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diff --git a/Documentation/virt/kvm/devices/vm.rst b/Documentation/virt/kvm/devices/vm.rst new file mode 100644 index 0000000000..a4d39fa1b0 --- /dev/null +++ b/Documentation/virt/kvm/devices/vm.rst @@ -0,0 +1,402 @@ +.. SPDX-License-Identifier: GPL-2.0 + +==================== +Generic vm interface +==================== + +The virtual machine "device" also accepts the ioctls KVM_SET_DEVICE_ATTR, +KVM_GET_DEVICE_ATTR, and KVM_HAS_DEVICE_ATTR. The interface uses the same +struct kvm_device_attr as other devices, but targets VM-wide settings +and controls. + +The groups and attributes per virtual machine, if any, are architecture +specific. + +1. GROUP: KVM_S390_VM_MEM_CTRL +============================== + +:Architectures: s390 + +1.1. ATTRIBUTE: KVM_S390_VM_MEM_ENABLE_CMMA +------------------------------------------- + +:Parameters: none +:Returns: -EBUSY if a vcpu is already defined, otherwise 0 + +Enables Collaborative Memory Management Assist (CMMA) for the virtual machine. + +1.2. ATTRIBUTE: KVM_S390_VM_MEM_CLR_CMMA +---------------------------------------- + +:Parameters: none +:Returns: -EINVAL if CMMA was not enabled; + 0 otherwise + +Clear the CMMA status for all guest pages, so any pages the guest marked +as unused are again used any may not be reclaimed by the host. + +1.3. ATTRIBUTE KVM_S390_VM_MEM_LIMIT_SIZE +----------------------------------------- + +:Parameters: in attr->addr the address for the new limit of guest memory +:Returns: -EFAULT if the given address is not accessible; + -EINVAL if the virtual machine is of type UCONTROL; + -E2BIG if the given guest memory is to big for that machine; + -EBUSY if a vcpu is already defined; + -ENOMEM if not enough memory is available for a new shadow guest mapping; + 0 otherwise. + +Allows userspace to query the actual limit and set a new limit for +the maximum guest memory size. The limit will be rounded up to +2048 MB, 4096 GB, 8192 TB respectively, as this limit is governed by +the number of page table levels. In the case that there is no limit we will set +the limit to KVM_S390_NO_MEM_LIMIT (U64_MAX). + +2. GROUP: KVM_S390_VM_CPU_MODEL +=============================== + +:Architectures: s390 + +2.1. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE (r/o) +--------------------------------------------- + +Allows user space to retrieve machine and kvm specific cpu related information:: + + struct kvm_s390_vm_cpu_machine { + __u64 cpuid; # CPUID of host + __u32 ibc; # IBC level range offered by host + __u8 pad[4]; + __u64 fac_mask[256]; # set of cpu facilities enabled by KVM + __u64 fac_list[256]; # set of cpu facilities offered by host + } + +:Parameters: address of buffer to store the machine related cpu data + of type struct kvm_s390_vm_cpu_machine* +:Returns: -EFAULT if the given address is not accessible from kernel space; + -ENOMEM if not enough memory is available to process the ioctl; + 0 in case of success. + +2.2. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR (r/w) +=============================================== + +Allows user space to retrieve or request to change cpu related information for a vcpu:: + + struct kvm_s390_vm_cpu_processor { + __u64 cpuid; # CPUID currently (to be) used by this vcpu + __u16 ibc; # IBC level currently (to be) used by this vcpu + __u8 pad[6]; + __u64 fac_list[256]; # set of cpu facilities currently (to be) used + # by this vcpu + } + +KVM does not enforce or limit the cpu model data in any form. Take the information +retrieved by means of KVM_S390_VM_CPU_MACHINE as hint for reasonable configuration +setups. Instruction interceptions triggered by additionally set facility bits that +are not handled by KVM need to by implemented in the VM driver code. + +:Parameters: address of buffer to store/set