1Generic vm interface
2====================================
3
4The virtual machine "device" also accepts the ioctls KVM_SET_DEVICE_ATTR,
5KVM_GET_DEVICE_ATTR, and KVM_HAS_DEVICE_ATTR. The interface uses the same
6struct kvm_device_attr as other devices, but targets VM-wide settings
7and controls.
8
9The groups and attributes per virtual machine, if any, are architecture
10specific.
11
121. GROUP: KVM_S390_VM_MEM_CTRL
13Architectures: s390
14
151.1. ATTRIBUTE: KVM_S390_VM_MEM_ENABLE_CMMA
16Parameters: none
17Returns: -EBUSY if a vcpu is already defined, otherwise 0
18
19Enables Collaborative Memory Management Assist (CMMA) for the virtual machine.
20
211.2. ATTRIBUTE: KVM_S390_VM_MEM_CLR_CMMA
22Parameters: none
23Returns: 0
24
25Clear the CMMA status for all guest pages, so any pages the guest marked
26as unused are again used any may not be reclaimed by the host.
27
281.3. ATTRIBUTE KVM_S390_VM_MEM_LIMIT_SIZE
29Parameters: in attr->addr the address for the new limit of guest memory
30Returns: -EFAULT if the given address is not accessible
31         -EINVAL if the virtual machine is of type UCONTROL
32         -E2BIG if the given guest memory is to big for that machine
33         -EBUSY if a vcpu is already defined
34         -ENOMEM if not enough memory is available for a new shadow guest mapping
35          0 otherwise
36
37Allows userspace to query the actual limit and set a new limit for
38the maximum guest memory size. The limit will be rounded up to
392048 MB, 4096 GB, 8192 TB respectively, as this limit is governed by
40the number of page table levels.
41
422. GROUP: KVM_S390_VM_CPU_MODEL
43Architectures: s390
44
452.1. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE (r/o)
46
47Allows user space to retrieve machine and kvm specific cpu related information:
48
49struct kvm_s390_vm_cpu_machine {
50       __u64 cpuid;           # CPUID of host
51       __u32 ibc;             # IBC level range offered by host
52       __u8  pad[4];
53       __u64 fac_mask[256];   # set of cpu facilities enabled by KVM
54       __u64 fac_list[256];   # set of cpu facilities offered by host
55}
56
57Parameters: address of buffer to store the machine related cpu data
58            of type struct kvm_s390_vm_cpu_machine*
59Returns:    -EFAULT if the given address is not accessible from kernel space
60	    -ENOMEM if not enough memory is available to process the ioctl
61	    0 in case of success
62
632.2. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR (r/w)
64
65Allows user space to retrieve or request to change cpu related information for a vcpu:
66
67struct kvm_s390_vm_cpu_processor {
68       __u64 cpuid;           # CPUID currently (to be) used by this vcpu
69       __u16 ibc;             # IBC level currently (to be) used by this vcpu
70       __u8  pad[6];
71       __u64 fac_list[256];   # set of cpu facilities currently (to be) used
72                              # by this vcpu
73}
74
75KVM does not enforce or limit the cpu model data in any form. Take the information
76retrieved by means of KVM_S390_VM_CPU_MACHINE as hint for reasonable configuration
77setups. Instruction interceptions triggered by additionally set facilitiy bits that
78are not handled by KVM need to by imlemented in the VM driver code.
79
80Parameters: address of buffer to store/set the processor related cpu
81	    data of type struct kvm_s390_vm_cpu_processor*.
82Returns:    -EBUSY in case 1 or more vcpus are already activated (only in write case)
83	    -EFAULT if the given address is not accessible from kernel space
84	    -ENOMEM if not enough memory is available to process the ioctl
85	    0 in case of success
86