5
+ u8 reserved[1824]; # reserved for future instructions
+};
+
+Parameters: address of a buffer to load the subfunction blocks from.
+Returns: -EFAULT if the given address is not accessible from kernel space.
+ 0 in case of success.
+
+2.6. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR_SUBFUNC (r/w)
+
+Allows user space to retrieve or change cpu subfunctions to be indicated for
+all VCPUs of a VM. This attribute will only be available if kernel and
+hardware support are in place.
+
+The kernel uses the configured subfunction blocks for indication to
+the guest. A subfunction block will only be used if the associated STFL(E) bit
+has not been disabled by user space (so the instruction to be queried is
+actually available for the guest).
+
+As long as no data has been written, a read will fail. The IBC will be used
+to determine available subfunctions in this case, this will guarantee backward
+compatibility.
+
+See 2.5. for a description of the parameter struct.
+
+Parameters: address of a buffer to store/load the subfunction blocks from.
+Returns: -EFAULT if the given address is not accessible from kernel space.
+ -EINVAL when reading, if there was no write yet.
+ -EBUSY if at least one VCPU has already been defined.
+ 0 in case of success.
+
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