the processor related cpu + data of type struct kvm_s390_vm_cpu_processor*. +:Returns: -EBUSY in case 1 or more vcpus are already activated (only in write case); + -EFAULT if the given address is not accessible from kernel space; + -ENOMEM if not enough memory is available to process the ioctl; + 0 in case of success. + +.. _KVM_S390_VM_CPU_MACHINE_FEAT: + +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 :ref:`KVM_S390_VM_CPU_MACHINE_FEAT` 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. + +.. _KVM_S390_VM_CPU_MACHINE_SUBFUNC: + +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 kma[16]; # valid with Message-Security-Assist-Extension 8 + u8 kdsa[16]; # valid with Message-Security-Assist-Extension 9 + u8 reserved[1792]; # 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 :ref:`KVM_S390_VM_CPU_MACHINE_SUBFUNC` 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. + +3. GROUP: KVM_S390_VM_TOD +========================= + +:Architectures: s390 + +3.1. ATTRIBUTE: KVM_S390_VM_TOD_HIGH +------------------------------------ + +Allows user space to set/get the TOD clock extension (u8) (superseded by +KVM_S390_VM_TOD_EXT). + +:Parameters: address of a buffer in user space to store the data (u8) to +:Returns: -EFAULT if the given address is not accessible from kernel space; + -EINVAL if setting the TOD clock extension to != 0 is not supported + -EOPNOTSUPP for a PV guest (TOD managed by the ultravisor) + +3.2. ATTRIBUTE: KVM_S390_VM_TOD_LOW +----------------------------------- + +Allows user space to set/get bits 0-63 of the TOD clock register as defined in +the POP (u64). + +:Parameters: address of a buffer in user space to store the data (u64) to +:Returns: -EFAULT if the given address is not accessible from kernel space + -EOPNOTSUPP for a PV guest (TOD managed by the ultravisor) + +3.3. ATTRIBUTE: KVM_S390_VM_TOD_EXT +----------------------------------- + +Allows user space to set/get bits 0-63 of the TOD clock register as defined in +the POP (u64). If the guest CPU model supports the TOD clock extension (u8), it +also allows user space to get/set it. If the guest CPU model does not support +it, it is stored as 0 and not allowed to be set to a value != 0. + +:Parameters: address of a buffer in user space to store the data + (kvm_s390_vm_tod_clock) to +:Returns: -EFAULT if the given address is not accessible from kernel space; + -EINVAL if setting the TOD clock extension to != 0 is not supported + -EOPNOTSUPP for a PV guest (TOD managed by the ultravisor) + +4. GROUP: KVM_S390_VM_CRYPTO +============================ + +:Architectures: s390 + +4.1. ATTRIBUTE: KVM_S390_VM_CRYPTO_ENABLE_AES_KW (w/o) +------------------------------------------------------ + +Allows user space to enable aes key wrapping, including generating a new +wrapping key. + +:Parameters: none +:Returns: 0 + +4.2. ATTRIBUTE: KVM_S390_VM_CRYPTO_ENABLE_DEA_KW (w/o) +------------------------------------------------------ + +Allows user space to enable dea key wrapping, including generating a new +wrapping key. + +:Parameters: none +:Returns: 0 + +4.3. ATTRIBUTE: KVM_S390_VM_CRYPTO_DISABLE_AES_KW (w/o) +------------------------------------------------------- + +Allows user space to disable aes key wrapping, clearing the wrapping key. + +:Parameters: none +:Returns: 0 + +4.4. ATTRIBUTE: KVM_S390_VM_CRYPTO_DISABLE_DEA_KW (w/o) +------------------------------------------------------- + +Allows user space to disable dea key wrapping, clearing the wrapping key. + +:Parameters: none +:Returns: 0 + +5. GROUP: KVM_S390_VM_MIGRATION +=============================== + +:Architectures: s390 + +5.1. ATTRIBUTE: KVM_S390_VM_MIGRATION_STOP (w/o) +------------------------------------------------ + +Allows userspace to stop migration mode, needed for PGSTE migration. +Setting this attribute when