Documentation/virt/kvm/devices/vm.rst - linux - Git at Google

 .. 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
         =========== ===============
	.. 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
	=========== ===============