migration mode is not active will have no +effects. + +:Parameters: none +:Returns: 0 + +5.2. ATTRIBUTE: KVM_S390_VM_MIGRATION_START (w/o) +------------------------------------------------- + +Allows userspace to start migration mode, needed for PGSTE migration. +Setting this attribute when migration mode is already active will have +no effects. + +Dirty tracking must be enabled on all memslots, else -EINVAL is returned. When +dirty tracking is disabled on any memslot, migration mode is automatically +stopped. + +:Parameters: none +:Returns: -ENOMEM if there is not enough free memory to start migration mode; + -EINVAL if the state of the VM is invalid (e.g. no memory defined); + 0 in case of success. + +5.3. ATTRIBUTE: KVM_S390_VM_MIGRATION_STATUS (r/o) +-------------------------------------------------- + +Allows userspace to query the status of migration mode. + +:Parameters: address of a buffer in user space to store the data (u64) to; + the data itself is either 0 if migration mode is disabled or 1 + if it is enabled +:Returns: -EFAULT if the given address is not accessible from kernel space; + 0 in case of success. + +6. GROUP: KVM_ARM_VM_SMCCC_CTRL +=============================== + +:Architectures: arm64 + +6.1. ATTRIBUTE: KVM_ARM_VM_SMCCC_FILTER (w/o) +--------------------------------------------- + +:Parameters: Pointer to a ``struct kvm_smccc_filter`` + +:Returns: + + ====== =========================================== + EEXIST Range intersects with a previously inserted + or reserved range + EBUSY A vCPU in the VM has already run + EINVAL Invalid filter configuration + ENOMEM Failed to allocate memory for the in-kernel + representation of the SMCCC filter + ====== =========================================== + +Requests the installation of an SMCCC call filter described as follows:: + + enum kvm_smccc_filter_action { + KVM_SMCCC_FILTER_HANDLE = 0, + KVM_SMCCC_FILTER_DENY, + KVM_SMCCC_FILTER_FWD_TO_USER, + }; + + struct kvm_smccc_filter { + __u32 base; + __u32 nr_functions; + __u8 action; + __u8 pad[15]; + }; + +The filter is defined as a set of non-overlapping ranges. Each +range defines an action to be applied to SMCCC calls within the range. +Userspace can insert multiple ranges into the filter by using +successive calls to this attribute. + +The default configuration of KVM is such that all implemented SMCCC +calls are allowed. Thus, the SMCCC filter can be defined sparsely +by userspace, only describing ranges that modify the default behavior. + +The range expressed by ``struct kvm_smccc_filter`` is +[``base``, ``base + nr_functions``). The range is not allowed to wrap, +i.e. userspace cannot rely on ``base + nr_functions`` overflowing. + +The SMCCC filter applies to both SMC and HVC calls initiated by the +guest. The SMCCC filter gates the in-kernel emulation of SMCCC calls +and as such takes effect before other interfaces that interact with +SMCCC calls (e.g. hypercall bitmap registers). + +Actions: + + - ``KVM_SMCCC_FILTER_HANDLE``: Allows the guest SMCCC call to be + handled in-kernel. It is strongly recommended that userspace *not* + explicitly describe the allowed SMCCC call ranges. + + - ``KVM_SMCCC_FILTER_DENY``: Rejects the guest SMCCC call in-kernel + and returns to the guest. + + - ``KVM_SMCCC_FILTER_FWD_TO_USER``: The guest SMCCC call is forwarded + to userspace with an exit reason of ``KVM_EXIT_HYPERCALL``. + +The ``pad`` field is reserved for future use and must be zero. KVM may +return ``-EINVAL`` if the field is nonzero. + +KVM reserves the 'Arm Architecture Calls' range of function IDs and +will reject attempts to define a filter for any portion of these ranges: + + =========== =============== + Start End (inclusive) + =========== =============== + 0x8000_0000 0x8000_FFFF + 0xC000_0000 0xC000_FFFF + =========== =============== |